bluuebunny/crossref_metadata_2025 huggingface dataset:
GROUNDWATER DISCHARGE AND ITS IMPACT ON SURFACE WATER QUALITY IN A CHESAPEAKE BAY INLET1
Authors: Reay William G. , Gallagher Daniel L. , Simmons George M.
Published: June 2007

ABSTRACT: Surface water, groundwater, and groundwater discharge quality surveys were conducted in Cherrystone Inlet, on Virginia's Eastern Shore. Shallow groundwater below agricultural fields had nitrate concentrations significantly higher than inlet surface waters and shallow groundwater underlying forested land. This elevated nitrate groundwater discharged to adjacent surface waters. Nearshore discharge rates of water across the sediment‐water interface ranged from 0.02 to 3.69 liters·m−2·hr−1 during the surveys. The discharge was greatest nearshore at low tide periods, and decreased markedly with increasing distance offshore. Vertical hydraulic heads, Eh, and inorganic nitrogen flux in the sediments followed similar patterns. Nitrate was the predominant nitrogen species discharged nearshore adjacent to agricultural land use, changing to ammonium farther offshore. Sediment nitrogen fluxes were sufficient to cause observable impacts on surface water quality; nitrate concentrations were up to 20 times greater in areas of groundwater discharge than in the main stem inlet water. Based on DIN:DIP ratios, nitrogen contributions from direct groundwater discharge and tidal creek inputs appear to be of significant ecological importance. This groundwater discharge links land use activity and the quality of surface water, and therefore must be considered in selection of best management practices and water quality management strategies.
OPTIMAL LONG‐TERM SCHEDULING OF STORMWATER DRAINAGE REHABILITATION1
Authors: Jacobs Timothy L. , Medina Miguel A. , Kaufman Neil , Wood David M.
Published: June 2007

ABSTRACT: A mathematical model is developed to optimally schedule long‐term stormwater infrastructure rehabilitation activities. The model is capable of considering multiple rehabilitation projects and is driven by overall cost eensiderations. Rehabilitation activities are scheduled based on perceived reliabilities and future deterioration expected within the specified planning horizon. Future growth within the stormwater drainage basin is incorporated using chance constraints that limit the likelihood that a stormwater discharge exceeds system conveyance capacity. Model structure and development are discussed, and a hypothetical example using a drainage network is presented.
A PRACTICAL MODEL INTEGRATING QUALITY ASSURANCE INTO ENVIRONMENTAL MONITORING1
Authors: Clark Malcolm J. R. , Whitfield Paul H.
Published: June 2007

ABSTRACT: A model of comprehensive environmental monitoring process with integral quality assurance is presented. This model views the monitoring process as iterative cycles of a series of elements: design, plan, protocols, preparation, field liaison, sample collection, sample handling, laboratory analysis, data transmission, data validation, data approval, data provision, statistical analysis, and reporting. Quality assurance is linked to each element, not just to laboratory analysis. The program of quality assurance ensures that environmental monitoring data are compatible with the project goals, are comparable between various sampling agencies, and maintain a high degree of scientific credibility. The key characteristics of the overall quality assurance process are detailed documentation, timely resolution of problems, regular reporting, and routine independent audits.
MODELING URBAN NONPOINT SOURCE POLLUTION WITH A GEOGRAPHIC INFORMATION SYSTEM1
Authors: Ventura Stephen J. , Kim Kyehyun
Published: June 2007

ABSTRACT: A geographic information system (GIS) was a useful aid in the assessment of urban nonpoint source pollution and the development of a pollution control strategy. The GIS was used for data integration and display, and to provide data for a nonpoint source model. An empirical nonpoint source loading model driven by land use was used to estimate pollutant loadings of priority pollutants. Pollutant loadings were estimated at fine spatial resolution and aggregated to storm sewer drainage basins (sewersheds). Eleven sewersheds were generated from digital versions of sewer maps. The pollutant loadings of individual land use polygons, derived as the units of analysis from street blocks, were aggregated to get total pollutant loadings within each sewershed. Based on the model output, a critical sewershed was located. Pollutant loadings at major sewer junctions within the critical sewershed were estimated to develop a mitigation strategy. Two approaches based on the installation of wet ponds were investigated ‐ a regional approach using one large wet pond at the major sewer outfall and a multisite approach using a number of smaller sites for each major sewer junction. Cost analyses showed that the regional approach would be more cost effective, though it would provide less pollution control.
COMPARATWE EVALUATION OF FREQUENCY DISTRIBUTIONS FOR LOUISIANA EXTREME RAINFALL1
Authors: Naghavi Babak , Yu Fang Xin , Singh Vijay P.
Published: June 2007

ABSTRACT: A comparative study of five popular frequency distributions and three parameter estimation methods was conducted by using 92 Louisiana rainfall data sets. Computed results showed that the log‐Pearson type 3 (LPEAR3) distribution was the most appropriate probability distribution for the Louisiana rainfall data. Furthermore, the method of moments was found to be the best estimation method for the LPEAR3 distribution based on descriptive performance indices. A first‐order error analysis was performed on the parameters of the LPEAR3 distribution. Computed results showed that the predicted quantiles of the LPEAR3 distribution were most sensitive to the population mean and relatively insensitive to the coefficient of the skewness of the distribution.
ECONOMIC EVALUATION OF AESTHETIC AMENITIES: A CASE STUDY OF RIVER VIEW1
Authors: Kulshreshtha S. N. , Gillies J. A.
Published: June 2007

ABSTRACT: Presence of a river in an urban setting may contribute positively to an aesthetically pleasing environment. Such aesthetic effects are not typically linked to specific economic activities and occur, for example, when residents are exposed to a river‐view. Qualities enhancing the aesthetic value of the river include the presence of parks, trails, and vegetation along the riverbanks. The value of aesthetic amenities provided by the South Saskatchewan to the City of Saskatoon residents was estimated in this study using non‐market methods. The implicit price of the river view was estimated using the Hedonic Price Model, whereas value through willingness to pay for property taxes or higher rents were also estimated using actual market data. The total annual value of the river to the City of Saskatoon through addition of aesthetic amenities was estimated at $1.2 million in 1989 dollars.
VARIATIONS IN NORTHERN SIERRA NEVADA STREAMFLOW: IMPLICATIONS OF CLIMATE CHANGE1
Authors: Pupacko Alex
Published: June 2007

ABSTRACT: Historical records of streamflow for an eastward‐ and a westward‐draining stream in the northern Sierra Nevada have been analyzed for evidence of changes in runoff characteristics and patterns of variability. A trend of increasing and more variable winter streamflow began in the mid‐1960s. Mean monthly streaniflow during December through March was substantially greater for water years 1965–1990 compared to water years 1939–1964. Increased winter and early‐spring streamflow during the later period is attributed to small increases in temperature, which increase the rain‐to‐snow ratio at lower altitudes and cause the snowpack to melt earlier in the season at higher altitudes. The timing of snowmelt runoff on the western slope of the Sierra Nevada is more sensitive than it is on the eastern slope to changes in temperature, owing to predominantly lower altitudes on the west side. This difference in sensitivity suggests that basins on the east side of the Sierra Nevada have a more reliable water supply (as snow storage) than western‐slope basins during warming trends.
USE OF A GEOGRAPHIC INFORMATION SYSTEM TO ASSEMBLE INPUT‐DATA SETS FOR A FINITE‐DIFFERENCE MODEL OF GROUND‐WATER FLOW1
Authors: Hinaman Kurt C.
Published: June 2007

ABSTRACT: A Geographic Information System (GIS) was used to expedite assembly of input‐data sets for a model of ground‐water flow in the Middle Patuxent River basin in Howard County, Maryland. The model grid was developed with GIS and used to select attributes from GIS data coverages. These attributes were then output from GIS into the input‐data sets, which included model boundaries, regolith thickness, bedrock‐surface altitude, stream locations, stream length, stream‐bottom altitude, and trans‐missivity. The ability to change large sets of spatial data quickly and accurately with GIS enhances the model‐calibration process. (KEY TERMS: GIS; ground water; Piedmont; Maryland; MODFLOW.)
DETERMINATION OF HYDRAULIC C.ONDUCTWITY TENSOR USING A NONLINEAR LEAST SQUARES ESTIMATOR1
Authors: Heidari M. , Heigold P. C.
Published: June 2007

ABSTRACT: Reliable and consistent estimation of the components of the hydraulic conductivity tensor provides information needed to make proper decisions regarding clean up and restoration of contaminated aquifers. In this study, the nonlinear least‐squares estimation technique was applied to drawdown versus time data from three or more observation wells to determine a theoretical ellipse of equal drawdown. The angle of rotation of this ellipse with respect to the working coordinate axes was determined by a procedure based on contouring the drawdowns at a given time. This ellipse, in turn, was used to estimate the directions and magnitudes of the horizontal components of the hydraulic conductivity tensor. The technique is applicable to confined, as well as leaky, aquifers. Sources of error in this technique include nonhomogeneity of the aquifer and partial penetration of the pumping and observation wells into the aquifer. The procedure presented may be used as an additional tool to verify computations of hydraulic conductivity anisotropy based on other techniques.
A REVIEW OF APPLICATION ISSUES OF THE METROPOLITAN WATER DISTRICT‐MAIN WATER FORECASTING SYSTEM1
Authors: Thompson James G. , Parker Michael , Templin William , Reynolds Robert R.
Published: June 2007

ABSTRACT: This paper reviews the processes that occurred during an application of the Metropolitan Water District (MWD)‐MAIN water use forecasting system for the City of Salinas, California. The review includes an analysis of sources of available data, methods for estimating input data, calibration, and verification of the MWD‐MAIN System, and an evaluation of the reliability of system output. We found that inexperienced users can have difficulty understanding the level of skill, knowledge, and amount of data that are required to produce reliable forecasts.

Some of the issues associated with application of the MWD‐MAIN System include the following:

All input data needed for accurate forecasts simply are not available for many cities and towns.

The data requirements are more extensive than many users anticipate.

Substantial requirements for manipulation of input data produces opportunity for error that creates major time demands in troubleshooting.

Calibration and verification for specific uses can be substantially more difficult than is readily apparent from the guidance manual.

Independent validity checks need to be done to validate system output.

If specified calibrating procedures do not produce reasonable results, reestimating slope coefficients is an option, but this requires resources and expertise that can easily exceed the limits of most users.

