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  • Artikel  (6)
  • Wiley  (6)
  • American Geophysical Union (AGU)
  • American Meteorological Society
  • Springer
  • 2010-2014  (6)
  • 1985-1989
  • Water Resources Research  (6)
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  • Artikel  (6)
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  • 1
    Publikationsdatum: 2013-10-03
    Beschreibung: The baseflow recession constant, K b , is used to characterize the interaction of groundwater and surface water systems. Estimation of K b is critical in many studies including rainfall-runoff modeling, estimation of low flow statistics at ungaged locations and baseflow separation methods. The performance of several estimators of K b are compared, including several new approaches which account for the impact of human withdrawals. A traditional semi-log estimation approach adapted to incorporate the influence of human withdrawals was preferred over other derivative-based estimators. Human withdrawals are shown to have a significant impact on the estimation of baseflow recessions, even when withdrawals are relatively small. Regional regression models are developed to relate seasonal estimates of K b to physical, climatic, and anthropogenic characteristics of stream-aquifer systems. Among the factors considered for explaining the behavior of K b , both drainage density and human withdrawals have significant and similar explanatory power. We document the importance of incorporating human withdrawals into models of the baseflow recession response of a watershed and the systemic downward bias associated with estimates of K b obtained without consideration of human withdrawals.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Publikationsdatum: 2013-03-06
    Beschreibung: Accurate estimation of the characteristics of the winter snowpack is crucial for prediction of available water supply, flooding, and climate feedbacks. Remote sensing of snow has been most successful for quantifying the spatial extent of the snowpack, although satellite estimation of snow water equivalent, fractional snow covered area, and snow depth is improving. Here we show that GPS observations of vertical land surface loading reveal seasonal responses of the land surface to the total weight of snow, providing information about the stored snow water equivalent. We demonstrate that the seasonal signal in SOPAC GPS vertical land surface position time series at six locations in the western United States is driven by elastic loading of the crust by the snowpack. GPS observations of land surface deformation are then used to predict the water load as a function of time at each location of interest and compared for validation to nearby SNOTEL observations of snow water equivalent. Estimates of soil moisture are included in the analysis and result in considerable improvement in the prediction of snow water equivalent.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Publikationsdatum: 2014-02-25
    Beschreibung: A thorough assessment of evapotranspiration (ET) pervades several important issues of the 21 st century including climate change, food-security, land-management, flood and drought prediction and water resources assessment and management. Such a proper assessment is of particular importance in the Ganga River Basin (GRB) with its backdrop of a rapidly increasing population pressure and unregulated use of water resources. Spatially averaged ET over the GRB is computed as the residual of atmospheric and terrestrial water budget computations using a combination of model simulations and satellite- and ground-based observations. The best estimate of monthly ET is obtained as the monthly mean of atmospheric and terrestrial water balance computations for the period 1980-2007. The mean monthly average of ET from these various estimates is 72.3 ± 18.8 mm month -1 . Monthly variations of ET peak between July and August and reach a minimum in February. For the entire study period, the rate of change of ET across the GRB is -11 mm yr -2 (i.e. mm/year/year). Alongside a notable influence of the 1997-1998 El Niño, results allude to the existence of interim periods during which ET trends varied significantly. More specifically, during the period of 1998-2002, the rate of decline increased to -55.8 mm yr -2 , which is almost 5-times the overall trend. Based on the correlation between ET and independent estimates of near-surface temperature and soil moisture, we can infer that the ET over the GRB is primarily limited by moisture availability. The analysis has important potential for use in large-scale water budget assessments and intercomparison studies. The analysis also emphasizes the importance of synergistic use of mutli-platform hydrologic information.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Publikationsdatum: 2013-04-24
    Beschreibung: A long-standing challenge for hydrologists has been a lack of observational data on global-scale basin hydrological behavior. With observations from NASA's Gravity Recovery And Climate Experiment (GRACE) mission, hydrologists are now able to study terrestrial water storage for large river basins (〉200,000 km 2 ), with monthly time resolution. Here we provide results of a time series model of basin-average GRACE terrestrial water storage anomaly and Global Precipitation Climatology Project (GPCP) precipitation for the world's largest basins. We address the short (10-year) length of the GRACE record by adopting a parametric spectral method to calculate frequency-domain transfer functions of storage response to precipitation forcing, and then generalize these transfer functions based on large-scale basin characteristics, such as percent forest cover and basin temperature. Among the parameters tested, results show that temperature, soil water-holding capacity and percent forest cover are important controls on relative storage variability, while basin area and mean terrain slope are less important. The derived empirical relationships were accurate (0. 54 ≤ E f ≤ 0.84) in modeling global-scale water storage anomaly time series for the study basins using only precipitation, average basin temperature, and two land-surface variables, offering the potential for synthesis of basin storage time series beyond the GRACE observational period. Such an approach could be applied towards gap filling between current and future GRACE missions, and for predicting basin storage given predictions of future precipitation.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Publikationsdatum: 2013-01-11
    Beschreibung: ABSTRACTS In this study we use observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to evaluate freshwater storage trends in the north-central Middle East, including portions of the Tigris and Euphrates River Basins and western Iran, from January 2003 to December 2009. GRACE data show an alarming rate of decrease in total water storage of approximately -27.2 ± 0.6 mm yr -1 equivalent water height, equal to a volume of 143.6 km 3 during the course of the study period. We use additional remote-sensing information and output from land-surface models to identify that groundwater losses are the major source of this trend. In our opinion, the approach used in this study provides an example of ‘best current capabilities’ in regions like the Middle East, where data access can be severely limited. Results indicate that the region lost 17.3 ± 2.1 mm yr -1 equivalent water height of groundwater during the study period, or 91.3 ± 10.9 km 3 in volume. Furthermore, results raise important issues regarding water use in transboundary river basins and aquifers, including the necessity of international water use treaties and resolving discrepancies in international water law, while amplifying the need for increased monitoring for core components of the water budget.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Publikationsdatum: 2013-04-18
    Beschreibung: The mathematical formulation of the Muskingum method, like that of many numerical schemes used for river routing, requires that all upstream river reaches be updated prior to updating the flow rate of any given reach. Due to this topological constraint, such numerical schemes have traditionally been solved in an upstream to downstream manner which imposes inherent limitations on the speedup that can be achieved in a parallel computing environment because each computing core has to wait for completion of all cores addressing upstream sub-basins prior to starting its own sub-basin. The research presented in this paper quantifies the exact influence among river reaches during the update step of the Muskingum method and shows that the influence decreases with increasing distance between two reaches until it becomes too small to be accounted for by floating-point arithmetic. A formal definition of the minimal distance from which the relative influence becomes numerically inexistent – the radius of influence – is presented. Based on this distance, expressed as a number of river reaches, a new estimate of the maximum theoretical speedup that can be achieved by the Muskingum method or by similar numerical schemes is presented and implies large potential gains in computing time when domains are much larger than the radius of influence. An application to the approximately 180,000 river reaches of the Upper Mississippi River Basin at a 15-minute time step over 2004 shows a radius of influence on the order of 150 river reaches. The speedup obtained for this application is much higher than previously thought possible, but also much lower than could be attained, suggesting that further investigations are necessary.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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