bluuebunny/crossref_metadata_2025 huggingface dataset:
SPATIAL ECONOMICS OF TARGETING MANURE POLICY1
Authors: Letson David , Gollehon Noel
Published: June 2007

ABSTRACT: Increasing specialization separates animal production from cropland, complicating manure management. To assist policy targeting efforts, we highlight areas where on‐farm use of manure may be problematic. Matching confined animal production with land, on the farm‐ rather than at the county‐level, gives our analysis an advantage over previous studies in avoiding aggregation problems. With manure‐based water quality problems, data aggregated to the county level may fail to convey the heterogeneity of animal production across regions and animal types. Aggregation bias blurs the distinction between areas with specialized animal production and those that merely have numerous animals. We estimate bias from using county aggregates, show its distribution spatially and by animal sector, and link it to concentration. Ongoing vertical integration in agriculture likely alters in‐county variability in facility scale and scope, and may influence decisions about which data we should gather and use.
INTERPRETATION OF THE DUAL PROGRAM FOR OPTIMAL GROUNDWATER HYDRAULIC CONTROL1
Authors: Ahlfeld David P.
Published: June 2007

ABSTRACT: Optimization formulations for hydraulic control that take the form of linear programs possess a corresponding dual linear program. The economic and physical interpretations of the dual linear program are examined for formulations in which hydraulic head in groundwater systems is constiained. In each case it is shown that the dual linear program has a physically meaningful interpretation. For a hydraulic gradient control formulation used for remedial analysis it is shown that the dual variable can be interpreted as the remedial benefit due to each gradient control constraint. The dual linear program maximizes the remedial benefit. The value of the dual variable can be used to compute such useful properties as the total remedial benefit of pumping at a specific location. For a formulation that optimizes aquifer yield while constraining drawdown the dual variable can be used to measure the total cost of drawdown capacity consumption per unit of pumping at a specific location. The dual program minimizes the cost of drawdown capacity consumption. By examining the meaning of the dual linear program an alternate statement of the problem under study is revealed. Quantities arising from the dual program add to the value of the optimization approach. Significant new information can be derived from existing linear optimization formulations with minimal additional computational effort.
GEOSTATISTICAL ANALYSIS OF HYDROGEOLOGY AND AGRICULTURAL LAND RECLAMATION IN SENEGAL RWER DELTA1
Authors: Babacar Ndiaye , Denis Isabel
Published: June 2007

ABSTRACT: The Diama dam is a dike that prevents the upstream intrusion of salt water into the lower part of the Senegal River during the low flow season. It is possible that a fraction of the salty lands from the delta region of the Senegal River will be eventually rendered fit for irrigated agriculture as a consequence of the building of this dam. A hydrogeologic survey, based on stratigraphic and piezometric data from a large monitoring well network, was conducted to describe the hydrogeologic setting of the delta alluvial aquifer and to predict the surface of reclaimable land. Geostatistical analysis, in particular kriging techniques, enables a better description of the spatial relationships of the diverse hydrogeologic variables. Since anterior studies demonstrated that the area of reclaimable lands depends mainly on the thickness of the surface clay layer, the geostatistical analysis of this variable indicates that from 40 percent to 80 percent of the lands of the delta region will eventually be cultivatable. The imprecision of this assessment is a result of the difficulty in defining a threshold for the appropriate thickness of the clay layer.
OUTLIER DETECTION IN TOTAL PHOSPHORUS CONCENTRATION DATA FROM SOUTH FLORIDA RAINFALL1
Authors: Ahn Hosung
Published: June 2007

ABSTRACT:Atmospheric deposition can be a significant source of phosphorus to South Florida's aquatic system. Deposition samples are often contaminated to varying degrees by bird droppings or other foreign materials. This study attempted to use statistical and other methods to detect and remove the outliers in the rain‐borne total phosphorus concentration data. Some outliers in the data were identified using field notes derived from visual inspection of the samples. Outlier detection statistics based on a simple linear regression were then used for additional data screening. As a result of these analyses, about 35 percent of the observed values were identified as outlying data which needed to be removed prior to further data analyses. Based on detected outliers in the data from 15 monitoring sites, a lumped cutoff value of 130 4mUg/L was determined. This lumped cutoff value may be useful for further quality control and analyses of the data from the region.
DETECTING BASE FLOW IMPACTS IN COASTAL PLAIN STREAMS1
Authors: Dow Charles L.
Published: June 2007

ABSTRACT: An established trend analysis methodology was applied to the problem of identifying and quantifying stream base flow impacts from water withdrawals and water loss through interbasin transfers. Impacts were simulated using base flow values selected from two U.S. Geological Survey (USGS) continuous record streamflow sites located within the Pinelands of southern New Jersey. Study site base flows were regressed against index site base flows with monotonic and step trend tests applied to the residuals from the regression model. The smallest, significantly detectable (α= 0.10) percentage reduction within a given simulation was used as an estimate of the sensitivity of a trend test. Evaluation of the trend analysis methodology led to the following practical considerations regarding trend test sensitivity. The proportion of study site base flow variability explained by index site base flows should be maximized, while at the same time minimizing positive, first‐order autocorrelation in the regression residuals. Given the importance of detecting autocorrelation, missing values should be avoided or minimized. The quarterly (three‐month) interval reduced the magnitude of autocorrelation relative to a shorter two‐month sampling interval. Sensitivity appeared to improve when equalizing the number of values before and after a base flow impact(s) while seasonally biased sampling appeared to reduce sensitivity. Based primarily on past trend detection studies, nonparametric tests were deemed a better choice over their parametric counterparts, due to the lack of stringent data distributional requirements coupled with little or no loss of power even when applied to normally distributed data.
TRANSPORT OF DIAZINON IN THE SAN JOAQUIN RIVER BASIN, CALIFORNIA1
Authors: Kratzer Charles R.
Published: June 2007

ABSTRACT: Most of the application of the organophosphate insecticide diazinon in the San Joaquin River Basin occurs in winter to control wood‐boring insects in dormant almond orchards. A federalstate collaborative study found that diazinon accounted for most of the observed toxicity of San Joaquin River water in February 1993. Previous studies focused mainly on west‐side inputs to the San Joaquin River. In this 1994 study, the three major east‐side tributaries to the San Joaquin River ‐ the Merced, Tuolumne, and Stanislaus rivers ‐ and a downstream site on the San Joaquin River were sampled throughout the hydrographs of a late January and an early February storm. In both storms, the Tuolumne River had the highest concentrations of diazinon and transported the largest load of the three tributaries. The Stanislaus River was a small source in both storms. On the basis of previous storm sampling and estimated travel times, ephemeral west‐side creeks probably were the main diazinon source early in the storms, whereas the Tuolumne and Merced rivers and east‐side drainages directly to the San Joaquin River were the main sources later. Although 74 percent of diazinon transport in the San Joaquin River during 1991–1993 occurred in January and February, transport during each of the two 1994 storms was only 0.05 percent of the amount applied during preceding dry periods. Nevertheless, some of the diazinon concentrations in the San Joaquin River during the January storm exceeded 0.35 μ/L, a concentration shown to be acutely toxic to water fleas. On the basis of this study and previous studies, diazinon concentrations and streamflow are highly variable during January and February storms, and frequent sampling is required to evaluate transport in the San Joaquin River Basin.
AUTOMATED METHODS FOR ESTIMATING BASEFLOW AND GROUND WATER RECHARGE FROM STREAMFLOW RECORDS1
Authors: Arnold J. G. , Allen P M.
Published: June 2007

ABSTRACT: To quantify and model the natural ground water recharge process, six sites located in the midwest and eastern United States where previous water balance observations had been made were compared to computerized techniques to estimate: (1) base flow and (2) ground water recharge. Results from an existing automated digital filter technique for separating baseflow from daily streamflow records were compared to baseflow estimates made in the six water balance studies. Previous validation of automated baseflow separation techniques consisted only of comparisons with manual techniques. In this study, the automated digital filter technique was found to compare well with measured field estimates yielding a monthly coefficient of determination of 0.86. The recharge algorithm developed in this study is an automated derivation of the Rorabaugh hydrograph recession curve displacement method that utilizes daily streamflow. Comparison of annual recharge from field water balance measurements to those computed with the automated recession curve displacement method had coefficients of determination of 0.76 and predictive efficiencies of 71 percent. Monthly estimates showed more variation and are not advocated for use with this method. These techniques appear to be fast, reproducible methods for estimating baseflow and annual recharge and should be useful in regional modeling efforts and as a quick check on mass balance techniques for shallow water table aquifers.
WATERSHED COUNCILS: AN EMERGING FORM OF PUBLIC PARTICIPATION IN NATURAL RESOURCE MANAGEMENT1
Authors: Griffin C. B.
Published: June 2007

ABSTRACT:There is increasing interest in using watershed councils to provide information to public natural resource managers, particularly in the western states. Watershed councils are composed of interested governmental and nongovernmental stakeholders that form to collaboratively manage water and other natural resources at the scale of a watershed. This research is the first step in a multi‐step policy analysis designed to answer the question of whether watershed councils are an improvement over traditional methods of public involvement in natural resource management. This paper outlines why watershed councils form and discusses their structure and operation. There is considerable variability in terms of watershed councils' goals, their effectiveness, stakeholder composition, their involvement in the “real” decision‐making process, types of participation that are allowed, leadership, financing, decision‐making procedures, efficiency, and temporal scale. These structural components are presented as a framework that can be used by researchers to develop criteria to evaluate watershed councils.
THE SOCIAL CONTEXT OF WESTERN WATER DEVELOPMENT1
Authors: Cortese Charles F
Published: June 2007

ABSTRACT: Social scientists were included in the planning and design for an integrated, trans‐basin water resource project. Within this complex project, a socioeconomic impact assessment (SIA) concentrated on identifying the social, political, and economic issues and potential impacts inherent in developing a city's water rights. Before the SIA began, some of the development alternatives had already generated widespread hostility and organized opposition from communities within the watershed. The SIA involved residents of affected communities in the study design and project planning. The study found a number of components that constituted the concerns, beliefs, and expectations about perceived, potential impacts that might result from the different alternatives. In most cases these issues constituted threats to valued environmental resources, valued community resources, the social environment, the economic base, and a secure future. The social science component was a key factor in the ultimate decision to pursue a particular alternative which was sensitive to the social and political issues, minimized environmental and socioeconomic impacts, and ultimately had support among the communities potentially affected. The experience from this case study suggests that the approach used can be applied successfully in the planning of other water development projects and result in cooperation from the wide range of interest groups that often present costly obstacles to such projects.
SCIENCE AND POLICY IN INTEGRATED WATERSHED MANAGEMENT: A CASE STUDY1
Authors: Letey J.
Published: June 2007

ABSTRACT: Policy and management plans can be enhanced through effective communication between researchers and decision makers. Differences in understanding can come from differences in professional cultures. Scientists deal with facts, proof and incremental progress whereas the decision makers are often faced with perceptions, emotions and deadlines. A case study is presented illustrating the interaction between the political system and science on a water management issue. Irrigation projects in the western San Joaquin Valley of California lead to a situation requiring subsurface drainage and disposal of the drainage water. The original plan was to discharge the drainage water in the Suisun Bay east of the San Francisco Bay. Severe damage to birds associated with selenium in the water led to a reevaluation of irrigation and drainage management options. Federal and state agencies cooperated to establish a San Joaquin Valley Drainage Program (SJVDP) which was to develop plans for solving the problem. Discharge to the Bay was politically eliminated as an option for evaluation, an action criticized by a National Research Council Committee as not being scientifically based. The SJVDP published a Management Plan in 1990 which contained proposals viewed by the scientific community as not necessarily incorrect but not completely justified based on the scientific knowledge at the time. A segment of the Citizens Advisory Committee that was part of the SJVDP consisting of representatives from the interest groups viewed the Management Plan as a negotiated agreement between the environmental and agricultural interests. Presently, an Activity Plan exists, consisting of technical committees to evaluate the current technical and economic evaluation of the management options proposed in the Management Plan. This case study illustrates that factors other than scientific facts have bearing on decisions. Successful management plans must be technically sound, economically viable and socially acceptable. The scientific community needs to evaluate its role in the policy making arena and to focus research on questions of greatest value to decision makers, as well as to scientific peers.
EFFECTWENESS OF INTEGRATED STORMWATER MANAGEMENT IN A PORTLAND, OREGON, WATERSHED1
Authors: Hottenroth Dawn , Harper Craig , Turner James
Published: June 2007

ABSTRACT: The City of Portland's stormwater management program, winner of EPA's Environmental Excellence Award for 1996, is committed to partnership‐based, cost‐effective, “green” approaches to healthy neighborhoods and water quality. The stormwater program encourages innovative, non‐structural pollution reduction techniques like native landscaping, stormwater pollution reduction bioswales and ponds, and public involvement and education.

Effectiveness of stormwater best management practices (BMPs) has been difficult to determine on a citywide basis. Recognizing this problem, the City of Portland launched the Parkrose Pilot Project in 1994 to test the effectiveness of a wide range of BMPs in a small watershed in north Portland, the Parkrose catchment, and monitor the results prior to citywide implementation. This catchment was selected because of its small size (144 acres), its representative mix of land uses, and an extensive record of water quality monitoring data.

This paper examines the City's strategy in selecting the Parkrose study area as a pilot watershed, the BMPs chosen for use in the watershed, and the results of the program to date. Final success of the Parkrose project will be gauged by the attainment of measurable pollution reduction within the catchment while providing opportunities for meaningful participation by the local community in achieving water quality. Involvement by private citizens in the community is crucial to the success of the project and to ensure compliance with the federal mandate to reduce pollutants to the maximum extent practicable.
INSTITUTIONAL FRAMEWORK FOR REGIONAL COOPERATION IN THE DEVELOPMENT OF WATER SUPPLY AND DEMAND IN THE MIDDLE EAST1
Authors: Haddad Marwan
Published: June 2007

ABSTRACT: Water is, and most likely will continue to be, one of the main concerns and potential causes of instability in the Middle East (ME). The contribution of the existing renewable water resources is limited and can not fulfill the long‐term projected gap between water supply and demand for most of the countries in the ME. An integrated regional approach for fulfilling this gap was preferred. A regional institutional framework was proposed for the implementation of this integrated regional approach and consists of a regional water board operating through three units for technical, implementation, and management aspects of project and activities. An analysis of the regional water supply and demand development, the design and policy making of the proposed institution, technology and water markets, cooperation, actors and beneficiaries, finances, and expected obstacles and constraints to the establishment and sustainable operation of the proposed institution are included.
OPTIMUM DESIGN OF BORDER IRRIGATION SYSTEM1
Authors: Khanjani M. J. , Barani G. A.
Published: June 2007

ABSTRACT: Border irrigation systems like most of the other surface irrigation systems, do not need too much energy and special equipment. Thus, many farmers have used this system for a long time. On the other hand, design of surface irrigation systems including border irrigation requires many input parameters, and need intensive engineering calculations. The burden of these requirements probably led the users to experimental design of the systems with low efficiencies. However, accurate design and high quality optimization of the border irrigation system that can result in a highly efficient system is possible.

In this study, an optimization model for border irrigation system is presented. The Hook Jeev's pattern search optimization method in conjunction with a general mathematical model of border irrigation is used to maximize the irrigation application efficiency. The border irrigation storage and distribution efficiencies, border slope and length, inflow rate, cutoff time, and the Manning's roughness coefficient are selected as constraints. The model is applied to field‐measured data. The results show that it is possible to select a suitable combination of the border system's parameters (border's length, inflow rate, and cutoff time) to obtain a maximum application efficiency.
ROLE OF EROSION PROCESSES IN TRANSFER OF RADIONUCLIDES: RESULTS OF FIELD EXPERIMENTS1
Authors: Khanbilvardi R. , Shestopalov V , Onishchenko I. , Bublyas V , Gudzenko V
Published: June 2007

ABSTRACT: An experimental one‐year fieldwork has been conducted in the vicinity of the Chernobyl NPP, within an agricultural watershed, to study the transfer of radionuclides brought into the environment by the disaster of 1986. Presented are results of observation of the washout of 137Cs from the runoff plot both in natural conditions and under artificial rainfalls. Beside traditional hydro‐logical methods, new techniques were used allowing to consider microtopographical peculiarities of the runoff plot and their role in the redistribution of radionuclides. The estimate of the annual mass balance for the soil and the radionuclides within the runoff plot has shown that, regardless of significant areal variation of their concentration, the 137Cs washout with the solid runoff resulted from artificial rainfalls amounts to some 1 percent of its reserves in the uppermost 5 cm of the topsoil. The same parameter for the natural runoff is lower by an order of magnitude. Both these factors of self‐purification are about two times less than natural radioactive decay of 137Cs.
ASSESSING INSTREAM FLOWS AND RESERVOIR OPERATIONS ON AN EASTERN IDAHO RWER1
Authors: Benjamin Lyn , Van Kirk Robert W.
Published: June 2007

ABSTRACT: A methodology for assessing reservoir management was applied to the historical conflict between winter fish and wildilife flows below Island Park Reservoir on Henrys Fork of the Snake River and the fulfillment of storage water rights. The methodology consists of (1) identifying impacts of flow regulation, (2) quantifying relationships among variables affecting physical reservoir fill, and (3) assessing effects of these discharges on the fulfillment of water rights in the context of a larger system of interrelated reservoirs. Winter (storage season) flows are critical to management of fish and wildlife populations below Island Park Dam, but flow regulation has resulted in decreased winter discharge. Allowable winter flows are a function of inflow, length of storage season, reservoir content at the start of storage season, and potential for downstream capture of excess storage season water discharged at Island Park. Modeling results indicate that winter flows in the range of those recommended for fish and wildlife management are attainable during average years but not during years when initial reservoir content is low. The methodology was successful in quantifying information useful to decision makers in a variety of agencies and disciplines and could be applied to solve water management problems on other regulated river systems.
A MULTI‐TIER APPROACH FOR AGRICULTURAL WATERSHED MANAGEMENT1
Authors: Rudra R. P. , Dickinson W. T. , Abedini M. J. , Wall G. J.
Published: June 2007

A multi‐tier approach for agricultural watershed management has been proposed. The approach involves identification of a watershed management issue/problem, selection or development of simple conceptual model suitable for the exploration of the issue/problem identified and appropriate to the database available, and application of the model the address the identified issue/problem. The procedure is repeated by increasing the complexity in the conceptual model until the identified issue/problem has been addressed satisfactorily. An application of the procedure to an example watershed in southern Ontario conditions is shown. The application example has revealed that for identification of temporal pattern of runoff and sediment loads a simple conceptual model is adequate. For identification of spatial location of the sediment source areas and for the development of a monitoring program for the evaluation of remedial strategies a more complex distributed agricultural watershed model is necessary.
EVALUATING THE PERSISTENCE OF RESIDENTIAL WATER CONSERVATION: A 1992–1997 PANEL STUDY OF A WATER UTILITY PROGRAM IN DELAWARE1
Authors: Wang Young‐Doo , Song Jae‐Shuck , Byrne John , Yun Sun‐Jin
Published: June 2007

This study systematically evaluates residential consumer responses to a utility conservation initiative based on an econometric analysis of a sample of 510 households served by Artesian Water Company, Inc. (New Castle County of Delaware). Using a panel study approach covering the period from 1992 to 1997, this study shows that Artesian's water conservation program has had statistically significant and persistent impacts on residential water consumption.
ESTIMATES OF RUNOFF USING WATER‐BALANCE AND ATMOSPHERIC GENERAL CIRCULATION MODELS1
Authors: Wolock David M. , McCabe Gregory J.
Published: June 2007

ABSTRACT: The effects of potential climate change on mean annual runoff in the conterminous United States (U.S.) are examined using a simple water‐balance model and output from two atmospheric general circulation models (GCMs). The two GCMs are from the Canadian Centre for Climate Prediction and Analysis (CCC) and the Hadley Centre for Climate Prediction and Research (HAD). In general, the CCC GCM climate results in decreases in runoff for the conterminous U.S., and the HAD GCM climate produces increases in runoff. These estimated changes in runoff primarily are the result of estimated changes in precipitation. The changes in mean annual runoff, however, mostly are smaller than the decade‐to‐decade variability in GCM‐based mean annual runoff and errors in GCM‐based runoff. The differences in simulated runoff between the two GCMs, together with decade‐to‐decade variability and errors in GCM‐based runoff, cause the estimates of changes in runoff to be uncertain and unreliable.
AN EVALUATION OF TWO HYDROLOGIC MODELS FOR CLIMATE CHANGE SCENARIOS1
Authors: Frakes Brent , Yu Zhongbo
Published: June 2007

ABSTRACT: Understanding the effects of climate change on water resources requires coupling atmospheric and hydrologic models. With the wide array of hydrologic models, from simple empirical to complex physically based, it is not clear which is preferable to simulate hydrologic variations over long time scales. To address this issue, a black‐box artificial neural network (ANN) model was compared to a distributed parameter conceptual Geographic Information System based Hydrologic Modeling System (GIS‐HMS). Both models computed daily direct surface runoff in four sub‐basins of the West Branch of the Susquehanna River Basin, Pennsylvania and were evaluated with five objective functions. Overall, results were comparable between models. However, the ANN was favored in the larger sub‐basins, while GIS‐HMS was more accurate in the smaller catchments. Both models were impaired by the poor spatial and temporal resolution of precipitation data and the simplified representation of antecedent soil‐moisture conditions. In the context of climate change, where simulations are limited by computing power, results suggest that both models are appropriate. When detailed simulations are essential, GIS‐HMS is a preferable model to use. On the other hand, the ANN model is more suitable when multiple scenarios require immediate analysis and the distributed qualities of runoff are not required.
THE EFFECTS OF CLIMATE CHANGE AND IRRIGATION ON CRITERION LOW STREAMFLOWS USED FOR DETERMINING TOTAL MAXIMUM DAILY LOADS1
Authors: Eheart J. Wayland , Wildermuth Amy J. , Herricks Edwin E.
Published: June 2007

ABSTRACT: This paper addresses the possible impacts of global climate change on low streamflows in the Midwest, both directly, through lower precipitation, and indirectly, by rendering irrigation profitable in areas where it has found little application in the past. In the analysis presented here, streamflow data are altered to represent the effect of climate change and stream‐supplied irrigation, and then used to estimate new values for two low‐flow criteria, the one‐ and seven‐day‐ten‐year low flows (7Q10 and 1Q10) under 20 climate change and irrigation scenarios. Additionally, the frequencies of violation of these two criteria, and multiple violations in a three‐year period, are determined.

Results show that the potential impact of the assumed climate change scenarios on low flow standards is substantial. A 25 percent decrease in mean precipitation results in a 63 percent reduction in design flow, even in the absence of irrigation. With irrigation, the reduction can be as much as 100 percent. The frequency of single violations of low flow criteria is found to increase several fold with irrigation. The frequency of multiple violations of low flow criteria in a three‐year period is sensitive to climate change, increasing from around 20 percent to nearly 100 percent as the climate change becomes more severe.
CLIMATE VARIABILITY AND FLOOD FREQUENCY ESTIMATION FOR THE UPPER MISSISSIPPI AND LOWER MISSOURI RIVERS1
Authors: Olsen J. Rolf , Stedinger Jery R. , Matalas Nicholas C. , Stakhiv Eugene Z.
Published: June 2007

ABSTRACT: This paper considers the distribution of flood flows in the Upper Mississippi, Lower Missouri, and Illinois Rivers and their relationship to climatic indices. Global climate patterns including El Niño/Southern Oscillation, the Pacific Decadal Oscillation, and the North Atlantic Oscillation explained very little of the variations in flow peaks. However, large and statistically significant upward trends were found in many gauge records along the Upper Mississippi and Missouri Rivers: at Hermann on the Missouri River above the confluence with the Mississippi (p = 2 percent), at Hannibal on the Mississippi River (p < 0.1 percent), at Meredosia on the Illinois River (p = 0.7 percent), and at St. Louis on the Mississippi below the confluence of all three rivers (p = 1 percent). This challenges the traditional assumption that flood series are independent and identically distributed random variables and suggests that flood risk changes over time.
DOWNSCALED CLIMATE AND STREAMFLOW STUDY OF THE SOUTHWESTERN UNITED STATES1
Authors: Miller Norman L. , Kim Jinwon , Hartman Robert K. , Farrara John
Published: June 2007

ABSTRACT: Downscaling coarse resolution climate data to scales that are useful for impact assessment studies is receiving increased attention. Basin‐scale hydrologic processes and other local climate impacts related to water resources such as reservoir management, crop and forest productivity, and ecosystem response require climate information at scales that are much finer than current and future GCM resolutions. The Regional Climate System Model (RCSM) is a dynamic downscaling system that has been used since 1994 for short‐term precipitation and streamflow predictions and seasonal hindcast analysis with good skill. During the 1997–1998 winter, experimental seasonal forecasts were made in collaboration with the NOAA Climate Prediction Center and UCLA with promising results. Preliminary studies of a control and 2°CO2 perturbation for the southwestern U.S. have been performed.
POTENTIAL EFFECTS OF CLIMATE CHANGE ON AGRICULTURAL WATER USE IN THE SOUTHEAST U.S.1
Authors: Hatch Upton , Jagtap Shrikant , Jones Jim , Lamb Marshall
Published: June 2007

ABSTRACT: Climate change has the potential to have dramatic effects on the agricultural sector nationally and internationally as documented in many research papers. This paper reports on research that was focused on a specific crop growing area to demonstrate how farm managers might respond to climate‐induced yield changes and the implications of these responses for agricultural water use. The Hadley model was used to generate climate scenarios for important agricultural areas of Georgia in 2030 and 2090. Linked crop response models indicated generally positive yield changes, as increased temperatures were associated with increased precipitation and CO2. Using a farm management model, differences in climate‐induced yield impacts among crops led to changes in crop mix and associated water use; non‐irrigated cropland received greater benefit since irrigated land was already receiving adequate moisture. Model results suggest that farm managers will increase cropping intensity by decreasing fallowing and increasing double cropping; corn acreage decreased dramatically, peanuts decreased moderately and cotton and winter wheat increased. Water use on currently irrigated cropland fell. The potential for increased water use through conversion of agriculturally important, but currently non‐irrigated, growing areas is substantial.
RESPONSE OF NORTH AMERICAN FRESHWATER LAKES TO SIMULATED FUTURE CLIMATES1
Authors: Hostetler S. W. , Small E. E.
Published: June 2007

ABSTRACT: We apply a physically based lake model to assess the response of North American lakes to future climate conditions as portrayed by the transient trace‐gas simulations conducted with the Max Planck Institute (ECHAM4) and the Canadian Climate Center (CGCM1) atmosphere‐ocean general circulation models (A/OGCMs). To quantify spatial patterns of lake responses (temperature, mixing, ice cover, evaporation) we ran the lake model for theoretical lakes of specified area, depth, and transparency over a uniformly spaced (50 km) grid. The simulations were conducted for two 10‐year periods that represent present climatic conditions and those around the time of CO2 doubling. Although the climate model output produces simulated lake responses that differ in specific regional details, there is broad agreement with regard to the direction and area of change. In particular, lake temperatures are generally warmer in the future as a result of warmer climatic conditions and a substantial loss (> 100 days/yr) of winter ice cover. Simulated summer lake temperatures are higher than 30°C over the Midwest and south, suggesting the potential for future disturbance of existing aquatic ecosystems. Overall increases in lake evaporation combine with disparate changes in A/OGCM precipitation to produce future changes in net moisture (precipitation minus evaporation) that are of less fidelity than those of lake temperature.
EFFECTS OF INTERANNUAL VARIATION OF PRECIPITATION ON STREAM DISCHARGE FROM RHODE RIVER SUBWATERSHEDS1
Authors: Correll David L. , Jordan Thomas E. , Weller Donald E.
Published: June 2007

ABSTRACT: The purpose of this study was to determine the relationships between precipitation at the seasonal and annual scale and water discharge per surface area for seven contiguous first ‐ and second‐order tributaries of the Rhode River, a small tidal tributary to Chesapeake Bay, Maryland, USA. The goal was to quantify the effects of a wide range of precipitation, representative of inter‐annual variations in weather in this region. The discharges measured included both overland storm flows and groundwater, since the aquifers were perched on a clay aquiclude. Precipitation varied from 824 to 1684 mm/yr and area‐weighted Rhode River watershed discharge varied from 130 to 669 mm/yr with an average of 332 mm/yr or 29.1 percent of average precipitation. Average annual dis. charges from three first‐order watersheds were significantly lower per surface area and varied from 16.0 to 21.9 percent of precipitation. Winter season precipitation varied from 125 to 541 mm. Area‐weighted Rhode River winter discharge varied from 26.3 to 230 mm with an average of 115 mm or 43.9 percent of average precipitation. Spring season precipitation varied from 124 to 510 mm and watershed discharge varied from 40.0 to 321 mm with an average of 138 mm or 46.9 percent of average precipitation. In the summer and fall seasons, watershed discharge averaged 40.6 and 40.9 mm or 13.5 and 14.3 percent of average precipitation, respectively. Except in winter, the proportion of precipitation discharged in the streams increased rapidly with increasing volume of precipitation. Stream order showed a higher correlation with volume of discharge than vegetative cover on the watershed.
LONG‐TERM GROUNDWATER MANAGEMENT BY A MODFLOW BASED DYNAMIC OPTIMIZATION TOOL1
Authors: Sun Min , Zheng Chunmiao
Published: June 2007

