bluuebunny/crossref_metadata_2025 huggingface dataset:
EVALUATION OF GREAT LAKES NET BASIN SUPPLY FORECASTS1
Authors: Croley Thomas E. , Lee Deborah H.
Published: June 2007

ABSTRACT: Evaluation of the Great Lakes Environmental Research Laboratory's (GLERL's) physically‐based monthly net basin supply forecast method reveals component errors and the effects of model improvements for use on the Laurentian Great Lakes. While designed for probabilistic outlooks, it is assessed for giving deterministic outlooks along with other net basin supply forecast methods of the U.S. Army Corps of Engineers and Environment Canada, and with a stochastic approach commissioned by the Corps. The methods are compared to a simple clima‐tological forecast and to actual time series of net basin supplies. Aetual net basin supplies are currently determined by estimating all components directly, instead of as water‐balance residuals. This is judged more accurate and appropriate for both forecasting and simulation. GLERL's physically‐based method forecasts component supplies while the other methods are based on residual supplies. These other methods should be rederived to be based on component supplies. For each of these other methods, differences between their outlooks and residual supplies are used as error estimates for the rederived methods and component supplies. The evaluations are made over a recent period of record high levels followed by a record drought. Net basin supply outlooks are better than climatology, and GLERL's physically‐based method performs best with regard to either component or residual net basin supplies. Until advances are made in long‐range climate outlooks, deterministic supply outlooks cannot be improved significantly.
THE VRANA LAKE HYDROLOGY (ISLAND OF CRES ‐ CROATIA)1
Authors: Bonacci Ognjen
Published: June 2007

ABSTRACT: The Vrana Lake on the island of Cres in the Adriatic Sea represents a specific phenomenon of karst hydrology. The island of Cres covers an area of 404.3 km2 with an average volume of 220 × 106 m3 of fresh water in the lake. The island has an average rainfall of 1,063 mm, with a Mediterranean climate. The lake has a bottom reaching a depth of 62 m below mean sea level. The average water level is 14 m above mean sea level. The most probable theories on the origin of the lake and its hycirologic‐hydrogeologic functioning state that it is a flooded poije in karst. The water budget method was used to define the lake catchments area at approximately 25 km2. During the last six years, there has been drastic decrease of about 3 m in the lake's water level. This phenomenon was analyzed and it was calculated that 53 percent of the water‐level decline was caused by water discharges from the lake to satisfy water supply demands, and 47 percent was due to a period of low precipitation during the analyzed period.
A MATHEMATICAL MODEL OF SALMONID SPAWNING HABITAT1
Authors: Havis Robert N. , Alonso Carlos V. , King John G. , Thurow Russell F.
Published: June 2007

ABSTRACT: A simulation model [Salmonid Spawning Analysis Model (SSAM)] was developed as a management tool to evaluate the relative impacts of stream sediment load and water temperature on salmonid egg survival. The model is useful for estimating acceptable sediment loads to spawning habitat that may result from upland development, such as logging and agriculture. Software in common use in the USA were adapted for use in gravel bedded rivers and linked to simulate water temperature (the USFWS Instream Water Temperature, SNTEMP model) and water and sediment routing (the USAE Scour and Deposition in Rivers and Reservoirs, HEC‐6 model, version 3.2). These models drive the redd (spawning nest) model (the USDA‐ABS Sediment Intrusion Dissolved Oxygen SIDO model) which simulates sediment intrusion and dissolved oxygen concentration in the redd environment. The SSAM model predictions of dissolved oxygen and water temperature compared favorably with field data from artificial redds containing hatchery chinook salmon eggs.
UTILIZATION OF A GEOGRAPHIC INFORMATION SYSTEM TO IDENTIFY THE PRIMARY AQUIFER PROVIDING GROUND WATER TO INDWIDUAL WELLS IN EASTERN ARKANSAS1
Authors: Baker Nancy T.
Published: June 2007

ABSTRACT: A Geographic Information System (GIS) was used to develop an automated procedure for identifying the primary aquifers supplying ground water to individual wells in eastern Arkansas. As mandated by state law, water‐use data are reported by ground‐water withdrawers annually to the Arkansas Soil and Water Conservation Commission, and stored in the Arkansas Site‐Specific Water‐Use Data System provided and supported by the U.S. Geological Survey. Although most withdrawers are able to provide the amount of water withdrawn and the depth of their wells, very few are able to provide the name of the aquifer from which they withdraw water.

GIS software was used to develop an automated procedure for identifying the primary aquifers supplying ground water to individual wells in eastern Arkansas. The software was used to generate a spatial representation of the bottom boundary for the Mississippi River Valley alluvial aquifer (the shallowest aquifer) in eastern Arkansas from well log‐data collected by the U.S. Geological Survey. The software was then used to determine the depth of the aquifer bottom at reported well locations to ascertain whether the Mississippi River Valley alluvial aquifer or a deeper aquifer was the primary aquifer providing water to each well. The alluvial aquifer was identified as the primary aquifer for about 23,500 wells.
PROBABILISTIC GREAT LAKES HYDROLOGY OUTLOOKS1
Authors: Croley Thomas E.
Published: June 2007

ABSTRACT: The Great Lakes Environmental Research Laboratory developed a semiautomatic software package for making hydrological outlooks for the Great Lakes. These include basin moisture storages, basin runoff, lake heat storage, lake evaporation, heat fluxes, and net lake supplies, one or more full months into the future. The package combines GLERL's rainfall‐runoff and lake evaporation models with near real‐time data reduction techniques to represent current system states. Users select historical meteorologic record segments as candidate future scenarios to generate deterministic near real‐time hydrological outlooks. GLERL has extended the package to make probabilistic outlooks for a decision‐maker who must estimate the risk associated with his decisions. GLERL matches National Weather Service meteorologic outlook probabilities by selecting groups of historical meteorologic sequences, and constructs embedded outlook intervals for each hydrologic variable of interest. Interval probabilities are assigned from comparisons over a recent evaluation period. This physically‐based approach for generating outlooks offers the ability, as compared to other statistically‐based approaches, to incorporate improvements in the understanding, of process dynamics as they occur in the future and to respond reasonably to conditions initial to a forecast (such as heat and moisture storages), not observed in the past.
RELATING TRENDS OF PRINCIPAL COMPONENTS TO TRENDS OF WATER‐QUALITY CONSTITUENTS1
Authors: Yu Yun‐Sheng , Zou Shimin
Published: June 2007

ABSTRACT: The seasonal Kendall test is used for detecting water‐quality trend or lack of trend for monthly data of 15 water‐quality constituents at 15 sampling stations in the Arkansas River, the Neosho River, and the Verdigris River basins. Trends of individual constituents and the trends of the first four principal components for the correlation matrix of water‐quality data at each station are determined, and the relationships between the trends of constituents and the trends of principal components are established. Using the principal components not only reduces the high dimensionality of the original data to a few principal components, but also presents an overall picture of water‐quality trend of these river basins.
NETWORK AND SUBWATERSHED PARAMETERS EXTRACTED FROM DIGITAL ELEVATION MODELS: THE BILLS CREEK EXPERIENCE1
Authors: Garbrecht Jurgen , Martz Lawrence W.
Published: June 2007

ABSTRACT: An automated extraction of channel network and sub‐watershed characteristics from digital elevation models (DEM) is performed by model DEDNM. This model can process DEM data of limited vertical resolution representing low relief terrain. Such representations often include ill‐defined drainage boundaries and indeterminate flow paths. The application watershed is an 84 km2 low relief watershed in southwestern Oklahoma. The standard for validation is the network and subwatershed parameters defined by the blue line method on USGS 7.5–minute topographic maps. Evaluation of the generated and validation networks by visual comparisons shows a high degree of correlation. Comparison of selected network parameters (channel length, slope, drainage density, etc.) and of drainage network composition (bifurcation, length, slope, and area ratios) shows that, on the average, the generated parameters are within 5 percent of those derived from the validation network. The largest discrepancies were found for the channel slope values. The results of this application demonstrate that DEDNM effectively addresses network definition problems often encountered in low relief terrain and that it can generate accurate network and subwatershed parameters under those conditions.
USING A GEOGRAPHIC INFORMATION SYSTEM TO DETERMINE THE RELATION BETWEEN STREAM QUALITY AND GEOLOGY IN THE ROBERTS CREEK WATERSHED, CLAYTON COUNTY, IOWA1
Authors: Kalkhoff S. J.
Published: June 2007

ABSTRACT: A geographic information system (GIS) was used to determine the relation between the stream‐water quality and underlying geology in Roberts Creek watershed, Clayton County, Iowa, for base‐flow conditions during the spring and summer of 1988–90. Geologic, stream, basin and subbasin boundaries, and water‐quality sampling‐site coverages were created by digitizing available maps. A contour coverage was created from digital line‐graph data. The areal extent of geologic units subcropping in each subbasin was quantified with GIS, and the results then were output and joined with the discharge and water‐quality data for statistical analyses. Illustrations showing the geology of the study area and the results of the study were prepared using GIS. By using GIS and a statistical software package, a weak but statistically significant relation was found between the water temperature, pH, and nitrogen concentrations in Roberts Creek and the underlying geology during base‐flow conditions.
EFFECTS OF THE TOPOGRAPHIC INDEX DISTRIBUTION ON PREDICTED RUNOFF USING GRASS1
Authors: Chairat Sihem , Delleur Jacques W.
Published: June 2007

ABSTRACT: The effects of digital elevation model resolutions and contour lengths on the distribution of the topographic index, a fundamental parameter for the hydrologic model, TOPMODEL, and their influence on the predicted peak flows are investigated in this paper. A small agricultural catchment (3.38 km2) is used to determine the catchment response modeled by TOPMODEL for three rainfall events.
A GEOGRAPHIC INFORMATION SYSTEM PROCEDURE TO QUANTIFY DRAINAGE‐BASIN CHARACTERISTICS1
Authors: Eash David A.
Published: June 2007

ABSTRACT: The Basin Characteristics System (BCS) has been developed to quantify characteristics of a drainage basin. The first of four main BCS processing steps creates four geographic information system (GIS) digital maps representing the drainage divide, the drainage network, elevation contours, and the basin length. The drainage divide and basin length are manually digitized from 1:250,000‐scale topographic maps. The drainage network is extracted using GIS software from 1:100,000‐scale digital line graph data. The elevation contours are generated using GIS software from 1:250,000‐scale digital elevation model data. The second and third steps use software developed to assign attributes to specific features in three of the four digital maps and analyze the four maps to quantify 24 morphometric basin characteristics. The fourth step quantifies two climatic characteristics from digitized State maps of precipitation data.

