摘要:

SummaryA novel estuarine flow model is proposed. It provides some two‐dimensional features while using an essentially one‐dimensional approach. The model is applied to the Upper Delaware Estuary, and is shown to match available field data with acceptable accuracy. The model is shown to be numerically stable and reasonably mass conservat

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04788.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryA novel model of pollution transport in estuaries is proposed. The model provides some two‐dimensional features of pollution transport while using an essentially one‐dimensional approach. The model is tested against data taken from a dye study conducted in the Delaware Estuary by the United States Environmental Protection Agency. The model is able to predict both lateral and downstream concentration profiles, and is shown to match field data with reasonable accur

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04789.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryAn economic analysis of nonpoint source pollution management was conducted for the Nansemond River and Chuckatuck Creek watersheds in Southeast Virginia. The potential effects of alternative public policies on farm income, land use, and pollution loadings were investigated. Regulatory programs could have quite different impacts depending on which pollutant is targeted. Cost‐share rates greater than 50 percent would have little additional effect on pollution from crop enterprises, but would reduce pollution from livesto

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04790.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryIn areas where there is little or no topographic relief and where soils, vegetation, geologic structure and other factors are essentially uniform, identification of drainage basin boundaries is difficult or impossible. In such a homogeneous landscape, however, assumptions may be made that the hydrologic and geomorphic controls over drainage basin development are constant within the area. If this is true, it is suggested, the drainage area of a stream is related solely to the stream length and factors governing the length‐area relationship are also constant. A simple formula based on these assumptions and the gravity model is proposed which can be used to estimate drainage divides in a homogeneous landscap

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04791.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryThe breakpoint rainfall hydrology and pesticide options of the field scale model CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems) were used to predict average concentrations of hexazinone [3 cyclohexyl‐6‐(dimethyl‐amino)‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione] in stormflow from four forested watersheds in the upper Piedmont region of Georgia. Predicted concentrations were compared with measured concentrations recorded over a 13‐month period. CREAMS accurately predicted hexazinone concetrations in the initial stormflow events which also contained the highest concentrations. The model underestimated the hexazinone concentrations in stormflow two months and greater following pesticide application. In a companion study, the daily rainfall option of the CREAMS model was used to evaluate the reltive risk associated with the maximum expected concentration of hexazinone, bromacil (5‐bromo‐3 sec‐butyl‐6 methyuracil), picloram (4‐amino‐3,5,6 trichloropicolinic acid), dicamba (3,6‐dichloro‐0‐anisic acid), and triclopyr {[(3,5,6‐trichloro‐2‐pyridinyl)oxy]acetic acid} in stormflow from small forested watersheds. The model predicted the following order of potential residue appearance in stormflow: bromacil>triclopyr>hexazinone>picloram>dicamba. Subsurface movement of residues via interflow and deep leaching losses are not simulated by

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04792.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryPrecipitation and runoff samples were collected for 13 storms in a nonindustrial urban area in Central Pennsylvania between July 1980 and June 1981. Runoff was collected from tree surfaces, a residential roof and street, a shopping mall parking lot, a downtown business district alley, and a heavily traveled street. Analysis of the water samples showed 10 to 25 percent of the nitrogen, 25 percent of the sulfate, and less than 5 percent of the phosphorus, potassium, and calcium in water below a tree was deposited by the precipitation. The residential roof caused insignificant changes in water chemistry. The results for the four paved areas showed that all the nitrogen, and from 16 to 40 percent of the sulfate and 13, 4, and 2 percent of the phosphorus, potassium, and calcium, respectively, in runoff was deposited by the precipitation. Precipitation can also be an important source of sulfate and phosphorus in runoff. All of the surfaces raised the pH of the runoff, with the largest increases, from a pH of 4 to about 7, occurring in runoff from the paved areas. Precipitation and runoff chemistry was not related to antecedent conditions such as the length of the preceding dry period.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04793.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryAbility to adequately estimate sediment yield is an important step in dealing effectively with soil erosion problems. Predictions of sediment yield made using the Universal Soil Loss Equation (USLE) with different forms of sediment delivery ratio (SDR) are compared with those made by Modified USLE (MUSLE) and a fundamentally derived Erosion‐Deposition Model (EDM). The USLE and USLE with SDR are poor predictors of sediment yield for individual storms compared to the MUSLE and EDM. Although MUSLE gave better results than USLE it showed somewhat more scatter of data points than the recently developed ED

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04794.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryIn urbanizing areas underlain by crystalline rocks an inventory of the usable ground water should form an important element in the land‐use planning process. Land‐use decisions are most often made upon water‐well yield data alone, but these data do not address the inventory question. A method utilizing local geology, stream lowflow characteristics, and pumping test data permitted outlining portions of Wake County, North Carolina, which are more favorable and those which are less favorable for ground water supply development. Information from state‐required 24‐hour pumping tests on 232 wells was supplemented by information from an additional 100 wells whose initial yields were determined by shorter pumping tests.Comparison of the ground water inventory values on a per acre or per square mile basis with average water use at various residential densities provides information useful to the responsible political body as it decides about population density distribution and the need for surface water supplies. For Wake Country an average density of one residential unit per acre appears generally permissible before overdraft of the ground water supplies becomes a significant risk. By utilizing the ground water inventory and patterns of ground water yields from various rock types, county officials can maximize the effectiveness of public facilities funds. The technique appears useful for other parts of the Piedmont region of the southeastern Unit

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04795.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryRainfall and runoff in the Tucson, Arizona, urban area can be used to augment residential and municipal water supplies. Residential rainfall‐harvesting systems include a catchment surface, collection and concentration components, separation and treatment units, storage capacity and distribution capability. A system to control runoff can divert water from urban washes for use in parks or other landscaped areas or can be used to enhance recharge to groundwater reservoirs. A reduction in flood hazards or peaks is a concurrent benefit of controlling and diverting runof

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04796.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryThe shallow Fairmont Lakes in southern Minnesota have been treated with copper sulfate for 58 years to reduce excessive algal growth. Copper sulfate was applied to five lakes at cumulative rates upo to 1647 kg/ha (1470 1b/acre), totaling 1.5 million kilograms. Data collected since treatment of the Fairmont Lakes began in 1921 provide alarming insights into lake responses to sustained chemical treatment with copper sulfate. Short‐term and long‐term effects have occurred. Short‐term effects include: a) the intended temporary killing of algae, b) dissolved oxygen depletion by decomposition of dead algae, c) accelerated phosphorus recycling from the lake bed and recovery of the algal population within 7 to 21 days, and d) occasional fish kills due to oxygen depletion or copper toxicity or both. Long‐term effects are shown to include: a) copper accumulation in the sediments, b) tolerance adjustments of certain species of algae to higher copper sulfate dosages, c) shift of species from green to blue‐green algae and from game fish to rough fish, d) disappearance of macrophytes, and e) reductions in benthic macroinvertebrates. The conclusion is that while copper sulfate treatments enjoy great popularity because they kill and remove algae almost instantaneously, other immediate or cumulative side effects can be harmful to many other aquatic

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1984.tb04797.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY