摘要:

ABSTRACT:The degradation of the optical aesthetics in the mouth of Onondaga Creek, New York, that occurs during high flow periods as a result of the influx of large quantities of suspended solids, is documented. Features of the degradation include very low clarity (Secchi disc minimum of approximately 0.1 m) and a brown ‘muddy’ appearance. The reduced clarity is mostly a result of increased light scattering. Loading and concentration profiles obtained for an approximately 35 km interval above the creek mouth over a wide range of flow indicates most of the suspended solids received during runoff events is resuspended stream sediment and eroded bank material. Application of microscopy‐based individual particle analysis techniques indicates that the origin of most of these deposits and much of the suspended solids during runoff events is point source inputs, termed ‘mud boils,’ located approximately 32 km upstream of the cr

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03991.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Both L‐moment and nonparametric frequency analyses were performed on a series of annual maximum floods from New Brunswick, Canada. The L‐moment analysis concluded that the data were generated from a unimodal Generalized Extreme Value (GEV) distribution. However, the nonparametric frequency analysis indicated that a majority of stations followed nonunimodal mixed distributions since peak flows occur during different seasons and are the result of different generating mechanisms. The coupling of L‐moment and nonparametric analyses facilitates mixed distribution identification. Thus, the nonparametric method helps in identifying underlying probability distribution, especially when samples arise from mixed distribu

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03992.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Concentrations of atmospheric CO2 and other radiatively active trace gases have risen since the Industrial Revolution. Such atmospheric modifications can alter the global climate and hydrologic cycle, in turn affecting water resources. The clear physical and biological sensitivities of water resources to climate, the indication that climate change may be occurring, and the substantial social and economic dependencies on water resources have instigated considerable research activity in the area of potential water resource impacts. We discuss how the literature on climate change and water resources responds to three basic research needs: (1) a need for water managers to clearly describe the climatic and hydrologic statistics and characteristics needed to estimate climatic impacts on water resources, (2) a need to estimate the impacts of climate change on water resources, and (3) a need to evaluate standard water management and planning methods to determine if uncertainty regarding fundamental assumptions (e.g., hydrologic stationarity) implies that these methods should be revised. The climatic and hydrologic information needs for water resource managers can be found in a number of sources. A proliferation of impact assessments use a variety of methods for generating climate scenarios, and apply both modeling approaches and historical analyses of past responses to climate fluctuations for revealing resource or system sensitivities to climate changes. Traditional techniques of water resources planning and management have been examined, yielding, for example, suggestions for new methods for incorporating climate information in real‐time water managemen

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03993.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Effects of long‐term prescribed burning on infiltration and interrill erosion were assessed on two longleaf pine‐bluestem sites in Louisiana. Treatments represented biennially‐applied winter, spring, or summer burning on an upland sandy loam site for 20 years; and annual winter or spring, and biennial winter or spring burns on a bottomland silt loam site for 10 years, with unburned controls. Immediate effects of burning were a reduction in surface cover, exposing soil to raindrop impact. Burning the sandy loam site increased interrill erosion after winter and spring treatments, but produced no immediate changes in infiltration capacity or time to runoff irrespective of treatment season. Rapid recovery of under‐story vegetation mitigated soil exposure. Biennial burning did not increase interrill erosion, or reduce infiltration capacity and time to runoff on the sandy loam site after 20 years. A complete herbaceous understory covered the silt loam site two years after treatment. Interrill erosion was not significantly increased, or infiltration capacity and time to runoff decreased on burning treatments than unburned controls on the silt loam site. Litter biomass was important in predicting interrill erosion. No surface cover condition could be linked to variability in infiltration capacity. This study provides evidence for the resiliency of a longleaf pine‐bluestem association to prescribe

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03994.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:We measured diurnal changes in water levels in three swamps dominated by pondcypress trees (Taxodium distichumvar.nuans) in central Florida for four years in order to obtain additional documentation of relatively low evapotranspiration (ET) rates. Two of these swamps were monitored for another three years after one of them was clearcut. Estimated annual ET from undisturbed cypress swamps varied from 38 cm/yr to 86 cm/yr, averaging 60 cm (not including interception). Faster ET rates may have been related to faster pondcypress growth rates, a greater proportion of hardwoods in the canopy, and clearcutting in the surrounding pine plantation. The average ET rate was considerably lower than ET rates that have been estimated for north Florida pine plantations. However, incorporating estimates of interception indicates that overall ET rates in pondcypress swamps may be only slightly lower than ET from pine plantations. ET decreased only 5 percent in one swamp after it was clearcut, indicating that this management practice is not likely to affect regional water balances.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03995.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Along a drainage network, there is a systematic variation of average flow parameters (width, depth, and velocity) at flows having the same flow duration. Hydraulic geometry equations mathematically express this interdependent relationship of stream‐flow characteristics for a basin for annual flow durations varying from 10 to 90 percent. However, the equations proposed so far have had rather poor predictive performance for low flows. An independent investigation of the variation of discharge with drainage area and annual flow duration demonstrates a consistent relationship between these parameters. The relationship for the high to median‐flow range differs, however, from that for the median— to low‐flow range. The proposed equations provide a better predictive performance for low flows than previous formulations and a versatile means of estimating flow parameters for streams throughout a basin. The improved basin hydraulic geometry equations have a wide range of applications in areas such as stream habitat assessment, water quality modeling, channel design, and stream restoration p

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03996.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Using a geographic information system, a regression model has been developed to identify and to assess potential sources of selenium in the Kendrick Reclamation Project Area, Wyoming. A variety of spatially distributed factors was examined to determine which factors are most likely to affect selenium discharge in tributaries to the North Platte River. Areas of Upper Cretaceous Cody Shale and Quaternary alluvial deposits and irrigated land, length of irrigation canals, and boundaries of hydrologic subbasins of the major tributaries to the North Platte River were digitized and stored in a geographic information system. Selenium concentrations in samples of soil, plant material, ground water, and surface water were determined and evaluated. The location of all sampling sites was digitized and stored in the geographic information system, together with the selenium concentrations in samples. A regression model was developed using stepwise multiple regression of median selenium discharges on the physical and chemical characteristics of hydrologic subbasins. Results indicate that the intensity of irrigation in a hydrologic subbasin, as determined by area of irrigated land and length of irrigation delivery canals, accounts for the largest variation in median selenium discharges among subbasins. Tributaries draining hydrologic subbasins with greater intensity of irrigation result in greater selenium discharges to the North Platte River than do tributaries draining subbasins with lesser intensity of irrigation.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03997.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:The temporal and locational attributes of water use data are ideally suited for analysis using a geographic information system (GIS) approach. A GIS combines spatial database management, statistical analysis, and cartographic modelling capabilities within a computer hardware and software configuration. Texas water use data for selected categories in 1980 and 1986 were analyzed using ARC/INFO to demonstrate the utility of GIS for water resource information management. Examples of data analysis and display are presented to illustrate the effectiveness of cartographic representations to communicate water use data.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03998.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:Aquifer pumping represents, in many geographical locations, an alternative and/or a complementary source of water to surface water supplies. Several Catalonian coastal towns in the northeastern corner of Spain are in this situation. Also, since pumped water is used to supply drinking water, the main purpose in managing these water resources is to supply, no matter the cost, the amount needed at every moment. In other words, the managers of these aquifers attempt to optimize firm water yield. If we think of these aquifers as underground reservoirs with fixed storage capacity, most of the techniques which are applied to surface reservoirs can be implemented. In this paper we use a Stochastic Dynamic Programming model to optimize the yield from the aquifer of the Ridaura River. The objective function in this model was chosen with the aim of maximizing the reliability of the target yields in each of four seasons.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb03999.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACT:The main factor in the location of medieval Cracow was drainage. In the 700‐year history of the City, there were numerous changes in water conditions, particularly in channel network, runoff, ground water level, and ice phenomena. The most dangerous threat to surface water and ground water in Cracow in the last decades has been from industrial and municipal sewage. Currently there are no rivers that meet Drinking Water Quality standards in Cracow. The quality of the ground water has declined because of infiltration of contaminated river water, water from sewage disposal ponds, and pollution from the atmosphere and soil. Cracow does not have enough waste water plants to meet its needs. Most municipal and industrial sewage has not been treated or has been treated only partially. Because of considerable contamination of surface and ground waters in Cracow, more than half of the city's fresh water is pumped about 50 kilometers from a reservoir on the Raba River. A Polish government declaration of April 4, 1989, recognized Cracow as an area of particular protection, and directed that a number of actions be undertaken for the protection of environmental qualit

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1992.tb04000.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY