摘要:

ABSTRACT:The U.S. Geological Survey has performed hundreds of time‐of‐travel and tracer dispersion studies in streams and estuaries nationwide. This paper presents an approach to unitizing this type of data to make it more universally usable in predicting the behavior of soluble contaminants entering waterways. Practical application of the superposition principle and of the scalene triangle as an approximation of the response curve from a slug injection of a solute are demonstrated to be a means of simulating the downstream effects of any form of soluble contaminant rele

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01906.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:Streambank protection projects are intended to prevent streambank erosion, thereby preventing streambank failure and maintaining a desirable channel alignment. Streambank erosion is a natural process of unaltered, dynamic river systems, and protection projects seek to impose stability on this natural system. The environmental impacts of such projects are primarily changes to terrestrial and aquatic habitats and to aesthetics. Adverse environmental impacts have been minimized and enhancement of existing habitat and aesthetics have been achieved through the development of new, innovative designs or modifications to existing designs and through use of construction and maintenance practices that promote habitat and aesthetics. Designs based on channel flow characteristics, e.g., revetments using a variety of structural materials, can result in preservation of wildlife habitat by reducing the use of structural protection by matching the erosion potential of flow at the bank with the protection capability of the materials used. Designs based on streambed stabilization prevent bank failure caused by bank undermining, result in preservation or establishment of streamside vegetation, and enhance aesthetics. Protection schemes that manage and preserve floodplains, berms, and riparian areas preserve the natural condition of the floodplain area. Designs based on deflection of erosive flows, e.g., dikes, minimize disturbance to the bank vegetation and create low‐velocity aquatic habitats. Use of vegetation for bank protection is most effective when used in combination with structural components. Construction and maintenance practices can be scheduled and modified to minimize impacts to floodplain areas and to enhance wildlife habitat while preserving the integrity of the protection structur

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01907.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:The influence of perceptions of water quality on the likelihood of recreating at a particular recreation site is investigated using a logit model. The model is estimated for St. Albans Bay, Vermont. A hypothetical improvement in water quality was shown to greatly increase the probability of at least one visit to the bay during a season. This implies that many recreationists who do not use the bay at present will do so if water quality improves. A demand model for predicting site visitation must, therefore, include current nonusers in the sample. Failure to do so would result in misleading predictions about future demand for the bay.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01908.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:Two methods of computing rainfall excess in the U.S. Army Corps of Engineers’flood hydrograph package (HEC‐1), the Initial and Uniform method and the Exponential method, are compared to evaluate the effects on modeled hydrograph accuracy. Two computed unit‐hydrograph parameters, time of concentration and storage coefficient, were also compared. Rainfall and runoff data from 209 storms in 32 gaged basins in Illinois were used to calibrate the HEC‐1 model. Three hydrograph characteristics ‐ sum of incremental flows, peak discharge, and time of peak discharge ‐ were used to evaluate modeled hydrograph accuracy. Mean percent error for each basin and hydrograph characteristic was computed. An evaluation of the mean errors indicates that, although some bias in modeled hydrograph accuracy is evident, rainfall excess computed using either method results in a computed hydrograph accuracy that is within generally accepted limits. Application of a linear‐regression model shows no significant differences in computed values of unit‐hydrog

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01909.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:A large number of agricultural drainage wells (ADWs) are located in north‐central Iowa. These wells permit sediments, pesticides, nitrate, and bacteria in surface and subsurface drainage water to enter regional aquifers that are currently being used for drinking‐water supplies, mostly by rural families and communities. This paper reports some possible alternatives to control the entry of surface and subsurface drainage waters into groundwater systems, and describes a methodology to make comprehensive economic feasibility studies of alternative drainage outlets. The estimated cost of providing main subsurface drains varied from $220 to $960 per hectare. If the use of ADWs was completely eliminated without providing alternative drainage, it is estimated that the average annual loss to the farmers of the area would be at least $270 per hectare in reduced crop yields. Of course, losses would be weather dependent and highly variable. Management practices to reduce the pollutant load in water draining to ADWs are also discus

