bluuebunny/crossref_metadata_2025 huggingface dataset:
GROUND WATER AS A SOURCE OF NUTRIENTS AND ATRAZINE TO STREAMS IN THE SOUTH PLATTE RIVER BASIN1
Authors: McMahon Peter B. , Litke David W. , Paschal James E. , Dennehy Kevin F
Published: June 2007

ABSTRACT: Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were measured in streams and ground water beneath the streams at 23 sites in the South Platte River basin of Colorado, Nebraska, and Wyoming to assess: (1) the role of ground water as a source of nutrients and atrazine to streams in the basin, and (2) the effect of land‐use setting on this process. Concentrations of nitrite plus nitrate, ammonia, orthophosphate, and atrazine were higher in ground water than in the overlying streams at 2, 12, 12, and 3 of 19 sites, respectively, where there was not a measurable hydraulic gradient directed from the stream to the ground water. Orthophosphate was the only constituent that had a significantly higher (p ≤ 0.05) concentration in ground water than in surface water for a given land‐use setting (range land). Redox conditions in ground water were more important than land‐use setting in influencing whether ground water was a source of elevated nitrite plus nitrate concentrations to streams in the basin. The ratios of nitrite plus nitrate in ground water/surface were were significantly lower (p ≤ 0.05) at sites having concentrations of dissolved oxygen in ground water ≤ 0.5 mg/L than at sites having dissolved oxygen concentrations ≥ 0.5 mg/L. Elevated concentrations of ammonia or atrazine in ground water occurred at sites in close proximity to likely sources of ammonia or atrazine, regardless of land‐use setting. These results indicate that land‐use setting is not the only factor that influences whether ground water is a source of elevated nutrient and atrazine concentrations to streams in the South Platte River Basin.
WATER QUALITY TRENDS IN LAKE TOHOPEKALIGA, FLORIDA, USA: RESPONSES TO WATERSHED MANAGEMENT1
Authors: James R. Thomas. , O'Dell Kim , Smith Val H.
Published: June 2007

ABSTRACT: Water quality in eutrophic Lake Tohopekaliga, Florida, improved markedly from 1982 to 1992 as a result of reductions in phosphorus and nitrogen loading to the lake. Annual budgets of water, chloride, phosphorus and nitrogen were constructed for the lake, and indicate it is a sink for phosphorus and a source for nitrogen. Water column concentrations of total phosphorus, soluble reactive phosphorus, total nitrogen, dissolved inorganic nitrogen, and chlorophyll a all declined as external inputs of nutrients decreased. Water column nitrogen: phosphorus ratios have increased, suggesting a probable shift from nitrogen‐ to phosphorus‐limitation. This apparent shift in nutrient limitation status also is supported by comparisons of the mean Trophic State Indices for phosphorus, nitrogen, and chlorophyll a. These improvements in water quality are attributed to the diversion of wastewater treatment plant effluent from the lake, and the increased use of wet retention ponds for stormwater runoff.
WESTERN WATER RESOURCES: THE DESERT IS BLOOMING, BUT WILL IT CONTINUE?1
Authors: Plummer Jenny L.
Published: June 2007

ABSTRACT: The arid Southwest of the United States is confronted with increasing water demands and a limited resource. Past efforts to meet water demand have been directed toward development of scarce water resources. While development programs have been successful in stretching available supply, few feasible development options remain. Furthermore, heavy water utilization has affected water quality within drainage basins. It seems likely that water management will play a much more significant role in water resource allocation in the future. This paper will examine water development activity in the Southwest to date. Attention will be given to several of the problems that have arisen. The paper will then examine water management options. Particular attention will be given to water management options being implemented in the State of Arizona.
DOWNSTREAM CHANNEL GEOMETRY FOR USE IN PLANNING‐LEVEL MODELS1
Authors: Allen Peter M. , Arnold Jeffrey C. , Byars Bruce W
Published: June 2007

ABSTRACT: There is considerable potential for use of channel dimension data in planning‐level models for resource and impact assessment. The channel dimension data is used to route flows and sediment through the basin. The cost of obtaining actual surveyed data for large watersheds is typically prohibitive. Predictive equations have been developed based on 674 stations from watersheds across the United States which encompass a wide variety of channel types and sizes. These equations were tested against an independent data set and found to be adequate for use in planning‐level models. Future research is advocated which would include data from regions and stream types not included in this study.
THE FLOOD HAZARD AND DYNAMICS OF THE URBAN RESIDENTIAL LAND MARKET1
Authors: Tobin Graham A. , Montz Burrell E.
Published: June 2007

ABSTRACT: Literature on the flood hazard/residential land market relationship is full of contradictory findings, many of which are counter‐intuitive to the belief that flooding has a negative impact on house prices. This research advances a conceptual framework through which these relationships might be re‐examined. Based on the expected utility model, the theoretical framework integrates the economic notion of capitalization with spatial and temporal characteristics of the flood hazard.

Four communities with different flood regimes are used to test the effect of flooding on the residential real estate market. Results show that, (1) there is an identifiable relationship between characteristics of the flood hazard and changes in house values; (2) the length of the recovery period is dependent on characteristics and expectations of flooding, attributes of the real estate market, and availability of capital to fuel recovery; and (3) dynamics of the urban market and spatial extent of the flood hazard influence these relationships. Further research is now necessary to examine these findings under different spatial, temporal, hydrological, and socio‐economic conditions.
INSTITUTIONAL BARRIERS TO WATER MARKETING IN THE WEST1
Authors: McCormick Zachary
Published: June 2007

ABSTRACT: Water marketing has been proposed as one means of reallocating water supplies in the western United States. While markets for western water currently exist and may be expected to expand, the institutional constraints within which the markets must operate will limit the ultimate size and efficiency of those markets. Lack of articulation of public interests in the water resource itself leads to incomplete definition of the private rights to use the water, and it is those private rights which are sold or leased in the market. The increase in size and efficiency of any market in water rights will be dependent on the willingness of legislatures to specifically define the nature and extent of public interests in water supplies, and detailed definition is unlikely.
LONG‐TERM CHANGES IN LOW‐FLOW CHANNEL WIDTHS WITHIN THE SOUTH UMPQUA WATERSHED, OREGON1
Authors: Dose Jeffrey J. , Roper Brett B.
Published: June 2007

ABSTRACT: Recent stream survey data (1989–1993) from 31 stream segments of 21 streams within the upper South Umpqua Watershed Oregon were compared to 1937 stream survey data collected from these same stream segments. Current low‐flow wetted stream widths of 22 of the 31 surveyed stream segments were significantly different than in 1937; 19 stream segments were significantly wider while the remaining three stream segments were significantly narrower. In only 1 of 8 tributaries to the South Umpqua River which had headwaters within land designated wilderness area did low‐flow stream channel width increase since 1937. Conversely, 13 of the 14 tributaries to the South Umpqua River which originated from lands designated as timber emphasis were significantly wider than in 1937. The observed change in stream width was linearly related to timber harvest (r2= 0.44), road density (r2= 0.45), and the amount of large organic debris remaining within the active stream channel (r2= 0.43). These findings suggest that timber harvest and road construction may have resulted in changes in channel characteristics. These channel changes may also be a factor in the observed decline of three of the four populations of anadromous salmonids within the basin.
WATER MARKETS AND DECENTRALIZED WATER RESOURCES MANAGEMENT: INTERNATIONAL PROBLEMS AND OPPORTUNITIES1
Authors: Easter K William , Hearne Robert
Published: June 2007

ABSTRACT: Because of its importance and the perceived inability of private sector sources to meet water demands, many countries have depended on the public sector to provide water services for their populations. Yet this has resulted in many inefficient public water projects and in inadequate supplies of good quality and reliable water. Decentralization of water management, including the use of water markets, cannot solve all of these water problems, but it can improve the efficiency of water allocation. When given adequate responsibility and authority, water user associations have effectively taken over water management activities at a savings to tax payers. Moreover, water markets add the potential benefit of improving water efficiency within a sector as well as providing a mechanism for reallocating water among sectors. The key question involves developing innovative mechanisms for reducing the transaction costs of organizing water users and of making water trades. Water rights need to be established which are recorded, tradable, enforceable, and separate from land if markets are to operate effectively. Also, institutions are needed that effectively resolve conflicts over water rights, including third party impacts and water quality concerns.
MORPHOLOGY OF BEDROCK STEP POOL SYSTEMS1
Authors: Duckson Don W. , Duckson Linda J.
Published: June 2007

ABSTRACT:One‐hundred‐and‐sixty step pools were examined that have developed in andesitic, basaltic, or dacitic lavas or in glaciofluvial sediments along several reaches of Soda Creek in the Three Sisters Wilderness of the Oregon High Cascades to determine whether such systems exhibit similar morphology. Pool shapes, sizes, and spacing were measured, and the hydraulic head loss calculated for each pool surface. Lithologic variations among 15 shape categories were not significant, but size attributes ‐ length, depth, and area ‐ of pools were systematically different by rock type. The energy lost at hydraulic jumps did not differ significantly among the four lithologies, suggesting that perhaps step pools represent similar stream channel adjustments in steep terrain.
DIFFERENCES BETWEEN MODELED SURPLUS AND USGS‐MEASURED DISCHARGE IN LAKE PONTCHARTRAIN BASIN, LOUISIANA1
Authors: Rohli Robert V , Grymes John M.
Published: June 2007

ABSTRACT: A one‐layer decreasing‐availability monthly water balance model is used to estimate monthly surplus that flows into the Lake Pontchartrain Basin from the Amite, Tickfaw, Natalbany, Tangipahoa, and Tchefuncte Rivers for water years 1949 through 1990. The modeled annual surplus for each drainage basin is compared to gauged annual discharge obtained from the United States Geological Survey. This provides an estimate of the differential success of the model over watersheds of various sizes, and also suggests appropriate adjustment factors to be used in future water balance analyses of similar basins in humid subtropical climate regions. Results show that annual surplus values agree well with the USGS values, after an annual adjustment of about 140 mm (11 to 28 percent of the basin surplus) is subtracted from the annual modeled totals to compensate for overestimation by the model. However, inter‐annual variability is high in the annual cycles. Winter and spring discharges can also be modeled successfully.
QUALITY STUDY OF GRAYWATER TREATMENT SYSTEMS1
Authors: Gerba Charles P. , Straub Timothy M. , Rose Joan B. , Karpiscak Martin M. , Foster Kennith E. , Brittain Richard G.
Published: June 2007

ABSTRACT: A residential single family dwelling was retrofitted to recycle graywater for landscape irrigation and toilet flushing. The objective of this study was to determine improvements in graywater quality by evaluating five simple graywater treatment systems that were easily adapted to the household plumbing. The treatment systems consisted of (1) water hyacinths and sand filtration, (2) water hyacinths, copper ion disinfection, and sand filtration, (3) copper ion disinfection and sand filtration, (4) copper/silver ion disinfection and sand filtration, and (5) 20–μm cartridge filtration. Water quality parameters measured were fecal and total coliform indicator bacteria, nitrates, suspended solids, and turbidity. Reductions in bacterial concentration, suspended solids and turbidity were achieved by all systems tested. Treatment reduced nitrate concentrations to an average of 2.6 mg/liter. Reductions in suspended solids, and turbidity were influenced more by the quality of the graywater entering the treatment system than the efficiency of the systems themselves. The water hyacinths and sand filtration system provided the best graywater quality in terms of the concentrations of fecal indicator bacteria. The system providing the best water quality in regard to average suspended solids after treatment was the water hyacinths, copper ion, and sand filtration system, and the best average turbidity was achieved by the copper/silver ion generating unit with sand filtration. All systems were capable of significant reductions in fecal indicator bacteria, suspended solids, and turbidity; however, additional treatment or disinfection would be necessary to further reduce the level of coliform and fecal coliform bacteria to achieve regulatory standards in the State of Arizona.
AN ANALYSIS OF SEASONAL FECAL COLIFORM LEVELS IN THE TCHEFUNCTE RWER1
Authors: Barbé Donald E. , Francis John C.
Published: June 2007

ABSTRACT: A model for estimating seasonal fecal coliform concentrations in the Tchefuncte River as a function of river discharge was developed. Data on fecal coliform concentration were obtained from the Louisiana Department of Health and Hospitals and were available for a period of 15 years (1975 through 1992) from three locations. Stream flow data were obtained from a gaging station of the U. S. Geological Survey at Folsom, Louisiana. These data were available for 49 years (1943 through 1991). The climate of the area is characterized by different precipitation/runoff mechanisms for the summer and winter seasons. The division for seasons used in this analysis was May through October (summer season), and November through April (winter season). Because of the combined effects of climatic mechanisms causing precipitation and the seasonal variation of evapotranspiration, runoff is greater in the winter season resulting in higher fecal coliform counts in the Tchefuncte River. Statistical analysis revealed a statistically significant relationship between fecal coliform concentration and discharge for each season, at each of three sites on the Tchefuncte River.
TECHNICAL CLARITY IN INTER‐AGENCY NEGOTIATIONS: LESSONS FROM FOUR HYDROPOWER PROJECTS1
Authors: Burkardt Nina , Lee Lamb Berton , Taylor Jonathan G. , Waddle Terry J.
Published: June 2007

ABSTRACT: We investigated the effect of technical clarity on success in multi‐party negotiations in the Federal Energy Regulatory Commission (FERC) licensing process. Technical clarity is the shared understanding of dimensions such as the geographic extent of the project, range of flows to be considered, important species and life stages, and variety of water uses considered. The results of four hydropower licensing consultations are reported. Key participants were interviewed to ascertain the level of technical clarity present during the consultations and the degree to which the consultations were successful. Technical clarity appears to be a prerequisite for successful outcomes. Factors that enhance technical clarity include simple project design, new rather than existing projects, precise definition of issues, a sense of urgency to reach agreement, a sense of fairness among participants, and consistency in participation. Negotiators should not neglect the critical pre‐negotiation steps of defining technical issues and determining appropriate studies, deciding how to interpret studies, and agreeing on responses to study results.
THE CRITICAL ROLE OF “UNUSED” RESOURCES1
Authors: Black Peter E.
Published: June 2007

ABSTRACT: The uneven temporal and spatial distribution of water on the Earth suggests an important role for the portion of the resource that is not directly used by humans. By extension, an important underlying theory about world‐wide resource distribution and function is inferred. Policies that control resource preservation and development need to take this theory into account. Some examples for the water resource are presented.
RELATION BETWEEN STREAM‐WATER QUALITY AND GEOHYDROLOGY DURING BASE‐FLOW CONDITIONS, ROBERTS CREEK WATERSHED, CLAYTON COUNTY, IOWA1
Authors: Kalkhoff Stephen J.
Published: June 2007

ABSTRACT: An investigation to determine the relation between stream water quality and geohydrology in the Roberts Creek watershed, Clayton County, Iowa, was conducted during selected base‐flow periods in 1988–90. Discharge measurements were made and water samples collected for analyses of nutrients and selected herbicides in 19 subbasins along the main stem and tributaries of Roberts Creek. The areal extent of unconsolidated and bedrock units subcropping in each subbasin was quantified. The hydrologic data were correlated statistically with the geologic data to determine relations. Roberts Creek generally gained water and had larger nitrogen concentrations in subbasins in which bess and alluvial material were underlain primarily by low‐permeability till and shale units. Roberts Creek generally lost water and had lower nitrate concentrations in subbasins with subcroppmg karstic units. Nitrogen concentrations decreased in streams underlain by the karstic units because the nitrogen removed by biological processes was not replaced by ground‐water inflow. Seepage from Roberts Creek to ground water in areas of subcropping karstic carbonate rocks reduced the flow, which reduced the velocity, causing increased residence time of water in the stream. The additional residence time may allow additional time for biological processes to remove nitrogen from solution. There was no significant relation between dissolved orthophosphate or atrazine and the underlying geology.
TREE‐RING RECONSTRUCTION OF UPPER GILA RWER DISCHARGE1
Authors: Meko David , Graybill Donald A.
Published: June 2007

