ALBERT

Notes: : Although estimation of hydraulic friction loss in pipelines is one of the most frequent routine computations made by water supply engineers, almost no post-construction analysis of the accuracy of these calculations exists in the literature. This paper reports the field measured friction losses in three one-mile sections of small diameter pvc pipe which had been in service for 10 years. Hazen-Williams and Darcy-Weisbach equations are examined to provide a framework for comparing Hazen-Williams coefficients recommended by pipe manufacturers to those obtained by the field measurements. The conclusion is that the CHW factor of 150 recommended by most pvc pipe manufacturers is too high for the diameter-velocity combinations encountered in rural dead-end small diameter lines. The measured coefficients averaged 133 which is close to that predicted by superimposing Hazen Williams coefficients on the Moody diagram from which the friction factor for the Darcy-Weisbach equation is obtained.

Notes: Abstract: This paper describes an interactive data and model generator that is intended to bridge the gap between the water resource enginner and planner and the mathematical progrmming systems approach to regional water supply planning. The optimization objective is to minimize total annual cost with respect to capital investment and operation and maintenance costs. The matrix generator formulates the necessary hydrologic, demographic and programming problem for system optimization. The interactive program guides the user through the input and optimization segments, totally eliminates the chore of manually structuring the model matrix aides in eliminating errors, and allows use by planners without skill in mathematical programming.

Notes: SUMMARY. Naidids live in a wide range of aquatic habitats but are particularly important numerically as part of the benthic fauna of rivers with stony substrates. In general they graze on bacteria and algae although some, particularly Chaetogaster spp., are mainly predaceous, and C. limnaei vaghini is a parasite of molluscs, chiefly Gastropoda. Food selection seems to be based largely on particle size although the food quality of the particles within the appropriate size-range influences rates of growth and reproduction.Major factors determining the distribution and abundance of naidid species are the nature of the substratum and the presence and kind of vegetation. Plants with a highly dissected form, a thick growth habit, and which permit the greatest periphyton development generally support the most abundant naidid populations. The oligochaete fauna of coarse substrates (stones and gravels) is often dominated by the Naididae but both species-richness and abundance of naidid populations are generally reduced where fine substrates (silts and muds) occur. The occurrence of worms within the substratum is also determined by its nature; naidids penetrate to depths of 20–70 cm in coarse substrates but rarely penetrate below 6 cm in mud. The principal factor limiting both depth penetration and the dominance of naidids in fine substrates is probably oxygen availability.Naidids reproduce both asexually and sexually, the former method predominating for most of the year. Asexual reproduction usually involves the budding-off of zooids but a few species fragment. Sexual reproduction is often infrequent; populations of some species produce few or no sexually mature individuals. In mature worms asexual reproduction virtually ceases. In populations that produce mature individuals there is apparently one sexual generation a year, usually occurring during the summer and autumn. Adults die soon after laying their cocoons.In general, naidids are most abundant during the summer months when rates of growth and asexual reproduction are stimulated by higher temperatures and a plentiful supply of food. A few species, however, e.g. Nais elinguis and Paranais litoralis, are more abundant in the spring.The response of naidid species to different kinds of pollution is varied but generally organic enrichment of rivers which have stony substrates results in a considerable (ten- to twenty-fold) increase in naidid abundance. Nais elinguis, N. barbata, N. communis, N. variabilis, and Chaetogaster diaphanus are often abundant in such rivers, the foremost species reaching densities of 200 000 m−2. Nais alpina, N. bretscheri, and N. pardalis appear to be relatively intolerant of organic enrichment. A substantial increase in naidid abundance is also promoted by the deposition of biologically inert particles (coal dust, china clay, sand) on the river bed.The importance of Naididae in relation to pollution surveillance of fresh waters is discussed.

Notes: Forty specimens of rainbow trout (54–127 g) were divided into 4 groups which were treated as follows: (a) normoxic clean water; (b) hypoxic clean water; (c) normoxic water with 10 ppm zinc for 10 h; (d) hypoxic water with 10 ppm zinc for 10 h. The zinc content was determined separately for each of the 4 gill arches on each side of the fish. Values for the zinc concentration were greater following the zinc treatments, but no significant difference between hypoxia and normoxia was observed. Differences in concentrations of zinc were found in different arches whether expressed per gram dry weight or per unit surface area of the secondary lamellae.