ABSTRACT: This paper describes a computer‐aided tool for selecting optimal management policies involving groundwater hydraulics over a large number of management periods. The tool, referred to as DOMODF, uses a dynamic optimization algorithm linked to an existing popular groundwater flow simulation code MODFLOW. It combines the expert knowledge of management policies with the effectiveness of optimization oriented search technique. Due to the dynamic nature of the search technique implemented in DOMODF, it is effective in dealing with long‐term decision making problems. DOMODF can be used as a guidance tool for finding desirable policies to achieve various groundwater management objectives, leading to considerable savings in management costs over those predicted by currently available policies that are fed into the tool as input. The preliminary test results show the promising potential of DOMODF as an effective long‐term groundwater management tool.
RECHARGE OF THE SNAKE RWER PLAIN AQUIFER: TRANSITIONING FROM INCIDENTAL TO MANAGED1
Authors: Johnson Gary S. , Sullivan Walter H. , Cosgrove Donna M. , Schmidt Robert D.
Published: June 2007

ABSTRACT: Declining ground‐water levels and spring discharges have heightened water user concerns about the sustainability of the Snake River Plain aquifer in southern Idaho. Diminished recharge from surface water irrigation and increased irrigation pumping have been depleting the aquifer at a rate of about 350,000 acre‐feet/year. Previously, aquifer conditions were treated as an uncontrollable consequence of weather and development activities. With increasing competition for available water, the State appears to be progressing through a three‐stage process of recharge management. The first stage is that which has occurred historically, where recharge is largely an incidental effect of surface water irrigation. The second stage is the implementation of intentional recharge with little regard to identifying or maximizing benefits. Idaho has been at this stage for the past few years. The State is entering a third stage in which recharge sites will be located and designed to meet specific water user and environmental objectives. Preliminary estimates using numerical and analytical models demonstrate that managed recharge within a few miles of the river will result in short‐term increases in spring discharge. More distant recharge sites are needed to provide longer‐term benefits. The primary challenge facing implementation of the managed recharge program will be the balancing of economic and environmental costs and benefits and to whom they accrue.
NUMERICAL MODEL OF A TRACER TEST ON THE SANTA CLARA RWER, VENTURA COUNTY, CALIFORNIA1
Authors: Nishikawa Tracy , Paybins K S. , Izbicki J. A. , Reichard E. G.
Published: June 2007

ABSTRACT: To better understand the flow processes, solute‐trans. port processes, and ground‐water/surface‐water interactions on the Santa Clara River in Ventura County, California, a 24‐hour fluorescent‐dye tracer study was performed under steady‐state flow conditions on a 45‐km reach of the river. The study reach includes perennial (uppermost and lowermost) subreaches and ephemeral subreaches of the lower Piru Creek and the middle Santa Clara River. The tracer‐test data were used to calibrate a one‐dimensional flow model (DAFLOW) and a solute‐transport model (BLTM). The dye‐arrival times at each sample location were simulated by calibrating the velocity parameters in DAFLOW. The simulations of dye transport indicated that (1) ground‐water recharge explains the loss of mass in the ephemeral middle subreaches, and (2) ground‐water recharge does not explain the loss of mass in the perennial uppermost and lowermost subreaches. The observed tracer curves in the perennial subreaches were indicative of sorptive dye losses, transient storage, and (or) photodecay ‐ these phenomena were simulated using a linear decay term. However, analysis of the linear decay terms indicated that photodecay was not a dominant source of dye loss.
ECONOMIC INCENTIVES FOR WATER CONSERVATION ON THE MONTEREY PENINSULA: THE MARKET PROPOSAL1
Authors: Haddad Brent M.
Published: June 2007

ABSTRACT: Literatures on price‐based urban water conservation and on market‐based mechanisms to manage natural resources suggest that market‐based management of urban/suburban water use may be feasible. A market‐based proposal that emerged from a water shortage on California's Monterey Peninsula is presented. In the proposal, conservation incentives arise both from an ability among end‐users of water to reduce consumption and sell use‐rights to water, and from a penalty price for consumption in excess of one's use rights. The amount of water associated with use rights is capped and varies according to hydrological, meteorological, ecological, and other criteria. Requirements for further study of the proposal are listed, and the role that similar market‐based mechanisms could play in urban water management is discussed.
CALIBRATION OF A STEADY‐STATE SEEPAGE MODEL FROM TRANSIENT RECOVERY OF FIELD DATA1
Authors: Guardo Mariano , Rohrer Kevin P
Published: June 2007

ABSTRACT: The South Florida Water Management District (District) constructed three experimental test cells (20 ± 50 feet = 6.1 ± 15.2 m) to determine the seepage influence of a major agricultural canal adjacent to the cells. These three cells represented the first stage of a series of experimental cells to determine the efficiency of algal‐bacterial communities (periphyton) to successfully remove phosphorus (P) from the water. This treatment technology is known as Periphyton‐based Stormwater Treatment Area (PSTA) and is being considered under the Supplemental Technology Program (Phase II) to comply with the Everglades Forever Act (EFA) of 1994. However, the efficiency of a PSTA in removing nutrients has not been documented yet. To determine the efficiency of PSTA technology to remove phosphorus (P) from the water, it is necessary to quantify all the components of the water budget. The purpose of the cells was to evaluate the potential seepage due to the operational range of stages into and out of the test cells. A steady‐state, two‐dimensional seepage (FastSEEP/SEEP2D) model was applied and successfully calibrated for that purpose. The model was calibrated using mean seepage flows obtained after drawdowns in each test cell, by pumping water out. These seepage flows as well as the boundary conditions (stages) were estimated by discretizing the recovery data. The recovery data represents the seepage from the agricultural canal into each of the test cells after the drawdowns, since the stages in the canal during the experiment did not change significantly and were high. Each of the three test cells was excavated to different bottom elevations to determine the effect of substrate differences on seepage rates. Values of hydraulic conductivity for five different layers in the models were based on field observations, lithologic descriptions, and slug tests. Modeled seepage produced reasonable results for the three test cells compared with estimated seepage from the recovery data, achieving a satisfactory calibration. The errors of the simulated seepage ranged from −6.1 to 16.8 percent (under and over estimation, respectively).
AFTER THE 1993 FLOOD: A WATER AND SURFICIAL BED SEDIMENT QUALITY SCENARIO ON THE ILLINOIS AND UPPER MISSISSIPPI RWERS1
Authors: Soong TaWei , Ettinger William H.
Published: June 2007

ABSTRACT: Effects of the 1993 flood on river water and sediment quality were investigated using historical data and data collected from the Illinois River and Upper Mississippi River in a post‐flood period. Overall the post‐flood results showed systematic reductions and individual changes in the water and sediment constituents.

The reductions in sediment metals and nutrients were most obvious at the Keokuk and Lock and Dam 26 stations. By analyzing and comparing the physical changes to the changes in water and sediment constituents at each station, it was found that physical processes such as sediment entrainment and, more importantly, the removal of fine sediment to be the main causes for the reduced concentrations in sediment constituents. On the other hand, sediment redistribution and associated secondary contamination could have caused the emergence of several water and sediment constituents that were undetected before the flood.
ESTABLISHING POLLUTANT LOAD REDUCTION TARGETS FOR THE INIIAN RWER LAGOON, FLORIDA1
Authors: Sigua Gilbert C. , Steward Joel S.
Published: June 2007

ABSTRACT. Establishment of seagrass‐based pollutant load reduction targets is a major aim of water quality management in the Indian River Lagoon (IRL) estuary. It is believed that light and water clarity are the limiting factors affecting seagrass abundance and distribution in the Lagoon. Thus, targeted reductions of nutrients, dissolved organic matter and for suspended sediments should achieve desired seagrass coverage goals. On an annual average, the Lagoon is receiving external loadings of 5,346, 771, and 54,408 metric tons per year of nitrogen (N), phosphorus (P), and total suspended solids (TSS), respectively. Most of the loadings are stormwater generated; thus, implementation of reduction targets will key in on major urban and agricultural stormwater systems. The process of developing targets requires the establishment of light requirements for seagrass. Two methods are being employed to develop such targets. One method is the application of a predictive, 3‐D model that accounts for the essential interactive processes of the Lagoon: hydrology, hydrodynamics, water quality, nutrient uptake/release, seagrass growth rates, and light attenuation. The other method is based simply on the comparison of loading rates between a developed sub‐basin with associated seagrass impacts and an undeveloped sub‐basin with adjacent healthy seagrass coverages. The latter method will provide the initial and preliminary targets that can be tested, confirmed, or modified by application of the 3‐D model.
CLIMATE CHANGE IMPACTS ON NEW YORK CITY'S WATER SUPPLY SYSTEM1
Authors: Blake Reginald , Khanbilvardi Reza , Rosenzweig Cynthia
Published: June 2007

ABSTRACT: It has been well established that the greenhouse gas loading of the atmosphere has been increasing since the mid 19th century. Consequently, shifts in the earth's radiative balance are expected with accompanying alterations to the earth's climate. With these anticipated, and perhaps already observable, changes in both global and regional climate, managers of regional water resources seek insight to the possible impacts climate change may have on their present and future water supplies. The types and degrees of impacts that climate change may have on New York City's water supply system were assessed in a study of a watershed at Allaben, New York. Hypothetical scenarios of future climate and climate change projections from three General Circulation Models (GCMs) were used in conjunction with the WatBal hydrological model and the Palmer Drought Severity Index (PDSI) to ascertain how runoff and soil moisture from this watershed may change in a warmer climate. For the worst case predictions, the results indicate that within the century of the 2000s, the watershed's air temperature may increase up to about 11°F, while its precipitation and runoff may decrease by about 13 and 30 percent, respectively. If this watershed is typical of the others within the New York City water supply system, the system's managers should consider implementing mitigation and adaptation strategies in preparation for the worst of these possible future conditions.