ABSTRACT: Effective planning for use of water resources requires accurate information on hydrologic variability induced by climatic fluctuations. Tree‐ring analysis is one method of extending our knowledge of hydrologic variability beyond the relatively short period covered by gaged streamflow records. In this paper, a network of recently developed tree‐ring chronologies is used to reconstruct annual river discharge in the upper Gila River drainage in southeastern Arizona and southwestern Arizona since A.D. 1663. The need for data on hydrologic variability for this semi‐arid basin is accentuated because water supply is inadequate to meet current demand. A reconstruction based on multiple linear regression (R2=0.66) indicates that 20th century is unusual for clustering of high‐discharge years (early 1900s), severity of multiyear drought (1950s), and amplification of low‐frequency discharge variations. Periods of low discharge recur at irregular intervals averaging about 20 years. Comparison with other tree‐ring reconstructions shows that these low‐flow periods are synchronous from the Gila Basin to the southern part of the Upper Colorado River Basin.
DESIGN BASIS FOR EVERGLADES STORMWATER TREATMENT AREAS1
Authors: Walker William W.
Published: June 2007

ABSTRACT: The State of Florida (1994) has adopted a plan for addressing Everglades eutrophication problems by reducing anthropogenic phosphorus loads. The plan involves implementation of Best Management Practices in agricultural watersheds and construction of regional treatment marshes (Stormwater Treatment Areas or STA's). This paper describes the development, testing, and application of a mass‐balance model for sizing STA's to achieve treatment objectives. The model is calibrated and tested against peat and water‐column data collected in Water Conservation Area‐2A (WCA‐2A), where phosphorus dynamics and eutrophication impacts have been intensively studied. The 26‐year‐average rate of phosphorus accretion in peat is shown to be proportional to average water‐column phosphorus concentration, with a proportionality constant of 10.2 m/yr (90 percent Confidence Interval = 8.9 to 11.6 m/yr). Spatial and temporal variations in marsh water‐column data suggest that drought‐induced recycling of phosphorus was important during periods of low stage in WCA‐2A. Maintaining wet conditions will be important to promote phosphorus removal in STA's. Sensitivity analysis of STA performance is conducted over the range of uncertainty in model parameter estimates to assess the adequacy of the model as a basis for STA design.
HYDROLOGIC SCENARIOS FOR SEVERE SUSTAINED DROUGHT IN THE SOUTHWESTERN UNITED STATES1
Authors: Tarboton David G.
Published: June 2007

ABSTRACT: This paper considers the risk of drought and develops drought scenarios for use in the study of severe sustained drought in the Southwestern United States. The focus is on the Colorado River Basin and regions to which Colorado River water is exported, especially southern California, which depends on water from the Colorado River. Drought scenarios are developed using estimates of unimpaired historic streamflow as well as reconstructions of streamflow based on tree ring widths. Drought scenarios in the Colorado River Basin are defined on the basis of annual flow at Lees Ferry. The risk, in terms of return period, of the drought scenarios developed, is assessed using stochastic models.
HYDROLOGIC AND ECONOMIC IMPACTS OF DROUGHT UNDER ALTERNATWE POLICY RESPONSES1
Authors: Booker James F.
Published: June 2007

ABSTRACT: A severe sustained drought in the Colorado River Basin would cause economic damages throughout the Basin. An integrated hydrologic‐economic‐institutional model introduced here shows that consumptive water users in headwaters states are particularly vulnerable to very large shortfalls and hence large damages because their rights are effectively junior to downstream users. Chronic shortfalls to consumptive users relying on diversions in excess of rights under the Colorado River Compact are also possible. Nonconsumptive water uses (for hydropower and recreation) are severely affected during the worst drought years as instream flows are reduced and reservoirs are depleted. Damages to these uses exceeds those to consumptive uses, with the value of lost hydropower production the single largest economic impact of a severe sustained drought. Modeling of alternative policy responses to drought suggests three general policy approaches with particular promise for reducing damages. Consumptive use damages can be reduced by over 90 percent through reallocation from low to high valued uses and through reservoir storage strategies which minimize evaporation losses. Reservoir management to preserve minimum power pool levels for hydropower production (and to maintain reservoir recreation) may reduce damages to these nonconsumptive uses by over 30 percent, but it may increase consumptive use shortfalls.
MITIGATING IMPACTS OF A SEVERE SUSTAINED DROUGHT ON COLORADO RWER WATER RESOURCES1
Authors: Sangoyomi Taiye B. , Harding Benjamin L.
Published: June 2007

ABSTRACT: We evaluated the effects of institutional responses developed for coping with a severe sustained drought (SSD) in the Colorado River Basin on selected system variables using a SSD inflow hydrology derived from the drought which occurred in the Colorado River basin from 1579–1616. Institutional responses considered are reverse equalization, salinity reduction, minimum flow requirements, and temporary suspension of the delivery obligation of the Colorado River Compact. Selected system variables (reservoir contents, streamflows, consumptive uses, salinity, and power generation) from scenarios incorporating the drought‐coping responses were compared to those from Baseline conditions using the current operating criteria. The coping responses successfully mitigated some impacts of the SSD on consumptive uses in the Upper Basin with only slight impacts on consumptive uses in the Lower Basin, and successfully maintained specified minimum streamflows throughout the drought with no apparent effect on consumptive uses. The impacts of the coping responses on other system variables were not as clear cut. We also assessed the effects of the drought‐coping responses to normal and wet hydrologic conditions to determine if they were overly conservative. The results show that the rules would have inconsequential effects on the system during normal and wet years.
A TEST OF SEVERAL EVAPORATION EQUATIONS FOR WATER TEMPERATURE SIMULATIONS IN LAKES1
Authors: Rasmussen A. H. , Hondzo M. , Stefan H. G.
Published: June 2007

ABSTRACT: Evaporative heat loss is an essential component of any heat budget used for the modeling of lake water temperatures. Seven evaporative heat loss equations were tested in a year‐round, physically‐based temperature and dissolved oxygen model for lakes. Deciding which equation to choose for use in the year‐round model was based on the goodness of fit of the simulated vs. measured surface temperatures, which were taken at a depth of 1 m below the water surface. An equation which includes free and forced convection components and which was previously used for cooling ponds gave the best fit between temperature simulations and measurements.
NEW DIRECTIONS IN FLOODPLAIN MANAGEMENT1
Authors: Galloway Gerald E.
Published: June 2007

ABSTRACT: Over the last 30 years, average annual riverine flood damages have exceed $2 billion. Damages associated with the Mississippi River Flood of 1993 exceeded $12 billion and these costs do not include the non‐quantifiable, human impacts of this disaster. In a report submitted to the White House in June 1994, a federal interagency floodplain management review committee proposed better ways to manage the nation's floodplains. The committee indicated that the 1993 Mississippi River flood was the result of a significant hydrometeorological event, that federal flood control efforts in the Mississippi basin had prevented nearly $20 billion in potential damages, and that, in spite of federal flood damage reduction efforts, throughout the nation people and property remain at risk to inevitable future flooding. It recommended that the division of decision and cost‐sharing responsibilities among federal, state and local governments be more clearly defined, and that the nation adopt a strategy of, sequentially, avoiding inappropriate use of the flood‐plain, minimizing vulnerability to damage through both nonstruc‐tural and structural means, and mitigating damages as they occur. The report did not call for abandonment of human use of the flood‐plain but argued for full consideration of the economic, social and environmental costs and benefits of all future floodplain activity.
COMMUNITY RESPONSE TO STORMWATER POLLUTION IN AN URBANIZED WATERSHED1
Authors: Kaufman Martin M.
Published: June 2007

ABSTRACT: A model is developed and tested to identify the factors influencing variation in community response to stormwater pollution. Basic constructs of the model use environmental hazard theory, integrated with analysis of community demographic and political forces affecting local government decision processes. Community stormwater response is measured by an index comprised of 12 response indicators. Selection criteria for the response indicators include their effectiveness, variability, and general representation of the spectrum of stormwater response activity. Observable activities are scored progressively based upon their relative ecosystem impacts. Weighted and unweighted indicator scores are computed, with a survey of stormwater experts providing the basis for the weights. Results indicate a wide variation in response levels among the selected communities. Regression analysis identifies four significant predictors of response at the watershed scale: the mean age of householder over 25, the total tax rate, community type (city or township), and the amount of green staff (presence of recycling coordinators, foresters, or environmental planners). This mix of predictors demonstrates the applicability of hazard theory to stormwater response, as community stormwater response is influenced by the capacity and economic means to effect change ‐ two central constructs of hazard theory.
STORMWATER DETENTION BASINS AND RESIDENTIAL LOCATIONAL DECISIONS1
Authors: Emmerling‐DiNovo Carol
Published: June 2007

ABSTRACT: Residents of seven subdivisions with wet and dry stormwater basins were questioned about the role the basin played in their decision to purchase their home. They were asked to estimate the impact of such basins on the image of residential developments and on lot values. Respondents believed that wet basins contributed positively to subdivision image and that lots in developments with wet basins were more valuable than comparable lots in dry basin subdivisions. Lots adjacent to wet basins were perceived as the most valuable, while those adjacent to dry basins were considered the least valuable.
GROUND WATER SOLUTE TRANSPORT, OPTIMAL REMEDIATION PLANNING, AND DECISION MAKING UNDER UNCERTAINTY1
Authors: Medina Miguel A. , Jacobs Timothy L. , Lin Weichao , Lin Kuo‐Ching
Published: June 2007

ABSTRACT: A groundwater quality modeling advisory system has been developed for the U.S. Air Force for use in investigating remediation alternatives for the cleanup of subsurface contamination. The system is capable of accounting for uncertainty, not only in the prediction of solute transport but also in the optimization of the remediation scheme through chance constraints. The system guides users in the selection of appropriate transport models through an algorithm independently tested with machine learning codes. An application to Hill Air Force Base, Utah, is presented for which different pump‐and‐treat strategies are considered: the results are evaluated in terms of the cumulative distribution of the contaminant concentration for each case and the tradeoff relationship between the cost of remediation and the probability that the remediation strategy exceeds an established maximum allowable contaminant concentration.
REGIONALIZATION OF LOW‐FLOW FREQUENCY ESTIMATES: AN ALABAMA CASE STUI)Y1
Authors: Rocky Durrans S. , Tomic Sasa
Published: June 2007

ABSTRACT:Low‐flow estimates, as determined by probabilistic modeling of observed data sequences, are commonly used to describe certain streamflow characteristics. Unfortunately, however, reliable low‐flow estimates can be difficult to come by, particularly for gaging sites with short record lengths. The shortness of records leads to uncertainties not only in the selection of a distribution for modeling purposes but also in the estimates of the parameters of a chosen model. In flood frequency analysis, the common approach to mitigation of some of these problems is through the regionalization of frequency behavior. The same general approach is applied here to the case of low‐flow estimation, with the general intent of not only improving low‐flow estimates but also illustrating the gains that might be attained in so doing. Data used for this study is that which has been systematically observed at 128 streamflow gaging sites across the State of Alabama. Our conclusions are that the log Pearson Type 3 distribution is a suitable candidate for modeling of Alabama low‐flows, and that the shape parameter of that distribution can be estimated on a regional basis. Low‐flow estimates based on the regional estimator are compared with estimates based on the use of only at‐site estimation techniques.
USING SENSITIVITY ANALYSIS TO ASSIST PARAMETER ZONATION IN GROUND WATER FLOW MODEL1
Authors: Jiao Jiu J. , Lerner David N.
Published: June 2007

ABSTRACT: For numerical modeling of ground water movement in a real aquifer system, the aquifer is usually divided into hydrogeologically defined zones, each with its own parameter values. The responses of the system, such as head or drawdown, are often available only in some of the zones. The estimated parameters of all the zones are based on the measured response in these limited zones. However, the estimates for some of the zones may be very uncertain, and these zones are therefore not justified by the data. In this paper, an approach is presented to understand which zone may produce uncertain parameter values and should be lumped with its neighbor. This approach is demonstrated using a regional numerical model for pumping test analysis in the Nottinghamshire aquifer, UK. A step‐by‐step process is used in identifying the aquifer zones and estimating their parameters based on the principle of using the smallest possible numbers of zones and parameters for adequate representation of the drawdown response. After the parameters of each zone are estimated, the sensitivity features of these parameters are examined. The results show that the parameters in one zone can be estimated properly by the drawdown in another zone only when there is significant sensitivity. For transmissivity, sensitivity between zones occurs when there is significant flow between them. For storativity, sufficient sensitivity can occur without large flows between the zones, provided that one zone causes significant drawdown in the other. This idea can be extended to the flow model for a large aquifer system. If the aquifer is divided in such a way that aquifer responses are not sensitive to the parameters in some of the zones, the parameters in those zones cannot be estimated properly and should be lumped into their neighboring zones. In this way, a simple but more reasonable model can be built.
LONG‐TERM AQUATIC HABITAT RESTORATION: MAHOGANY CREEK, NEVADA, AS A CASE STUDY1
Authors: Myers Thomas J. , Swanson Sherman
Published: June 2007

ABSTRACT: We compared the recovery from abusive grazing of aquatic habitat due to different range management on two geomorphically similar rangeland streams in northwest Nevada. Managers excluded livestock from the Mahogany Creek watershed from 1976 to 1990 while allowing rotation of rest grazing on its tributary Summer Camp Creek. Bank stability, defined as the lack of apparent bank erosion or deposition, improved through the study period on both streams, but periodic grazing and flooding decreased stability more on Summer Camp Creek than flooding alone on Mahogany Creek. Pool quantity and quality on each stream decreased because of coarse woody debris removal and sediment deposition during a drought. Fine stream bottom sediments decreased five years after the removal of livestock, but sedimentation increased during low flows in both streams below road crossings. Tree cover increased 35 percent at both streams. Thus, recovery of stability and cover and decreased sedimentation are compatible with rotation of rest grazing on Summer Camp Creek. Width/depth ratio and gravel/cobble percent did not change because they are inherently stable in this stream type. Management activities such as coarse woody debris removal limited pool recover and road crossings increased sedimentation.
A COMPARISON OF GEOSTATISTICAL METHODOLOGIES USED TO ESTIMATE SNOW WATER EQUIVALENT1
Authors: Carroll Steven S. , Cressie Noel
Published: June 2007

ABSTRACT: The need to monitor and forecast water resources accurately, particularly in the western United States, is becoming increasingly critical as the demand for water continues to escalate. Consequently, the National Weather Service (NWS) has developed a geostatistical model that is used to obtain areal estimates of snow water equivalent (the thtal water content in all phases of the snowpack), a major source of water in the West. The areal snow water equivalent estimates are used to update the hydrologic simulation models maintained by the NWS and designed to produce extended streamflow forecasts for river systems throughout the United States. An alternative geostatistical technique has been proposed to estimate snow water equivalent. In this research, we describe the two methodologies and compare the accuracy of the estimates produced by each technique. We illustrate their application and compare their estimation accuracy using snow data collected in the North Fork Clearwater River basin in Idaho.
USING VALUES IN PLANNING WASTEWATER FACILITIES FOR METROPOLITAN SEATTLE1
Authors: Keeney Ralph L. , McDaniels Timothy L. , Ridge‐Cooney Vicky L.
Published: June 2007

ABSTRACT: This paper uses the fundamental values of decision makers to guide a long‐term wastewater planning process at Seattle Metro, a major utility district. Multiattribute value assessment is used to elicit the objectives of several elected officials and other key decision makers. The results are structured into a fundamental objectives hierarchy and a means‐ends objectives network. A set of measures to indicate the performance of planning alternatives in terms of the fundamental objectives is developed. Preliminary value tradeoffs between objectives are elicited from several elected officials. The results of these steps are useful for many aspects of long‐term planning: facilitating communication about values and priorities; designing attractive alternatives that are more likely to serve stakeholder interests; identifying information needed to evaluate alternatives; clarifying the relative importance of information about different impacts; providing a basis for quantitative evaluation of the alternatives with multiple objective analysis; and focusing attention on key tradeoffs that will affect the choice of alternatives.
A COMPARISON OF METHODS FOR CALCULATION OF RADAR‐RAINFALL HOURLY ACCUMULATIONS1
Authors: Liu Chunyan , Krajewski Witold F.
Published: June 2007

ABSTRACT: We compared two interpolation schemes for calculation of hourly accumulation of radar‐rainfall. The schemes are: (1) the Advection Method, and (2) the Space‐Time Kriging Method. The performance of the methods is investigated using numerical simulation experiments. Space‐time evolution of rainfall fields is generated from a stochastic model. The generated fields are sampled following typical radar scanning strategies, and the investigated schemes are applied to obtain accumulated rainfall patterns. The statistical results and a visual analysis of the graphical images suggest that it is advisable to use an interpolation scheme for radar observations even when storm velocity is not high. The Space‐Time Kriging Method provides the best results for low wind velocity. The Advection Method has the smallest standard deviation and mean absolute error, and preserves well the true rainfall pattern for high wind velocity.
CO‐KRIGING TO INCORPORATE SCREENING DATA: HUDSON RIVER SEDIMENT PCBs1
Authors: Butcher Jonathan B.
Published: June 2007

ABSTRACT: Kriging methods of geostatistical analysis provide valuable techniques for analysis of sediment contamination problems, including interpolation of concentration maps from point data and estimation of global mean concentrations. Sample collection efforts frequently include preliminary screening data of considerably more extensive coverage than the laboratory analyses on which estimation is usually based. How should these be incorporated in kriging? Screening and laboratory analysis constitute two separate estimates of the same spatial field but of very different characteristics. A modified version of co‐kriging is developed to include the imprecise screening information in the analysis of contaminant distribution. Use of the method is demonstrated on a data set of sediment PCB samples from the Upper Hudson River, for which preliminary categorical mass spectrometry screening was used to select a smaller set of samples for gas chromatograph analysis. The method is widely applicable to many situations of contaminant and natural resource estimation.
A MODEL FOR PREDICTING LAKE SEDIMENT OXYGEN DEMAND FOLLOWING HYPOLIMNTETIC AERATION1
Authors: Moore Barry C. , Chen Ping‐Hung , Funk William H. , Yonge David
Published: June 2007

ABSTRACT: Hypolimnetic aeration is a widely used technique for lake restoration and fisheries enhancement. However, system design still depends on application of “safety factors” to observed oxygen demand rates, in large part because actual oxygen demand may be greater after aeration than before. Laboratory incubations of sediment show that sediment oxygen demand (SOD) rates follow mixed order kinetics, with an initial period of zero order reaction, followed by first order kinetics. The transition from zero to first order kinetics may correspond to the transition from laminar to turbulent flow. This suggests that SOD reaction kinetics are governed by thickness of the diffusive sublayer adjacent to the sediments. Therefore, zero and first order reaction regions correspond with oxygen diffusion limitation and substrate limitation, respectively. Such a mechanism would account for the induced oxygen demand observed following hypolimnetic aeration and would reconcile differences in SOD reaction orders noted in the literature. This paper describes development of equations based on laboratory SOD incubations for predicting induced oxygen demand following hypolimnetic aeration.
HYDROLOGIC LANDSCAPES ON THE DELMARVA PENINSULA PART 1: DRAINAGE BASIN TYPE AND BASE‐FLOW CHEMISTRY1
Authors: Phillips Patrick J. , Bachman L. Joseph.
Published: June 2007

ABSTRACT: The relation between landscape characteristics and water chemistry on the Delmarva Peninsula can be determined through a principal‐component analysis of basin characteristics. Two basin types were defined by factor scores: (1) well‐drained basins, characterized by combinations of a low percentage of forest cover, a low percentage of poorly drained soil, and elevated channel slope; and (2) poorly drained basins, characterized by a combinations of an elevated percentage of forest cover, an elevated percentage of poorly drained soil, and low channel slopes. Results from base‐flow sampling of 29 basins during spring 1991 indicate that water chemistry of the two basin types differ significantly. Concentrations of calcium, magnesium, potassium, alkalinity, chloride, and nitrate are elevated in well‐drained basins, and specific conductance is elevated. Concentrations of aluminum, dissolved organic carbon, sodium, and silica are elevated in poorly drained basins whereas specific conductance is low. The chemical patterns found in well‐drained basins can be attributed to the application of agricultural chemicals, and those in poorly drained basins can be attributed to ground‐water flowpaths. These results indicate that basin types determined by a quantitative analysis of basin characteristics can be related statistically to differences in base‐flow chemistry, and that the observed statistical differences can be related to major processes that affect water chemistry.
PERFORMANCE OF A NEW POLYMERIC WATER DISINFECTANT1
Authors: Sun G. , Chen T Y , Habercom M. S. , Wheatley W. B. , Worley S. D.
Published: June 2007

ABSTRACT: A new insoluble N‐halamine polymeric disinfectant material has been tested in a water filter application to determine (1) its tendencies to leach undesirable decomposition products, (2) its range of potential applicability, and (3) its regenerability. In flowing water tests, poly‐1,3‐dichloro‐5‐methyl‐5‐(4‘‐vinylphenyl)hydantoin (Poly‐I) leached only small amounts of total organic carbon, free and total chlorine, anions, and volatile organics such as trihalomethanes. Furthermore, Poly‐I provided bactericidal efficacy over the pH range 4.5 to 9.5 and at temperatures as high as 37°C. Poly‐I is deactivated by reducing agents such as sodium thiosulfate and by ethanol; following deactivation, it can be regenerated by exposure to flowing aqueous free chlorine. Poly‐I appears suitable for use as a biocidal filter for small potable and recreational waters, for it is effective over a wide pH and temperature range and is readily regenerable. It would not be useful, however, for disinfection of large bodies of water such as in city treatment plants because of its cost and the large amount of the material that would be necessary.
USING UNCENSORED TRACE‐LEVEL MEASUREMENTS TO DETECT TRENDS IN GROUND WATER CONTAMINATION1
Authors: Dakins Maxine E. , Porter P. Steven. , West Michele , Rao S. Trivikrama.
Published: June 2007

ABSTRACT: Environmental decision making involving trace‐levels of contaminants can be complicated by censoring, the practice of reporting concentrations either as less than the limit of detection (LOD) or as not detected (ND) when a test result is less than the LOD. Censoring can result in data series that are difficult to meaningfully summarize, graph, and analyze through traditional statistical methods. In spite of the relatively large measurement errors associated with test results below the LOD, simple and meaningful analyses can be carried out that provide valuable information not available if data are censored. For example, an indication of increasing levels of contamination at the fringe of a plume can act as an early warning signal to trigger further study, an increased sampling frequency, or a higher level of remediation at the source. This paper involves the application of nonparametric trend analyses to uncensored trace‐level groundwater monitoring data collected between March 1991 and August 1994 on dissolved arsenic and chromium for seven wells at an industrial site in New York.
ENVIRONMENTAL IMPACT ASSESSMENT OF TAILINGS DISPERSAL FROM A URANIUM MINE USING TOXICITY TESTING PROTOCOLS1
Authors: Rippon G. D. , Riley S. J.
Published: June 2007

ABSTRACT: Toxicity testing is a means of establishing the environmental risk of a uranium tailings release. It is valuable in designing tailings containment structures because it assists in setting acceptable levels of risk for the design. This paper presents details of toxicity tests of the tailings from Ranger Uranium Mine, Northern Territory, Australia. The results suggest that the non‐radiological toxicity of the tailings is low. The environmental risk of a tailings release is more likely to be related to the physical impacts of the tailings, including infilling of billabongs and changes in the sedimentology of riparian ecosystems rather than their biogeochemical impact. Two major results were: (1) water from treatment with washed tailing fines were not toxic to Hydra viridissima, and (2) mixtures of washed tailings fines and natural floodplain sediment (overlying water or elutriates) were not toxic to Hydra viridissima or Moinodaphnia macleayi.
SYNTHESIS OF DATA FROM STUDIES BY THE NATIONAL IRRIGATION WATER‐QUALITY PROGRAM1
Authors: Seiler Ralph L.
Published: June 2007

ABSTRACT: From 1986 to 1993, the National Irrigation Water‐Quality Program (NIWQP) of the U.S. Department of the Interior studied whether contamination was induced by irrigation drainage in 26 areas of the Western United States. In 1992, a study to evaluate and synthesize data collected during these 26 investigations began. Selenium, boron, and molybdenum are the trace elements and DDT the pesticide most commonly found in surface water at concentrations exceeding chronic criteria for the protection of aquatic life. In six of the areas, the median selenium concentration exceeded the criterion. Aquatic‐life criteria have not been developed for uranium, but the median uranium concentration exceeded the proposed Maximum Contaminant Level for drinking water in seven areas. A principal components analysis indicates that severity of selenium contamination is not related to the severity of contamination by boron, molybdenum, and arsenic. Arsenic, boron, molybdenum, and selenium concentrations are nearly the same in both filtered and unfiltered samples, which indicates that contaminant concentrations in filtered samples can be directly compared with biological‐effects data developed using unfiltered samples. At a given site, selenium concentrations in surface water can change by an order of magnitude during the course of a year and from one year to another.