ALBERT

Notes: In 1987, the Scottish Office commissioned vertical aerial photography for the whole of Scotland at 1:24 000 scale. The paper describes the need for this national coverage, the physical and economic constraints and the acquisition of the photographs. The principal use of the photography, as a database for measuring land cover change in Scotland, is summarised and numerous other projects are also described. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Le Bureau des Affaires Écossaises a commandé en 1987 une couverture photographique aérienne verticale au 1:24000 sur ľensemble de ľÉcosse. On présente dans cet article les besoins qui ont motivé cette couverture, les contraintes économiques el physiques correspondantes et le déroulement de sa saisie. On donne un aperçu de la principale utilisation de ces photographies, destiniées à constituter une base de données pour la détermination des modifications intervenues en Écosse dans ľoccupation du sol; de nombreux autres projets sont également mentionées. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Im Jahre 1987 gab das Scottish Office Auftrag zur Luftbildaufnahme im Maβstab 1:24000 von ganz Schottland. Im Artikel werden die Notwendigkeit für diese vollständige nationale Bedeckung, für die physikalischen und ökonomischen Zwangsbedingungen und für die Beschaffung der Fotos beschrieben. Die prinzipielle Nutzung der Fotografie als Datenbasis zur Bestimmung der Landnutzungsänderung in Schottland wird hervorgehoben und zahlreiche andere Projekte werden ebenso beschrieben.

Notes: Maintaining the quality of aerial photographic products with time requires a simultaneous retention of both image and dimensional characteristics. These factors are prerequisites for maintaining aesthetic value and ensuring no distortion of information occurs. It is, however, the recent experience of archivists that many negatives and prints are suffering irreversible deterioration. Degradation is typified by image fading, the presence of surface crystalline deposits which obscure any image and significant dimensional distortion. This paper relates those factors which influence stability, principally temperature, relative humidity and oxygen, and correlates them to structural changes in the materials. In addition an overview is given of methods of monitoring and of inhibiting breakdown. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Pour maintenir la qualité des produits photographiques aériens dans le temps, il faut satisfaire auxproblèmes de conservation à la fois de ľimage et de ses qualités dimensionnelles. Ce sont des préalables nécessaires au maintien de la qualité esthétique du document et àľabsence de distorsion dans ses données. C'est que ľexpérience récente des archivistes a montré que nombre de négatifs et de tirages subissaient actuellement des détériorations irréversibles. Ces détériorations sont caractérisees par ľaffaiblissement de ľimage, ľapparition de dépôts cristallins en surface qui obscurcissent ľimage et ľexistence de variations dimensionelles importantes. On examine dans cet article les facteurs qui pertubent cette conservation, essentiellement la température, ľhumidité relative et ľoxydation et on les corrèle avec les changements structured des matériaux. On donne de plus un aperçu des méthodes permettant de suivre et de freiner ces altérations. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Das Gewährleisten der Qualität von Luftbilderzeugnissen in Abhängigkeit der Zeit erfordert die gleichzeitige Bewahrung sowohl der Bild- als auch der Dimensionscharakteristika. Diese Faktoren sind die Voraussetzungen zur Erhaltung des ästhetischen Wertes und gewährleisten, daβ keine Verzerrung der Informationen auftritt. Es ist jedoch neuste Erfahrung von Archivaren, daβ viele Negative und Kopien irreversible Wertminderungen erleiden. Das wird sichtbar durch das Verblassen von Bildern, das Auftreten von kristallinen Ablagerungen aufder Oberfläche, die Bilddetails verdecken und durch signifikante Dimensionsänderungen. Der Betrag bezieht sich auf solche Faktoren, die die Stabilitat beeinflussen, vor allem Temperatur, relative Luftfeuchte und Sauerstoff und korreliert diese mit strukturellen Veranderungen des Materials. Zusätzlich wird ein Überblick über Verfahren zur Materialbeobachtung und der Verminderung von dessen Verderb gegeben.

Notes: During both the First and Second World Wars, much effort was put into obtaining and interpreting aerial photographs for military reconnaissance purposes. Initially this material was classified; however, with the passing of time, much has now been declassified and is accessible to the general public. There is a large variety of information which can be of use to a number of disciplines. This material includes photographic prints, interpretation manuals, interpretation reports, plans of targets, and technical details of cameras, lenses and mountings. The use of this material will be demonstrated with examples from the United Kingdom, France and Italy, primarily for civil engineering site studies. The varied sources of this material will be discussed. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Au cours de la première et de la seconde Guerre Mondiale, on a déployé beaucoup ď efforts dans le receuil et ľ interprétation de photographies aériennes à des fins de reconnaissance militaire. Au début on classifia ces documents; mais maintenant, le temps ètant écoulé, on en a déclassifié une grande partie pour la rendre accessible au grand public. On peut ainsi y trouver toutes sortes ď informations qui peuvent être utiles à de nombreuses disciplines. Ces documents comprennent des tirages photographiques, des manuels ď interprétation, des rapports ď interprétation, des plans ď objectifs (militaires), et des détails techniques sur les chambres photographiques, leurs objectifs et leurs montures. Ľ intérêt du recours à ces documents est illustré par des examples provenant du Royaume-Uni, de France et ďItalie, essentiellement dans le domaine du génie civil pour des études de sites. On examine également les diverses origines de ces documents. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Während des 1. und 2. Weltkrieges wurde vielAufwand zur Gewinnung und Interpretation von Luftbildern für militärische Erkundungszwecke geleistet. Anfänglich wurde dieses Material unter Verschluβ gehalten, im Laufe der Zeitjedoch wurde vielesfreigegeben und ist nun der Öffentlichkeit zugänglich. Es gibt eine Vielzahl von Informationen, die für eine Anzahl von Disziplinen von Nutzen sein kann. Das Material umfaβt Fotokopien, Interpretationsmanuale, Interpretationsberichte, Pläne von Zielen und technische Details über Kameras, Objektive und Aufhängungen. Die Nutzung dieses Materials wirdan Hand von Beispielen aus dem Vereinigten Königreich, aus Frankreich und aus Italien gezeigt, und zwar vor allem für Analysen von Baustellen. Die vielfältigen Quellen für dieses Material werden diskutiert.

Notes: Low cost analytical plotters for use with 35 mm and 70 mm metric and non-metric photography are increasingly being considered as a means of introducing photogrammetry to non-photogrammetrists. One of these instruments, an Adam Technology MPS-2, recently formed the basis for a research project into the feasibility of such non-specialist use. During the project, an MPS-2 users' group was formed and many of the current users were asked to complete a questionnaire detailing their experiences with the instrument. Almost 40 users responded and their replies are given in this paper, which begins by outlining the project and goes on to discuss the comments received. The paper ends with an appraisal of the MPS-2 as seen through the eyes of its users and concludes that, considering its relatively low cost, it is definitely worthy of consideration by non-specialists. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On considère actuellement de plus en plus que les appareils de réstitution analytiques bon marché, permettant ľemploi des photographies 35 mm et 70 mm, métriques et non-métriques, constituent un bon moyen ďinitiation des non-photogrammètres à la photogrammétrie. Ľun de ces instruments, le MPS-2 de la Société Adam Technology, a servi de base à une action de recherche sur lafaisabilitéďun tel emploi par des non-spécialistes. On a formé, dans le cadre de cette action de recherche, un groupe ďutilisateurs du MPS-2, à la plupart desquels on a adressé un questionnaire leur demandant de détailler leur expérience de cet appareil. On a reçu près de 40 réponses ďutilisateurs et ľon reproduit ces réponses dans cet article. Après avoir esquisé les grandes lignes de cette action de recherche, on commente les réponses reçues. On termine sur une appréciation du MPS-2 vu par les utilisateurs et on en conclut que, étant donné son coût relativement faible, cet appareil mérite absolument ďêtre pris en compte par les non-spécialistes. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Preiswerte analytische Auswertegeräte für die Auswertung von 35 mm-und 70 mm-Fotos, die mit Meβkammern und Nichtmeβkammern aufge-nommen wurden, werden zunehmend als Mittel zur Einführung der Phologrammetrie bei Nichtphotogrammetem angesehen. Eines dieser Geräte, ein MPS-2 von Adam Technology, bildete kürzlich die Grundlage für ein Forschungsprojekt zum Nutzen solcher Anwendungen für Nicht-spezialisten. Während des Projektes wurde eine MPS-2-Nutzergruppe gebildet und viele der gegenwärtigen Nutzer wurden gebeten, einen Fragebogen zu vervollständigen und ihre Erfahrungen mit dem Gerät mitzuteilen. Zunächst wird das Projekt skizziert, und dann werden die erhaltenen Kommentare diskutiert. Der Artikel schlieβt mit einer Bewertung des MPS-2, wie er mit den Augen seiner Nutzer gesehen wird und schluβfolgert, daβ er unter Beachtung seiner relativ geringen Kosten deutlich die Aufmerksamkeit der Nichtspezialisten verdient.

Notes: The evolution of quality assurance at the Ordnance Survey of Great Britain (OS) is described. Quality control methods have been adopted to cope with the change from graphical to digital products and processes, but the human inspector remains indispensable. Following an agreement that the OS will archive large volumes of digital data captured by public utility contractors, quality assurance procedures for the acceptance of batches of digital maps have been based on an elaboration of standards BS 6001 (IS02859). A quality assurance certification scheme for land survey organisations based on BS 5750 (ISO9001) is under discussion. However, following recent government initiatives in quality management, the OS is now committed to the philosophy of total quality management and registration schemes for quality assurance could eventually become obsolete. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Cet article traite de ľévolution de ľassurance-qualitéàľOrdnance Survey (OS) de Grande-Bretagné. On a adopté a ľOS des méthodes de contrôle-qualité permettant de faire face aux changements résultant du passage de la forme graphique à la forme numérique pour les procédés el les produits, tout en conservant unepart ďintervention humaine indispensable dans les controles. Comme suite à une convention passée avec les services publics selon laquelle ľOS doit archiver ďimportantes quantités des donnees numiriques que ceux-ci auront receuillies, on se conformera à un système de normes BS 6001 (ISO 2859) pour les procédés ďassurance-qualité lors de la recette technique des lots de cartes numériques. La discussion porte actuellement sur un projet de certification ďassurance-qualité et de registre pour les organismes de levé foncier, en se basant sur la norme BS 5750 (ISO 9001). Toutefois, aprés les récentes initiatives gouvernementales en matière de gestion de la qualityé, ľOS se trouve maintenant confrontéà la philosophie ďune gestion de la qualityé-totale, ce qui pourrait finalement rendre périmés les projets ďassurance-qualité actuels. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Es wird die Entwicklung der Qualitätssicherung beim Ordnance Survey (OS) in Groβbritannien beschrieben. Dazu wurden Verfahren zur Qualitätskontrolle entwickelt, die dem Wechsel von graphischen zu digitalen Erzeugnissen und Prozessen genügen, aber der menschliche Faktor bleibt dabei unentbehrlich. Entsprechend einer Vereinbarung, wonach der OS groβe Mengen digitaler Daten archiviert, die durch öffentlich bestellte Vertragspartner erfaβt wurden, beruhen die Verfahren zur Qualitätssicherung für die Annahme von Datensätzen digitaler Karten auf der Ausarbeitung der Standards BS 6001 (ISO 2859). Diskutiert wird gegenwärtig ein auf dem Standard BS 5750 (ISO 9001) basierendes Nachweisschema zur Qualitätssicherung und ein Register für Organisationen, die sich mit Landvermessungen beschüftigen. Folgt man jedoch jüngsten Initiativen der Regierung in bezug auf die Behandlung der Qualität, so ist der OS der Philosophie zur totalen Qualitätsverwaltung und Registratur verpflichtet, denn die Qualitätsgewährleistung könnte möglicherweise unüblich werden.

