bluuebunny/crossref_metadata_2025 huggingface dataset:
REGIONAL AND TEMPORAL PATTERNS OF TOTAL SOLUTES IN THE SASKATCHEWAN RWER BASIN1
Authors: Taylor Barry R. , Hamilton Hal R.
Published: June 2007

ABSTRACT: In the Saskatchewan River Basin (365,000 km2), which drains the Canadian prairie from the Rocky Mountains east to Manitoba, concentrations of total solutes are usually within the range of 100 to 1000 mg/L. Total solutes levels in tributaries increase markedly from west to east across the basin, as mountain snowmelt and dilute surface runoff are replaced by ion‐rich ground water and concentrated prairie runoff as the major influences on solute concentrations. In contrast, total solutes concentrations in main‐stem rivers are nearly constant, ranging 200–300 mg/L, with only a small increase across the basin. Dilute mountain runoff dominates solute concentrations in main‐stem rivers, despite the influx of increasingly ion‐rich water from tributaries.

The principal long‐term trends in total solute concentrations across the basin, as revealed by linear and sine‐curve regressions, were due to the construction of reservoirs, which depress the natural winter maximum in solute concentrations and disrupt the sinusoidal annual pattern, while sharply reducing seasonal variation. These regression methods did not show anticipated anthropogenic increases in salt load in the Red Deer or South Saskatchewan Rivers, but a trend of slowly increasing solutes concentrations (2 mg/L/yr) was detected for autumn flows in the lower Bow River. Municipal wastes from the City of Calgary or irrigation return flows are probably responsible for this increase.
TOTAL SOLUTES LOADS AND GEOCHEMICAL YIELDS IN THE SASKATCHEWAN RIVER BASIN1
Authors: Taylor Barry R. , Hamilton Hal R. , Macdonald Gordon
Published: June 2007

ABSTRACT: River solute loads have seldom been measured in very large, complex drainage basins, nor have the methods of calculating loads been critically examined. For sites in the Saskatchewan River Basin, Canada, rating curves were poor predictors of solute loads because correlations between discharge and total solutes concentration were weak (R2 < 0.05 in most cases) and suffered from hysteresis. In contrast, the interval method produced reliable estimates in all seasons and sites tested, and was little affected by sampling schedule. The limit of precision (SE) for estimates of mean annual or seasonal solute load was 10–15 percent of the mean (5 percent in very small basins), reached with 10 years or more of data.

Two‐thirds or more of total annual solute load was transported during the open‐water season, but the proportion carried during winter increased from 8 percent to 34 percent from the upstream to the downstream end of the basin, due to reservoirs retaining and mixing water. Annual loads of total solutes varied from 6.2 × 104 tonnes in foothills tributaries to almost 4.0 × 106 tonnes in the Saskatchewan River near the mouth. But, on an areal basis, the mountain and foothills region was the dominant solute source, producing 43–97 tonnes/km2/yr, compared with only 3–22 tonnes/km2/yr for prairie rivers. This difference is a consequence of greater rainfall and, hence, more rapid erosion in the mountains.
THE OPPORTUNITY COST OF TIME AND AVERTING EXPENDITURES FOR SAFE DRINKING WATER1
Authors: Laughland Andrew S. , Musser Lynn M. , Musser Wesley N. , Shortle James S.
Published: June 2007

ABSTRACT:A survey of individuals during aGiardiacontamination incident provided data to calculate the cost of boiling, hauling, or purchasing water to avoid infection. Three different approaches to the valuation of time were used to assess the implications of the opportunity cost of time for the measurement of averting costs. Mean monthly household averting costs were $33.47 using family income to value time, $13.07 using the minimum wage to value time, and $5.60 using zero opportunity cost of time. Comparisons of the mean costs for different sources and household characteristics indicated the value of time from family income was too high and that the other methods of valuing time were superior.
CHAPARRAL CONTROL IN MOSAIC PATTERN INCREASED STREAMFLOW AND MITIGATED NITRATE LOSS IN ARIZONA1
Authors: Davis Edwin A.
Published: June 2007

ABSTRACT:In a 16‐year paired watershed study in Arizona, a 303‐acre chaparral watershed was treated by helicopter in a mosaic pattern (55 percent of watershed) with tebuthiuron herbicide pellets to control the moderately dense, heavy water‐using chaparral. The objective was to determine if annual stream discharge could be increased without degrading other resource values. An adjacent untreated chaparral watershed served as the control on which to base the water quantity and quality treatment effects. Annual streamflow was increased by 1.5 to 5 inches over a seven‐year evaluation period. The streamflow increase was accompanied by a small but statistically significant increase in nitrate concentration. The relatively small nitrate response was attributed to the mosaic treatment. Nitrate released from the converted areas was diluted by streamflow from untreated areas, thereby reducing nitrate concentrations in streamflow at the watershed outlet.
MODELING WATER BALANCE WITH THE ERHYM MODEL ON SOUTH TEXAS RANGELANDS1
Authors: Weltz Mark A. , Blackburn Wilbert H.
Published: June 2007

ABSTRACT: Understanding the hydrologic processes of rangeland plant communities is essential to determine if water augmentation through shrub management is feasible. Vegetation manipulation studies are costly, difficult to accurately replicate, and often require more than 10 years to determine treatment effect on the water budget. If properly applied, hydrologic simulation models are an attractive alternative for assessing vegetation manipulation practices. The ERHYM‐II model was evaluated to determine if it was capable of simulating the water balance for honey mesquite shrub clusters, grass interspaces, and bare soil in south Texas. The simulated water budget was within 2 percent of the measured evapotranspiration for the shrub clusters and grass interspaces. The model underestimated the number of runoff events and overestimated runoff volume for the grass interspace and shrub clusters. Simulated runoff was overestimated by approximately twofold for the grass interspace and threefold for the shrub clusters. Although simulated runoff was substantially overestimated, observed and simulated runoff only accounted for 3 to 6 percent of annual rainfall for the grass and shrub dominated areas, respectively. Simulated evapotranspiration was underestimated by 18 percent and soil water content was overestimated by 82 percent for the bare soil. The model underestimated evapotranspiration for the bare soil as a result of restricting evaporative losses to the first soil layer. Based on our analysis, the ERHYM‐II model has the potential for simulating the annual water balance for semiarid rangeland plant communities where runoff and deep drainage are limited components of the water balance.
PRELIMINARY OBSERVATIONS ON WATER QUALITY OF STORM RUNOFF FROM FOUR SELECTED RESIDENTIAL ROOFS1
Authors: Chang Mingteh , Crowley Christopher M.
Published: June 2007

ABSTRACT: Storm runoff from four characteristic types of residential roofs and incident rainwater were monitored for 47 storm events over a six‐month period at Nacogdoches, Texas, to study water quality conditions for 20 element and four chemical variables. The total element concentration in storm runoff from each roof type was greater than that of rainwater in the open. Differences in element concentrations in storm runoff among the four roof types were statistically significant (α≤ 0.05) with the differences for the wood shingle roof being the greatest and that for terra cotta clay roof being the least. The median concentrations of four element variables exceeded the Texas surface water quality standards, while 12 variables exceeded the standards at least one time in all samples collected. Zinc concentrations violated the Standard ranging from 85.7 percent of the samples for the wood shingle roof to 66.0 percent for the composite shingle, the greatest exceedances of all 24 variables studied. Storm characteristics and gutter maintenance level had some effects on these water quality conditions. The study suggested that roof types can be important to water pollution management programs. More detailed studies on roof water quality in major municipalities are required.
AUTOMATED EXTRACTION OF DRAINAGE NETWORK AND WATERSHED DATA FROM DIGITAL ELEVATION MODELS1
Authors: Martz Lawrence W. , Garbrecht Jurgen
Published: June 2007

ABSTRACT: This paper discusses a computer program which extracts a number of watershed and drainage network properties directly from digital elevation models (DEM) to assist in the rapid parameterization of hydrologic runoff models. The program integrates new and established algorithms to address problems inherent in the analysis low‐relief terrain from raster DEMs similar to those distributed by the U.S. Geological Survey for 7.5‐minute quadrangles. The program delineates the drainage network from a DEM, and determines the Strahler order, total and direct drainage area, length, slope, and upstream and downstream coordinates of each channel link. It also identifies the subwatershed of each channel source and of the left and right bank of each channel link, and assigns a unique number to each network node. The node numbers are used to associate each subwatershed with the channel link to which it drains, and can be used to control flow routing in cascade hydrologic models. Program output includes tabular data and raster maps of the drainage network and subwatersheds. The raster maps are intended for import to a Geographical Information System where they can be registered to other data layers and used as templates to extract additional network and subwatershed information.
THE DEVELOPMENT OF THE NILE HYDROMETEOROLOGICAL FORECAST SYSTEM1
Authors: Barrett Curtis B.
Published: June 2007

ABSTRACT: The National Oceanic and Atmospheric Administration is developing a river forecast system for the Nile River in Egypt. The river forecast system operates on scientific work stations using hydrometeorological models and software to predict inflows into the high Aswan Dam and forecast flow hydrographs at selected gaging locations above the dam

The Nile Forecasting System (NFS) utilizes satellite imagery from the METEOSAT satellite as the input to the forecast system. Satellite imagery is used to estimate precipitation over the Blue Nile Basin using five different techniques. Observed precipitation data and climatic statistics are used to improve precipitation estimation. Precipitation data for grid locations are input to a distributed water balance model, a hill slope routing model, and a channel routing model. A customized Geographic Information System (GIS) was developed to show political boundaries, rivers, terrain elevation, and gaging network. The GIS was used to develop hydrologic parameters for the basin and is used for multiple display features.
THE DEVELOPMENT AND IMPLEMENTATION OF A GIS‐BASED CONTAMINANT SOURCE INVENTORY OVER THE SPOKANE AQUIFER, SPOKANE COUNTY WASHINGTON1
Authors: Lackaff Beatrice B. , Hunt Bruce J. , Von Essen Ian E.
Published: June 2007

ABSTRACT: U.S. Environmental Protection Agency (EPA) statutes require identification of all potential sources of contamination within a wellhead protection area. All wells over Spokane County's aquifer are included in one wellhead protection zone called the Aquifer Sensitive Area (ASA).

A GIS‐based Contaminant Source Inventory (CSI) was developed for the ASA. Datasets listing businesses and agencies within the ASA were imported into the GIS from state, county, city, and local agencies. These datasets were selected, joined, and sorted using GIS relational database capabilities into one ASA “business master file.” Map files were projected and transformed into common coordinates. Next, business sites within the master file were spatially related by address to the digital map files. Likely Critical Materials Users (CMU) were identified by sorting on selected standard Industrial Codes (SIC). Additional files of CMUs were imported into the Contaminant Source Inventory. GIS queries were performed to locate specific materials, quantities, and storage facilities, and to analyze CMU activity within selected buffer zones.

This project demonstrated the usefulness of GIS technology in the development, management, maintenance, and analysis of vast quantities of data associated with a local wellhead protection pro. gram.
DEVELOPMENT OF A WATER SUPPLY PROTECTION MODEL IN A GIS1
Authors: Griner Axel J.
Published: June 2007

ABSTRACT: As part of a larger model to identify lands suitable for acquisition, a water supply protection model was developed using the Southwest Florida Water Management District's GIS. Several hydrologic and hydrogeologic data layers were overlaid to develop maps showing ground‐water supply suitability, protection areas for surface‐water supply, protection areas for major public supply wells, susceptibility to ground‐water contamination, and recharge to the Floridan aquifer. These intermediate layers were combined into a final map to prioritize protection areas for water supply.
MANAGEMENT AND ANALYSIS OF WATER‐USE DATA USING A GEOGRAPHIC INFORMATION SYSTEM1
Authors: Juracek Kyle E. , Kenny Joan F
Published: June 2007

ASSTRACT: As part of its mission, the U.S. Geological Survey conducts water‐resources research. Site‐specific and aggregate water‐use data are used in the Survey's National Water‐Use Information Program and in various hydrologic investigations. Both types of activities have specific requirements in terms of water‐use data access, analysis, and display. In Kansas, the Survey obtains water‐use information from several sources. Trpically, this information is in a format that is not readily usable by the Survey. Geographic information system (GIS) technology is being used to restructure the available water‐use data into a format that allows users to readily access and summarize site‐specific water‐use data by source (i.e., surface or ground water), type of use, and user‐defined area.
GEOGRAPHIC INFORMATION SYSTEM BASED NONPOINT POLLUTION MODELING1
Authors: Robinson Kurt J. , Ragan Robert M.
Published: June 2007

ABSTRACT: The reauthorization of the Clean Water Act reemphasizes the need for regional scale monitoring and management of nonpoint pollution loads. The magnitude of the task will require that local governments and their consultants integrate information systems and modeling if they are to manage the massive data sets and conduct the array of simulations that will be needed to support the decision making processes. Interfacing geographic information systems (GIS) and nonpoint pollution modeling is a logical approach. The objective of the present study was to use the 37,000‐acre area defined by the Kensington Quadrangle sheet in Montgomery County, Maryland, to show that GIS‐supported nonpoint pollution modeling is practical and economically attractive. The purpose of the GIS is to estimate the spatial distribution of nonpoint nitrogen, phosphorous, zinc, lead, BOD, and sediment using a model developed by the Northern Virginia Planning District Commission. The system allows the user to change land uses in subareas to simulate the consequences of additional development or alternate management strategies. The tests show that in‐house development of this type of special purpose GIS is a practical alternative to vendor supplied systems and that the required databases can be developed quite reasonably.
MODELING MULTIPLE CRITICAL DEPTHS1
Authors: Traver Robert G.
Published: June 2007

ABSTRACT: This paper explores the occurrence of multiple critical depths in one‐dimensional computational models of open channel systems. The mathematical formulation is reviewed, including examination of the number of possible roots by Descartes' Rule. Governing equations and dependent variables are scrutinized using two compound cross sections. Occurrence tendencies are reviewed for singular channels. Critical flow is introduced as a tool to determine the existence and location of computationally based multiple critical depths. A strategy to manage multiple critical depths in existing one‐dimensional steady or unsteady models is proposed.
REVISITING STATE WATER RIGHTS LAW1
Authors: Jay Davis Ray
Published: June 2007

ABSTRACT: Water resources professionals should be engaged actively in revisiting state water rights law. During the past four years, sponsored by the American Society of Civil Engineers with cooperation of other water resources organizations, over a hundred engineers, hydrologists, geographers, lawyers, administrators, educators, water users, and other persons interested in water law have been preparing a Model State Water Rights Code. Preliminary drafts of the Model Code have been considered in four states, and its provisions will be disseminated nationally to state legislators and other policy makers upon formal publication in September 1994. The Model Code gathers the best provisions from state water laws into comprehensive regulated riparian and prior appropriation provisions, includes commentaries explaining how its textual sections address water resources planning and management issues, and references similar language in current state water statutes. The goal of the Code Project is to provide materials which will assist legislators so they can enact effective, efficient, and equitable water laws. In the future, the Code drafting group will expand its efforts to develop legal guidelines for allocating shared transboundary water resources, water quality law, federal water statutes, and other water resources legal issues.
CHANGING THE APPROPRIATION DOCTRINE UNDER THE MODEL STATE WATER CODE1
Authors: Matthews Olen Paul
Published: June 2007

ABSTRACT: The American Society of Civil Engineers (ASCE) Model State Water Code provides suggested statutory language and commentary helpful in guiding western water law reform. Departing from the past preference for stream diversions and consumptive uses, the code is sensitive to the public's interest in maintaining environmental quality. The traditional doctrine protected inefficient uses and in some states hampered transfers. The model code addresses these issues as well as advocating integrated manage. meat and water resource planning. The debate on how to reform water law has already started, and the model code provides material useful in the reform process. Even with the current draft code, a few gaps exist for later resolution.
A SPATIAL DECISION SUPPORT SYSTEM FOR ASSESSING AGRICULTURAL NONPOINT SOURCE POLLUTION1
Authors: Srinivasan R. , Engel B. A.
Published: June 2007

ABSTRACT: A spatial decision support system (SDSS) was developed to assess agricultural nonpoint source (NPS) pollution using an NPS pollution model and geographic information systems (GIS). With minimal user interaction, the SDSS assists with extracting the input parameters for a distributed parameter NPS pollution model from user‐supplied GIS base layers. Thus, significant amounts of time, labor, and expertise can be saved. Further, the SDSS assists with visualizing and analyzing the output of the NPS pollution simulations. Capabilities of the visualization component include displays of sediment, nutrient, and runoff movement from a watershed. The input and output interface techniques/algorithms used to develop the SDSS, along with an example application of the SDSS, are described.
USE OF PEBBLE COUNTS TO EVALUATE FINE SEDIMENT INCREASE IN STREAM CHANNELS1
Authors: Potyondy John P , Hardy Terry
Published: June 2007

ABSTRACT: The pebble count, a quick and simple technique for characterizing streambed materials, has long been used by geomorphologists, hydrologists, and river engineers. This paper describes how pebble counts have been used to monitor fine sediment (particles less then 6 mm in size) on the Boise National Forest. Data from two watersheds subjected to major wildfires and the failure of a dam are discussed. Following wildfires, pebble count data showed increases in streambed fines followed by improvement of the stream substrate with time as the watersheds recovered. For the dam failure, pebble count data showed an increase in fines in the stream below the failure and were used to track the distance of sediment movement downstream. Pebble counts may be best used where fine sediment on channel substrates are a concern, such as in granitic watersheds where coarse sands are a large component of bedload and land‐disturbing activities introduce fine sediment into streams. Pebble counts are found to be a simple and rapid monitoring method that can be used to help determine whether or not land management activities or land disturbances are introducing fine sediment into streams.
THE RATIONAL METHOD FOR PEAK FLOW RATE ESTIMATION1
Authors: Hromadka T. V. , Whitley R. J.
Published: June 2007

ABSTRACT: The Rational Method continues to be the most widely used approach for estimating P‐year return frequency peak flow rates for small catchments of about one square mile or less in area. The Balanced Design Storm unit hydrograph method is perhaps the second most widely used technique for estimating peak flow rates (and is the most widely used method for developing runoff hydrographs) but is generally considered to be more accurate than the Rational Method. In this paper, both of these T‐year return frequency peak flow rate estimators are shown to be mathematically comparable. The close similarity between these two approximators may help explain why the Rational Method continues to be widely used even though other more computationally sophisticated techniques are readily available due to widespread computer software.
ANALYSIS OF WIND‐ AND SHIP‐INDUCED SEDIMENT RESUSPENSION IN DULUTH‐SUPERIOR HARBOR1
Authors: Erdmann John B. , Stefan Heinz G. , Brezonik Patrick L.
Published: June 2007

ABSTRACT: Suspended solids and ammonium concentration profiles measured at five locations in Duluth‐Superior Harbor during July‐October 1985 were analyzed to quantify wind and ship effects on sediment resuspension and resulting harbor water quality. Wind components from the SE quadrant correlated strongly with depth‐averaged suspended solids concentrations that were unaffected by ship passage or thermal stratification. Winds from that quadrant have the largest fetch in the harbor. The highest correlation (r2= 0.93) was with the 6‐hour average of the ESE wind velocity component. Multiple linear regression analysis of data from post‐ship passage concentration profiles yielded numerical estimates of settling velocities of 0.08 to 0.25 cm s−1, typical of ship‐resuspended sediments, and vertical eddy diffusivities of 4 to 13 cm2 s1. The results suggest that ambient vertical eddy diffusivities in the harbor are less than 4 cm2 s−1 in the absence of ship passages and with winds less than 5 m s−1 (10 knots).
DEVELOPMENT OF A NONDEGRAIATION POLICY FOR HIGH QUALITY WATERS1
Authors: Albert Richard C.
Published: June 2007

ABSTRACT: The development of a nondegradation policy for high quality waters is a complex and often controversial process. This paper discusses the development of a nondegradation policy for two components of the National Wild and Scenic Rivers System. Water quality in these reaches of the Delaware River is threatened by rapid growth and development and the cumulative impacts from numerous wastewater discharges and nonpoint sources of pollution. The Delaware River Basin Commission, with assistance from its member states and the National Park Service, conducted a highly public, six‐year planning process to develop a nondegradation policy that protected existing water quality without impinging upon local and state economic development objectives. The resulting non‐degradation policy includes such features as numeric definitions of existing water quality and measurable change; stringent point source requirements; nonpoint source requirements including watershed planning requirements; and other water quality management policies.
CHEMICAL ANALYSIS OF CO2 REMOVAL IN TRAY AERATORS1
Authors: La Motta Enrique J.
Published: June 2007

ABSTRACT: This paper presents a discussion of the chemistry of CO2 removal in tray aerators, and different sets of equations that are applicable to several initial water chemical conditions are proposed. These chemical equations and a statistical model to predict the kinetic constant were tested with field data observed by other researchers in pilot units and in a full scale plant. The water temperature in their experiments was around 15°C.
ESTIMATING LOW‐FLOW QUANTILES FROM DRAINAGE‐BASIN CHARACTERISTICS IN NEW HAMPSHIRE AND VERMONT1
Authors: Dingman S. Lawrence. , Lawlor Stephen C.
Published: June 2007

ABSTRACT: This study systematically develops, validates, and compares alternative approaches for estimating quantiles of the distribution of annual minimum seven‐day‐average flows (7Q) for ungaged, unregulated drainage basins in New Hampshire and Vermont via regression on map‐measurable drainage‐basin characteristics. At 47 gaging stations in the region, the hypotheses that 7Q is log normally distributed and serially independent are not rejected, and the regional average spatial correlation is R= 0.35. Step‐forward examination of a suite of potential predictor variables revealed that logarithm of drainage area, mean elevation, and fraction of basin covered with sand and gravel deposits are significant predictors of quantiles of 7Q. The regression equations were incorporated into four approaches to estimate the 7Q value with a nonexceedence probability of 0.1, 7Q10. Comparison of observed values and values predicted via a delete‐one jackknife resampling validation indicates that one of the approaches gives estimates with acceptable bias and precision, with median relative error of 33 percent and prediction error of 64 percent. This is equivalent to the precision obtainable with only one to two years of gaging records. In spite of this limited precision, the approaches developed herein are useful for predicting 7Q quantiles at ungaged sites. Further improvement in precision will likely be possible only by exploiting the spatial correlation of annual 7Q.
SENSITIVITY OF A PRAIRIE WETLAND TO INCREASED TEMPERATURE AND SEASONAL PRECIPITATION CHANGES1
Authors: Poiani Karen A. , Johnson W. Carter. , Kittel Timothy G. F.
Published: June 2007

ABSTRACT: We assessed the potential effects of increased temperature and changes in amount and seasonal timing of precipitation on the hydrology and vegetation of a semi‐permanent prairie wetland in North Dakota using a spatially‐defined, rule‐based simulation model. Simulations were run with increased temperatures of 2°C combined with a 10 percent increase or decrease in total growing season precipitation. Changes in precipitation were applied either evenly across all months or to individual seasons (spring, summer, or fall).

The response of semi‐permanent wetland P1 was relatively similar under most of the seasonal scenarios. A 10 percent increase in total growing season precipitation applied to summer months only, to fall months only, and over all months produced lower water levels compared to those resulting from the current climate due to increased evapotranspiration. Wetland hydrology was most affected by changes in spring precipitation and runoff. Vegetation response was relatively consistent across scenarios. Seven of the eight seasonal scenarios produced drier conditions with no open water and greater vegetation cover compared to those resulting from the current climate. Only when spring precipitation increased did the wetland maintain an extensive open water area (49 percent).

Potential changes in climate that affect spring runoff, such as changes to spring precipitation and snow melt, may have the greatest impact on prairie wetland hydrology and vegetation. In addition, relatively small changes in water level during dry years may affect the period of time the wetland contains open water. Emergent vegetation, once it is established, can survive under drier conditions due to its ability to persist in shallow water with fluctuating levels. The model's sensitivity to changes in temperature and seasonal precipitation patterns accentuates the need for accurate regional climate change projections from general circulation models.
REVISITING THE DEGREE‐DAY METHOD FOR SNOWMELT COMPUTATIONS1
Authors: Rango A. , Martinec J.
Published: June 2007

ABSTRACT: The simple, empirical degree‐day approach for calculating snowmelt and runoff from mountain basins has been in use for more than 60 years. It is frequently suggested that the degree‐day method be replaced by the more physically‐based energy balance approach. The degree‐day approach, however, maintains its popularity, applicability, and effectiveness. It is shown that the degree‐day method is reliable for computing total snowmelt depths for periods of a week to the entire snowmelt season. It can also be used for daily snowmelt depths when utilized in connection with an adequate snowmelt runoff model for computing the basin runoff. The degree‐day ratio is shown to vary seasonally as opposed to being constant as is often assumed. Additionally, in order to evaluate the degree‐day ratio correctly, the changing snow cover extent in a basin during the snowmelt season must be taken into account. It is also possible to combine the degree‐day approach with a radiation component so that short time interval (<24 hours) computations of snowmelt depth can be made. When snowmelt input is transformed to basin output (runoff) by a snowmelt runoff model, there is little difference between the degree‐day approach and a radiation‐based approach. This is fortuitous because the physically‐based energy balance models will not soon displace the degree‐day methods because of their excessive data requirements.
THE TREE‐RING RECORD OF SEVERE SUSTAINED DROUGHT1
Authors: Meko David , Stockton Charles W. , Boggess W. R.
Published: June 2007

ABSTRACT: Frequent and persistent droughts exacerbate the problems caused by the inherent scarcity of water in the semiarid to arid parts of the southwestern United States. The occurrence of drought is driven by climatic variability, which for years before about the beginning of the 20th century in the Southwest must be inferred from proxy records. As part of a multidisciplinary study of the potential hydrologic impact of severe sustained drought on the Colorado River, the physical basis and limitations of tree rings as indicators of severe sustained drought are reviewed, and tree‐ring data are analyzed to delineate a “worst‐case” drought scenario for the Upper Colorado River Basin (UCRB). Runs analysis of a 121‐site tree‐ring network, 1600–1962, identifies a four‐year drought in the 1660s as the longest‐duration large‐scale drought in the Southwest in the recent tree‐ring record. Longer tree‐ring records suggest a much longer and more severe drought in 1579–1598. The regression estimate of the mean annual Colorado River flow for this period is 10.95 million acre‐feet, or 81 percent of the long‐term mean. The estimated flows for the 1500s should be used with caution in impact studies because sample size is small and some reconstructed values are extrapolations.
COMPETING WATER USES IN THE SOUTHWESTERN UNITED STATES: VALUING DROUGHT DAMAGES1
Authors: Booker James F , Colby Bonnie G.
Published: June 2007

ABSTRACT: Economic benefit functions of water resource use are estimated for all major offstream and instream uses of Colorado River water. Specific benefit estimates are developed for numerous agricultural regions, for municipal uses, and for cooling water in thermal energy generation. Economic benefits of hydropower generation are given, as are those for recreation on Colorado River reservoirs and on one free‐flowing reach. Marginal and total benefit estimates for Colorado River water use are provided. The estimates presented here represent a synthesis of previous work, providing in total a comprehensive set of economic demand functions for competing uses of Colorado River water. Non‐use values (e.g., benefits of preserving endangered species) are not estimated.
USE OF THE KRIGING METHOD FOR STUDYING CHARACTERISTICS OF GROUND WATER DROUGHTS1
Authors: Chang Tiao J. , Teoh Choo B.
Published: June 2007

round water drought events were derived by taking a truncation level through the time series of daily ground water depth that are recorded elevation differences between the water table and land surface at a well site. Droughts of various truncation levels at 70, 80, 90, and 95 percent, were obtained, where a 70 percent truncation level means that 70 percent of ground water depth data are less than or equal to the truncated value. The conditional probability that a drought occurring at a certain truncation level will prolong and advance to that of the next higher level was estimated. The regionalization analysis was conducted assuming that conditional probabilities estimated at selected wells are regionalized variables. Contour lines of conditional probabilities for each truncation level were constructed to express their spatial variability in the region. Estimation errors associated with the regionalization were reasonably small.
REVIEW OF DETERMINATION OF INSTREAM FLOW REQUIREMENTS WITH SPECIAL APPLICATION TO AUSTRALIA1
Authors: Karim Khalid , Gubbels Maureen E. , Goulter Ian C.
Published: June 2007

ABSTRACT: A critical examination of the techniques used to assess and specify environmental instream flow requirements is provided. The strengths and weaknesses of individual techniques are evaluated on both an absolute and a comparative basis. Particular attention is given to the problem of specifying environmental flow requirements in Australia where the hydrology has distinctly different characteristics to those in countries where most of the models for prediction of instream flow requirements were developed. Broad recommendations as to the suitability and use of the different techniques for different conditions are provided.
CLIMATE, SNOW COVER, GLACIERS, AND RUNOFF IN THE TIEN SHAN, CENTRAL ASIA1
Authors: Aizen Vladimir B. , Aizen Elena M. , Melack John M.
Published: June 2007

ABSTRACT: The Pica Shan, a mountainous region located on the northern periphery of central Asia, has a wide range of climatic and hydrological conditions. On the basis of long term data from 348 meteorological and glaciological stations, the annual distribution of precipitation in different regions and elevational zones of the Tien Shan was calculated. Major climatic features are the entrance of moisture during spring‐summer, small winter precipitation, decrease of precipitation towards the east and the center of the mountains or with distance up valleys, and increase of precipitation with altitude up to crest‐lines of ranges. Annual total evaporation from snow can be 50–60 mm per year, reaching 30 percent of snow accumulation.

Four main groups of rivers were identified: rivers with mainly snow nourishment, rivers with mainly glacial nourishment, rivers with mainly rain nourishment, and rivers with mainly ground water nourishment. Coefficient of runoff variation in Tien Shan's rivers is about 0.20, and coefficient of glacial runoff variation is about 0.15. Glacial runoff is 15–20 percent of the total volume of river runoff.
SIMULATING TILE DRAINAGE AND NITRATE LEACHING UNDER A POTATO CROP1
Authors: Madramootoo Chandra A. , Wiyo Kenneth A. W. , Enright Peter
Published: June 2007

ABSTRACT: A 2.2‐hectare potato (Solanum tuberosum L. cv Chieftain) field at Saint Leonard d'Aston, Quebec (lat. 72° 24′ 30″ long. 46° 5′ 30″) was instrumented to measure tile drain flow over two growing seasons, 1989 and 1990. The soil was a Sainte Jude sandy loam. Soil properties and nitrate concentrations in the drain flow were measured. The CREAMS (Chemicals, Runoff and rosion from agricultural Management systems) computer simulation model was validated for the study site. CREAMS underpredicted event percolation depths. However, total monthly percolation depths were close to observed values. CREAMS overpredicted event nitrate concentrations leached to tile drainage. There was a poor match between predicted and observed event nitrate concentrations in drain flow (coefficient of predictability, CPA= 104.95). Based on a sensitivity analysis, input parameters, representative of local conditions, were determined for the CREAMS hydrology and nutrient submodels.
ECOSYSTEM MANAGEMENT AND THE CONSERVATION OF AQUATIC BIODWERSITY AND ECOLOGICAL INTEGRITY1
Authors: Frissell Christopher A. , Bayles David
Published: June 2007

ABSTRACT: Ecologically effective ecosystem management will require the development of a robust logic, rationale, and framework for addressing the inherent limitations of scientific understanding. It must incorporate a strategy for avoiding irreversible or large‐scale environmental mistakes that arise from social and political forces that tend to promote fragmented, uncritical, short‐sighted, inflexible, and overly optimistic assessments of resource status, management capabilities, and the consequences of decisions and policies. Aquatic resources are vulnerable to the effects of human activities catchment‐wide, and many of the landscape changes humans routinely induce cause irreversible damage (e.g., some species introductions, extinctions of ecotypes and species) or give rise to cumulative, long‐term, large‐scale biological and cultural consequences (e.g., accelerated erosion and sedimentation, deforestation, toxic contamination of sediments). In aquatic ecosystems, biotic impoverishment and environmental disruption caused by past management and natural events profoundly constrain the ability of future management to maintain biodiversity and restore historical ecosystem functions and values. To provide for rational, adaptive progress in ecosystem management and to reduce the risk of irreversible and unanticipated consequences, managers and scientists must identify catchments and aquatic networks where ecological integrity has been least damaged by prior management, and jointly develop means to ensure their protection as reservoirs of natural biodiversity, keystones for regional restoration, management models, monitoring benchmarks, and resources for ecological research.
MODELING PREVENTION ALTERNATWES FOR NONPOINT SOURCE POLLUTION AT A WELLFIELD IN FLORIDA1
Authors: Tsihrintzis Vassilios A. , Fuentes Hector R. , Gadipudi Rao K
Published: June 2007

ABSTRACT: Agricultural and urban activities in the West Wellfield Interim Protection Area (WWIPA), located in West Dade County in South Florida, have the potential to impact both the environmentally sensitive Everglades and the Biscayne Aquifer. The Hydrological Simulation Program‐FORTRAN (HSPF) is used to simulate surface runoff, ground water recharge, and transport of sediments, nutrients, and pesticides in the WWIPA, as a basis to quantify impacts and evaluate alternatives. Presented are four model test runs that consider current conditions, the effect of future urbanization of the agricultural land, as well as two preventive actions to minimize pollution levels. Preventive actions include application of minimum required rates of fertilizers and replacement of fertilizers by sewage sludge. Model results show that under current practices, sediments, nutrients, and pesticides are present in surface runoff and nutrients enter the ground water, and that both urbanization and preventive actions result in pollutant reductions.
A COMPARISON OF TWO METHODS FOR MULTIOBJECTIVE OPTIMIZATION FOR RESERVOIR OPERATION1
Authors: Liang Qingfu , Johnson Lynn E. , Yu Yun‐Sheng
Published: June 2007

ABSTRACT: Two major objectives in operating the multireservoir system of the Upper Colorado River basin are maximization of hydroelectric power production and maximization of the reliability of annual water supply. These two objectives conflict. Optimal operation of the reservoir system to achieve both is unattainable. This paper seeks the best compromise solution for an aggregated reservoir as a surrogate of the multireservoir system by using two methods: the constraint method and the method of combined stochastic and deterministic modeling. Both methods are used to derive the stationary optimal operating policy for the aggregated reservoir by using stochastic dynamic programming but with different objective functions and minimum monthly release constraints. The resulting operating policies are then used in simulated operation of the reservoir with historical inflow records to evaluate their relative effectiveness. The results show that the policy obtained from the combination method would yield more hydropower production and higher reliability of annual water supply than that from the constraint‐method policy.
INTEGRATING A GEOGRAPHIC INFORMATION SYSTEM, A SCIENTIFIC VISUALIZATION SYSTEM, AND A PRECIPITATION MODEL1
Authors: Hay L. E. , Knapp L. K.
Published: June 2007

ABSTRACT: Investigating natural, potential, and human‐induced impacts on hydrologic systems commonly requires complex modeling with overlapping data requirements, plus massive amounts of one‐ to four‐dimensional data at multiple scales and formats. Given the complexity of most hydrologic studies, the requisite software infrastructure must incorporate many components including simulation modeling and spatial analysis with a flexible, intuitive display. Integrating geographic information systems (GIS) and scientific visualization systems (SVS) provides such an infrastructure. This paper describes an integrated system consisting of an orographic precipitation model, a GIS, and an SVS. The results of this study provide a basis for improving the understanding of hydro‐climatic processes in mountainous regions. An additional benefit of the integrated system, the value of which is often underestimated, is the improved ability to communicate model results, leading to a broader understanding of the model assumptions, sensitivities, and conclusions at a management level.
PREDICTING DOWNSLOPE TRAVEL OF GRANITIC SEDIMENTS FROM FOREST ROADS IN IDAHO1
Authors: F Megahan W. , Ketcheson G. L.
Published: June 2007

ABSTRACT: The length and volume of granitic sediment deposits were measured annually over a 4.5‐year period below 6.6 km of forest roads constructed on headwater watersheds in the mountains of Idaho. Sediment deposits were identified by source of runoff, location of the deposit terminus, and various site factors including descriptors of hillside sediment storage capacity. Prediction equations were developed using linear regression for travel distance of sediment originating from fill slopes, rock drains, and culverts, with r2 values ranging from 0.70 for fill slopes to 0.91 for culverts. Cumulative volume of erosion and length of obstructions on the hillside were statistically significant variables in the equation for fills and rock drains; hillside gradient and runoff source area also appeared in the equation for culverts. Sensitivity analysis showed that the volume of erosion was the most sensitive variable in all cases. A dimensionless relationship relating the volume of sediment storage on slopes to sediment travel distance was also developed. This study makes it possible for land managers to assess the risk of sediment delivery to channels from alternative road designs, locations, and erosion control practices and provides a means to evaluate the cumulative effects of past road construction on sedimentation.
EVALUATION OF WATER QUALITY AND MONITORING IN THE ST. LUCIE ESTUARY, FLORIDA1
Authors: Chamberlain Robert , Hayward Donald
Published: June 2007

ABSTRACT: The St. Lucie River and its tributaries form a major estuarine system on the southeast coast of Florida. This system is strongly affected by anthropogenic influences, including controlled releases of freshwater from Lake Okeechobee through the St. Lucie Canal and an extensive artificial drainage and irrigation system in the watershed. In the present study, three years of biweekly water quality monitoring data from the estuary were examined. The major stresses to the system stem from high variability of the salinity, frequent low dissolved oxygen (DO) events, and light limitation due to high levels of humic substances brought into the system with the fresh water. Nutrient levels also are high. Management goals for the system, including improvement of DO and water clarity, will require reduction in quantity and variability of freshwater releases.
INCREASING REGULATORS' CONFIDENCE IN POINT‐NONPOINT POLLUTANT TRADING SCHEMES1
Authors: Taffand Norman Senjem Steven J.
Published: June 2007

ABSTRACT: One of the principal stumbling blocks to regulatory agencies' adopting pollutant trading schemes is the complex of uncertainties surrounding any change in institutions. This is especially true if nonpoint pollution sources are to be involved along with point sources. Regulators are understandably reluctant to switch from tried‐and‐true point source permit systems, even if trading schemes can be shown (on paper, at least) to result in lower public expenditures. We propose a set of practical criteria for point‐nonpoint pollutant trading systems that promise to increase regulators' confidence that the new system will be equally effective in controlling pollution and at the same time more likely to capture efficiencies in pollution reduction practices.
EVALUATION OF AN INDUCED INFILTRATION MODEL AS APPLIED TO GLACIAL AQUIFER SYSTEMS1
Authors: Conrad Loren P , Beljin Milovan S.
Published: June 2007

ABSTRACT: Numerical models were used to examine the limitations of the assumptions used in an analytical induced infiltration model. The assumptions tested included negligible streambed effects, negligible areal recharge, two‐dimensional ground water flow, fully penetrating rivers and wells, and constant surface water stage. For situations that deviate from the underlying assumptions, the analytical model becomes a less reliable predictor of induced infiltration. The numerical experiments show that streambed effects cannot be neglected if the streambed conductivity is more than one order of magnitude lower than the aquifer hydraulic conductivity. Areal recharge cannot be neglected if the ground water basin receives more than 5 in/yr of areal recharge. Three‐dimensional flow effects due to well partial penetration cannot be neglected if the ratio of horizontal hydraulic conductivity to vertical hydraulic conductivity (Kh/Ku) is greater than 10. Surface water elevation fluctuations can significantly influence the induced infiltration rate, depending on the degree of fluctuations and the ground water hydraulic gradient.
UNCERTAINTY IN ESTIMATING BANKFULL CONDITIONS1
Authors: Johnson Peggy A. , Heil Thomas M.
Published: June 2007

ABSTRACT: Bankfull depth and discharge are basic input parameters to stream planform, stream restoration, and highway crossing designs, as well as to the development of hydraulic geometry relationships and the classification of streams. Unfortunately, there are a wide variety of definitions for bankfull that provide a range of values, and the actual selection of bankfull is subjective. In this paper, the relative uncertainty in determining the bankfull depth and discharge is quantified, first by examining the variability in the estimates of bankfull and second by using fuzzy numbers to describe bankfull depth. Fuzzy numbers are used to incorporate uncertainty due to vagueness in the definition of bankfull and subjectivity in the selection of bankfull. Examples are provided that demonstrate the use of a fuzzy bankfull depth in sediment trans. port and in stream classification. Using fuzzy numbers to describe bankfull depth rather than a deterministic value allows the engineer to base designs and decisions on a range of possible values and associated degrees of belief that the bankfull depths take on each value in that range.