These are problems typical of most complex models. Reviews such as this can help users to appreciate the level of data required, and to use the MWD‐MAIN System in a more effective and efficient manner.
CLASSIFICATION OF ENVIRONMENTAL HYDROLOGIC BEHAVIORS IN THE NORTHEASTERN UNITED STATES1
Authors: Kim Kyehyun , Hawkins Richard H.
Published: June 2007

ABSTRACT: Environmental response to acidic deposition results from movement of water through the ecosystem. As a part of the environmental studies for acidic deposition sponsored by the U.S. Environmental Protection Agency (EPA), hydrologic classification based on regional baseflow properties was done. To obtain the amount of baseflow, a flow separation method was developed based on the division of streamflows into “baseflow” and “other” runoff sources. Because of the differences in the flow paths and exposure duration, the two components were assumed to be associated with distinct geo‐chemical responses. Individual annual hydrographs were analyzed using 31 separation slopes to determine the amount of baseflow. A total of 1575 streamflow stations in the Northeastern U.S. were analyzed through the access of a long‐term daily stream‐flow data base. An interactive computer program was developed to obtain baseflow properties and other hydrologic characteristics of each station. The output from this analysis was used to perform cluster analysis to classify streamflow behaviors. The clustering output showed different regional boundaries than those currently used by the EPA for water quality studies.
EFFECTS OF CLIMATE CHANGE ON WATER RESOURCES IN THE DELAWARE RWER BASIN1
Authors: Wolock David M. , McCabe Gregory J. , Tasker Gary D. , Moss Marshall E.
Published: June 2007

ABSTRACT: The effects of potential climate change on water resources in the Delaware River basin were determined. The study focused on two important water‐resource components in the basin: (1) storage in the reservoirs that supply New York City, and (2) the position of the salt front in the Delaware River estuary. Current reservoir operating procedures provide for releases from the New York City reservoirs to maintain the position of the salt front in the estuary downstream from freshwater intakes and ground‐water recharge zones in the Philadelphia metropolitan area.

A hydrologic model of the basin was developed to simulate changes in New York City reservoir storage and the position of the salt front in the Delaware River estuary given changes in temperature and precipitation. Results of simulations indicated that storage depletion in the New York City reservoirs is a more likely effect of changes in temperature and precipitation than is the upstream movement of the salt front in the Delaware River estuary. In contrast, the results indicated that a rise in sea level would have a greater effect on movement of the salt front than on storage in the New York City reservoirs. The model simulations also projected that, by decreasing current mandated reservoir releases, a balance can be reached wherein the negative effects of climate change on storage in the New York City reservoirs and the position of the salt front in the Delaware River estuary are minimized. Finally, the results indicated that natural variability in climate is of such magnitude that its effects on water resources could overwhelm the effects of long‐term trends in precipitation and temperature.
RESERVOIR SEDIMENTATION RATES LINKED TO LONG‐TERM CHANGES IN AGRICULTURAL LANI) USE1
Authors: McIntyre Sherwood C.
Published: June 2007

ABSTRACT: Long‐term land use and reservoir sedimentation were quantified and linked in a small agricultural reservoir‐watershed system without having historical data. Land use was determined from a time sequence of aerial photographs, and reservoir sedimentation was determined from cores with 137Cs dating techniques. They were linked by relating sediment deposition to potential sediment production which was determined by the Universal Soil Loss Equation and by SCS estimates for gullied land. Sediment cores were collected from Tecumseh Lake, a 55‐ha reservoir with a 1,189‐ha agricultural watershed, constructed in 1934 in central Oklahoma. Reservoir sediment deposition decreased from an average of 5,933 Mg/yr from 1934 to 1954, to 3,179 Mg/yr from 1954 to 1962, and finally to 1,017 Mg/yr from 1962 to 1987. Potential sediment production decreased from an average of 29,892 to 11,122 and then to 3,589 Mg/yr for the same time periods as above, respectively. Reductions in deposition and sediment production corresponded to reductions in cultivated and abandoned cropland which became perennial pasture. Together, cultivated and abandoned cropland accounted for 59 percent of the watershed in 1937, 24 percent in 1954, and 10 percent in 1962. Roadway erosion, stream bank erosion, stored stream channel sediment, and long‐term precipitation were considered, but none seemed to play a significant role in changing sediment deposition rates. Instead, the dominant factor was the conversion of fields to perennial pastures. The effect of conservation measures on reservoir sedimentation can now be quantified for many reservoirs where historical data is not available.
SOUTH PLATTE RIVER BASIN ‐ COLORADO, NEBRASKA, AND WYOMING1
Authors: Dennehy Kevin F. , Litke David W , Tate Cathy M. , Heiny Janet S.
Published: June 2007

ABSTRACT: The South Platte River Basin was one of 20 study units selected in 1991 for investigation under the U.S. Geological Survey's National Water‐Quality Assessment (NAWQA) program. One of the initial tasks undertaken by the study unit team was to review the environmental setting of the basin and assemble ancillary data on natural and anthropogenic factors in the basin. The physical, chemical, and biological quality of the water in the South Platte River Basin is explicitly tied to its environmental setting. The resulting water quality is the product of the natural conditions and human factors that make up the environmental setting of the basin.