Notes: Photogrammetric measurements within environmental test chambers which incorporate viewing ports constitute an application of multi-media photogrammetry. Perturbations to the incident bundles of rays due to refraction must therefore be taken into account. In this paper, refraction compensation for the case of antenna measurements within thermal vacuum chambers is discussed. Correction models applicable to the camera invariant refracting surfaces of a glass window and vacuum chamber are reviewed, especially error compensation using the approach of analytical selfcalibration. Results of a sequence of measurements of a satellite antenna are then analysed to illustrate the high measurement accuracies which are afforded by the selfcalibration approach. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les déterminations photogrammétriques dans un environnement de caissons ď essais munis de hublots de visée, constituent une application de la photogrammetrie à trovers des milieux multiples. II y a lieu par conséquent de tenir compte des perturbations que subissent lesfaisceaux de rayons lumineux incidents par suite de la réfraction. On examine dans cet article la compensation de la réfraction dans le cas de mesures sur des antennes placées dans des enceintes thermiques sous vide. On analyse les modèles de correction applicables aux surfaces réfractantes invariantes de la chambre photographique et de ľ enceinte à vide, comprenant des fenêtres en verre, en s'attachant plus particulièrement à une compensation ď erreurs basée sur des méthodes ď auto-étalonnage analytique. On présente ensuite les résultats ď une série de mesures portant sur une antenne de satellite, qui illustrent le haut degré de précision atteint par cette méthode ďauto-étalonnage. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Photogrammetrische Messungen innerhalb von Umwelt-Testkammern, die auch Öffnungen zum Durchblick enthalten, stellen eine Anwendung der Multimedien-Photogrammetrie dar. Demzufolge müssen Störungen wegen Refraktion bei den Aufnahmestrahlenbündeln berücksichtigt werden. Im vorliegenden Beitrag wird die Kompensation der Refraktion für Antennenmessungen in thermalen Vakuum-Kammern diskutiert. Korrekturmodelle, die auf die kamerainvarianten brechenden Oberflächen eines Fensterglases und die Vakuum-Kammer angewandt werden können, werden analysiert, besonders unter dem Gesichtspunkt, daß eine Fehlerkorrektur mittels Selbstkalibrierung erfolgt. Dann werden Ergebnisse einer Folge von Messungen an der Satellitenantenne analysiert, um die hohe Meßgenauigkeit darzustellen, die aus dem Ansatz zur Selbstkalibrierung resultiert.

Notes: This paper describes some experimental investigations into the variation of digital terrain model (DTM) accuracy with sampling interval, based on data acquired using stereophotogrammetric methods. The main factors affecting DTM accuracy are reviewed and various alternative schemes for carrying out experimental tests on DTM accuracy are outlined. Detailed information is given about the test areas, source data sets and check point data sets, followed by a discussion concerning the special design of this experiment. The experimental results are reported and, finally, a critical analysis of the test results is presented.〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On presente dans eel article quelques études expérimentales sur la variation de ľ exactitude ďun modèle numerique du terrain (MNT) en fonction de ľintervalle ďéchantillonnage de données obtenues à partir de méthodes stéréophotogrammétriques. On examine les facteurs principaux qui interviennent sur ľ exactitude ď un MNT et ľ on esquisse divers projets permettant de mener au choix des essais expérimentaux sur ľ exactitude ďun MNT. On fournit des informations détaillées sur les polygones ď essai utilisés, lesjeux de données concernant les points de vérification et ceux de l'altimétrie initiale, suivies ďune présentation de la conception particulière de ces études. On décrit les résultats expérimentaux obtenus et ľ on termine cet article par une analyse critique des résultats de ľ essai. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Im Artikel werden einige experimentelle Untersuchungen zur Variation der Genauigkeit von Digitalen Geländemodellen (DTM) beschrieben, wobei ein Rasterintervall verwendet wurde, das auf stereophotogrammetrischer Datenerfassung basierte. Es werden die Haupteinfluβfaktoren auf die Genauigkeit der DTM betrachtet und verschiedene alternative Wege zur Testung der DTM-Genauigkeit skizziert. Detaillierte Angaben erfolgen zu den Testgebieten, den Quelldaten-Sätzen und den Datensätzen der Kontrollpunkte mit anschlieβenden Ausführungen zur speziellen Gestaltung dieses Versuchs. Die Versuchsergebnisse werden angegeben, und abschlieβend erfolgt ihre kritische Analyse.

Notes: Hertfordshire County Council makes extensive use of aerial photography obtained from the ten yearly air survey of the entire county. This paper emphasises the value of the photography for specialist applications in the Planning and Estates Department, but also considers other uses. Details are given of photographic products and of a land use survey based on photo-interpretation. Finally, the future policy on the commissioning of aerial photography for Hertfordshire is considered, taking into account the potential of satellite imagery, the requirements of the existing GIS system for association with aerial photography and the possibility of additional revenue from more assertive marketing of photographic products. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Le Conseil du Comté de Hertfordshire se sert considérablement des photographies aériennes obtenues dans le cadre du levé aérien décennal de tout le comté. On souligne dans cet article ľintérét que trouvent, dans ces photographies, les spécialistes du Ministère de ľAménagement et ľon examine également ďautres utilisations. On fournit des détails sur les produits photographiques et sur un levéďusage du sol obtenu à partir ďune photo-interpretation. Enfin on examine la politique envisagée àľavenir pour ľexécution de la couverture aérienne de ľHertfordshire, qui prendre en compte les possibilityés de ľimagerie spatiale, les besoins ďintégration de la photographie aérienne dans les SIG actuels, et les revenus supplémentaires qui devraient provenir ďune démande commerciale plus soutenue sur les produits photographiques. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Der Hertfordshire County Council macht regen Gebrauch von Luft-bildern, die vor 10 Jarhen von der ganzen Grafschaft aufgenommen wurden. In dem Beitrag wird der Wert der Bilder für die Nutzung durch Spezialisten bei der Planning and Estates Department betont, aber est werden auch andere Anwendungen betrachtet. Es werden Details über fotografische Erzeugnisse und tiber eine auf der Photointerpretation basierende Land-nutzungserhebung angegeben. Schlieβlich wird die künftige Politik bei Aufträgen zur Luftbildaufnahme für Hertfordshire dargelegt, wobei das Potential von Satellitenbildern, die Anforderungen des bestehenden GISzur Verbindung mil Luftbildern und die Möglichkeit zusätzlicher Einnahmen dureh gröβere Vermarktung fotografischer Erzeugnisse in Betracht gezogen werden.

Notes: Woodland ecology necessarily involves a time dimension. It is seldom possible to understand the ecology of a wood without knowing its history. Although the history of many woods extends back far beyond the invention of photography, aerial photographs come at a period when the written record of woodland is often poor. They are also of great help in mapping woods as they are today. Some historic details can be learnt from recent photographs, others from historic aerial photographs. Photographs taken in the Second World War, such as those of England taken by the Germans and preserved in the United States, record an important and otherwise ill-documented period. This paper reviews the kinds of information that can be extracted from present and past aerial photographs and discusses the limitations of aerial survey and other forms of remote sensing as a means of measuring past and future changes. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Ľécologie sylvestre comprend la dimension du temps. Onne pent guère s'entendre àľéecologie ďun bois sans connaître son histoire. Bien que ľ histoire ďun grand nombre de bois s'étende longuement avant la découverte de la photographie, la photographie aérienne commence à une époque où il y à souvent des lacunes à la documentation écrite des bois. Elle est très utile, aussi, pour la cartographie des bois comme ils existent aujourd'hui. Des particulariés historiques s'apprennent ďaprès des photographies récentes, des autres ďaprès des photographies aériennes historiques. Parmi les photos les plus utiles sont celles de la IIe guerre mondiale, comme celles de la France prises par la Royal Air Force et conservées àľUniversité de Keele. Cette communication passe en revue les informations qu'on peut extraire des photographies aériennes du présent et du passé, et discute les bornes des levés aériens et spatiaux comme moyen de contrôler les changements du passé et du futur. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Die Waldökologie enthalt eine Zeitdimension. Selten ist es moglich, die Ökologie eines Waldes zu begreifen, ohne mit seiner Geschichte getraut zu sein. Obwohl die Geschichte mancher Wälder weit vor die Entdeckung der Photographie sich ausdehnt, die Luftphotographie kommt zu einer Zeit, wo schriftliche Urkunden der Wälder oft fehlen. Luftbilder sind auch sehr nutzvoll für die Kartographie von dem heutigen Zustandder Wälder. Einige historische Angaben werden von jungeren, andere von historischen Luftaufnahmen geschöpft. Unter den wertvollsten Luftbildern sind die von dem zweiten Weltkrieg, z. B. die britische Aufnahmen von Deutschland und Österreich, die jetzt in der Universität Keele aufbewahrt sind. Diese Abhandlung rezensiert die Auskünfte, die aus jüngere und historische Luftphotographie ausgeschöpft werden können, und diskutiert die Beschrankungen der Luft- und Weltraumvermessung als Zeugnis vergangener und zukünftiger Veranderungen.

Notes: In many photogrammetric applications, speed is often critical and high accuracy is only a secondary consideration. To use a metric camera in such situations would be quite uneconomical. Non-metric cameras are inexpensive to buy, use and maintain. A top quality 35mm amateur single lens reflex camera might cost £ 1000, an order of magnitude below that of a metric camera. In addition, they are robust, mobile and require a minimum of accessories. In short, they are ideal for rapid, medium to low accuracy work. However, in contrast with a metric camera, a non-metric camera lacks a stable inner orientation, fiducial reference system and standard method of calibration. This paper relates to a final year undergraduate project carried out at City University, London which dealt with such a calibration. The aim of the work was to determine (a) whether or not a 35mm SLR camera had a stable interior orientation and, if so, the best way of determining that orientation and (b) the accuracy of measurement that might be attained with such a camera. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Dans de nombreuses applications photogrammetriques la vitesse constitute souvent le paramètre critque, tandis que la haute précision ne vient seulement qu'en seconde position. Utiliser dans ces conditions une chambre métrique serait tout à fait anti-économique. Les chambres non métriques sont peu coûteuses àľ achat, en utilisation et pour leur entretien. Un appareil reflex, 35 mm, ď amateur, à lentille simple, de haute qualityé, peut coûter £1000, ce qui est inferieur ďun ordre de magnitude au coût ďune chambre métrique. De plus ces chambres non métriques sont robustes, faciles à transporter et n'ont besoin que d'un minimum ďaccessoires. En résumé elles sont idéales pour des travaux rapides et une précision de moyenne à faible. En revanche les chambres non métriques manquent de stabilityé dans leur orientation interne, sont dépourvues de systèmes de repères de fond de chambre et n‘ont pas de méthode ďétalonnage standard. Cet article, qui résulte ďun project effectuéà la City University de Londres par un étudiant, dans sa dernière année, trait ďun tel étalonnage. Son objectif est de déterminer (a) si un appareil 35 mm SLR a ou non une orientation intérieure stable, et si oui, quelle est la meilleure façon ď obtenir cette orientation et (b) la précision de mesure que ľ on peut atteindre avec un tel appareil. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Bei vielen photogrammetrischen Anwendungen ist die Geschwindigkeit oft kritisch, und hohe Genauigkeit ist erst von zweiter Bedeutung. In solchen Situationen eine Meβkammer zu benutzen, wäre sehr unökonomisch. Nichtmeβkammern sind bezüglich Anschaffung, Nutzung und Wartung billig. Eine Qualitäts-Spiegelreflexkamera mit 35 mm-Objektiv mag ca. £1000 kosten, was einen Bruchteil der Kosten für eine Meβkammer darstellt. Zusätzlich sind sie robust, mobil und erfordern ein Minimum an Zubehör. Kurzgefaβt, sie sind ideal für schnelle Arbeiten für mittlere und niedere Genauigkeit. Im Gegensatz zu Meβkammern fehlen bei Nichtmeβkammern jedoch eine stabile innere Orientierung, ein Rahmenmarken-Referenzsystem und ein Standardverfahren der Kalibrierung. Der Beitrag bezieht sich auf ein im Abschlufijahr an der City University in London durchgefuhrtes Projekt, das sich mit solch einer Kalibrierung beschäftigte. Zielstellung der Arbeit war es (a) zu bestimmen, ob eine 35 mm SLR-Kamera eine stabile innere Orientierung und (b) die mil solcher Kamera erhältliche Meβgenauigkeit herauszufinden.

Notes: Tests of Agfa-Gevaert A viphot Pan 200S air film were carried out by the authors, operationally and sensitometrically. Encouraging results are presented. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les auteurs ont effectué des essais sur lefilm aérien Aviphot Pan 2005 ďAgfa-Gevaert, de façon à la fois pratique et sensitométrique. lis présentent les résultats encourageants obtenus. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Von den Autoren wurden operationelle und sensitometrische Tests mil dem Luftbildfilm Aviphot Pan 2005 von Agfa Gevaert durchgeführt. Dazu werden ermutigende Ergebnisse dargestellt.

Notes: Book Reviewed in this article:GEODÄTISCHE ASTRONOMIE. By R. Sigl.PHYSICAL PRINCIPLES OF REMOTE SENSING. By W. G. Rees.EUROPEAN SPACE DIRECTORY 1991. Sixth Edition. Sponsored by Eurospace. Edited by D. Shirvanian.COMPUTER VISION AND IMAGE PROCESSING. Edited by A. Barrett.FRENCH-ENGLISH GLOSSARY ON SPOT, REMOTE SENSING AND THEIR APPLICATIONS. By S. T. Dyson.COLONEL SIR GEORGE EVEREST CB FRS: PROCEEDINGS OF BICENTENARY CONFERENCE AT THE ROYAL GEOGRAPHICAL SOCIETY, 8th NOVEMBER 1990. Edited by J. R. Smith.GEOGRAPHIC INFORMATION SYSTEMS: THE MICROCOMPUTER AND MODERN CARTOGRAPHY. Edited by D. R. F. Taylor.OUR SECRET LITTLE WAR. By L. N. Abrams.BRITAIN'S CHANGING ENVIRONMENT FROM THE AIR. Edited by T. Bayliss-Smith and S. Owens.THE SECOND BOOK OF BRITAIN'S RAILWAYS FROM THE AIR. Text by C. Leigh with photographs by Aerofilms Ltd.THE LAKE DISTRICT FROM THE AIR. Photographs by Aerofilms Ltd. Captions by S. Acland and E. Leeming.PLANETARY MAPPING. Edited by R. Greeley and R. M. Batson.ELECTROMAGNETIC DISTANCE MEASUREMENT. By C. D. Burnside.INTERPRETABILITY OF SPOT DATA FOR GENERAL MAPPING. By E. Ahokas, J. Jaakkola and P. Sotkas.GEOMETRISCHE GRUNDLAGEN DER LUFTBILDINTERPRETATION. By B. Pfeiffer and G. Weimann.LOOKING AT PHOTOGRAPHS: A GUIDE TO TECHNICAL TERMS. By G. Baldwin.AERIAL ARCHAEOLOGY, VOLUME 12. Edited by D. A. Edwards.GEOGRAPHIC INFORMATION 1991: THE YEARBOOK OF THE ASSOCIATION FOR GEOGRAPHIC INFORMATION. Edited by J. Cadoux-Hudson and D. I. Heywood.PHOTOGRAMMETRIE: ANWENDUNGEN IN WISSENSCHAFT UND TECHNIK. By K. Regensburger.

Notes: : Six applications of multiobjective decision making techniques for finding optimal or satisfying operating rules for reservoir systems are presented. The examples include situations with hydropower vs. water supply (for irrigation), flood control vs. low flow augmentation, selection of an operating rule, low-flow vs. reliability, and low flow and recreation vs. water quality. The techniques applied include the constraint method, compromise programming, goal programming, Tchebycheff approach (max-mm), Consensus, and ELECTRE I and II.

Notes: : Development of optimal operational policies for large-scale reservoir systems is often complicated by a multiplicity of conflicting project uses and purposes. A wide range of multiobjective optimization methods are available for appraising tradeoffs between conificting objectives. The purpose of this study is to provide guidance as to those methods which are best suited to dealing with the challenging large-scale, nonlinear, dynamic, and stochastic characteristics of multireservoir system operations. As a case study, the selected methodologies are applied to the Han River Reservoir System in Korea for four principal project objectives: water supply and low flow augmentation; annual hydropower production, reliable energy generation, and minimization of risk of violating firm water supply requirements. Additional objectives such as flood control are also considered, but are imposed as fixed constraints.

Notes: : Game-theoretic models are developed for describing and analyzing the inspection and enforcement process, especially as it relates to environmental laws and regulations in North America. Based on these models, systems using irrevocable control orders can be compared to those relying on court determination of guilt and punishment. The cost-effectiveness of environmental enforcement can be systematically assessed in terms of factors such as the private gains for violators, the costs of inspection, penalties, and the social value of deterring violations. The policy implications of the analysis, especially with reference to environmental protection, are emphasized.

Notes: : The operational problems of a reservoir are expressed by three coordinates: space, time stage, and objective. The operational procedure is formulated using dynamic programming as a multi-objective problem. After comparing the scalar and the vector optimization, the scalar optimization technique is applied to turbidity analysis in a reservoir.

Notes: The basis of the archival photogrammetric technique is reviewed briefly. Applications of the method in both research and commercial contracts are described and have resulted in further development of the method. 〈section xml:id="abs1-2"〉〈title type="main"〉RésuméOn analyse rapidement les bases des techniques d'archivage photogrammétrique. On présente des applications de cette méthode à la fois dans le domaine de la recherche et pour des contrats commerciaux; ces applications ont donné lieu à de nouveaux développements de la méthode.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungDie Grundlagen der photogrammetrisehen Archivierung werden kurz dargestellt. Anwendungen des Verfarhens, sowohl bei der Forschung als auch bei kommerziellen Verträgen werden beschrieben und beeinflussen die Weiterentwicklung der Methode.

Notes: Book Reviewed in this article:PROCEEDINGS: SPACE IMAGERY AND NEWS GATHERING FOR THE 1990s: SO WHAT? SYMPOSIUM ON FOREIGN POLICY AND REMOTE SENSING. Edited by R. A. MCDONALD.AN INTRODUCTION TO IMAGE PROCESSING. By A. Marion.DIGITALE BILDVERARBEITUNG: ANWENDUNG IN PHOTOGRAMMETRIE, KAR-TOGRAPHIE UND FERNERKUNDUNG. Second edition. Edited by H.-P. Bähr and T. Vögtle.INTRODUCTION TO REMOTE SENSING. By A. P. Cracknell and L. W. B. Hayes.DESIGN OF MISSION OPERATIONS SYSTEMS FOR SCIENTIFIC REMOTE SENSING. By S. D. Wall and K. W. Ledbetter.EARTH'S NATURE FROM SPACE–A STUDY OF THE NATURAL RESOURCES OF THE EARTH USING SATELLITE DATA. Edited by N. P. Kozlov.MARTIN HOTINE: DIFFERENTIAL GEODESY. Edited with commentaries by J. Zund.GRUNDLAGEN DER GEO-INFORMATIONSSYSTEME. BAND 1. HARDWARE, SOFTWARE UND DATEN. By R. Bill and D. Fritsch.REMOTE SENSING GEOLOGY. By R. P. Gupta.RAUMBEZOGENE INFORMATIONSSYSTEME. Second edition. By W. Göpfert.DIGITAL PHOTOGRAMMETRIC SYSTEMS. Edited by H. Ebner, D. Fritsch and C. Heipke.APPLICATIONS OF REMOTE SENSING IN ASIA AND OCEANIA–ENVIRONMENTAL CHANGE MONITORING. Edited by S. Murai.REMOTE SENSING OF FOREST RESOURCES: THEORY AND APPLICATION. By J. A. Howard.OBTENÇÃO E USO DE FOTOGRAFIAS AÉREAS DE PEQUENO FORMATO. By A. A. Disperati.EINKAUFSFÜHRER FÜR DAS VERMESSUNGSWESEN. Compiled by B. Harzer.ARCHAEOLOGICAL PROSPECTING AND REMOTE SENSING. By I. Scollar, A. Tabbagh, A. Hesse and I. Herzog.TEST ON ORTHOPHOTO AND STEREO-ORTHOPHOTO ACCURACY. By G. Ducher.MULTILINGUAL DICTIONARY OF REMOTE SENSING AND PHOTOGRAMMETRY: ENGLISH-FRENCH-BENGALI. English to Bengali translation by G. B. Das.AN ILLUSTRATED RECORD OF ORDNANCE SURVEY IN IRELAND.COORDINATE SYSTEMS AND MAP PROJECTIONS. Second edition. By D. H. Maling.PROCEEDINGS RESOURCE TECHNOLOGY 90: SECOND INTERNATIONAL SYMPOSIUM ON ADVANCED TECHNOLOGY IN NATURAL RESOURCES MANAGEMENT, NOVEMBER 12–15, 1990, WASHINGTON, D.C., USA. Edited by G. J. Buhyoff.

Notes: Two of the speakers at a one-day symposium, held on 31st October, 1990 and concerned with the adoption of new equipment and techniques, comment on the introduction of forward motion compensation in air survey cameras and on a specification for architectural photogrammetry.

Notes: Deux des conférenciers ďun symposium ďune journée, qui s'est tenu le 31 octobre 1990 et fut consacré aux problèmes du choix de nouvelles techniques et de nouveaux équipements, présentent des commentaires sur ľemploi de la compensation du filé longitudinal dans les chambres de prises de vues aériennes et sur la normalisation en photogrammétrie architecturale.〈section xml:id="abs1-2"〉〈title type="main"〉ZusammenfassungZwei der Redner aufeinem eintägigen Symposium, das am 31.10.90 zur Thematik der Einführung neuer Technik und Verfahren stattfand, beschäftigen sich mit der Einführung der Bildwanderungskompensation in Lufibildmeβkammern und einer Spezifikation für die Architekturphotogrammetrie.

Notes: Following a brief historical review of the background to this survey of the Tomb of Christ, Jerusalem, some details of the procedures adopted during the 1989 and 1990 site visits are described. Computations and photogrammetry following the 1989 site visit are summarised and illustrated. Some preliminary results of the 1990 control survey computations of quasi-sequential least squares estimates are given.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméAprès avoir fourni un bref aperçu historique des conditions dans lesquelles s'est effectué le relevé du Tombeau du Christ, à Jérusalem, les auteurs donnent quelques détails sur les procédés utilisés lors des visites sur le site en 1989 et en 1990. Un résumé accompagnéďillustrations décrit les travaux de calculs et de photogrammétrie qui ont suivi la visite du site en 1989. Quant à celle de 1990, on peut y trouver quelques résultats préliminaires des calculs sur le levé de contrôle, avec des évaluations issues des moindres carrés.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungNach einem kurzen historischen Überblick über die Vorgeschichte dieser Vermessung des Grabes von Christi in Jerusalem werden einige Einzelheiten der 1989 und 1990 während der Besuche vor Ort angewandten Verfahren beschrieben. Die im Anschluβ an die örtlichen Arbeiten im Jahre 1989 durchgeführten Berechnungen und photogrammetrischen Auswertungen werden zusammengefaβt und dargestellt. Schlieβlich werden einige vorläufige Ergebnisse der 1990 erfolgten Berechnungen zur Paβpunktbestimmung mittels quasi-sequentieller Schätzungen nach der Methode der kleinsten Quadrate mitgeteilt.

Notes: Aerial photogrammetry, chosen to overcome access problems during the survey for the London Jubilee Line Extension, needed to achieve 1:200 scale accuracies. This paper discusses the survey methods employed and the effects of using quality procedures in a commercial environment. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On a choisi, pour les levés ďextension de la ligne du Jubilée de Londres, la photogrammétrie aérienne parce qu‘elle permettait de surmonter les problémes ďacces. La précision requise correspondait àľéchelle du 1:200. On examine dans cet article les méthodes de levé utilisées et les répercussions de ľemploi de procédures-qualité dans un environnement commercial. 〈section xml:id="abs1-3"〉〈title type="main"〉.Zusammenfassung Die Aerophotogrammetrie, die aus Gründen der Zugänglichkeit während der Vermessung für die Erweiterung der Londoner Jubiläums-Linie als Vermessungsverfahren ausgewählt wurde, muβte eine Genauig-keit für den Kartenmaβstab 1:200 gewährleisten. Im Artikel werden die angewandten Meverfahren und die Einflüsse bei Nutzung von Qualitäts-kontrollen aus der Sicht einer kommerziellen Umgebung diskutiert.

Notes: The authors discuss systems for the three dimensional measurement of microscopic features, in particular the pits made by isolated bone resorbing cells (osteoclasts) in test substrates with flat surfaces; such measurements may be used to assay the work done by these cells. Confocal light microscopy, with its very shallow depth of field, seems to be replacing scanning electron microscopic stereophotogrammetry as the preferred method for such measurement. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les auteurs examinent les systèmes de mesures tri-dimensionelles ďobjets microscopiques tels que, en particulier, les cavités creusies dans des substrats expérimentaux, déposés sur des surfaces plates, par des cellules isolées résorbant les os (ostéoclastes). On peut recourir à de telles mesures pour évaluer le travail effectué par ces cellules. Il semble que dans ces mesures, on tende à remplacer la stéréophotogrammétrie au microscope électronique à balayage par la microscopie à lumière confocale qui possède une très faible profondeur de champ et emporte la préférence. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Die Autoren diskutieren Systeme zur dreidimensionalen Ausmessung von Mikroskopabbildungen, insbesondere der Vertiefungen, die durch isolierte, Knochen resorbierende Zellen (Osteoklaster) in Testsubstraten mit ebenen Oberflächen verursacht wurden. Solche Messungen konnen zur Prüfung der von diesen Zellen geleisteten Arbeit genutzt werden. Die Mikroskopie mit konfokalem Licht und einer sehr geringen Gesichtsfeldtiefe scheint die Stereophotogrammetrie mittels Rasterelektronen-mikroskop als der bevorzugten Methode für solche Messungen zu ersetzen.

Notes: Fully digital photogrammetric close range systems allow for on line or even real time processing of data. This gives access to a great number of new applications, especially in those cases where a moving object has to be dynamically recorded or a moving sensor has to be positioned and oriented in three dimensional space, as is the case in robotics. This article gives a brief survey of the problems and potential of these new systems and techniques. Aspects of fast data acquisition and processing are addressed and a concise description of the DIPS II digital station is provided. The accuracy of digital systems is reviewed and two significant new algorithmic developments are referenced. Finally, three characteristic projects demonstrate the potential and performance of digital close range photogrammetry. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les systèmes utilisés en photogrammétrie à courte distance permettent, lorsqu'ils sont entièrement numériques, un traitement en ligne des donnés, et même en temps réel. Cela ouvre la voie à un grand nombre ďapplications nouvelles, particulièrement lorsqu'il s'agit ďun objet mobile qu'il faut enregistrer dynamiquement ou ďun capteur mobile qu'il faut localiser et orienter dans un espace à trois dimensions, comme c'est lecas en robotique. On examine brièvement dans cet article les problèmes et les possibilityés de ces nouvelles techniques et de ces nouveaux systèmes. On aborde quelques aspects concernant la saisie et le traitement rapide des donnés et ľonfournit une brève description du poste numérique DIPS II. On analyse la précision des sytémes numériques et ľon mentionne deux nouveaux développements algorithmiques importants. Enfin on illustre les possibilityés de la photogrammétrie numérique à courte distance et les résultats atteints, en s'appuyant sur trois projets typiques. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Vollständig digitale Systeme in der Nahbereichsphotogrammetrie gestatten die On-line-oder sogar Echtzeitdatenverarbeitung. Das ermöglicht eine groβe Anzahl neuer Anwendungen, besonders in solchen Fällen, wo ein bewegtes Objekt dynamisch registriert oder ein bewegter Sensor im dreidimensionalen Raum positioniert und orientiert werden soil, z.B. im Falle von Robotern. Im Artikel wird eine kurze Übersicht über die Probleme und die Möglichkeiten dieser neuen Systeme und Verfahren gegeben. Aspekte der schnellen Datenerfassung und -verarbeitung werden angesprochen, und es erfolgt eine knappe Beschreibung der digitalen Arbeitsstation DIPS II. Die Genauigkeit digitaler Systeme wird analysiert und zwei signifikant neue algorithmische Entwicklungen werden zitiert. Abschlieβend demonstrieren drei charackteristische Projekte die Möglichkeiten und Leistungsfähigkeit der digitalen Nahbereichsphotogrammetrie.

Notes: The well established use of air survey photography in Ordnance Survey mapping programmes since the Second World War contrasts markedly with spasmodic experiments in earlier years. Even so, the author laments the absence of photography which is known to have been taken in the 1920s and 1930s and which underlines the need for appropriate preservation of air photography of the recent past. 〈section xml:id="abs1-2"〉〈title type="main"〉RésuméL'utilisation de la photographie aérienne qui fait désormais tout à fait partie intégrante de programmes cartographiques de I'Ordnance Survey, contraste de façon notable avec les à-coups qui ont caractérisé les expériences des premières années. L'auteur n'en déplore pas moins I'absence des photographies que l'on sait avoir été prises dans les années 1920 et 1930; cela souligne la nécessité d'une conservation adéquate des photographies aéiennes remontant à un proche passé.〈section xml:id="abs1-3"〉〈title type="main"〉ZusammenfassungDie nach dem 2. Weltkrieg gut organisierte Nutzung der Aerophotogrammetrie beim Ordnance Survey kontrastiert markant zu den verkrampften Versuchen in früheren Jahren. Desgleichen beklagt der Autor das Fehlen von Fotos, die in den 20er und 30er Jahren aufgenommen wurden, was die Notwendigkeit einer geeingneten Aufbewahrung von Luftbildern aus der jüngsten Vergangenheit zeigt.

Notes: A technique for preparing simple, large scale maps of remote and poorly surveyed areas is described, whereby semicontrolled aerial photograph print laydowns are superimposed on enlarged satellite imagery. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On décrit une technique permettant de réaliser des cartes à grande échelle, simples, sur des régions lointaines et mal cartographiées: elle consiste à superposer des photomoisai'ques aériennes à des agrandissements ďimages-satellite. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Beschreibung eines Verfahrens zur Herstellung einfacher groβmaβ-stäbiger Karten von entlegenen, nur gering vermessenen Gebieten, wobei paβpunktmäβig gering gestützte Luftbildverbände vergröβerten Satelliten-bildern überlagert werden.

Notes: The authors describe and illustrate the successful provision of a survey /light navigation and camera control system which is based on reception of GPS signals in the survey aircraft, linked to an onboard computer. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les auteurs décrivent et illustrent la mise en æuvre réussie ďun système de navigation aérienne et de commande de la chambre de levés photographiques, basé sur la réception des signaux GPS dans ľavion photographe avec connexion àľordinateur de bord. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Die Autoren beschreiben und veranschaulichen die erfolgreiche Installierung eines Systems zur Navigation des Bildflugs und Steuerung der Luftbildmeβkammer, das auf dem Empfang von GPS-Signalen und ihrer Verbindung mit einem Bordrechner des Bildflugzeugs basiert.

Notes: Relative positioning of camera air stations by postprocessing of differential GPS phase observations is capable of very high accuracy and its application to aerial triangulation is expected to be simple and highly economic. The method is reviewed and some technical and operational problems are discussed. Results of experimental flight tests show that airborne GPS positioning is precise (to the order of a few centimetres) and that systematic errors can occur. The application to aerial triangulation is described methodically, including the compensation of systematic GPS errors in the combined block adjustment. Theoretical simulation studies and practical results show that GPS supported blocks have high accuracy and can generally be based on only four ground control points. The system is most economic and applicable to the full scale range of photogrammetric mapping. It is ready for practical use, as all necessary tools are available. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé La détermination relative des points de prise de vues ďune chambre aérienne par traitement en différé des observations de phase ďun GPS différentiel, est susceptible ďune très haute precision et ilfaut s'attendre à ce que son emploi en aéro-triangulation soil simple et ďun grand intérêt économique. Ľauteur analyse cette méthode en discutant de quelques problèmes techniques et opérationnel correspondants. Les résultats de vols expérimentaux montrent que la localisation par un GPS aéroporté est précise (de ľordre de quelques centimètres) mais que des erreurs systématiques peuvent se produire. Ľapplication de cette méthode à aérotriangulation est présentée méthodiquement, en s'étendant sur la compensation des erreurs systématiques du GPS lors de la compensation globale du bloc. En se basant sur des études théoriques de simulation et des résultats pratiques, on montre que des blocs assistés par le GPS ont une haute précision et que ľon peut généralement se contenter de quatre points ďappui seulement. Un tel système est on ne peut plus économique et s'applique à toute la gamme ďéchelles de la cartographie photogrammetrique. II est prêt àľemploi, tous les outils nécessaires étant disponibles. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Die relative Postionierung der Aufnahmeorte von Lufbildmeβkammern mit Hilfe der Datennachbearbeitung von differentiellen GPS-Phasenmess-ungen kann sehrgenau sein, und ihre Anwendung aufdieAerotriangulation wird als einfach und höchst ökonomisch eingeschätzt. Das Verfahren wird dargestellt und einige technische und operationelle Probleme werden diskutiert. Die Ergebnisse von expeimentellen Befliegungen zeigen, daβ die flugzeuggetragene GPS-Positionierung prdzise (in der Gröβenordnung weniger Zentimeter) ist, und daβ systemalische Fehler auftreten können. Die Anwendung auf die Aerotriangulation wird methodisch dargestellt, einschlieβlich der Kompensation systematischer GPS-Fehler in einer kombi-nierten Blockausgleichung. Theoretische Simulation und praktisch erzielte Ergebnisse zeigen, daβ GPS-gestutzte Blöcke eine hohe Genauigkeit besitzen und generell auf nur 4 Geländepaβpunkte gestützt zu werden brauchen. Das System ist höchst ökonomisch und auf den vollen Bereich der photogrammetrischen Kartenherstellung anwendbar. Es ist zur Nutzung bereit, da alle notwendigen Werkzeuge verfügbar sind.

Notes: The development of small format aerial photography had its beginnings in the Ontario Ministry of Natural Resources (formerly Lands and Forests) in the late 1960s. It was thought that the periodic acquisition of large blocks of aerial survey photography (every 10 years) for forest inventory was not current enough to be useful for local forest management. To fill the time gap, update photography would be necessary in order to document and measure the impact of logging practices on the forest inventory. To accomplish this, aerial photographic trials using readily available 35mm cameras were carried out to determine if the data acquired from these small format cameras using black and white films could be used to revise the forest inventory maps in the province. The trials were successful and resulted in a rapid course of investigations aimed at refining the technique. Numerous articles published by Zsilinszky (1968, 1972a, b, c and 1979) document the early development of the supplementary aerial photography (SAP) technique in the Ontario Ministry of Natural Resources. Zsilinszky (1979) was a review of the status of the technique over the previous ten years. The purpose of this paper is to report on advances in SAP, or small format aerial photography (SFAP) as it is known in other parts of the world, in the Ontario government since 1979. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Les origines du développement de la photographie à petit format remontent à la fin des années 1960, au Ministère des Ressources Naturelles de ľOntario (appelé anciennement des Terres et Forêts). On estimait alors que ľexecution périodique de grands blocs de levés photographiques aériens, saisis tous les dix ans pour ľinventaire forestier, ne permettait pas une utilisation suffisamment courante pour la gestion des forêts locales. Pour cela il fallait avoir dans ľintervalle des photographies complémen-taires, à jour, permettant ďobserver et de mesurer ľinfluence des pratiques ďabbatage du bois sur ľinventaire forestier. Dans ce but on a effectué des essais de photographie aérienne à partir de chambres photographiques 35 mm, facilement disponibles, pour déterminer si ľon pouvait utiliser les données issues de ces chambres à petit format, sur film noir et blanc, pour réviser les cartes de ľinventaire forestier de la province ďOntario. Les éssais etant réussis, on mit en æuvre un programme de recherches visant à améliorer cette technique. De nombreux articles publicés par Zsilinszky (1968, 1972, a b et c, et 1979) jalonnent les premiers développements de cette technique de photographie aérienne supptémentaire (P.A.S.) au Ministère des Ressources Naturelles de ľOntario. Ľarticle de Zsilinszky de 1979 présente un tableau de ľétat de la technique au cours des dix années précedentes. Cet article se propose de faire un rapport sur le progrès depuis 1979, dans le province ďOntario, de cette technique P.A.S., appelée photographie aérienne à petit format (P.A.P.F.) dans ďautres parties du monde. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusamtnenfassung Die Entwicklung der kleinformatigen Luftbildaufnahme hatte beim Ontario Ministry of Natural Resources (früher: Land und Forsten) ihren Ursprung am Ende der 60er Jahre. Man dachte, daβ die periodische Aufnahme von groβen Luftbildverbänden zur Forstinventur (aller 10 Jahre) für die lokale Forstverwaltung nicht aktuell genug wäre. Um die Zeitlücke zu füllen, waren neue Luftbilder notwendig, um den Druck der Holzfällung-spraktiken auf die Forstinventur zu dokumentieren und zu messen. Um dieses zu erreichen, wurden Versuche zur Luftaufnahme mit 35 mm Kameras durchgefuhrt, um zu bestimmen, ob die von diesen Kleinformat-kameras auf Schwarzweiβ-Film registrierten Daten zur Revision der Forstinventur-Karten in der Provinz verwendet werden konnten. Die Versuche waren erfolgreich und führten zu einer raschen Zunahme von Untersuchungen, um die Verfahren zu verfeinern. Zahlreiche von Zsilinszky (1968, 1972 a, b, c und 1979) veröffentlichte Beiträge dokumentieren die frühe Entwicklung der Methode der ergänz-enden Luftbildaufnahme (SAP) beim Ontario Ministry of Natural Resources. Der Beitrag von Zsilinszky aus dem Jahre 1979 gab einen Überblick über den Stand dieses Verfahrens in den zurückliegenden 10 Jahren. Der Zweck dieses Artikels ist es, über Fortschritte der SAP-Methode oder Kleinformatluftbildaufnahmen (SFAP) in anderen Teilen der Welt, soweit sie bei der Regierung in Ontario bekannt sind, seit 1979 zu berichten.

Notes: This paper discusses development of a monoscopic measurement system for oblique photography, based upon space resection by collinearity. The method consists of enlarging 35 mm slides with a colour laser scanned copier, then digitising surveyed targets with a standard digitising tablet. Particular attention is given to systematic errors introduced by enlarging and digitising as well as to the accuracy of space resection solutions. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On examine dans cet article le développement ďun systeme de mesure monoscopique pour photographies obliques, basé sur le relèvement dans ľespace et les équations de colinéarité. La méthode consiste à agrandir dans un copieur balayé par un laser de couleur, les diapositives 35 mm, puis à numériser sur une petite table à numériser standard les cibles qui ont été relevées. Les erreurs systématiques provenant de ľagrandissement et de la numérisation font ľobjet ďune attention particulière, ainsi que la précision des solutions du relévement dans ľespace. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Im Artikel wird die Entwicklung eines monoskopischen Meβsystems für Schrägbilder diskutiert, das auf dem Rückwärtseinschnitt nach der Kolli-nearitätsbedingung beruht. Die Methode basiert auf der Vergröβergung von 35 mm-Diapositiven mit einem Laser-Farbkopierer und der nachfolgenden Digitalisierung vermessener Zieltafeln mit einem Standard-Digitalisier-tablett. Besondere Aufmerksamkeit wird sowohl den systematischen Feh-lern, die durch Vergröβerung und Digitalisierung entstehen, als auch der Genauigkeit der räumlichen Berechnungen gewidmet.

Notes: With the wider use of small format cameras for photogrammetric purposes and the requirement of companies to maintain a high level of quality assurance, there has been an increasing demand for the calibration and re-calibration of metric, semimetric and non-metric cameras. University College London has developed a technique for calibrating a range of small format cameras and this paper details the methods used and summarises the results obtained. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé Au fur et à mesure que se répand ľemploi ďappareils à petit format dans les applications photogramétriques et que les entreprises demandent le maintien ďun haut niveau de qualityé, on assiste à des exigences accrues pour ľetalonnage et le ré-étalonnage des chambres métriques, quasi-métriques et non métriques. On a mis au point àľUniversity College de Londres une méthode pour étalonner toute une gamme ďappareils à petit format; on présente celle-ci en détail dans cet article en résumant les résultats obtenus. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Mit der breiteren Nutzung von Kleinformat-Kameras für photogram-metrische Zwecke und der Forderung von Betrieben nach einem hohen Qualitätssicherungs-niveau haben sich gesteigerte Anforderungen an die Kalibrierung und Rekalibrierung von Meβkammern, Teilmeβkammern und Nichtmeβkammern ergeben. Am University College in London wurde ein Verfahren zur Kalibrierung einer Reihe von Kleinformatkameras entwickelt, und in diesem Artikel werden die Methoden im Detail dargestellt und die erhaltenen Ergebnisse zusammengefaβt.

Notes: An investigation has been made into the feasibility of using a low cost Decca navigation receiver for vertical aerial block photography. The latest generation of low cost Decca receivers, manufactured by Philips, represents a substantial advance, but while the marine version, type APN Mark 4, has sufficiently high resolution to be of use, it fails at light aircraft speeds. The aeronautical version works well at light aircraft speeds but its resolution is not sufficiently high. However, the Mark 5 marine version has now been developed and initial airborne trials have proved very satisfactory. 〈section xml:id="abs1-2"〉〈title type="main"〉Résumé On a effectué une recherche sur la possibilitéď utiliser un récepteur de navigation Decca bon marché pour la saisie de blocs de photographies aériennes verticales. Les récepteurs bon marché Decca de la dernière génération, construits par Philips, constituent un progrès considérable; mais si la version marine, modèle APN-Mark 4, a une résolution suffisamment grande pour un tel emploi, elle n‘est pas adaptéà la vitesse ď un vecteur aérien même léger. En revanche la version aérienne fonctionne bien à la vitesse des avions légers, mais sa résolution n'est pas suffisante. II semble toutefois que la nouvelle version marine Mark 5 qui vient ďêtre développé, ait subi avec succès ses premiers essais aériens. 〈section xml:id="abs1-3"〉〈title type="main"〉Zusammenfassung Zur Nutzbarkeit eines preiswerten Decca-Navigationsempfängers für die Aufnahme von Luftbildblöcken wurden Untersuchungen durchgeführt. Die neueste Generation billiger Decca-Empfänger von Philips stellt einen substantiellen Fortschritt dar, aber während die marine Version vom Typ APN Mark 4 eine genügend hohe Auflösungfür die Anwendung hat, versagt sie bei Geschwindigkeiten leichter Flugzeuge. Die aeronautische Version arbeitet gut bei Geschwindigkeiten von Leichtflugzeugen, aber ihre Auflösung ist nicht ausreichend. Jetzt wird aber die marine Version Mark 5 entwickelt, und erste Luftversuche haben sich als sehr zufriedenstellend erwiesen.

Notes: : CREAMS was applied to a field-sized watershed planted to cotton in the Limestone Valley region of northern Alabama. The field was cultivated for three years with conventional tillage (CvT) followed by three years of conservation tillage (CsT). CREAMS is composed of three components: hydrology, erosion, and chemistry. Surface runoff and losses of sediment, N and P were simulated and results were compared with the observed data from the watershed. Curve numbers recommended in the CREAMS user's guide were not adequate for the watershed conditions. The hydrology submodel improved runoff simulation from CvT and CsT when field-data based curve numbers were used. The erosion submodel demonstrated that CsT reduced sediment loss more than CvT, even though CsT had higher runoff than CvT. The nutrient submodel based on the simulated runoff and sediment underpredicted N loss for both CvT and CsT. This submodel, however, accurately predicted P loss for CvT, but underpredicted for CsT (50 percent lower than the observed). The results of CREAMS simulation generally matched the observed order of magnitude for higher runoff, lower sediment, and higher N and P losses from CsT than from CvT.

Notes: : Many approaches are available for operation of a multipurpose reservoir during flood season; one of them is allocation of storage space for flood control. A methodology to determine a reservoir operation policy based on explicit risk consideration is presented. The objective of the formulation is to maximize the reservoir storage at the end of a flood season while ensuring that the risk of an overflow is within acceptable limits. The Dynamic Programming technique has been used to solve the problem. This approach has been applied to develop operation policies for an existing reservoir. The performance of the policy was evaluated through simulation and was found to be satisfactory.

Notes: : A numerical simulation model was developed to predict the vertical and lateral percolation losses from a ponded agricultural field. The two-dimensional steady-state unsaturated/ saturated flow equation was solved using the finite-difference technique. A constant ponding depth was maintained at the soil surface with different water table conditions in an application of the model for rice fields bordered by bunds. Field experiments were conducted for two different water table depths to collect data on the spatial distribution of volumetric soil-moisture content for model verification. The measured soil-moisture content values were found to be in close agreement with those predicted by the model.The sensitivity analysis of the model with selected hydrologic conditions shows that the model is most sensitive to the values of saturated hydraulic conductivity, but relatively less sensitive to water table depth, ponding depth, and evaporation rate from the soil surface. It implies that, in a ponded rice field condition, the lateral and vertical percolation losses are mostly governed by the hydraulic conductivity of the soil. The vertical percolation losses were almost equal to the saturated hydraulic conductivity values and, in most cases, these losses increased with deeper water table depths. The lateral percolation losses also increased with deeper water table depths; however, these losses were relatively small in comparison to the vertical percolation losses. The vertical and lateral percolation losses increased with the increase in ponding depths. The lateral percolation losses through the bund decreased when the evaporation losses increased from the soil surface. The results of this study indicate that the percolation losses from a ponded field may be predicted accurately for a wide range of soil and hydrological conditions when the values of hydraulic conductivity, evaporation rate, depth of ponding, and water table depth are accurately known.

Notes: : The black disk method for measuring visual water clarity in situ is becoming established as a simple but robust method for optically characterizing natural waters. However, in spite of its virtues, the method is limited by a practical visibility minimum of around 0.1 m and the requirement for direct access to the water body at a point where there is adequate lighting for the visual observations. A method has been devised for measuring black disk clarity off-site on samples of waters, diluted if necessary, and contained in a trough constructed of galvanized steel. In 23 streams, rivers, and lakes of diverse optical and physical character, measurements of visual clarity of water samples contained in troughs agreed closely with in situ measurements and correlated well (inversely) with the beam attenuation coefficient measured by transmissometer. Therefore, at sites where in situ measurement is difficult, visual clarity of waters can be measured offsite on a water sample. Furthermore, the visibility of samples diluted with tap water of known clarity was predictable from a simple balance on light attenuation. This means that useful visual clarity measurements on very turbid waters and effluents can be made in a trough containing volumetrically diluted samples, so extending application of the black disk method to very low visual ranges.

Notes: : Geochemistry of fine-fraction streambed sediments collected from the upper illinois River basin was surveyed in the fall of 1987 as part of the U.S. Geological Survey National Water-Quality Assessment pilot projects. The survey included 567 samples analyzed for 46 elements. Three distinctive distribution patterns were found for seven U.S. Environmental Protection Agency priority pollutants surveyed, as well as for boron and phosphorus: (1) enrichment of elements in the Chicago urban area and in streams draining the urban area relative to rural areas, (2) enrichment in main stems relative to tributaries, and (3) enrichment in low-order streams at high-population-density sites relative to low-population-density sites. Significant differences in background concentrations, as measured by samples from low-order streams, were observed among five subbasins in the study area. Uncertain geochemical correspondence between low-order, background sites and high-order, generally metal enriched sites prevented determination of background levels that would be appropriate for high-order sites. The within-sample ratio of enriched elements was variable within the Chicago area but was constant in the Illinois River downstream from Chicago. Element ratios imply a composite fine-fraction sediment in the Illinois River of 35–40 percent Des Plaines River origin and 60–65 percent Kankakee River origin.

Notes: : Most water-resouree investigations in semiarid basins of the Great Basin in western North America conclude that ground-water recharge from direct precipitation on the valley floor is negligible. However, many of these basins contain large areas covered by unvegetated, active sand dunes that may act as conduits for ground-water recharge. The potential for this previously undocumented recharge was investigated in an area covered by sand dunes in Desert Valley, northwestern Nevada, using a deep percolation model. The model uses daily measurements of precipitation and temperature th determine energy and moisture balances, from which estimates of long-term mean annual recharge are made. For the study area, the model calculated a mean annual recharge rate of as much as 1.3 inches per year, or 17 percent of the long-term mean precipitation. Model simulations also indicate that recharge would be virtually zero if the study area were covered by vegetation rather than dunes.

Notes: : A general methodology for fuzzy clustering analysis is developed and illustrated with a case study of water quality evaluation for Dianshan Lake, Shanghai, China. Fuzzy clustering analysis may be used whenever a composite classification of water quality incorporates multiple parameters. In such cases, the technique may be used as a complement or an alternative to comprehensive assessment. In fuzzy clustering analysis, the classification is determined by a fuzzy relation. After a fuzzy similarity matrix has been established and the fuzzy relation stabilized, a dynamic clustering chart can be developed. Given a suitable threshold, the appropriate classification is worked out. The methodology is relatively simple, and the results can be interpreted to provide valuable information to support decision making and to aid water quality management.

Notes: : An irrigation model based on a modified Thornthwaite water balance was used to simulate the effects of various hypothetical climatic changes on annual irrigation demand in a humidtemperate climate. The climatic-change scenarios consisted of combinations of changes in temperature, precipitation, and stomatal resistance of plants to transpiration. The objectives were to (1) examine the effects of long-term changes in these components of climatic change on annual irrigation demand, and (2) identify which of these factors would cause the largest changes in annual irrigation demand.Hypothetical climatic changes that only included increases in temperature and changes in precipitation resulted in increased annual irrigation demand, even with a 20 percent increase in precipitation. The model results showed that, for the ranges of changes in temperature and precipitation used in this study, changes in irrigation demand were more sensitive to changes in temperature than to changes in precipitation. Model results also indicated that increased stomatal resistance to transpiration counteracted the effects of increases in temperature and decreases in precipitation on irrigation demand. Changes in irrigation demand were even more sensitive to changes in stomatal resistance than to changes in temperature. A large amount of uncertainty is associated with predictions of future climatic conditions; however, uncertainty associated with natural climatic variability may be larger and may mask the effects of climatic change on irrigation demand.

Notes: : A study was conducted over a six-year period in East-Central Ohio to determine the effects of surface mining and reclamation on physical watershed conditions and on ground-water hydrology in three ground-water zones in three small experimental watersheds. Mining disturbances in watersheds adjacent to the experimental sites affected ground-water levels in the undisturbed experimental watersheds prior to actual mining in the experimental sites. New subsurface flow paths, with different characteristics, formed during mining and reclamation. At all three sites mining dewatered the saturated zone above the underclay of the mined coal seam. Mining and reclamation affected ground-water levels below the mined coal seam in the middle and lower zones within at least two sites. Ground-water level recovery in the mined upper saturated zone was slow and irregular both temporally and spatially after reclamation. Hydraulic conductivities of postmining (Phase 3) spoil were generally greater than those of Phase 1 bedrock, but wide spatial variability was observed. Modelers need to be aware of the complexities of new flow paths and physical characteristics of subsurface flow media that are introduced by mining and reclamation, including destruction of the upper-zone clay.

Notes: : This report presents the results of a survey of hydrology faculties of colleges and universities in the United States and Canada. Information is presented on topics covered in classes, allocation of class periods to individual topics, textbooks, prerequisites, computer use, and accreditation categories for hydrology courses offered by engineering departments. Hydrology courses generally require courses in fluid mechanics, mathematics, statistics, and computer science as prerequisites. Topics that receive the largest allocation of time in both introductory and advanced courses include rainfall-runoff relations, the hydrologic cycle, routing and open channel flow, and statistics. Advanced courses place greater emphasis on watershed models than do the introductory courses. Hydrology courses at both levels allocate the smallest amounts of time to snow hydrology ground-water hydrology, and “other topics.” Very few courses include field or experimental work. In a discipline where computer modeling is a major tool, this lack of field and data-collection experience may lead students to underestimate the uncertainties associated with data used to calibrate models and the modeling results themselves.Survey responses on hydrology courses taught in departments other than civil engineering were too few to permit detailed analysis. Most of these courses spend approximately two-thirds of available class time on the same topics as presented in engineering hydrology courses. The balance of class time is spent on topics that emphasize the specialized interest of the particular discipline, such as soil physics and soil moisture in agricultural engineering.

Notes: : A computer model was developed, based on the Green-Ampt infiltration equation, to computed rainfall excess for a single precipitation event. The model requires an estimate of parameters related to hydraulic conductivity, wetting front section, and fillable porosity of the soil layers. Values of parameters were estimated from soil textural averages or regression equations based on percent sand, percent clay, and porosity. Average values of effective porosity and wetting front suction were largely acceptable due to the relatively low variability and low model sensitivity to the parameters. Hydraulic conductivity was the most erratic constituent of the loss rate computation due to the high variability and the high sensitivity of the computed infiltration to the parameter.The performance of the Green-Ampt infiltration model was tested through a comparison with the SCS curve number procedure. Seven watersheds and 23 storms with precipitation of one inch or greater were used in the comparison. For storms with less than one inch of rainfall excess, the SCS curve number procedure generally gave the best results; however, for six of the seven storms with precipitation excess greater than one inch, the Green-Ampt procedure delivered better results. In this comparison, both procedures used the same initial abstractions.The separation of rainfall losses into infiltration, interception, and surface retention is, in theory, an accurate method of estimating precipitation excess. In the second phase of the study using nine watersheds and 39 storms, interception and surface retention losses were computed by the Horton equations. Green-Ampt and interception parameters were estimated from value sin the literature, while the surface retention parameter was calibrated so that the computed runoff volumes matched observed volumes. A relationship was found between the surface retention storage capacity and the 15-day antecedent precipitation index, month of year, and precipitation amount.

Notes: : The degradation of the optical aesthetics in the mouth of Onondaga Creek, New York, that occurs during high flow periods as a result of the influx of large quantities of suspended solids, is documented. Features of the degradation include very low clarity (Secchi disc minimum of approximately 0.1 m) and a brown ‘muddy’ appearance. The reduced clarity is mostly a result of increased light scattering. Loading and concentration profiles obtained for an approximately 35 km interval above the creek mouth over a wide range of flow indicates most of the suspended solids received during runoff events is resuspended stream sediment and eroded bank material. Application of microscopy-based individual particle analysis techniques indicates that the origin of most of these deposits and much of the suspended solids during runoff events is point source inputs, termed ‘mud boils,’ located approximately 32 km upstream of the creek mouth.

Notes: : Recent developments in multiple objective decision making methods presented in the upcoming sequence of research papers are evaluated and compared with respect to their usefulness in addressing challenging problems in water resources management. Because many of the decision making techniques originated in the field of operational research, the historical evolution of this field is outlined and the current need for developing a wide range of techniques for employment in strategic decision making is pointed out. Informative attributes for classifying decision making techniques are given to allow a practitioner to select decision aids that can best model the key characteristics of the particular problems under study. By systematically applying a wide variety of multiple objective decision making techniques to many different kinds of water resources problems, the authors of the papers clearly demonstrate the effectiveness of utilizing these methods for assisting in making both tactical and strategic decisions in water resources management.

Notes: : Multicriterion decision making (MCDM) techniques were used to analyze a groundwater contamination management problem from the viewpoint of conflicting multiple objectives. The groundwater management model was used to find a compromise strategy for trading off fresh water supply, containment of the waste, and total pumping cost in a hypothetical confined aquifer affected by previous waste disposal action. A groundwater flow model was used to formulate the hydraulic constraints. A linear system model was used to describe drawdown and velocity as functions of the decision variables which were pumping rates. The model determines the pumping location and rates. A modified c-constraint method was used to generate the set of nondominated solutions which were the alternative compromise strategies. Three different MCDM techniques, Compromise programming (CP), ELECTRA II and MCQA II, were used to select a “satisficing” alternative. Analysis of the results showed that, although these techniques follow different principles, the same preferred strategies were reached. Also, it was noticed that maintaining high groundwater velocities is expensive and difficult. In order to meet a two year target date, large amounts of water had to be pumped. Therefore, rapid restoration results in large pumping volumes and high costs.

Notes: : The temporal and locational attributes of water use data are ideally suited for analysis using a geographic information system (GIS) approach. A GIS combines spatial database management, statistical analysis, and cartographic modelling capabilities within a computer hardware and software configuration. Texas water use data for selected categories in 1980 and 1986 were analyzed using ARC/INFO to demonstrate the utility of GIS for water resource information management. Examples of data analysis and display are presented to illustrate the effectiveness of cartographic representations to communicate water use data.

Notes: : Aquifer pumping represents, in many geographical locations, an alternative and/or a complementary source of water to surface water supplies. Several Catalonian coastal towns in the northeastern corner of Spain are in this situation. Also, since pumped water is used to supply drinking water, the main purpose in managing these water resources is to supply, no matter the cost, the amount needed at every moment. In other words, the managers of these aquifers attempt to optimize firm water yield. If we think of these aquifers as underground reservoirs with fixed storage capacity, most of the techniques which are applied to surface reservoirs can be implemented. In this paper we use a Stochastic Dynamic Programming model to optimize the yield from the aquifer of the Ridaura River. The objective function in this model was chosen with the aim of maximizing the reliability of the target yields in each of four seasons.

Notes: : A lumped, in time and space, model of stream-aquifer interactions is developed. The model is based upon mass balance and ancillary phenomenological equations that can evaluate changes in streamflow and groundwater quantity and quality. The model is applied to the Santa Margarita River, San Diego County, California to assess the impacts of proposed discharges of reclaimed wastewater on streamflows and underlying groundwaters. The model is relatively simple and economical to apply, thus minimizing analysis costs.

Notes: : During waning flood flows in gravel-bed streams, finegrained bedload sediment (sand and fine gravel) is commonly winnowed from zones of high shear stress, such as riffles, and deposited in pools, where it mantles an underlying coarse layer. As sediment load increases, more fine sediment becomes available to fill pools. The volume of fine sediment in pools can be measured by probing with a metal rod, and, when expressed as the fraction (V*) of scoured residual pooi volume (residual pool volume with fine sediment removed), can be used as an index of the supply of mobile sediment in a stream channel. Mean values of V* were as high as 0.5 and correlated with qualitative evaluations of sediment supply in eight tributaries of the Trinity River, northwestern California. Fine-sediment volume correlated strongly with scoured pool volume in individual channels, but plots of V* versus pool volume and water surface slope revealed secondary variations in fines volume. In sediment-rich channels, V* correlated positively with scoured pool volume; in sediment-poor channels, V* correlated negatively with water-surface slope. Measuring fine sediment in pools can be a practical method to evaluate and monitor the supply of mobile sediment in gravel-bed streams and to detect and evaluate sediment inputs along a channel network.

Notes: : Federal agencies in the U.S. and Canada continuously examine methods to improve understanding and forecasting of Great Lakes water level dynamics in an effort to reduce the negative impacts of fluctuating levels incurred by interests using the lakes. The short term, seasonal and long term water level dynamics of lakes Erie and Ontario are discussed. Multiplicative, seasonal ARIMA models are developed for lakes Erie and Ontario using standardized, monthly mean level data for the period 1900 to 1986. The most appropriate model identified for each lake had the general form: (1 0 1)(0 1 1)12. The data for each lake were subdivided by time periods (1900 to 1942;1 943 to 1986) and the model coefficients estimated for the subdivided data were similar, indicating general model stability for the entire period of record. The models estimated for the full data sets were used to forecast levels 1,2,3, and 6 months ahead for a period of high levels (1984 to 1986). The average absolute forecast error for Lake Erie was 0.049m, 0.076m, 0.091 m and 0.128m for the 1, 2,3, and 6 month forecasts, respectively. The average absolute forecast error for Lake Ontario was 0.058m, 0.095m, 0.120m and 0.136m for the 1,2,3, and 6 month forecasts, respectively. The ARIMA models provide additional information on water level time series structure and dynamics. The models also could be coordinated with current forecasting methods, possibly improving forecasting accuracy.

Notes: : A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method.

Notes: : The aim of this paper is to present a multicriteria methodology for decision aid at the stage of programming a water supply system (WSS) for a rural area. The programming stage is an intermediate one between planning and designing water supply facilities, and can be decomposed into two problems: (a) setting up a priority order of water users, taking into account socio-economic criteria; and (b) choosing the best technical variant of the WSS. Among the criteria considered for the latter problem, there is a criterion of distance between the socio-economic priorities of users and the precedence orders of users according to the technical programming, which plays a coordinating role between problems (a) and (b). All steps of the presented methodology are illustrated by a real case study.

Notes: : A hydrologic investigation to determine vertical and seasonal variation of atrazine, alachlor, cyanazine, and nitrate at one location and to relate the variation to ground-water movement in the Iowa River alluvium was conducted in Iowa County, Iowa, from March 1986 to December 1987. Water samples were collected at discrete intervals through the alluvial sequence from the soil zone to the base of the aquifer. Alachlor, atrazine, and cyanazine were detected most frequently in the soil zone but also were present in the upper part of the alluvial aquifer. Alachlor was detected sporadically, whereas, atrazine, cyanazine, and nitrate were present throughout the year. In the alluvial aquifer, the herbicides generally were not detected during 1986 and were present in detectable concentrations for only a short period of time in the upper 1.6 meters of the aquifer during 1987. Nitrate was present throughout the alluvium and was stratified in the alluvial aquifer. The largest nitrate concentrations were detected in the middle part of the aquifer. Nitrate concentrations were variable only in the upper 2 meters of the aquifer. Vertical movement of herbicides and nitrate in the soil correlated with precipitation and degree of saturation. A clay layer retarded vertical movement of atrazine but not nitrate from the soil layer to the aquifer. Vertical movement could not account for the chemical variation in the alluvial aquifer.

Notes: : Surface water, groundwater, and groundwater discharge quality surveys were conducted in Cherrystone Inlet, on Virginia's Eastern Shore. Shallow groundwater below agricultural fields had nitrate concentrations significantly higher than inlet surface waters and shallow groundwater underlying forested land. This elevated nitrate groundwater discharged to adjacent surface waters. Nearshore discharge rates of water across the sediment-water interface ranged from 0.02 to 3.69 liters·m−2·hr−1 during the surveys. The discharge was greatest nearshore at low tide periods, and decreased markedly with increasing distance offshore. Vertical hydraulic heads, Eh, and inorganic nitrogen flux in the sediments followed similar patterns. Nitrate was the predominant nitrogen species discharged nearshore adjacent to agricultural land use, changing to ammonium farther offshore. Sediment nitrogen fluxes were sufficient to cause observable impacts on surface water quality; nitrate concentrations were up to 20 times greater in areas of groundwater discharge than in the main stem inlet water. Based on DIN:DIP ratios, nitrogen contributions from direct groundwater discharge and tidal creek inputs appear to be of significant ecological importance. This groundwater discharge links land use activity and the quality of surface water, and therefore must be considered in selection of best management practices and water quality management strategies.

Notes: : On February 12, 1992, a portion of the Ventura River, California, flowed through the Ventura Beach RV Resort which had recently been constructed across a major historically active distributary of the Ventura River delta. State and local land-use planners recognized the flood hazards associated with the site, but decision-makers relied on analytical methods developed by the U.S. Army Corps of Engineers and flood-hazard categories developed by the Federal Emergency Management Agency, which did not adequately reflect the mobile nature of the Ventura River channel and distributaries. A better understanding of the historical behavior of the Ventura River could have averted the flood damages experienced in 1992. Low intensity recreational, agricultural, or habitat restoration use of the site would minimize potential flood damages and obviate the need for structural flood protection that would impact the river's natural resources. Continued operation of the recreational vehicle park could result in additional flood damages in the relatively near future; recognizing the limitations of the flood-modeling methodologies used for the Ventura Beach RV Resort could prevent similar miscalculations of flood potential in comparable situations.

Notes: he influence of woody vegetation on the reliability of a sandy levee was investigated using field data in seepage and slope stability analyses. Field data were collected from selected sites within a 10-km segment of a channel levee on the Sacramento River near Elkhorn, California. Root architecture and distribution were determined using the profile-wall method in which root cross sections were exposed in the vertical wall of an excavated trench. Transects running both parallel and perpendicular to the crest of the levee were excavated at six sites. Each site was dominated by different plant species: five sites were adjacent to trees or woody shrubs, while one supported only herbaceous growth. Lateral plant roots were primarily restricted to, and modified, the near-surface soil horizons to a depth of approximately 1 meter. Root area ratios (RARs) did not exceed 2.02 percent and generally decreased exponentially with depth. At depths greater than 20 cm, mean RARs for sites dominated by wood species were not significantly different from the mean RAB for the herbaceous site. No open voids clearly attributable to plant roots were observed. Roots reinforced the levee soil and increased shear resistance in a measurable manner. Infinite slope and circular arc stability analyses were performed on the landward and riverward slopes under different hydraulic loading conditions. Infinite slope analyses indicated increasing root area ratio from 0.01 percent to 1 percent increased the factor of safety from less than one to more than seven. Circular arc analyses indicated that even the lower measured root concentrations sufficed to increase safety factors for arcs with maximum depths of about 1 m from less than one to about 1.2. Our findings suggest that allowing woody shrubs and small trees on levees would provide environmental benefits and would enhance structural integrity without the hazards associated with large trees such as wind-throwing.

Notes: : Confined production of poultry results in significant volumes of waste material which are typically disposed of by land application. Concerns over the potential environmental impacts of poultry waste disposal have resulted in ongoing efforts to develop management practices which maintain high quality of water downstream of disposal areas. The timing of application to minimize waste constituent losses is a management practice with the potential to ensure high quality of streams, rivers, and lakes downstream of receiving areas. This paper describes the development and application of a method to identify which time of year is best, from the standpoint of surface water quality, for land application of poultry waste. The procedure consists of using a mathematical simulation model to estimate average nitrogen and phosphorus losses resulting from different application timings, and then identifying the timings which minimize losses of these nutrients. The procedure was applied to three locations in Arkansas, and three different criteria for optimality of application timing were investigated. One criterion was oriented strictly to water quality, one was oriented only to crop production, and the last was a combination. The criteria resulted in different windows of time being identified as optimal. Optimal windows also varied with location of the receiving area. The results indicate that it is possible to land-apply poultry waste at times which both minimize nutrient losses and maximize crop yield.

Notes: : Infiltration trenches are an effective stormwater management alternative for the control of urban runoff from small areas. Perforated pipes buried within the gravel of an infiltration trench are used to distribute the inflowing runoff along the length of the trench. Laboratory tests are described that characterize the hydraulics of the orifices in perforated pipes. The results show that the steady-state exfiltration of water from the pipe into a surrounding gravel trench can be described by the orifice equation.

Notes: : Thirty-five lakes in southern Labrador sampled in 1981 were resampled in 1989 and water chemistry values were compared between visits. Results showed higher pH, specific conductance, acid neutralization capacity, color, and base cations values in 1989, though sulfate, the ion most likely to reflect acid precipitation impacts, did not vary. The major ion changes measured were probably due to natural hydrological variations and not to changes in acid inputs.Results from the 1989 data showed a slight, but significant, decrease in water sulfate concentration trend from western to eastern Labrador, though most values, even in the western portion of the study area, fell close to the values considered “background” by Brakke et at. (1989). Base cation concentrations exceeded those which could be predicted from weathering by carbonic and bicarbonic acid. Assuming that little weathering is generated by acid precipitation in this region, the excess cations measured are probably a result of bedrock dissolution from organic acids generated by plant decomposition. Calculations showed that organic acid effect could be responsible for 9 to 52 percent of total weathering in the study basins.

Notes: : Texans participate directly in water policy decision-making through a referendum process involving amendment of the state's constitution. Prior to 1985, Texans voted on eight amendments. Five of these were ratified (1957, 1962, 1966, 1971, 1976), and collectively resulted in the creation of the Water Development Fund, with an authorization level of $600 million, and the Texas Water Development Board, the organization charged with administering the fund. Three other amendments were defeated in 1969, 1976, and 1981 by ever-increasing margins. From 1985 to 1991, six additional amendments were proposed and subsequently ratified, resulting in a $1.8 billion increase in Water Development Fund authorization and the creation of an agricultural water conservation fund and bond insurance program. County-level electoral data for the 1985–1991 referenda were mapped to assess sectional and regional factors underlying public opinion regarding these water resource development and funding programs. Regional contrasts were most pronounced for the 1989 and 1991 referenda that targeted economically distressed areas across the state, particularly the colonias located along the Rio Grande, and the 1989 amendment that removed a time limit on the issuance of agricultural water conservation bonds. As a specific case study, the Texas experience could serve as a guide in California where similar constitutional restrictions require tax and spending programs to be approved by voters, and in other states that may be considering the development of similar state-level financial programs for water projects.

Notes: : As an alternative to the conventional single-peak design storms commonly used in hydrologic practice, a large number of Southeastern Pennsylvania storm events were selected from hourly U.S. National Oceanographic and Atmospheric Administration (NOAA) records, and their temporal distributions were analyzed. From these recorded events, design storms of a typical distribution were developed for storm durations between 6 and 18 hours. All of these generated design storms have two or more peaks. The conventional single peak as well as the “typical” multi-peak storms were then applied to a simulated watershed. It was found that the multi-peak storms consistently produced more dispersed hydrographs with lower runoff peaks than the conventional single peak storms.

Notes: : A study was conducted to determine the effects of surface mining and reclamation on ground-water chemistry in three saturated zones in each of three small East-Central Ohio water-sheds. The extensive disturbances of mining and reclamation: (1) caused more changes in constituent concentrations in the upper zone than in lower zones, most of which were statistically significant increases (many were “drastic”); (2) affected ground-water chemistry in lower zones - those that were not physically disturbed; (3) tended to increase the frequency of exceedance of regulated constituents in all saturated zones; and (4) affected the chemistry of surface baseflow water at the watershed outlets. Several constituents were still changing at the end of the project within all sites and zones.

Notes: : A multi-criteria approach to ground water quality monitoring network design is developed. The methodology combines multi-criteria decision making (MCDM) and modifications of geostatistical variance reduction analysis. Composite programming, a distance based optimization algorithm that employs a hierarchial structure, is used for the MCDM component of the design methodology. MCDM allows the consideration of numerous, often conflicting, design criteria. The methodology is useful for identifying the preferred combination of direct borehole and indirect geo-electric data. It also permits the use of prior information during initial stages of network development. Multi-variate kriging is employed to evaluate network performance using the combination of direct borehole data and indirect geoelectric data. Weighted measures of estimation variance are used as primary measures of performance, with the reduction in estimation variance being computed by the fictitious point method. Case study results demonstrate that the network design methodology can be used in both early and late phases of network development. It also leads to selection of the preferred combination and spatial orientation of direct and indirect data sources while considering cost-effectiveness and performance of alternative designs.

Notes: : A multiple objective framework for water resources problems possessing uncertain or imprecise elements is provided using distance-based concepts, fuzzy set theory, and fuzzy arithmetic. The case of regional management of a karstic aquifer in Hungary in which six conflicting objectives and six alternatives have been identified illustrates the methodology The objectives are classified into three groups of two objectives each, namely: (1) environmental (aesthetics, thermal springs temperature), (2) economic (mining, tourism), and (3) water quality (nitrates, phosphates). Both environmental objectives are formulated under fuzziness, and all objectives are scaled using the extension principle. Fuzzy compromise programming (FCP-I) is then applied; here, all six objectives are entered in a single lp norm measuring the distance between each alternative and an ideal point. Next, fuzzy composite programming (FCP-II) is developed; here, a trade off is first made within each group of objectives, and then an upper level trade-off takes place between the three groups. The fuzzy numbers describing each alternative as a result from applying these techniques are ranked to yield an ordering of the alternatives. The results of applying FCP.I, FCP-II, and two different ordering techniques are compared. The FCP-II technique appears to provide a relatively simple approach at hierarchical or multilevel multiple objective decision-making, where uncertainty is described by fuzziness. (KEY TERMS: compromise programming; fuzzy arithmetic; fuzzy sets; hierarchical criteria; karstic aquifer; lp, norms; mining; multiple objectives; thermal springs.)

Notes: : A research project was undertaken for the U.S. Army Corps of Engineers to determine the relative utility and effectiveness of four well-known multicriteria decision making (MCDM) models for applications in realistic water resources planning settings. A series of experiments was devised to examine the impact of rating and ranking procedures on the decision making behavior of users (e.g., planners, managers, analysts, etc.) when faced with situations involving multiple evaluation criteria and numerous alternative planning projects. The four MCDM models tested were MATS-PC, EXPERT CHOICE, ARIADNE, and ELECTRE.Two groups of analysts and decision makers were tested. One group consisted of experienced U.S. Army Corps planners, while the other was comprised of graduate students. Based on a series of nonparametric statistical tests, the results identified EXPERT CHOICE as the preferred MCDM model by both groups based largely on ease of use and understandability. ARIADNE fostered the largest degree of agreement within and among the two groups of individuals tested. The tests also lend support to the claim that rankings are not affected significantly by the choice of decision maker (i.e., who uses any of these MCDM models) or which of these four models is used.

Notes: : A method for selecting a most appropriate multicritenon decision making (MCDM) technique for watershed resources management is modeled as a multicriterion problem. The procedure consists of identifying a set of feasible MCDM techniques, and evaluating them with respect to four sets of choice criteria, namely (1) problem related, (2) decision-maker (DM)/analyst related, (3) technique-related, and (4) solution-related criteria. Altogether 15 techniques are evaluated in terms of 24 criteria, forming an evaluation matrix of criteria versus alternative MCDM techniques. The evaluation matrix is then analyzed by means by a composite programming algorithm resulting in a preference ranking of the alternatives. Application of the techniques to a watershed resources management problem illustrates the method throughout the paper. (KEY TERMS: alternative selection; watershed resources management; multicriterion decision making; composite programming.)

Notes: : The detrimental impacts of acid rain have become widely publicized, but effective and equitable methods to mitigate the acid rain problem remain to be found. This paper focuses on conflicts involved in allocation of the total emission loads to be reduced to respective pollution sources of acid rain, and proposes a game-theory approach to the resolution of the conflict. With an example abstracted from a hypothetical case study in the United States of America and Canada, a systematic analysis is performed and policy implications of the results examined to assess the applicability of the proposed model.

Notes: : The performance of a flood warning system can be characterized statistically by three variables: the expected number of detections per year, ND; the expected number of false warnings per year, NP; and the expected lead time of a warning, LT. The Performance Tradeoff Characteristic (PTC) of a warning system is a set of all combinations (ND, NP, and LT) that are feasible to attain in a given system. The concept of PTC is an evolution of the concept of ROC (Relative Operating Characteristic) widely used in detection theory. Each characteristic, ROC and PTC, can be displayed graphically in the form of a family of curves. The displays offer an aid to engineering planning and design of flood warning systems. (KEY TERMS: flood forecasts; flood warnings; reliability; detection; Relative Operating Characteristic; Performance Tradeoff Characteristic.)

Notes: : Effects of long-term prescribed burning on infiltration and interrill erosion were assessed on two longleaf pine-bluestem sites in Louisiana. Treatments represented biennially-applied winter, spring, or summer burning on an upland sandy loam site for 20 years; and annual winter or spring, and biennial winter or spring burns on a bottomland silt loam site for 10 years, with unburned controls. Immediate effects of burning were a reduction in surface cover, exposing soil to raindrop impact. Burning the sandy loam site increased interrill erosion after winter and spring treatments, but produced no immediate changes in infiltration capacity or time to runoff irrespective of treatment season. Rapid recovery of under-story vegetation mitigated soil exposure. Biennial burning did not increase interrill erosion, or reduce infiltration capacity and time to runoff on the sandy loam site after 20 years. A complete herbaceous understory covered the silt loam site two years after treatment. Interrill erosion was not significantly increased, or infiltration capacity and time to runoff decreased on burning treatments than unburned controls on the silt loam site. Litter biomass was important in predicting interrill erosion. No surface cover condition could be linked to variability in infiltration capacity. This study provides evidence for the resiliency of a longleaf pine-bluestem association to prescribed burning.

Notes: : Two simple interactive techniques are developed and illustrated by means of two different real-life examples in Thailand. The first technique, Evolutionary Sequential Multiobjective Problem Solving (ESEMOPS), is an open-ended algorithm designed for planning problems with discrete alternatives. ESEMOPS helps the decision making group (DMG) develop progressively a preference function over the alternatives. The algorithm follows an evolutionary “breeding” strategy to generate a small set of good alternative solutions. This heuristic search, which does not guarantee that the adopted ‘satisfactum’ is an efficient solution leads to plausible results when applied to the planning of the Mae Khlong-Chao Phraya interbasin water transfer and irrigation system. The second algorithm, Search Beam Method (SBM) is essentially a series of one-dimensional searches for an efficient point along a “beam” passing through a goal point. Repeated search towards displayed goal points is leading to a set of quasi non-dominated solutions. SBM is illustrated by the Ubol Ratana reservoir control problem with the two conflicting objectives of energy generation and irrigation water supply. Neither ESEMOPS nor SBM require that weights, utilities, or pairwise tradeoffs be assessed. These features have been very much appreciated by a real DMG presented with the two techniques.

Notes: : We surveyed over 2000 lakes in the State of Massachusetts (1983–1984) to examine the spatial variations in their acid-base chemistry. Our survey differed from previous surveys by including small lakes and nonpristine urban lakes. For samples collected in October 1983 and 1984, the median acid neutralizing capacity (ANC) was 184 μeq L−1 and 5.9 percent were acidic (ANC≤O). Small lakes (〈4 ha) were more likely to be acidic than large lakes. Generally, sulfate was the dominant acidifying agent, although organic anions were dominant in some of the lakes in the Cape Cod Region. The ionic composition of the lakes showed strong regional patterns which appear to be related to geology and human population density. An analysis of variance of ANC shows the six regional categories in the state explain 51 percent of the variance, while a combined general linear model of lake drainage type, color, elevation, size, silica, and hydrogen ion deposition could explain only 4.9 percent of the variation in ANC. Calcium rich, high ionic strength lakes were present in the marble bedrock in the west, and relatively dilute lakes dominated by sodium and chloride were found near the coast. Chloride concentrations were also related to population density, suggesting road salt as a likely contributing source.

Notes: : The ability to predict extreme floods is an important part of the planning process for any water project for which failure will be very costly. The length of a gage record available for use in estimating extreme flows is generally much shorter than the recurrence interval of the desired flows, resulting in estimates having a high degree of uncertainty. Maximum likelihood estimators of the parameters of the three parameter lognormal (3PLN) distribution, which make use of historical data, are presented. A Monte Carlo study of extreme flows estimated from samples drawn from three hypothetical 3PLN populations showed that inclusion of historical flows with the gage record reduced the bias and variance of extreme flow estimates. Asymptotic theory approximations of parameter variances and covariances calculated using the second and mixed partial derivatives of the log likelihood function agreed well with Monte Carlo results. First order approximations of the standard deviations of the extreme flow estimates did not agree with the Monte Carlo results. An alternative method for calculating those standard deviations, the “asymptotic simulation” method, is described. The standard deviations calculated by asymptotic simulation agree well with the Monte Carlo results.

Notes: : This paper presents a study which used a standard, hydraulic computer model to generate detailed design information to support conflict analysis of a water resource use issue. As an extension of previous studies, the conflict analysis in this case included several scenarios for stability analysis - all of which reached the conclusion that compromising, shared access to the water resources available would result in the most benefits to society. This expected equilibrium outcome was found to maximize benefit-cost estimates.

Notes: : Records of hourly water temperatures for two streams in the Upper Mississippi River basin were used to find the error between instantaneous measurements of stream water temperatures and true daily averages. The instantaneous summer water temperature measurements were assumed to be collected during daylight hours, and measurement times were selected randomly. The absolute error at the 95 percent confidence level of randomly collected stream water temperatures was less than 0.9°C for a 1 to 5m deep large river, but as large as 3.6°C for a 0.3 to lm deep small stream. Temperature readings of morning samples were usually below daily average values, and afternoon readings were usually above. Daily mean water temperatures were obtained with less than 0.23°C standard deviation from true daily averages if the daily maximum and minimum water temperatures were averaged. Sample results were obtained for the open water (summer) season only, since diurnal water temperature fluctuations in ice covered streams are usually negligible.

Notes: : The Palmer Drought Severity Index, which is intended to be of reasonable comparable local significance both in space and time, has been extensively used as a measure of drought for both agricultural and water resource management. This study examines the spatial comparability of Palmer's (1965) definition of severe and extreme drought. Index values have been computed for 1035 sites with at least 60 years of record that are scattered across the contiguous United States, and quantile values corresponding to a specified index value were calculated for given months and then mapped.The analyses show that severe or extreme droughts, as defined by Palmer (1965), are not spatially comparable in terms of identifying rare events. The wide variation across the country in the frequency of occurrence of Palmer's (1965) extreme droughts reflects the differences in the variability of precipitation, as well as the average amount of precipitation. It is recommended first, that a drought index be developed which considers both variability and averages; and second, that water resource managers and planners define a drought in terms of an index value that corresponds to the expected quantile (return period) of the event.

Notes: : As part of a major project to provide the Rhine delta protection from North Sea floods, the Dutch installed sluices at Haringvliet in the late 1960s and converted the Haringvliet-Hollandsch Diep-Biesbosch (HHB) estuary into a tidally-damped, fresh-water system. Two decades later, the Dutch Rijkswaterstaat commissioned a study of alternative policies for managing the sluices and removing contaminated bottom sediments, including policies which would at least partially restore estuarine conditions to the HHB. This paper describes the public policy analysis comprising that study, focusing on the role played by formal mullicriteria evaluation (MCE), including the Analytic Hierarchy Process. Through the tasks of value-tree structuring, impact measurement, and criterion prioritization, the MCE influenced the entire structure of the analysis, became an integral part of it, and, despite initial skepticism among the participants about the utility of multicriteria analysis, was subsequently accepted and viewed favorably by the majority of them.

Notes: : The Fairbanks Water Treatment Plant in Fairbanks, Alaska, processes approximately 3 MGD of drinking water using lime softening. Approximately 0.3 MGD of lime-sludge from the treatment process is combined with effluent from a nearby power plant and discharged to the Chena River. There is little information available on the impact of water-treatment sludge discharges, and virtually no information on the impacts of such discharges in polar environments. Concern surrounding the discharge of water treatment sludges have centered on alum-sludge due to the potential toxic effects of aluminum. Because of the relatively benign composition of lime-sludge, very little research has been published. However, there is the possibility that discharge of solids will result in sedimentation, accumulation of solids, and subsequent impacts on benthic organisms. This paper reports on the results of a study to determine if lime-sludge discharge from the water treatment plant is adversely impacting the river environment. The results provide basic information on the important variables of concern in lime-discharges to rivers.Samples from the discharge of the water treatment plant and combined water treatment plant/power plant effluent were collected weekly over a one-year period, and in-stream benthic and water column samples were collected biweekly during the fall and spring. Sediment and water quality data indicate that while significant accumulation of sludge solids is found downstream of the water treatment plant outfall, they are flushed out of the system by spring flows, which are significantly increased by snow melt. This process is most likely repeated on a yearly cycle.Hence, the data suggest that the FMUS water treatment plant's discharge of lime-sludge is probably not adversely impacting the river. More generally, this may indicate that the natural flow variations and sediment-laden characteristics of Arctic, glacier-fed rivers may assimilate large quantities of nonputrescible solids without significant changes in the natural river environment. Further research in this area is required to verify this conclusion.

Notes: : Most forest lands are managed for multiple purposes, among them timber production and water supply. Conflicts often arise in such cases because logging is perceived as a threat to water quality. These conflicts can result from uncertain factual information, from differences in underlying social values, or from imbalances in the incidence of costs and benefits. Resulting conificts may go unresolved because existing institutional structures fail to address the real roots of the dispute. When such conificts go unresolved, benefits are often lost, and social, political, and managerial costs are high. This study found that the roots of conifict may lie in value differences or in interest impacts, but attention may be focused inappropriately and unproductively on factual issues. It suggests that at least some long-standing disputes in the management of forested watersheds may be resolved by identifying the root causes of these disputes and choosing those actions, whether they be changes in management guidelines or altered institutional structures, which are appropriate to those causes.