Compared to manual methods of measurement, the BCS provides a reduction in the time required to quantify the 26 basin characteristics. Comparison tests indicate the BCS measurements are not significantly different from manual topographic‐map measurements for 11 of 12 primary drainage‐basin characteristics. Tests indicate the BCS significantly underestimates basin slope. Comparison‐measurement differences for basin slope, main channel slope, and basin relief appear to be due to limitations in the digital elevation model data.
CAUSES OF UGHT AVI'ENUATION IN TAMPA BAY AND CHARLOTTE HARBOR, SOUTHWESTERN FLORIDA1
Authors: McPherson Benjamin F , Miller Ronald L.
Published: June 2007

ABSTRACT: Vertical attenuation of photosynthetically active radiation (PAR) in clear waters of central Florida theoretically can vary almost 50 percent during a sunny summer day as a result of changing solar elevation. We used a simple formula to partially adjust the attenuation coefficient in Tampa Bay and Charlotte Harbor for changing solar elevation of the direct beam and then used multiple regression analysis to estimate the relative contribution of different water properties or constituents to the adjusted attenuation coefficient, kadj. Color, on an average, was responsible for 18 percent of kadj, chlorophyll a for 21 percent, nonchiorophyll suspended matter for 55 percent, and seawater for the remaining 6 percent. In both estuaries, kadj increased with decreasing salinity as a result of freshwater runoff adding color, suspended matter, and nutrients. Nutrients affected attenuation by stimulating phytoplankton growth and increasing concentrations of chlorophyll a. Reduced nutrient loading to upper Tampa Bay (Hilisborough Bay) in the early to mid‐1980's appears to have decreased concentrations of chlorophyll a, increased water clarity, and increased seagrass recolonization. Assuming other attenuating substances remained unchanged, the decrease in the average concentration of chlorophyll a from 30 to 15 μg L−1 would correspond to an increase in the depth of light penetration necessary for seagrass survival (>10 percent incident light) from 1.0 to 1.5 m, which, on a relatively flat sea bed (slope of 2 m/km), would increase the area potentially available for seagram recolonization by 0.25 km2/km of shoreline.
REGIONAL FLOOD EQUATIONS FOR THE PROVINCES OF ONTARIO AND QUEBEC1
Authors: Gingras Denis , Adamowski Kaz , Pilon Paul J.
Published: June 2007

ABSTRACT:When nonparametric frequency analysis was performed on 183 stations from Ontario and Quebec, unimodal and multimodal maximum annual flood density functions were discovered. In order to determine generating mechanisms, a monthly partitioning of the annual maximum floods was undertaken. The timing of the floods revealed that the unimodal distributions reflected a single flood generating mechanism while the multi‐modal densities reflected two or more mechanisms. Based on the division of the flood series by mechanisms, nine homogeneous regions were delineated. L‐moment distributional homogeneity tests along with smaller standard errors for the regional equations supported the delineation.
STATUS AND PROSPECTS OF KAREZ IRRIGATION1
Authors: Kahlown Muhammad Akram , Hamilton Joel R.
Published: June 2007

ABSTRACT: The karez is a traditional irrigation water source, consisting of hand‐dug horizontal wells, that is still used in parts of South Asia, the Middle East, and North Africa. This paper describes the construction, management, and current problems of karez irrigation systems based on investigations conducted in Baluchistan Province, Pakistan. While karezes have served irrigation needs well in the past, they are now threatened by high costs of labor for construction and maintenance, and by the encroachment of tubewells which lower the water tables on which the karez systems depend. Possible methods for improving karez performance and needs for research are discussed.
VISUALIZATION OF TRENDS AND FLUCTUATIONS IN CLIMATIC RECORDS1
Authors: Garbrecht Jurgen , Fernandez Glenn P
Published: June 2007

ABSTRACT: Small systematic changes in climatic records are often poorly visualized by standard time series plots because they are usually hidden by the magnitude and variability of the data values themselves. A visualization approach based on the rescaled adjusted partial sums (RAPS) which overcomes the above‐stated shortcomings is presented. This visualization highlights trends, shifts, data clustering, irregular fluctuations, and periodicities in the record. Additional information on the number, magnitude, shape, frequency, and timing of fluctuations and trends can also be inferred. The visualization approach can be used for preliminary visual inspection of a time series, to gain a feel for the data, and/or to guide and focus subsequent statistical tests and analyses. It is not intended as a substitute for standard statistical analysis. Alternatively, the visualization approach can be used to display findings of a time series analysis. The capabilities and limitations of the approach are discussed and illustrated for two time series of annual rainfall values.
INTEGRATION OF A BASIN‐SCALE WATER QUALITY MODEL WITH GIS1
Authors: Srinivasan R. , Arnold J. G.
Published: June 2007

ABSTRACT: Geographic Information Systems (GIS) have been successfully integrated with distributed parameter, single‐event, water quality models such as AGNPS (AGricultural NonPoint Source) and ANSWERS (Areal Nonpoint Source Watershed Environmental Response Simulation). These linkages proved to be an effective way to collect, manipulate, visualize, and analyze the input and output date of water quality models. However, for continuous‐time, basin large‐scale water quality models, collecting and manipulating the input data are more time‐consuming and cumbersome due to the method of disaggregation (subdivisions are based on topographic boundaries). SWAT (Soil and Water Assessment Tool), a basin‐scale water quality model, was integrated with a GIS to extract input data for modeling a basin. This paper discusses the detailed development of the integration of the SWAT water quality model with GRASS (Geographic Resources Analysis Support System) GIS, along with an application and advantages. The integrated system was applied to simulated a 114 sq. km upper portion of the Seco Creek Basin by subdividing it into 37 subbasins. The average monthly predicted streamflw is in agreement with measured monthly streamflw values.
RECHARGE ESTIMATES USING A GEOMORPHIC/DISTRIBUTED‐PARAMETER SIMULATION APPROACH, AMARGOSA RWER BASIN1
Authors: Osterkamp W. R. , Lane L. J. , Savard C. S.
Published: June 2007

ABSTRACT: Average‐annual volumes of runoff, evapotranspiration, channel loss, upland (interchannel) recharge, and total recharge were estimated for watersheds of 53 channel sites in the Amargosa River basin above Shoshone, California. Estimates were based on a water‐balance approach combining field techniques for determining streamflow with distributed‐parameter simulation models to calculate transmission losses of ephemeral streamflow and upland recharge resulting from high‐magnitude, low‐frequency precipitation events. Application of the water‐balance models to the Amargosa River basin, Nevada and California, including part of the Nevada Test Site, suggests that about 20.5 million cubic meters of water recharges the ground‐water reservoir above Shoshone annually. About 1.6 percent of precipitation becomes recharge basinwide. About 90 percent of the recharge is by transmission loss in channels, and the remainder occurs when infrequent storms yield sufficient precipitation that soil water percolates beyond the rooting zone and reaches the zone of saturation from interchannel areas. Highest rates of recharge are in headwaters of the Amargosa River and Fortymile Wash; the least recharge occurs in areas of relatively low precipitation in the lowermost Amargosa River watershed.
CHARACTERIZATION OF SURFACE WATER QUALITY ALONG A WATERSHED DISTURBANCE GRADIENT1
Authors: Zampella Robert A.
Published: June 2007

ABSTRACT. Characterizing ecological indicators such as water quality is necessary to effectively manage human‐dominated systems such as the New Jersey Pinelands. Pinelands surface waters are naturally acidic and low in nutrients and other dissolved substances. Water quality for 14 Pinelands stream sites monitored by the U.S. Geological Survey was characterized in relation to land use. A gradient of increasing pH, specific conductance, and concentration of dissolved calcium, dissolved magnesium, total nitrite + nitrate‐nitrogen, total ammonia‐nitrogen, and total phosphorus was associated with a watershed disturbance gradient of increasing land use intensity and waste water flow. These two parallel gradients emphasized the significant effect that watershed disturbance can have on natural water chemistry in the Pinelands. The results of this study can be applied to planning and regulatory programs in the Pinelands.
WATER QUALITY DURING STORM EVENTS FROM TWO CONSTRUCTED WETLANDS RECEWING MINE DRAINAGE1
Authors: Stark Lloyd R. , Brooks Robert P , Williams Frederick M. , Stevens S. Edward. , Davis Luise K
Published: June 2007

ABSTRACT: Flow rates, pH, iron concentration, and manganese concentration were measured during several storm events at two constructed wetlands receiving mine water. During a substantial rain event, flow rates at both the wetland outlets surpassed flow rates at the wetland inlets, reflecting incident rainfall and differences in wetland area at the two sites. A significant positive correlation existed between local rainfall and outflow rates at the larger wetland, but not between rainfall and inflow rates. During storm events, outlet pH, relative to inlet pH, was slightly elevated at the larger wetland, and depressed at the smaller wetland. However, over the course of one year, rainfall was uncorrelated to outlet pH in the larger wetland. A substantial rain event at the smaller wetland resulted in a temporary elevation in outlet iron concentrations, with treatment efficiency reduced to near zero. However, in the larger wetland, outlet iron concentrations were not significantly affected by storm events. Although rainfall and outlet iron concentration were not significant correlates at the larger wetland, flow rate was positively correlated to outlet iron concentration. A normal manganese treatment efficiency of 50 percent at the smaller wetland was reduced to zero during a heavy rain.
EXAMINING LAND USE INFLUENCES ON STREAM HABITATS AND MACROINVERTEBRATES: A GIS APPROACH1
Authors: Richards Carl , Host George
Published: June 2007

ABSTRACT: Geographic Information Systems (GIS) were used to assess the relationships between land use patterns and the physical habitat and macroinvertebrate fauna of streams within similar sized watersheds. Eleven second or third order watersheds ranging from highly urbanized to heavily forested were selected along Lake Superior's North Shore. Land use patterns within the watersheds were quantified using readily available digital land use/land cover information, with a minimum mapping resolution of 16 ha. Physical habitat features, describing substrate characteristics and stream morphology, were characterized at sample points within each stream. Principle component and correlation analyses were used to identify relationships between macroinvertebrates and stream physical habitat, and between habitat and land use patterns. Substrate characteristics and presence of coarse woody debris were found to have the strongest correlations with macreinvertebrate assemblage richness and composition. Agricultural and urban land use was correlated with substrate characteristics. Algal abundance, associated with macroinvertebrate compositional differences, was correlated with housing density and non‐forest land covers. The use of readily available spatial data, even at this relatively coarse scale, provides a means to detect the primary relationships between land use and stream habitat quality; finer‐resolution GIS databases are needed to assess more subtle influences, such as those due to riparian conditions.
INCENTIVE‐BASED NONPOINT SOURCE POLLUTION ABATEMENT IN A REAUTHORIZED CLEAN WATER ACT1
Authors: Braden John B. , Netusil Noelwah R. , Kosobud Richard F
Published: June 2007

ABSTRACT: This paper summarizes key provisions of the Clinton Administration's proposals for change in the Clean Water Act. Two of the important themes for change are tougher controls for non‐point source pollution and the use of market‐based instruments. A detailed analysis of market‐based abatement suggests limited potential for reducing costs. The keys to nonpoint source pollution control are clearer definition of property rights combined with changes in government programs that encourage polluting activities.
REAUTHORIZING THE CLEAN WATER ACT: LOOKING TO TANGIBLE VALUES1
Authors: Adler Robert W.
Published: June 2007

ABSTRACT: The degree of progress achieved under the 1972 Clean Water Act is reviewed by reference to traditional measures of program implementation, and to evidence of tangible, or “real‐world” progress, such as beach closures, drinking water contamination, fishing bans and advisories, species health, and habitat degradation. Significant progress has been made in reducing pollution from point sources, but large point source releases of toxic and other pollutants remain. Little progress has been made in addressing runoff pollution, and in protecting aquatic habitats. Clean Water Act reauthorization should focus on pollution prevention to reduce further the release of toxics by point sources, a new program of mandatory but flexible controls on sources of runoff, and watershed protection programs to promote habitat protection and restoration. Economic factors should be considered in Clean Water Act programs, but must be balanced against scientific and governmental factors as well.
NITROGEN AND PHOSPHORUS IN WATER AS RELATED TO ENVIRONMENTAL SEVI'ING IN NEBRASKA1
Authors: Helgesen J. O. , Zelt R. B. , Stamer J. K.
Published: June 2007

ABSTRACT: Spatial distributions of nitrogen and phosphorus in water were related to environmental setting as part of a regional water‐quality assessment of the Central Nebraska Basins. The environmental settings (Sandhills, Loess Hills, Glaciated Area, and Platte Valley) were characterized by different concentrations of nitrogen and phosphorus in ground water and stream water. Statistically significant differences in nitrate concentrations in both ground‐water and stream‐water samples were related to regional distributions of cropland and rangeland. Nitrate concentrations were larger, especially in shallow ground water, in environmental settings dominated by cropland and associated fertilizer use than in settings dominated by rangeland. Similarly, total‐nitrogen and nitrate concentrations were relatively large in selected streams draining primarily cropland. Comparative concentrations of phosphorus in stream water on the basis of environmental setting were similar to those of nitrogen, although the largest phosphorus concentrations probably relate to wastewater discharge into small streams. Nitrogen and phosphorus concentrations in much of the Platte River apparently reflected the quality of water entering the study unit from upstream and limited base‐flow contributions from within the Platte Valley itself.
ADMINISTRATIVE, INSTITUTIONAL, AND STRUCTURAL CHARACTERISTICS OF AN ACTIVE WATER MARKET1
Authors: Michelsen An M.
Published: June 2007

ABSTRACT: Voluntary water transfers through markets have been advocated by many diverse groups as a means to reallocate scarce water supplies in the semi‐arid western U.S. Although transfers of water rights have occurred almost since the creation of prior appropriation laws over a century ago, functioning water markets have been very slow to develop and are few in number. The structure, composition, administration and transactions of one of the most well established water markets, shares in the Bureau of Reclamation, Colorado‐Big Thompson project, are examined to better understand the institutional and transfer conditions that sustain an active water market. Results from a detailed study of C‐BT project records reveal that between 1970 and 1993 there were 2,698 transactions through which over one‐third of the project water changed ownership or type of use. Further analysis shows that the transactions involved many individual sellers and categories of buyers with different uses, including agricultural buyers. The transfer activity and efficiency of the C‐BT market has lead some to suggest that it be used as a model for other markets. However, because this market has fewer institutional restrictions, a well developed infrastructure and unique market conditions, it will be difficult to transfer this model to other areas without accompanying modifications in water right administration and institutions.
THE GROUND WATER FLUX OF NITROGEN AND PHOSPHORUS TO BERMUDA'S COASTAL WATERS1
Authors: Simmons J. A. Kent. , Lyons W. Berry.
Published: June 2007

ABSTRACT: The concentrations of dissolved fixed inorganic nitrogen (ΣN) in Bermuda ground waters can be very high due to both natural and anthropogenic processes. The high anthropogenic flux is due to domestic cesspit operation. Mass balance calculations indicate that ground water seepage, especially rich in ΣN, is a major source of nutrients into the near shore coastal zone of Bermuda. The ground water flux of ΣN is approximately 1.5 to 4 times that of the sewage flux of ΣN to Bermuda's nearshore waters. This input of ΣN may be important in the development of algal blooms in these waters. Our work, coupled with other recent investigations, suggests that the ground water input of nutrients into nearshore marine waters is an important process globally.
PARTITIONING SMALL SCALE SPATIAL VARIABILITY OF RUNOFF AND EROSION ON SAGEBRUSH RANGELAND1
Authors: Pierson F B. , Blackburn W. H. , Van Vactor S. S. , Wood J. C.
Published: June 2007

ABSTRACT: Most hydrologic models require input parameters which represent the variability found across an entire landscape. The estimation of such parameters is very difficult, particularly on rangeland. Improved model parameter estimation procedures are needed which incorporate the small‐scale and temporal variability found on rangeland. This study investigates the use of a surface soil classification scheme to partition the spatial variability in hydrologic and interrill erosion processes in a sagebrush plant community. Four distinct microsites were found to exist within the sagebrush coppice‐dune dune‐interspace complex. The microsites explained the majority of variation in hydrologic and interrill erosion response found on the site and were discernable based on readily available soil and vegetation information. The variability within each microsite was quite low and was not well correlated with soil and vegetation properties. The surface soil classification scheme defined in this study can be quite useful for defining sampling procedures, for understanding hydrologic and erosion processes, and for parameterizing hydrologic models for use on sagebrush range‐land.
ARTIFICIAL GROUND WATER RECHARGE EXPERIMENTS IN CARBONATE AND CLASTIC AQUIFERS OF KUWAIT1
Authors: Mukhopadhyay Amitabha , Szekely Ferenc , Senay Yildir
Published: June 2007

ABSTRACT: Injection of water and subsequent withdrawal were carried out in three existing water wells (SU‐10, C‐105, and SU‐135A) in Kuwait. The objective of the study was to assess the technical feasibility of artificial recharge in the carbonate Dammam Formation and the clastic Kuwait Group aquifers. In the absence of any pretreatment of injection water and measures for maintenance of line pressure, clogging from suspended solids and air entrapment occurred in all three experiments. It was, however, possible to inject for one month in Wells SU‐10 and C‐105 where injection took place in the Dammam aquifer. In Well SU‐135A, where the Kuwait Group aquifer was the target for injection, clogging became so severe that the injection experiment had to be abandoned. The injection/withdrawal data were analyzed with the help of a multi‐aquifer flow model and a transport model. The models took into account the effects of crossflow within the boreholes on the distribution of intake and discharge rates for different aquifers, and hence, on the recovery efficiency. The experiments suggested that the artificial recharge of the Dammam and the Kuwait Group aquifers was technically feasible. The problem of clogging was, however, more severe for the Kuwait Group.
WHITHER WORLD WATER?1
Authors: Rodda John C.
Published: June 2007

ABSTRACT: The last decade has seen accelerated interest in international hydropolitics. Yet, the international politics of the world's fresh water are highly complicated, some might even say byzantine. This paper discusses some of these complications, the background to them, and the place of fresh water in recent environmental initiatives, particularly in UNCED. It proposes a way forward for the future in order to improve international cooperation to assist in averting the coming water crisis.
REGIONAL SCALE TREND MONITORING OF INDICATORS OF TROPHIC CONDITION OF LAKES1
Authors: Larsen D. P. , Urquhart N. S. , Kugler D. L.
Published: June 2007

ABSTRACT:The U.S. Environmental Protection Agency has proposed a sample survey design to answer questions about the ecological condition and trends in condition of U.S. ecological resources. To meet the objectives, the design relies on a probability sample of the resource population of interest (e.g., a random sample of lakes) each year on which measurements are made during an index period. Natural spatial and temporal variability and variability in the sampling process all affect the ability to describe the status of a population and the sensitivity for trend detection. We describe the important components of variance and estimate their magnitude for indicators of trophic condition of lakes to illustrate the process. We also describe models for trend detection and use them to demonstrate the sensitivity of the proposed design to detect trends. If the variance structure that develops during the probability surveys is like that synthesized from available databases and the literature, then the trends in common indicators of trophic condition of the specified magnitude should be detectable within about a decade for Secchi disk transparency (0.5–1 percentiyear) and total phosphorus (2–3 percent/year), but not for chlorophyll‐a (> 3–4 percent/year), which will take longer.
USING CURVE NUMBERS TO DETERMINE BASELINE VALUES OF GREEN‐AMPT EFFECTIVE HYDRAULIC CONDUCTIVITIES1
Authors: Risse L. M. , Liu B. Y. , Nearing M. A.
Published: June 2007

ABSTRACT: Since the trend in infiltration modeling is currently toward process‐based approaches such as the Green‐Ampt equation, more emphasis is being placed on methods of determining appropriate parameters for this approach. The SCS curve number method is an accepted and commonly used empirical approach for estimating surface runoff, and is based on numerous data from a variety of sources. The time and expense of calibrating process‐based infiltration parameters to measured data are often prohibitive. This study uses curve number predictions of runoff to develop equations to estimate the “baseline” hydraulic conductivities (Kb) for use in the Green‐Ampt equation. Curve number predictions of runoff were made for 43 soils. Kb values in the Water Erosion Prediction Project (WEPP) model were then calibrated so that the annual runoff predicted by WEPP was equal to the curve number predictions. These calibrated values were used to derive an equation that estimated Kb based on the percent sand, percent clay, and cation exchange capacity of the soil. Estimated values of Kb from this equation compared favorably with measured values and values calibrated to measured natural runoff plot data. WEPP predictions of runoff using both optimized and estimated values of Kb were compared to curve number predictions of runoff and the measured values. The WEPP predictions using the optimized values of Kb were the best in terms of both average error and model efficiency. WEPP predictions using estimated values of Kb were shown to be superior to predictions obtained from the curve number method. The runoff predictions all tended to be biased high for small events and low for larger events when compared to the measured data. Confidence intervals for runoff predictions on both an annual and event basis were also developed for the WEPP model.
COMPARISON OF THE MAGNITUDE OF EROSION ALONG TWO LARGE REGULATED RIVERS1
Authors: Schmidt John C. , Grams Paul E. , Webb Robert H.
Published: June 2007

ABSTRACT: Historical inventories of sand bar number and area are sufficient to detect large‐scale differences in geomorphic adjustment among regulated rivers that flow through canyons with abundant debris fans. In these canyons, bedrock and large boulders create constrictions and expansions, and alluvial bars occur in associated eddies at predictable sites. Although these bars may fluctuate considerably in size, the locations of these bars rarely change, and their characteristics can be compared through time and among rivers. The area of sand bars exposed at low discharge in Hells Canyon has decreased 50 percent since dam closure, and most of the erosion occurred in the first nine years after dam closure. The number and size of sand bars in Grand Canyon downstream from Glen Canyon Dam have decreased much less; the number of sand bars decreased by 40 percent in some 8.3‐km reaches, but by less than 20 percent elsewhere. These differences are in part related to the fact that flood regulation is much greater in Grand Canyon than in Hells Canyon, and that downstream tributaries resupply sediment to Grand Canyon but not to most of Hells Canyon.
HYDRODYNAMIC SIMULATIONS OF A CONSTRUCTED WETLAND IN SOUTH FLORIDA1
Authors: Guardo Mariano , Tomasello Richard S.
Published: June 2007

ABSTRACT: This paper describes the application of the SHEET2D model to the Florida's Everglades Nutrient Removal (ENR) Project. The ENR Project is a 3815 acre (1545 ha) pilot project, located in Palm Beach County. The operation of the treatment system will be used to demonstrate the performance of larger scale constructed wetland systems for removal of phosphorus from Everglades Agricultural Area (EAA) stormwater runoff. It is currently the largest stormwater wetland treatment system in the world.

The SHEET2D model was used to analyze the performance of the ENR Project. SHEET2D is a two‐dimensional, depth‐averaged hydrodynamic model that is applicable to shallow water flow conditions. Subsequently, results from SHEET2D simulations were used to develop the ENEMOD model. ENRMOD is a lumped parameter box water quality model that can be used to analyze the long term performance of the ENR project with respect to hydrology and phosphorus uptake. Localized short‐circuiting in the agricultural ditches within the project area was analyzed by using the RBFVM‐2D model, which is a finite volume hydrodynamic model that is also applicable to shallow water flow conditions.

The SHEET2D model was employed to simulate the hydraulics of the structures between cells and the hydrodynamics of the sheet‐flow moving across the buffer cell and treatment cells. Collection, distribution, and larger discharge canals within the project were simulated by means of the MultiBasin Routing (MBR) model features that are built into the SHEET2D model. Constant inflows (75 to 600 cfs [2.1 to 17 m3/s]) were used in all runs to simulate the discharge of the ENR Project based on the proposed operating schedule for the outflow pump station. The model simulated 30 days to reach steady state conditions. Under steady state conditions, the hydraulic retention times were computed for the project and the split of flow between the two treatment trains of the entire project from the common buffer cell. Additionally, design components such as height of the levees, capacity of the structures, and hydrographs at specified grids were obtained.
CHARACTERISTICS AND CONTRIBUTING CAUSES OF AN ABNORMAL FREQUENCY OF FLOOD‐PRODUCING RAINSTORMS AT CHICAGO1
Authors: Huff Floyd A.
Published: June 2007

ABSTRACT:Major hydrometeorological factors pertinent to defining and understanding the hydrologic characteristics of urban and other small‐basin storms were investigated using data from a continuous 44‐year operation of a recording raingage network in Chicago. Factors included: the frequency distribution of basin mean rainfall and its relation to storm maximum precipitation; the spatial distribution characteristics of each storm, including storm rainfall reduction factors which are widely used in hydrologic design problems; and weather‐related causes related to the frequency and intensity of severe rainstorms in the Chicago area in recent years. Results have indicated that urban mean rainfall frequencies were overestimated in earlier studies in which they were derived from point/areal mean rainfall ratios obtained from much shorter records on rural networks. Reduction factors were found to vary between urban and rural storm systems due to urban‐related effects. Two factors were found to be potential contributors to the characteristics of severe rainstorm occurrences at Chicago. These include urban‐induced rain enhancement and an upward climatic trend in the occurrence of heavy rainfall events during the sampling period. Study results should be generally applicable to other large urban areas in the Midwest and other regions of similar precipitation climate.
NITRATE CONCENTRATIONS IN KARST SPRINGS IN AN EXTENSWELY GRAZED AREA1
Authors: Boyer D. G. , Pasquarell G. C.
Published: June 2007

ABSTRACT: The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Karst areas comprise about 18 percent of the Region's land area. An estimated one‐third of the Region's farms, cattle, and agricultural market value are located on karst terrain. Nitrate concentrations were measured in several karst springs in Southeastern West Virginia in order to determine the impact of animal agriculture on nitrate pollution of the karst ground water system. Karst basins with 79, 51, 16, and 0 percent agriculture had mean nitrate concentrations of 15.8, 12.2, 2.7, and 0.4 mg/l, respectively. A strong linear relationship between nitrate concentration and percent agricultural land was shown. Median nitrate concentration increased about 0.19 mg l‐1 per percent increase in agricultural land. Weather patterns were also found to significantly affect the median nitrate concentrations and the temporal variability of those concentrations. Lower nitrate concentrations and lower temporal variability were observed during a severe drought period. It was concluded that agriculture was significantly affecting nitrate concentrations in the karst aquifer. Best management practices may be one way to protect the ground water resource.
ASSESSMENT OF RESTORED RWERINE HABITAT USING RCHARC1
Authors: Peters Mitchell R. , Abt Steven R. , Watson Chester C. , Fischenich Craig , Nestler John M.
Published: June 2007

ABSTRACT: The Riverine Community Habitat Assessment and Restoration Concept (RCHARC) was developed to integrate habitat enhancement into the stream restoration process. RCHARC assumes that aquatic habitat quality is closely related to hydraulic diversity based upon a “comparison standard” reach approach to stream restoration. A Beta test was performed by applying the RCHARC process to Rapid Creek in Rapid City, South Dakota. Standard and restored stream reaches were selected and data were collected. A comparison of field data and velocity‐depth distributions indicated that the restored stream closely replicated the standard reach. The RCHARC methodology has the potential to assess habitat quality for planned comparison reaches and indicate the level of success resulting from restoration.
THE LAW OF THE COLORADO RIVER: COPING WITH SEVERE SUSTAINED DROUGHT1
Authors: MacDonnell Lawrence J. , Getches David H. , Hugenberg William C.
Published: June 2007

ABSTRACT: The waters of the Colorado River are divided among seven states according to a complex ‘Law of the River’ drawn from interstate compacts, international treaties, statutes, and regulations. The Law of the River creates certain priorities among the states and the Republic of Mexico, and in the event of a severe sustained drought, the Law of the River dictates the distribution of water and operation of the elaborate reservoir system. Earlier work indicated that there is remarkable resilience in the system for established uses of water in the Lower Basin of the Colorado River. This work shows, based on an application of the Law of the River using computer modeling of operations of facilities on the Colorado River, that there may be serious environmental consequences and related legal restraints on how the water is used in times of shortage and that the existing legal and institutional framework governing the Colorado River does not adequately address all the issues that would be raised in a severe sustained drought. Several possible legal options for dealing with drought in the context of the Law of the River are identified.
SOCIAL IMPLICATIONS OF SEVERE SUSTAINED DROUGHT CASE STUDIES IN CALIFORNIA AND COLORADO1
Authors: Krannich Richard S. , Keenan Sean P. , Walker Michael S. , Hardesty Donald L.
Published: June 2007

ABSTRACT: Survey data collected in the San Joaquin Valley of southern California and the Grand Valley of western Colorado reveal that residents of both areas believe that a severe sustained drought is likely to occur within the next 20–25 years and that their communities would be seriously impacted by such an event. Although a severe sustained drought affecting the Colorado River Basin would cause major economic and social disruptions in these and other communities, residents express little support for water management alternatives that would require significant shifts in economic development activities or in water use and allocation patterns. In particular, residents of these areas express little support for strategies such as construction and growth moratoriums, mandatory water conservation programs, water transfers from low‐to high‐population areas, water marketing, or reallocations of water from agricultural to municipal/industrial uses. This rejection of water management strategies that would require a departure from “business as usual” with respect to water use and allocations severely restricts the capacity of these and similar communities to respond effectively should a severe sustained drought occur.
MANAGING THE COLORADO RIVER IN A SEVERE SUSTAINED DROUGHT AN EVALUATION OF INSTITUTIONAL OPTIONS1
Authors: Lord William B. , Booker James F , Getches David M. , Harding Benjamin L. , Kenney Douglas S. , Young Robert A.
Published: June 2007

ABSTRACT: This paper presents a summary of the findings and recommendations of the studies of severe, sustained drought reported in this special issue. The management facilities and institutions were found to be effective in protecting consumptive water users against drought, but much less effective in protecting nonconsumptive uses. Changes in intrastate water management were found to be effective in reducing the monetary value of damages, through reallocating shortages to low‐valued uses, while only water banking and water marketing, among the possible interstate rule changes, were similarly effective. Players representing the basin states and the federal government in three gaming experiments were unable to agree upon and effect major changes in operating rules. The conclusions are (1) that nonconsumptive water uses are highly vulnerable to drought, (2) that consumptive uses are well‐protected, (3) that drought risk is greatest in the Upper Basin, (4) that the Lower Basin suffers from chronic water shortage but bears little drought risk, (5) that opportunities exist for win‐win rule changes, (6) that such rule changes are extremely difficult to make, and (7) that intrastate drought management is very effective m in reducing potential damages.