This description of the environmental setting of the South Platte River Basin and its implications to the water quality will help guide the design of the South Platte NAWQA study. Natural conditions such as physiography, climate, geology, and soils affect the ambient water quality while anthropogenic factors such as water use, population, land use and water‐management practices can have a pronounced effect on water quality in the basin. The relative effects of mining, urban, and agricultural land‐ and water‐uses on water‐quality constituents are not well understood. The interrelation of the surface‐water and ground‐water systems and the chemical and biological processes that affect the transport of constituents needs to be addressed. Interactions between biological communities and the water resources also should be considered. The NAWQA program and the South Platte River Basin study will provide information to minimize existing knowledge gaps, so that we may better understand the effect these natural conditions and human factors have on the water‐quality conditions in the basin, now and in the future.
EFFECT OF SIMULATED CLIMATE CHANGE ON SNOWMELT RUNOFF MODELING IN SELECTED BASINS1
Authors: van Katwijk V. F. , Rango A. , Childress A. E.
Published: June 2007

ABSTRACT: The projected increase in the concentration of CO2 and other greenhouse gases in the atmosphere is likely to result in a global temperature increase. This paper reports on the probable effects of a temperature increase and changes in transpiration on basin discharge in two different mountain snowmelt regions of the western United States. The hydrological effects of the climate changes are modeled with a relatively simple conceptual, semi‐distributed snowmelt runoff model. Based on the model results, it may be concluded that increased air temperatures will result in a shift of snowmelt runoff to earlier in the snowmelt season. Furthermore, it is shown that it is very important to include the expected change in climate‐related basin conditions resulting from the modeled temperature increase in the runoff simulation. The effect of adapting the model parameters to reflect the changed basin conditions resulted in a further shift of streamflow to April and an even more significant decrease of snowmelt runoff in June and July. If the air temperatures increase by approximately 5°C and precipitation and accumulated snow amounts remain about the same, runoff in April and May, averaged for the two basins, is expected to increase by 185 percent and 26 percent, respectively. The runoff in June and July will decrease by about 60 percent each month. Overall, the total seasonal runoff decreases by about 6 percent. If increased CO2 concentrations further change basin conditions by reducing transpiration by the maximum amounts reported in the literature, then, combined with the 5°C temperature increase, the April, May, June, and July changes would average +230 percent, +40 percent, −55 percent, and −45 percent, respectively. The total seasonal runoff change would be +11 percent.
SUBSTATE INSTITUTIONAL INNOVATION FOR MANAGING LAKES AND WATERSHEDS: A WISCONSIN CASE STUDY1
Authors: Nakamura Liane , Born Stephen M.
Published: June 2007

ABSTRACT: Since the 1970s, there has been extensive experimentation with new approaches to water and land resources management at the state and local levels. There is a critical need to document, assess, and synthesize lessons learned from the nation's recent experience with subnational institutional changes in environmental management. This paper examines institutional changes aimed at more integrated water and related resources management at the substate level of government. We describe innovative institutional changes in a case study of Dane County, Wisconsin, and assess the implementation and preliminary consequences of these changes.

Dissatisfaction with watershed and lake management results and perceptions of institutional inadequacy led to significant changes in the structure and rules for county resources management. A new entity was created to focus watershed management responsibilities. The scope of authority and powers were expanded. However, these changes all occurred within the framework of a general purpose unit of government. The new institutional arrangements have achieved a number of milestones, although it is premature to fully assess resource outcomes. The substantive changes, implementation tactics, and overall experience in Dane County's reforms ‐ especially with regard to addressing intergovernmental tensions and decentralized management, limited authorities and funding, and public and constituency support ‐ have useful implications for other substate efforts at more comprehensive and integrated water resources management.
CHANGING WATER BALANCE OVER TIME IN RUSH CREEK, EASTERN CALIFORNIA, 1860–19921
Authors: Kondolf G. Mathias. , Vorster Peter
Published: June 2007

ABSTRACT: Rush Creek, the principal tributary to Mono Lake, has undergone profound hydrologic modifications as a result of flow regulation for hydroelectric generation and irrigation, diversions for irrigated agriculture, and diversions for water export to the City of Los Angeles. Lower Rush Creek (the lowermost 13 km downstream of Grant Lake Reservoir) was dry by 1970, but now receives flow as a result of court‐ordered efforts to restore former ecological conditions. Using available historic data and recent field measurements, we constructed the water balance for Lower Rush Creek, identifying six distinct historical periods characterized by very different patterns of gain and loss. The hydrologic patterns must be understood as a basis for modeling ecosystem response to stream‐flow alteration. A gradually gaining stream under natural conditions, the advent of irrigation diversions caused the middle reaches of Lower Rush Creek to be often completely dry, while irrigation‐recharged springs still maintained a baseflow in the downstream “Meadows” ranch. Increased water exports from the basin subsequently reduced irrigation and dried up the springs.
INTEGRATING GEOGRAPHIC INFORMATION SYSTEMS AND MODFLOW FOR GROUND WATER RESOURCE ASSESSMENTS1
Authors: Richards Christopher J. , Roaza Honesto , Roaza Ruth Montgomery
Published: June 2007

ABSTRACT: The Floridan Aquifer is the primary source of water in the coastal area of Santa Rosa County, Florida. In order to optimize well field design and analyze aquifer stress problems, the USGS MODFLOW code (McDonald and Harbaugh, 1988) is applied to develop a numerical computer model of the aquifer. The Geographical Information System (GIS) is the primary tool used in the development of the model grid, performance of the modeling procedure, and model analysis. The GIS is used in generating multiple grids in which to simulate both regional scale and local scale flow. The grid topology is recorded in geographic coordinates which facilitates geo‐referencing and orientation of the grid to base maps and data coyerages. The GIS allows data transfer from various coverages to the nodes of the block centered grid where hydrogeologic information is stored as attributes to the grid coverage. From this grid coverage, pertinent information is queried within the GIS environment and used to generate the input files for the MODFLOW simulation. After MODFLOW execution, simulated heads and drawdown are imported into the grid coverage where residual error and recharge rates can be calculated. Contoured surfaces are then created for selected data sets including simulated heads, drawdown, residual error, and recharge rates. Model calibration is conducted utilizing the GIS to generate and process data sets associated with model simulations.
PRECIPITATION MEASUREMENT BIASES IN THE UNITED STATES1
Authors: Legates David R. , DeLiberty Tracy L.
Published: June 2007

ABSTRACT:Gage‐induced biases in monthly precipitation are estimated and removed at 1818 stations across the continental United States from 1950 through 1987. Deleterious effects of the wind and wetting losses on the interior walls of the gage were considered. These “corrected” estimates were obtained using site‐specific information including wind speed, shelter‐height air temperature, gage height, and sheltering. Wind speed and air temperature were interpolated at stations for which these data were not available using a spherically‐based, nearest neighbor interpolation procedure. Results indicate that, as expected, biases are greater in the winter than the summer owing to the increased problems (particularly wind‐induced) of measuring snowfall. In summer, percent errors range between 4 and 6 percent over nearly three‐quarters of the United States with slightly larger errors over the Rocky Mountains. By contrast, winter biases are highly correlated with snowfall totals and percentage errors increase poleward, mimicking patterns of snowfall frequency. Since these biases are not trivial, they must be accounted for in order to obtain accurate and reliable time‐series. If these biases are not properly addressed, serious errors can be introduced into climate change, hydrologic modeling, and environmental impact research.
INTEGRATION OF GEOGRAPHIC INFORMATION SYSTEMS AND A COMPUTER MODEL TO EVALUATE IMPACTS OF AGRICULTURAL RUNOFF ON WATER QUALITY1
Authors: He Chansheng , Riggs James F , Kang Yung‐Tsung
Published: June 2007

ABSTRACT: This study integrates an Agricultural Non‐Point Source Pollution Model (AGNPS), the Geographic Resource Analysis Support System (GRASS) (U.S. Army Corps of Engineers, 1987), and GRASS WATERWORKS (a hydrologic modeling tool box being developed at the Michigan State University Center for Remote Sensing) to evaluate the impact of agricultural runoff on water quality in the Cass River, a subwatershed of Saginaw Bay. AGNPS is used to estimate the amounts, origin, and distribution of sediment, nitrogen (N), and phosphorus (P) in the watershed. GRASS and GRASS WATERWORKS are used to generate parameters needed for AGNPS from digital maps, which include soil association, land use, watershed boundaries, water features, and digital elevation. Outputs of the model include spatially distributed estimates of volume and peak runoff, overland and channel erosion, sediment yields, and concentrations of nitrogen and phosphorus. Management scenarios are explored in the AGNPS model to minimize sedimentation and nutrient loading. Scenarios evaluated include variations in crop cover, tillage methods, and other agricultural management practices. In addition, areas vulnerable to erosion are identified for best management practices.
MAXIMIZING THE VALUE OF INFORMATION FOR GROUND WATER PROTECTION: THREE TEST CASES1
Authors: Flockhart Dina E. , Sham Chi Ho , Xiao Yan
Published: June 2007

ABSTRACT: Public awareness of the importance of protecting the nation's water supplies is growing. Recent studies have shown a substantial increase in the perceived value of protecting water supplies for future use. In the Northeast, much of the water supply comes from ground water. This paper examines three test cases, each with different approaches for using geographic information systems (GIS) for ground water protection planning. In Wellfleet, Massachusetts, build‐out scenarios were used to support regulatory and land acquisition decisions for siting a public water supply well. In Hadley, Massachusetts, the focus was on a decision support model for septic suitability assessment in support of regulatory efforts and infrastructure expansion. For Cortland County, New York, an interactive graphic user interface was created to facilitate the manipulation and recombination of a large volume of data by county officials to target ground water pollution prevention efforts. As personal computers become more powerful and inexpensive, and GIS data become more readily available, community and county governments are turning to GIS as a tool for developing comprehensive resource protection plans. Once appropriate data are input, a GIS can effectively and efficiently be used to derive outcomes of various land use plans and regulations.
HYDROLOGIC MODELING WITH REMOTELY SENSED DATABASES1
Authors: Cruise J. F. , Miller R. L.
Published: June 2007

ABSTRACT: An integrated remotely sensed database was used as the basis for a hydrologic and sediment transport modeling effort for an agricultural area of western Puerto Rico. Classified spectral images of airborne radiance data provided ground cover information and were used in conjunction with topographic and soils data to guide model construction and provide input to the water balance and sediment yield simulations. Runoff and sediment discharge from hydrologically homogeneous regions were routed through the drainage network and combined at the basin outlet. The model was used to simulate four years of observed sediment discharge from the basin. Relative contributions to the total sediment yield of forested and agricultural areas were determined and compared.
DEVELOPMENT OF A BASIN GEOMORPHIC INFORMATION SYSTEM USING A TIN‐DEM DATA STRUCTURE1
Authors: Tachikawa Y , Shiiba M. , Takasao T
Published: June 2007

ABSTRACT: To make a distributed rainfall‐runoff model, it is very important to build a model of topographic surface of a basin which takes account of the direction of water flow. In this paper, a geographic information system in hydrologic modeling, the BGIS (Basin Geomorphic Information Systems) are presented for modeling a river basin using a TIN‐DEM (Triangulated Irregular Network ‐ Digital Elevation Model) data structure. The BGIS have two core systems, which are the TIN‐DEM generating system and the topographic analysis system. In the TIN‐DEM generating system, landscapes are modeled as a set of contiguous non‐overlapping terangular facets whose vertices are made up of points on a regular grid DEM and on river segments. These triangular facets are subdivided, if needed, so that each of them has only one side through which water flows out. The TIN‐DEM generating system is made up of four modules, (1) a module for generating triangles from a grid DEM, (2) a module for getting rid of pits, (3) a module for joining discontinuous valley segments to a channel network, (4) a module for subdividing triangular facets. In the topographic analysis system, using datasets processed with the TIN‐DEM generating system, a watershed source area for any segments in a stream network are delineated automatically, and topographic attributes of slopes, aspects, flow path lengths and upslope contributing areas are computed.
A COMPARISON OF SURFACE RUNOFF AND SEDIMENT YIELDS FROM LOW‐ AND HIGH‐SEVERITY SITE PREPARATION BURNS1
Authors: Robichaud P. R. , Waldrop T A.
Published: June 2007

ABSTRACI:. Slash burning is a common site preparation technique used after timber harvest throughout the Southeastern United States. Little quantitative information exists on the hydrologic response to burn severity. This study compared the effects of low‐severity and high‐severity burns on runoff and sediment yields during rainfall simulation and during natural rainfall in the Southern Appalachian Mountains. Fire severity was largely determined by moisture conditions of the forest floor prior to ignition. Runoff and sediment yield variability was high between plots within the same treatment area due to differences in forest floor characteristics and infiltration rates. Conditions of high‐severity resulted when burning was conducted with relatively dry fuels. Sediment yields were 40‐times greater for the high‐severity treatment areas than the low‐severity treatment areas.
SOIL MOISTURE SENSORS FOR CONTINUOUS MONITORING1
Authors: Amer Saud A. , Keefer Timothy O. , Weltz Mark A. , Goodrich David C. , Bach Leslie B.
Published: June 2007

ABSTRACT: Certain physical and chemical properties of soil vary with soil water content. The relationship between these properties and water content is complex and involves both the pore structure and constituents of the soil solution. One of the most economical techniques to quantify soil water content involves the measurement of electrical resistance of a dielectric medium that is in equilibrium with the soil water content. The objective of this research was to test the reliability and accuracy of fiberglass soil‐moisture electrical resistance sensors (ERS) as compared to gravimetric sampling and Time Domain Reflectometry (TDR). The response of the ERS was compared to gravimetric measurements at eight locations on the USDA‐ABS Walnut Gulch Experimental Watershed. The comparisons with TDR sensors were made at three additional locations on the same watershed. The high soil rock content (≥45 percent) at seven locations resulted in consistent overestimation of soil water content by the ERS method. Where rock content was less than 10 percent, estimation of soil water was within 5 percent of the gravimetric soil water content. New methodology to calibrate the ERS sensors for rocky soils will need to be developed before soil water content values can be determined with these sensors.
DIQUAT DISTRIBUTION IN WATER AFTER APPLICATION TO SUBMERSED WEEDS1
Authors: Langeland K A. , Fox A. M. , Laroche F B. , Martin B. B. , Martin D. F. , Norris C. D. , Wang C.
Published: June 2007

ABSTRACT: Diquat herbicide and rhodamine WT dye were applied in a lake to three 1.6 ha plots either with a polymer, which reportedly aids in sinking and confinement of aquatic herbicides, or without a polymer. Diquat and dye concentrations were measured at three different depths in the water column within the plots during the first three hours after application to determine vertical distribution of diquat and dye, and in composite samples at fixed distances from the plot up to 168 hours after application to determine movement out of the treated plots. Diquat and dye were homogeneous in the water column when no polymer was used, but were concentrated near the surface when polymer was used. This distribution may have resulted from temperature stratification. Polymer did not affect movement of diquat or dye out of the plots. The half‐lives of diquat within the plots were 25 (SE=6.2) hr, 39 (SE=4.3) hr, and 25 (SE=2.0) hr. Forty‐six percent of samples collected at the edges of the plots did not contain detectable diquat residues and only 66 percent of those samples with detectable diquat contained greater than the potable water tolerance (10 ppb). Diquat was not found in any samples 168 hours after application 61 m or farther from the edge of the plots. Dye and diquat concentrations were weakly correlated within and outside the plots. Dye half‐lives were consistently higher than diquat, which suggests that the herbicide was removed from the water by plants and sediments more rapidly than dye.
USE OF WATER FROM THE ANCIENT MAKKAH GALLERIES FOR IRRIGATION1
Authors: Abu‐Rizaiza Omar S. , Mohorjy Abdullah M.
Published: June 2007

ABSTRACT: Due to the spread of Islam in the seventh century the number of pilgrims to the City of Makkah increased sharply, resulting in an acute water shortage. To solve this problem, galleries were built to collect water from the upstream of Wadi Naaman and transfer it to Makkah.

Expansion of Makkah and the absence of any mapping of the galleries have resulted in the destruction of a part of the galleries. This caused a discontinuity of flow in the galleries and, consequently, the ground water table is rising at a rate of 0.48 m/yr, causing environmental problems. Research was conducted to rehabilitate the destructed part of the galleries, and to find an appropriate use for the ground water. The study found that the quality of the ground water is suitable for landscaping purposes, that is, for the irrigation of trees and ornamental plants.
FUZZY DECISION MAKING IN GROUND WATER NITRATE RISK MANAGEMENT1
Authors: Lee Yong W. , Dahab Mohamed F , Bogardi Istuan
Published: June 2007

ABSTRACT: Ground water nitrate contamination is widespread in the United States and especially prevalent in agriculture‐intensive areas such as the Midwest. To reduce human health risks (i.e., methemoglobinemia and cancer risks) from nitrates in ground water supplies, several nitrate risk‐management strategies can be developed based on acceptable levels of human health risks, the reasonableness of the cost required for risk reduction, and the technical feasibility of nitrate‐control methods. However, due to a lack of available information, assessing risk, cost, and technical feasibility contains elements of uncertainty.

In this paper, a nitrate risk‐management methodology using fuzzy sets in combination with a multicriterion decision‐making (MCDM) technique is developed to assist decision makers in evaluating, with uncertain information, possible regulatory actions along with the various nitrate risk‐management strategies in order to determine an appropriate strategy. The methodology is illustrated using data from a community with a nitrate water‐quality problem.
USING WATER HYACINTH TO TREAT MUNICIPAL WASTEWATER IN THE DESERT SOUTHWEST1
Authors: Karpiscak Martin M. , Foster Kennith E. , Hopf Susan B. , Bancroft John M. , Warshall Peter J.
Published: June 2007

ABSTRACT: Water hyacinth (Eichhornia crassipes L.) has shown to be effective in the treatment of municipal wastewater in a pilot study begun in January 1989 by the Pima County Wastewater Management Department and researchers associated with The University of Arizona's Office of Arid Lands Studies in the Sonoran Desert near Tucson. The influent pumped into the pilot facility's six raceways (ponds) typically has been treated secondary effluent diverted from a conventional treatment facility, although primary effluent from the same facility also has been treated. The Secondary Influent Treatment System has met the Arizona Department of Environmental Quality (ADEQ) tertiary standard for BOD5 and TSS of 10 mg/l for every month of its operation since March 1990; the Primary Influent Treatment System met the ADEQ secondary standard for BOD5 and TSS of 30 mg/1 for most of the 10 months it was in operation.
ESTIMATION OF VOLUME‐DURATION‐FREQUENCY RELATIONS OF UNGAGED SMALL URBAN STREAMS IN OHIO1
Authors: Sherwood James M.
Published: June 2007

ABSTRACT: This paper describes methods for estimating volume‐duration‐frequency relations of urban streams in Ohio with drainage areas less than 6.5 square miles. The methods were developed to assist engineers in the design of hydraulic structures on urban streams for which temporary storage of water is an important element of the design criteria. Multiple‐regression equations were developed for estimating maximum flood volumes of d‐hour duration and T‐year recurrence interval (dVT). Maximum annual flood‐volume data for all combinations of six durations (1, 2, 4, 8, 16, and 32 hours) and six recurrence intervals (2, 5, 10, 25, 50, and 100 years) were analyzed. The significant explanatory variables in the resulting 36 volume‐duration‐frequency equations are drainage area, average annual precipitation, and basin‐development factor. Standard errors of prediction for the 36 dVT equations range from ±28 percent to ±44 percent.
DESERT HOUSE: A DEMONSTRATION/EXPERIMENT IN EFFICIENT DOMESTIC WATER AND ENERGY USE1
Authors: Karpiscak Martin M. , Brittain Richard G. , Foster Kennith E.
Published: June 2007

ABSTRACT: In May 1993, a single‐family home and adjoining information center opened to the public at the Desert Botanical Garden in Phoenix, Arizona. Desert House is designed as an example of what can be achieved today using available technology to improve residential water and energy efficiency. The home is expected to reduce water and energy use by 40 percent compared with that for the typical three‐bedroom, single‐family residence in the Phoenix area. Water‐conserving features include: landscape design employing low‐water use plants, minimum turf area, mulch around plants to reduce evaporation, and drip irrigation system; spa cover for evaporation reduction; rainwater harvesting; low‐flow shower heads, faucets, and toilets; and graywater reuse system. The home will be occupied by a family and monitored for water and energy use by computer. Visitors are able to access real time water and energy use data about the home, as well as tour the information center, technical exhibits, surrounding landscape, and the home when it is open (one afternoon a week).
JUDICIAL RESOLUTION OF TRANSBOUNDARY WATER CONFLICTS 1
Authors: Matthews Olen Paul
Published: June 2007

ABSTRACT: Transboundary water conflicts occur under four circumstances. Because water is mobile, more than one political unit or owner has power to use water as it sequentially moves through the hydrologic cycle. Even when water doesn't move, jurisdictional conflicts occur because multiple political units regulate water simultaneously. When a river is a boundar uncertainty of ownership or jurisdiction occurs as the river shifts its course through natural processes. Lastly, limitations on who may use water may be imposed by export bans or more indirect measures like taxation. Legal solutions to transboundary conflicts are limited to litigation, legislation, and negotiated agreements. This paper examines the judicial solution.
INTERSTATE WATER ALLOCATION COMPACTS IN THE WESTERN UNITED STATES ‐ SOME SUGGESTIONS1
Authors: McCormick Zachary L.
Published: June 2007

ABSTRACT: Agreements between states, or compacts, provide a mechanism for resolving transboundary resource issues. The twenty‐two compacts allocating the water of rivers among states in the western United States are examined to provide guidance for drafters of future compacts. The method of allocation selected for a compact reflects the state's allocation of the risk of dry years. Allocations based on models have been unsuccessful. Percentage allocations are good for fairly apportioning risk, but conflict with principles of prior appropriation. Guarantees of minimum flows should be used with great care, to avoid any state becoming a guarantor of natural phenomena over which it has no control. Disputes should be anticipated, and a dispute resolution mechanism agreed upon. Arbitration or litigation are likely to prove the most politically acceptable. Compacts should be comprehensive in scope, encompassing groundwater as well as surface use. Federal claims should also be addressed, and some form of protection from subsequent changes of federal policy should be incorporated in the agreement and its ratifying legislation.
HYDROLOGIC MODELING OF LAND PROCESSES IN PUERTO RICO USING REMOTELY SENSED DATA1
Authors: Cruise J. F. , Miller R. L.
Published: June 2007

ABSTRACT: An integrated, multi‐disciplinary effort to model land processes affecting Mayaguez Bay in western Puerto Rico is described. A modeling strategy was developed to take advantage of remotely sensed data. The spatial, interannual, and seasonal variability of sediment discharges to the bay were also evaluated. Classified images of remotely sensed data revealed the spatial distribution and quantities of land use classes in the region and aided in the discretization of the watershed into homogeneous regions. These regions were modeled using a geomorphic modeling technique based upon spatially averaged parameters.

Simulation results from the modeling effort compared favorably with observations at two locations within the watershed. Results showed that runoff and sediment loads from the area exhibit a marked seasonal trend and that deforested areas located in the foothill regions of the watershed contribute a disproportionate share of the sediment load to the bay. In years when rainfall distributions are uniformly distributed over the area, the sediment yields may be up to 100 percent higher than years when the rainfall is concentrated in the heavily forested mountainous regions.
ECONOMICS OF SCREENING FOR PESTICIDES IN GROUND WATER1
Authors: Natarajan Usha , Rajagopal R.
Published: June 2007

ABSTRACT: In the United States, millions of dollars are currently spent to monitor water quality for a whole suite of organic compounds. However, results of several surveys conducted in the past decade indicate that only a few pesticides occur in a small proportion of wells. Screening methods based on historical evidence of contamination patterns and knowledge of the locales will have significant potential to reduce these costs and effectively identify contamination problems. In this paper, the economics of utilizing two screening methods, sequential analysis and sample compositing, in the design of monitoring strategies is captured In the form of mathematical models and illustrated for a state‐level monitoring program. When the two methods are adopted, the total analytical cost to conclusively identify contaminated wells in a network of 4,000 wells is shown to range from $12,500 to $1,575,000 depending on the extent of contamination. In contrast, the total analytical cost of a conventional program where all the wells in the network are sampled and tested for a standard suite of pesticides at a cost of $250/sample is one million dollars. Given such wide range in costs, it is prudent to incorporate the screening concepts presented in this paper in the development of cost‐effective monitoring programs.
PRIORITIZING NONPOINT SOURCE PHOSPHORUS LOADING USING A GRASS‐MODELING SYSTEM1
Authors: Chen Zhenquan , Storm Daniel E. , Smolen Michael D. , Haan C. T. , Gregory Mark S. , Sabbagh George J.
Published: June 2007

ABSTRACT: A UNIX‐based windows application was developed to integrate a phosphorus transport model with the Geographic Resources Analysis Support System (GRASS). The system prioritizes potential phosphorus loading from fields or cells in a watershed and can evaluate the effects of alternate management practices on phosphorus yield. The model simulates phosphorus loading by using a daily mass balance on a unit‐area basis and incorporates the effects from rainfall, topography, soil properties, fertilizer and animal waste application, and management. Model predictions include dissolved and sediment‐bound phosphorus yield, runoff volume, and sediment yield. Within the integrated GRASS‐modeling system, the user can obtain model input data, execute the model using various options, rank model input and out. put data, and display them as GRASS‐based maps or data tables. All functions are menu driven, developed using C language and X‐window tools to run on a SUN workstation platform. The system provides a powerful and efficient tool for prioritizing phosphorus loading from nonpoint sources.