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01910.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:Many water wells developed in the Middle Mississippian Greenbrier Group of central Greenbrier County, West Virginia, are very productive because of the abundant solution conduits in this karst aquifer. Water from these wells, all of which (with one exception) are clustered in a small area about eight kilometers northwest of Lewisburg, West Virginia, is typically very hard (calcium‐magnesium‐bicarbonate type). Of 74 wells sampled, eight showed sulfate concentrations ranging from 600 to 1700 mg/l. These wells also showed a much higher than average concentration of calcium, magnesium, chloride, sodium, and, in a few cases, iron. The water from several of these wells was not potable. Previously unpublished work has suggested that dolomite and gypsum dissolution have contributed magnesium and sulfate ions to the ground water. It is also likely that, where sodium, chloride, and iron concentrations are above background, halite dissolution and pyrite oxidation are contributing to the problem. All of these minerals are often associated with the basal waterbearing strata of the Greenbrier Group. In addition, it is possible that the wells are receiving deeply circulating ground waters, via fracture zones, which feed many other well‐known sulfur and/or thermal springs in the central Appalac

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01911.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:A large‐scale simulation/optimization model provides schedules for operation of water and power for the California State Water Project (SWP). The SWP consists of a series of reservoirs linked by rivers, pumping plants, canals, tunnels, and generating plants and is operated by the California Department of Water Resources. The Department provides water to municipal and agricultural users, and manages its electrical loads and resources. The model, therefore, performs hydraulic and electrical computations leading to optimal operation of the entire system. It consists of hydraulic network programming components to meet the storage objectives at all the reservoirs, a linear programming component to determine the schedules at pumping and generating plants, an electrical network programming component to balance electrical loads and resources, and a number of other simulation components. It operates on yearly, weekly, and daily bases. It is primarily used for real‐time operation of the SWP and can provide hourly detail schedules which are implemented by the SWP staff via a computerized sys

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01912.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:The annual distribution of flow in a drainage basin within a given region is a function of many factors. These may include annual distribution of rainfall, basin orientation, ground cover, or presence of glaciers. Since the North Cascades region of northern Washington State has little variation in precipitation distribution by month, and the region has significant snowpack, one would predict that in an unregulated basin, basin elevation would be one of the most important factors impacting an annual hydrograph distribution. Such a prediction can be made since the higher a drainage basin is, the larger the portion of runoff that would occur as late spring snowmelt. Given that there is a relationship between elevation distribution and annual hydrograph, the problem becomes one of how to use this relationship to model an ungaged basin's hydrograph. This study concludes that, within the North Cascades region and perhaps within other regions, an effective method of determining annual flow distribution is to model ungaged flows in the same manner as flows from a gaged basin with an elevation distribution similar to that of the subject basin.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01913.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:The movement of precipitation water infiltrating through the material (refuse) of solid waste landfills is examined via numerical solution of the equations of continuity, and motion (Darcy's Law).The solution of the equations is obtained by a fully implicit, finite‐difference scheme. Both unsaturated and saturated surface conditions are considered, making the scheme suitable for real‐time simulation of net precipitation and moisture redistribution events.A sensitivity analysis showed that for unsaturated surface conditions the solution is primarily affected by hydraulic conductivity and capillary diffusivity, and is relatively independent of the space and time steps. In addition, the precipitation averaging process is shown to be critical in the correct computation of moisture transport during the time period where the transition from unsaturated to saturated conditions occurs.The model presented herein is suitable for analysis of water movement through landfills, and the design of bottom collection syst

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01914.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

ABSTRACT:A cascade model for forecasting municipal water use one week or one month ahead, conditioned on rainfall estimates, is presented and evaluated. The model comprises four components: long term trend, seasonal cycle, autocorrelation and correlation with rainfall. The increased forecast accuracy obtained by the addition of each component is evaluated. The City of Deerfield Beach, Florida, is used as the application example with the calibration period from 1976–1980 and the forecast period the drought year of 1981. Forecast accuracy is measured by the average absolute relative error (AARE, the average absolute value of the difference between actual and forecasted use, divided by the actual use). A benchmark forecast is calculated by assuming that water use for a given week or month in 1981 is the same as the average for the corresponding period from 1976 to 1980. This method produces an AARE of 14.6 percent for one step ahead forecasts of monthly data and 15.8 percent for weekly data. A cascade model using trend, seasonality and autocorrelation produces forecasts with AARE of about 12 percent for both monthly and weekly data while adding a linear relationship of water use and rainfall reduces the AARE to 8 percent in both cases if it is assumed that rainfall is known during the forecast period. Simple rainfall predictions do not increase the forecast accuracy for water use so the major utility of relating water use and rainfall lies in forecasting various possible water use sequences conditioned on sequences of historical rainfall dat

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1986.tb01915.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY