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891.
Derek B. Booth 《Journal of the American Water Resources Association》1990,26(3):407-417
ABSTRACT: Urbanization of a drainage basin results in pervasive hydrologic changes that in turn initiate long-term changes in stream channels. Increases in peak discharges and in durations of high flows result in either quasi-equilibrium channel expansion, where cross-section area increases in near-proportion to the discharge increase, or catastrophic channel incision, where changes occur far out of proportion to the discharge increases that initiated them. Field data and hydrologic modeling of rapidly urbanizing basins in King County, Washington, define conditions of flow, topography, geology, and channel roughness that identify streams susceptible to incision. Channel slope and geologic material are particularly critical; thus simple map overlays, nearly irrespective of contributing drainage area, provide a valuable planning tool for identification of susceptible terrain. Where such conditions exist, basal shear stress provides a quantifiable parameter for predicting likely problems, although knickpoints are typical in such settings and confound simple calculation of sediment-transport rates. Where urbanization proceeds in such areas, effective mitigation of the incision hazards requires a degree of stormwater control far in excess of standards typically applied to present development activity. 相似文献
892.
Gregory J. McCabe David M. Wolock Lauren E. Hay Mark A. Ayers 《Journal of the American Water Resources Association》1990,26(4):633-643
ABSTRACT: The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous United States. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO2 conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO2 conditions. Results indicate that temperature and precipitation changes under doubled-CO2 conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic-change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation. 相似文献
893.
894.
John B. Whitcomb 《Journal of the American Water Resources Association》1990,26(6):921-926
ABSTRACT: A water use model was developed to estimate water savings from installation of low-flow showerheads and toilet displacement devices in residential housing. The model measures household water use in per capita terms with adjustments for age of occupants, household income, if occupants responsible for direct payment of water bill, and type of water fixtures. Detailed data on 308 single family residences involved with a pilot retrofit program in the Seattle, Washington, area were analyzed. We estimated per capita indoor water use to decline by 6.4 and 2.1 percent from complete installation of low-flow showerheads and toilet displacement devices, respectively. 相似文献
895.
896.
Summary The deposition of particulates emanating from the south of Nottingham, UK, where the coal-fired power station of Ratcliffe- on-Soar is an important industry was assessed using snow samples, dry deposition gauges, and precipitation gauges.Effects of leaf characteristics in terms of shape, surface area, presentation, and cuticular texture on particulate accumulation were examined. Leaves possessing a large surface area, rough cuticular surface and with a horizontal presentation, were particularly effective in the accumulation of particulates. The penetration of particulates through the foliar canopy is discussed.The senior author is Section Leader and Principal Lecturer in Ecology in the Department of Life Sciences at Trent Polytechnic. 相似文献
897.
Summary Plants and animals were investigated to ascertain their- radioactivity values on both dune sites (machair) and inter-tidal sites on the western coast of Barra, Outer Hebrides, UK. Material in both habitats was clearly contaminated. The accumulation of-radioactivity through food webs to organisms such asNucella lapillus (dog whelk) in the inter-tidal sites and in sheep and cattle in terrestrial sites is described.Dr F.B. Pyatt is the Section Leader and Principal Lecturer in Ecology in the Department of Life Sciences at Trent Polytechnic. Dr E.H. Beaumont was previously Lecturer in Zoology at St Hugh's College, University of Oxford, Oxford, UK. 相似文献
898.
Gregory J. McCabe Mark A. Ayers 《Journal of the American Water Resources Association》1989,25(6):1231-1242
ABSTRACT: The Thornthwaite water balance and combinations of temperature and precipitation changes representing climate change were used to estimate changes in seasonal soil-moisture and runoff in the Delaware River basin. Winter warming may cause a greater proportion of precipitation in the northern part of the basin to fall as rain, which may increase winter runoff and decrease spring and summer runoff. Estimates of total annual runoff indicate that a 5 percent increase in precipitation would be needed to counteract runoff decreases resulting from a warming of 2°C; a 15 percent increase for a warming of 4°C. A warming of 2° to 4°C, without precipitation increases, may cause a 9 to 25 percent decrease in runoff. The general circulation model derived changes in annual runoff ranged from ?39 to +9 percent. Results generally agree with those obtained in studies elsewhere. The changes in runoff agree in direction but differ in magnitude. In this humid temperate climate, where precipitation is evenly distributed over the year, decreases in snow accumulation in the northern part of the basin and increases in evapotranspiration throughout the basin could change the timing of runoff and significantly reduce total annual water availability unless precipitation were to increase concurrently. 相似文献
899.
James B. Reynolds Rodney C. Simmons Alan R. Burkholder 《Journal of the American Water Resources Association》1989,25(3):625-635
ABSTRACT: During the summers of 1982, 1983, and 1985, we assessed the effects of placer mining sedimentation on Arctic grayling, Thymallus arcticus, in the headwaters of Birch Creek, northeast of Fairbanks, Alaska. We compared differences between two streams (one that was undisturbed and one with mining activity upstream) near the confluence. Studies of caged fish demonstrated that, if grayling could not escape from streams carrying mining sediments, they would either die at high rates (sac fry) or suffer gill damage, starvation, and slowed maturation (age-O fingerlings and age-2 juveniles). Indirect effects of sedimentation, through loss of summer habitat for feeding and reproduction, may more severely affect grayling populations than the direct effects of sedimentation on the health and survival of individual fish. 相似文献
900.
B. Lussier G. E. Mohr I. C. Goulter 《Journal of the American Water Resources Association》1989,25(1):111-116
ABSTRACT: The techniques of conflict analysis derived from game theory were applied to the Shoal Lake water supply conflict in southeastern Manitoba, Canada. The issue of conflict is the desire of an Indian Band in the area to build cottage lots near the intake for water supply for the City of Winnipeg. The City of Winnipeg contends that such a development would seriously affect the quality of water supplied to the City, thereby increasing its treatment costs significantly. The four major players defined for the conflict are the City of Winnipeg, Indian Band No. 40, the Province of Manitoba, and the Federal Department of Indian and Northern Affairs. The results of the conflict analysis suggest that the introduction of the provincial and federal government into the conifict will not assist significantly in its resolution and that further progress on the resolution is unlikely until the results of Federal Environment Assessment Review office hearing become available. 相似文献