bluuebunny/crossref_metadata_2025 huggingface dataset:
OPTICAL IMPACTS AND SOURCES OF SUSPENDED SOLIDS IN ONONDAGA CREEK, U.S.A.1
Authors: Effler Steven W. , Johnson David L. , Jiao Jianfu F. , Perkins MaryGail
Published: June 2007

ABSTRACT: The degradation of the optical aesthetics in the mouth of Onondaga Creek, New York, that occurs during high flow periods as a result of the influx of large quantities of suspended solids, is documented. Features of the degradation include very low clarity (Secchi disc minimum of approximately 0.1 m) and a brown ‘muddy’ appearance. The reduced clarity is mostly a result of increased light scattering. Loading and concentration profiles obtained for an approximately 35 km interval above the creek mouth over a wide range of flow indicates most of the suspended solids received during runoff events is resuspended stream sediment and eroded bank material. Application of microscopy‐based individual particle analysis techniques indicates that the origin of most of these deposits and much of the suspended solids during runoff events is point source inputs, termed ‘mud boils,’ located approximately 32 km upstream of the creek mouth.
EVAPOTRANSPIRATION FROM FLORIDA PONDCYPRESS SWAMPS1
Authors: Ewel Katherine C. , Smith Joel E.
Published: June 2007

ABSTRACT: We measured diurnal changes in water levels in three swamps dominated by pondcypress trees (Taxodium distichum var. nuans) in central Florida for four years in order to obtain additional documentation of relatively low evapotranspiration (ET) rates. Two of these swamps were monitored for another three years after one of them was clearcut. Estimated annual ET from undisturbed cypress swamps varied from 38 cm/yr to 86 cm/yr, averaging 60 cm (not including interception). Faster ET rates may have been related to faster pondcypress growth rates, a greater proportion of hardwoods in the canopy, and clearcutting in the surrounding pine plantation. The average ET rate was considerably lower than ET rates that have been estimated for north Florida pine plantations. However, incorporating estimates of interception indicates that overall ET rates in pondcypress swamps may be only slightly lower than ET from pine plantations. ET decreased only 5 percent in one swamp after it was clearcut, indicating that this management practice is not likely to affect regional water balances.
ALTERNATIVE APPROACH TO THE FORMULATION OF BASIN HYDRAULIC GEOMETRY EQUATIONS1
Authors: McConkey Sally A. , Singh Krishan P.
Published: June 2007

ABSTRACT: Along a drainage network, there is a systematic variation of average flow parameters (width, depth, and velocity) at flows having the same flow duration. Hydraulic geometry equations mathematically express this interdependent relationship of stream‐flow characteristics for a basin for annual flow durations varying from 10 to 90 percent. However, the equations proposed so far have had rather poor predictive performance for low flows. An independent investigation of the variation of discharge with drainage area and annual flow duration demonstrates a consistent relationship between these parameters. The relationship for the high to median‐flow range differs, however, from that for the median— to low‐flow range. The proposed equations provide a better predictive performance for low flows than previous formulations and a versatile means of estimating flow parameters for streams throughout a basin. The improved basin hydraulic geometry equations have a wide range of applications in areas such as stream habitat assessment, water quality modeling, channel design, and stream restoration projects.
OPTIMAL MANAGEMENT OF RELIEF WELLS NEAR WATERTON RESERVOIR1
Authors: Chau T. S.
Published: June 2007

ABSTRACT: This study considers the design and analysis of nonpumped well systems to provide pressure relief in the Cochrane aquifer, which is hydraulically connected to the Waterton Reservoir, Analyses of the relief well management problem are performed with a management model formulated by the combined simulation‐optimization approach. The model determines active relief well sites and their optimal discharge schedules. The existing relief wells are inadequate to provide the desirable pressure relief. The locations and design capacities of two new relief well systems are determined by the management model. The relationships between reservoir level and well discharge are estimated for these two well systems.
MODELING PERCOLATION LOSSES FROM A PONDED FIELD UNDER VARIABLE WATER‐TABLE CONDITIONS1
Authors: Kalita P. K. , Kanwar R. S. , Rahman M. A.
Published: June 2007

ABSTRACT: A numerical simulation model was developed to predict the vertical and lateral percolation losses from a ponded agricultural field. The two‐dimensional steady‐state unsaturated/ saturated flow equation was solved using the finite‐difference technique. A constant ponding depth was maintained at the soil surface with different water table conditions in an application of the model for rice fields bordered by bunds. Field experiments were conducted for two different water table depths to collect data on the spatial distribution of volumetric soil‐moisture content for model verification. The measured soil‐moisture content values were found to be in close agreement with those predicted by the model.

The sensitivity analysis of the model with selected hydrologic conditions shows that the model is most sensitive to the values of saturated hydraulic conductivity, but relatively less sensitive to water table depth, ponding depth, and evaporation rate from the soil surface. It implies that, in a ponded rice field condition, the lateral and vertical percolation losses are mostly governed by the hydraulic conductivity of the soil. The vertical percolation losses were almost equal to the saturated hydraulic conductivity values and, in most cases, these losses increased with deeper water table depths. The lateral percolation losses also increased with deeper water table depths; however, these losses were relatively small in comparison to the vertical percolation losses. The vertical and lateral percolation losses increased with the increase in ponding depths. The lateral percolation losses through the bund decreased when the evaporation losses increased from the soil surface. The results of this study indicate that the percolation losses from a ponded field may be predicted accurately for a wide range of soil and hydrological conditions when the values of hydraulic conductivity, evaporation rate, depth of ponding, and water table depth are accurately known.
ERRORS RELATED TO RANDOM STREAM TEMPERATURE DATA COLLECTION IN UPPER MISSISSIPPI RIVER WATERSHED1
Authors: Preud'homme E. B. , Stefan H. G.
Published: June 2007

ABSTRACT: Records of hourly water temperatures for two streams in the Upper Mississippi River basin were used to find the error between instantaneous measurements of stream water temperatures and true daily averages. The instantaneous summer water temperature measurements were assumed to be collected during daylight hours, and measurement times were selected randomly. The absolute error at the 95 percent confidence level of randomly collected stream water temperatures was less than 0.9°C for a 1 to 5m deep large river, but as large as 3.6°C for a 0.3 to lm deep small stream. Temperature readings of morning samples were usually below daily average values, and afternoon readings were usually above. Daily mean water temperatures were obtained with less than 0.23°C standard deviation from true daily averages if the daily maximum and minimum water temperatures were averaged. Sample results were obtained for the open water (summer) season only, since diurnal water temperature fluctuations in ice covered streams are usually negligible.
EFFECTS OF LIME‐SLUDGE DISCHARGE ON AN ARCTIC RIVER1
Authors: Tumeo Mark A.
Published: June 2007

ABSTRACT: The Fairbanks Water Treatment Plant in Fairbanks, Alaska, processes approximately 3 MGD of drinking water using lime softening. Approximately 0.3 MGD of lime‐sludge from the treatment process is combined with effluent from a nearby power plant and discharged to the Chena River. There is little information available on the impact of water‐treatment sludge discharges, and virtually no information on the impacts of such discharges in polar environments. Concern surrounding the discharge of water treatment sludges have centered on alum‐sludge due to the potential toxic effects of aluminum. Because of the relatively benign composition of lime‐sludge, very little research has been published. However, there is the possibility that discharge of solids will result in sedimentation, accumulation of solids, and subsequent impacts on benthic organisms. This paper reports on the results of a study to determine if lime‐sludge discharge from the water treatment plant is adversely impacting the river environment. The results provide basic information on the important variables of concern in lime‐discharges to rivers.

Samples from the discharge of the water treatment plant and combined water treatment plant/power plant effluent were collected weekly over a one‐year period, and in‐stream benthic and water column samples were collected biweekly during the fall and spring. Sediment and water quality data indicate that while significant accumulation of sludge solids is found downstream of the water treatment plant outfall, they are flushed out of the system by spring flows, which are significantly increased by snow melt. This process is most likely repeated on a yearly cycle.

Hence, the data suggest that the FMUS water treatment plant's discharge of lime‐sludge is probably not adversely impacting the river. More generally, this may indicate that the natural flow variations and sediment‐laden characteristics of Arctic, glacier‐fed rivers may assimilate large quantities of nonputrescible solids without significant changes in the natural river environment. Further research in this area is required to verify this conclusion.
SPATIAL COMPARABILITY OF THE PALMER DROUGHT SEVERITY INDEX1
Authors: Guttman Nathaniel B. , Wallis James R. , Hosking J. R. M.
Published: June 2007

ABSTRACT:The Palmer Drought Severity Index, which is intended to be of reasonable comparable local significance both in space and time, has been extensively used as a measure of drought for both agricultural and water resource management. This study examines the spatial comparability of Palmer's (1965) definition of severe and extreme drought. Index values have been computed for 1035 sites with at least 60 years of record that are scattered across the contiguous United States, and quantile values corresponding to a specified index value were calculated for given months and then mapped.

The analyses show that severe or extreme droughts, as defined by Palmer (1965), are not spatially comparable in terms of identifying rare events. The wide variation across the country in the frequency of occurrence of Palmer's (1965) extreme droughts reflects the differences in the variability of precipitation, as well as the average amount of precipitation. It is recommended first, that a drought index be developed which considers both variability and averages; and second, that water resource managers and planners define a drought in terms of an index value that corresponds to the expected quantile (return period) of the event.
SLUDGE APPLICATION EFFECTS ON RUNOFF, INFILTRATION, AND WATER QUALITY1
Authors: Bruggeman A. C. , Mostaghimi S.
Published: June 2007

ABSTRACT: Land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and ground water. A rainfall simulator was used the investigate the effects of freshly applied sludge on infiltration, and on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three‐run sequence was used to simulate different initial moisture conditions. Runoff, sediment, and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally‐tilled plots and surface applied at no‐till plots, at rates of 0, 75, 150 kg‐N/ha. Steady‐state infiltrability increased as a result of sludge application, although the no‐till practice was more effective in increasing the infiltrability than the sludge application. No‐till practices greatly reduced runoff, sediment, and nutrient losses from the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally‐tilled plots. This effect was more pronounced during the third rainstorm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions.
THE FARM LEVEL EFFECTIVENESS OF SELECTED IRRIGATION POLICY MEASURES1
Authors: Brown W. J. , Roy R. G. , Kulshreshtha S. N.
Published: June 2007

ABSTRACT: The on‐farm economic effectiveness of government capital grants, subsidized interest rates, and the Canadian Wheat Board (CWB) delivery quota levels in terms of adoption and/or expansion of irrigation in Saskatchewan is tested. The annualized net income at 5 and 20 years of three representative farm types ‐ a dryland grain farm, an irrigated grain farm, and an irrigated mixed farm ‐ are used in the analysis. Tradeoffs between income levels and the risks associated with adoption/expansion of irrigation are evaluated using mean‐standard deviation tradeoff and stochastic dominance. Risk differences arise due to reduced business risk through higher yields and increased financial risk through higher borrowing when adopting or expanding irrigation. Capital grants and subsidized interest rates are effective policy measures for dryland grain farms adopting irrigation because the farms are left in a similar risk position. However, these grants and interest rates are not effective policy measures in the medium run (5 years) for irrigated grain farms expanding irrigation because they lower the farm's risk efficiency. In the long run (20 years), the capital grants and subsidized interest rates need to be combined with open CWB delivery quotas before the risk position can be improved for irrigated grain farms expanding irrigation. Finally, the grants and interest rates need to be combined with increased irrigated hay production for risk efficiency to increase in both the medium and long run (5 and 20 years, respectively) on irrigated mixed farms expanding irrigation.
TEMPORARY WATER TRANSFERS FOR DRY‐YEAR WATER SUPPLY1
Authors: Clark John R. , Abt Steven R.
Published: June 2007

ABSTRACT: Temporary transfers of water for dry year water supply are analyzed for cost and operational feasibility. The temporary transfer is implemented as part of a water rights option agreement (WROA) between a lesson and a lessee. First, engineering analysis determines the technical feasibility and operations plan under the Colorado doctrine of prior appropriation. The cost of the WROA to a water utility is estimated. Other considerations in the agreement are discussed. The WROA is compared to other dry‐year supply alternatives using a water system simulation model to obtain expected cost and operational performance characteristics.
DEVELOPING A FIELD COMPONENT IN HYDROLOGIC EDUCATION1
Authors: MacDonald Lee H.
Published: June 2007

ABSTRACT: Recent assessments have emphasized the lack of a field and laboratory component in hydrologic education at the university level. Consequences of this lack include: (1) an unwarranted faith in published data; (2) lack of appreciation for the spatial and temporal variability of most hydrologic processes; (3) lack of appreciation for the difficulty of collecting good quality field data; (4) an inability to design and execute projects to collect field data; (5) a lack of field experience which can be applied when confronted with different problems or new environments; (6) an inability to evaluate published materials or models against “field reality;” (7) an excessive reliance on, and trust in, theoretical or conceptual models; and (8) reduced potential for lifelong learning through observation and analysis. Field courses need not be costly or difficult, but the instructor must be willing to adapt to the uncertainty and problems associated with field measurements. A recently updated course on watershed measurements at Colorado State University illustrates the type of field courses which can be developed if there is the necessary commitment and flexibility. The lack of a current text can be overcome by assembling selected portions of existing government documents, and a sample bibliography is included.
SEDIMENT RATING CURVES FOR A CLEARCUT PONDEROSA PINE WATERSHED IN NORTHERN ARIZONA1
Authors: Lopes Vicente L. , Ffolliott Peter F.
Published: June 2007

ABSTRACT: Data from a 455‐acre clearcut ponderosa pine forest watershed in northern Arizona were used to identify relationships between suspended sediment concentration and streamflow discharge. Sediment rating curves were derived by geometric least‐squares regression using 515 paired suspended sediment concentration and streamflow discharge measurements obtained from 1974 through 1982. Scatter about the straight line relationship was found when all available pairs of suspended‐sediment‐concentration and streamflow measurements were used together. The effect of some of the variation was offset by subdividing the data set on the basis of streamflow generation mechanisms. Improved descriptive power also was achieved when separate rising‐ and falling‐stage data sets were considered in deriving the sediment rating curves. Most noticeable was the improvements within low‐intensity, frontal rainfall events. There was no significant improvement in descriptive power when separate rising‐ and falling‐stage data sets were considered in deriving the sediment rating curves for snowmelt‐runoff events. Higher suspended sediment concentrations were observed during the rising stage of hydrographs than for similar flows on the falling stage, mainly for winter‐rainfall with insignificant snow accumulation on the ground and rain‐on‐snow events.
APPLICATION OF GEOGRAPHIC INFORMATION SYSTEMS TO GROUNDWATER MONITORING NETWORK DESIGN1
Authors: Hudak Paul F. , Loaiciga Hugo A. , Schoolmaster F Andrew
Published: June 2007

ABSTRACT: Effective monitoring configurations for contaminant detection in groundwater can be designed by analyzing the spatial relationships between candidate sampling sites and aquifer zones susceptible to contamination. Examples of such zones are the domain underlying the contaminant source, zones of probable contaminant migration, and areas occupied by water supply wells. Geographic information systems (GIS) are well‐suited to performing key groundwater monitoring network design tasks, such as calculating values for distance variables which quantify the proximity of candidate sites to zones of high pollution susceptibility, and utilizing these variables to quantify relative monitoring value throughout a model domain. Through a case study application, this paper outlines the utility of GIS for detection‐based groundwater quality monitoring network design. The results suggest that GIS capabilities for analyzing spatially referenced data can enhance the field‐applicability of established methodologies for groundwater monitoring network design.
RIO GRANDE VALLEY, COLORADO, NEW MEXICO, AND TEXAS1
Authors: Ellis Sherman R. , Levings Gary W. , Carter Lisa F. , Richey Steven F. , Radell Mary Jo
Published: June 2007

ABSTRACT: The Rio Grande Valley National Water‐Quality Assessment study unit encompasses about 45,700 square miles in Colorado, New Mexico, and Texas upstream from the gaging station Rio Grande at El Paso, Texas, and includes surface‐water closed basins east of the Continental Divide in New Mexico, and the San Luis Closed Basin in Colorado. The mean annual precipitation ranges from less than 6 to more than 50 inches; potential evapo‐transpiration ranges from less than 35 to more than 80 inches per year. Land use is mainly rangeland, forest land, and cropland. Total irrigated acreage in 1990 was about 914,000 acres and water use was about 3,410,000 acre‐feet. Two structural settings are found in the study unit: alluvial basins and bedrock basins. The alluvial basins can have through‐flowing surface water or be closed basins. The discussion of streamflow and water quality for the surface‐water system is based on four river reaches for the 750 miles of the main stem. The quality of the ground water is affected by both natural process and human activities and by nonpoint and point sources. Nonpoint sources for surface water include agriculture, hydromodification, and mining operations; point sources are mainly discharge from wastewater treatment plants. Nonpoint sources for ground water include agriculture and septic tanks and cesspools; point sources include leaking underground storage tanks, unlined or manure‐lined holding ponds used for disposal of dairy wastes, landfills, and mining operations.
FOREST PRACTICES AS NONPOINT SOURCES OF POLLUTION IN NORTH AMERICA1
Authors: Binkley Dan , Brown Thomas C.
Published: June 2007

ABSTRACT:Forest management activities may substantially alter the quality of water draining forests, and are regulated as nonpoint sources of pollution. Important impacts have been documented, in some cases, for undesirable changes in stream temperature and concentrations of dissolved oxygen, nitrate‐N, and suspended sediments. We present a comprehensive summary of North American studies that have examined the impacts of forest practices on each of these parameters of water quality. In most cases, retention of forested buffer strips along streams prevents unacceptable increases in stream temperatures. Current practices do not typically involve addition of large quantities of fine organic material to streams, and depletion of streamwater oxygen is not a problem; however, sedimentation of gravel streambeds may reduce oxygen diffusion into spawning beds in some cases. Concentrations of nitrate‐N typically increase substantially after forest harvesting and fertilization, but only a few cases have resulted in concentrations approaching the drinking‐water standard of 10 mg of nitrate‐NIL. Road construction and harvesting increase suspended sediment concentrations in streamwater, with highly variable results among regions in North America. The use of best management practices usually prevents unacceptable increases in sediment concentrations, but exceptionally large responses (especially in relation to intense storms) are not unusual.
MEASURING EVAPORATION WITH CERAMIC BELLANI PLATE ATMOMETERS1
Authors: Fontaine Thomas A. , Todd Don E.
Published: June 2007

ABSTRACT: Ceramic atmometers were tested to determine their usefulness for measuring evaporation in water resources applications. Field experiments were used to evaluate the precision, responsiveness to a range of potential evaporation conditions in a forested catchment, and interpretation of water loss of Bellani plate atmometers. The experiments, conducted from April to October in a warm, humid climate in the southeastern United States, indicate that atmometers can be reliable monitoring instruments for estimating potential evaporation. The small size, portability, low internal thermal mass, low cost, and ability to integrate the effect of radiation, air temperature, humidity and windspeed into one direct measurement of potential evaporation, make atmometers a useful instrument for certain water resources applications.
VALIDATION OF AGNPS FOR SMALL WATERSHEDS USING AN INTEGRATED AGNPS/GIS SYSTEM1
Authors: Mitchell J. K. , Engel B. A. , Srinivasan R. , Wang S. S. Y.
Published: June 2007

ABSTRACT: The AGNPS (AGricultural NonPoint Source) model was evaluated for predicting runoff and sediment delivery from small watersheds of mild topography. Fifty sediment yield events were monitored from two watersheds and five nested subwater‐sheds in East Central Illinois throughout the growing season of four years. Half of these events were used to calibrate parameters in the AGNPS model. Average calibrated parameters were used as input for the remaining events to obtain runoff and sediment yield data. These data were used to evaluate the suitability of the AGNPS model for predicting runoff and sediment yield from small, mild‐sloped watersheds.

An integrated AGNPS/GIS system was used to efficiently create the large number of data input changes necessary to this study. This system is one where the AGNPS model was integrated with the GRASS (Geographic Resources Analysis Support System) GIS (Geographical Information System) to develop a decision support tool to assist with management of runoff and erosion from agricultural watersheds. The integrated system assists with the development of input GIS layers to AGNPS, running the model, and interpretation of the results.
SUMMARY OF MODIFICATIONS OF THE U.S. GEOLOGICAL SURVEY MODULAR, FINITE‐DIFFERENCE, GROUND‐WATER FLOW MODEL TO READ AND WRITE GEOGRAPHIC INFORMATION SYSTEM FILES1
Authors: Orzol Leonard L. , McGrath Timothy S.
Published: June 2007

ABSTRACT: The U.S. Geological Survey modular, three‐dimensional, finite‐difference, ground‐water flow model, commonly called MODFLOW, has been modified so that it can read and write files used by a geographic information system (GIS). The modified model program is called MODFLOWARC.

The design of MODFLOWARC parallels the design of the ground‐water flow model program MODFLOW. The names of the variables, modules, and submodules used to explain the operations of MODFLOWARC were derived from the names used in MODFLOW. During the data input phase, MODFLOWARC reads array control records similar to the original control records of MODFLOW, except an additional variable is added. This additional variable is the name of the computer files containing array data in GIS format. Data output is achieved by setting record/input flags and by supplying a variable that is the name of the directory where the output data will be recorded. The modifications to MODFLOW were minimized so that MODFLOWARC will operate on an existing ground‐water flow model without modifying array control records.
THE INFLUENCE OF (x, y) UNCERTAINTY ON PREDICTION ERROR AND CONTOUR LINES FROM A THREE‐DIMENSIONAL SURFACE1
Authors: Mitchell James E.
Published: June 2007

ABSTRACT: In geohydrology, three‐dimensional surfaces are typically represented as a series of contours. Water levels, saturated thickness, precipitation, and geological formation boundaries are a few examples of this practice. These surfaces start as point measurements that are then analyzed to interpolate between the known point measurements. This first step typically creates a raster or a set of grid points. In modeling, subsequent processing uses these to represent the shape of a surface. For display, they are usually converted to contour lines. Unfortunately, in many field applications, the (x, y) location on the earth's surface is much less confidently known than the data in the z dimension.

To test the influence of (x, y) locational accuracy on z dimension point predictions and their resulting contours, a Monte Carlo study was performed on water level data from northwestern Kansas. Four levels of (x, y) uncertainty were tested ranging in accuracy from one arc degree‐minute (± 2384 feet in the x dimension and ± 3036 feet in the y dimension) to Global Positioning Systems (GPS) accuracy (± 20 feet for relatively low cost systems). These span the range of common levels of locational uncertainty in data available to hydrologists in the United States.

This work examines the influence that locational uncertainty can have on both point predictions and contour lines. Results indicate that overall mean error exhibits a small sensitivity to locational uncertainty. However, measures of spread and maximum errors in the z domain are greatly affected. In practical application, this implies that estimates over large regions should be asymptotically consistent. However, local errors in z can be quite large and increase with (x, y) uncertainty.
LAKEMAP: A 2‐D AND 3‐D MAPPING SYSTEM FOR VISUALIZING WATER QUALITY DATA IN LAKES1
Authors: Samuels William B.
Published: June 2007

ABSTRACT: The visualization of water quality data in lakes was achieved by integrating the U.S. Environmental Protection Agency's (EPA) STORET water quality database, lake shoreline polygons from EPA's Reach File (version 3), and the UNIMAP 2‐D and 3‐D interactive mapping and modeling software. Based on lake name (and state abbreviation), a lake shoreline polygon can be accessed from the Reach File. The coordinates of the polygon are portrayed by the U.S. Geological Survey (USGS) 1:100,000 scale Digital Line Graph (DLG) hydrography layer. This polygon is passed, in turn, to the STORET water quality file. Monitoring stations located within the polygon boundary are extracted along with the complete sampling survey. Specific parameters, such as total phosphorus, pH, ammonia, and optional time and depth restrictions can be selected to build a file of x, y, z1, z1…, zn data which is imported to UNIMAP. Up to four parameters, including depth, can be selected at a time. Within UNIMAP, the data is gridded and then displayed as a 2‐D color contour map, 3‐D perspective contour map, or 2‐D projected time or depth slices. This system operates on the EPA ES9000 mainframe computer located in Research Triangle Park (RIP), North Carolina. LAKEMAP is the culmination of an effort to bridge the gap between the vast array of environmental data collected by the EPA and the complex analytical and display software resident on the mainframe.
DEVELOPMENT OF WATERSIIED MODELS FOR TWO SIERRA NEVADA BASINS USING A GEOGRAPHIC INFORMATION SYSTEM1
Authors: Jeton Anne E. , Smith J. LaRue.
Published: June 2007

ABSTRACT: Techniques were developed using vector and raster data in a geographic information system (GIS) to define the spatial variability of watershed characteristics in the north‐central Sierra Nevada of California and Nevada and to assist in computing model input parameters. The U.S. Geological Survey's Precipitation‐Runoff Modeling System, a physically based, distributed‐parameter watershed model, simulates runoff for a basin by partitioning a watershed into areas that each have a homogeneous hydrologic response to precipitation or snowmelt. These land units, known as hydrologic‐response units (HRU's), are characterized according to physical properties, such as altitude, slope, aspect, land cover, soils, and geology, and climate patterns. Digital data were used to develop a GIS data base and HRIJ classification for the American River and Carson River basins. The following criteria are used in delineating HRU's: (1) Data layers are hydrologically significant and have a resolution appropriate to the watershed's natural spatial variability, (2) the technique for delineating HRU's accommodates different classification criteria and is reproducible, and (3) HRU's are not limited by hydrographic‐subbasin boundaries. HRU's so defined are spatially noncontiguous. The result is an objective, efficient methodology for characterizing a watershed and for delineating HRU's. Also, digital data can be analyzed and transformed to assist in defining parameters and in calibrating the model.
INTEGRATING GEOGRAPHIC INFORMATION SYSTEMS IN GROUND‐WATER APPLICATIONS USING NUMERICAL MODELING TECHNIQUES1
Authors: Roaza Honesto , Roaza Ruth Montgomery , Wagner Jeffry R.
Published: June 2007

ABSTRACT: The Sand and Gravel Aquifer is the sole source of potable water in Escambia County, Florida. In order to better understand the hydraulics of the aquifer, a numerical computer model of the aquifer was developed. The model applied a finite element technique which allowed for density‐dependent transport and flow in three dimensions. The modeling technique was integrated with GIS to develop a system for optimal management of the resource.

The GIS was the primary tool in the development of the model grid, as well as being the integral component in the modeling procedure. Multiple model grids were developed for simulating regional flow and local flow/transport phenomena. The model grids were generated by the GIS where nodal and element sequencing were recorded. The grid topology was stored in the GIS with the element numbers, node numbers, and the related hydrogeologic attributes. The Triangulated Irregular Network (TIN) module was used for transferring interpolated value between GIS coverages. TIN allowed a fit of the model grid to the physical dimensions of the aquifer and for interpolating boundary values for telescopically refined grids. Calculations between TIN surfaces provided the residuals of the dependent variable from observed TIN surfaces.

Model calibration was conducted within the GIS environment through a combination of visual and relational querying. The GIS provided an integrated environment which facilitated model analyses and data storage and retrieval.
POLICY DROUGIT: THE CASE OF SOUTH FLORIDA1
Authors: Thompson Peter , Lynne Gary D.
Published: June 2007

ABSTRACT: In this paper, we review recent experience with drought in south Florida, and report some results of a study of the likely agricultural economic impacts of drought. Our conclusions can be summarized as follows. (1) Whether a period of low rainfall becomes a “drought” in south Florida is determined largely by institutional factors. (2) The impacts of a drought event are dependent on the rules the Water Management District uses to manage the event. If the rules involve effective reductions in irrigation supply, the financial impacts may be large, but are sensitive to the way in which cutbacks are imposed. (3) Current drought management regulations do not appear to minimize the short‐run cost of drought. (4) Current policies which seek to minimize the short‐run cost of drought are inconsistent with dynamically‐optimal policies.
THE REGULATED RIPARIAN VERSION OF THE ASCE MODEL WATER CODE: THE THIRD WAY TO ALLOCATE WATER1
Authors: Dellapenna Joseph W.
Published: June 2007

ABSTRACT: Lawyers, engineers, and hydrologists are accustomed to thinking of water law as falling into one of two incompatible models: riparian rights (under which water is allocated by courts according to the relative reasonableness of the competing uses) and appropriative rights (under which water is allocated according to the temporal priority of the competing uses, largely by the action of the water users themselves but perfected by the issuance of an administrative permit). Usually unnoticed is the existence of a third approach, which I have dubbed “regulated riparianism.” Under regulated riparianism, water is allocated by water permits issued after an administrative determination of the reasonableness of the proposed use before the use is commenced. This system, now in place in about half of the states east of Kansas City (plus Hawaii), thus is fundamentally different from either the traditional ripanan rights that it replaces or the appropriative rights found in western states.
RIVER‐BED SEDIMENTATION CAUSED BY OFF‐ROAD VEHICLES AT RIVER FORDS IN THE VICTORIAN HIGHLANDS, AUSTRALIA1
Authors: Brown Katherine J.
Published: June 2007

ABSTRACT: This study investigates some of the effects occurring at recreational off‐road vehicle (ORV) crossings on two rivers in eastern Victoria, where many road crossings occur at low‐level fords. Further, it provides a method whereby the amount of sediment redeposited downstream of a ford can be measured. Attention is drawn to the fact that sediment is contributed to the river by five major processes: the creation of wheel ruts and concentration of surface runoff, the existence of tracks and exposed surfaces, the compaction and subsequent reduction in the infiltration rate of soils leading to increased surface runoff, backwash from the vehicle, and undercutting of banks by bow wave action. The last two of these processes have not been reported previously. Sediment collection experiments in two Victorian upland rivers indicate a mean deposition rate at the stream bed of approximately 1000 g m−2 over a period of 30 days.
DISTRIBUTION AND GRAIN‐SIZE PARTITIONING OF METALS IN BOVFOM SEDIMENTS OF AN EXPERIMENTALLY ACIDIFIED WISCONSIN LAKE1
Authors: Elder John F
Published: June 2007

ABSTRACT: A study of concentrations and distribution of major and trace elements in surficial bottom sediments of Little Rock Lake in northern Wisconsin included examination of spatial variation and grain‐size effects. No significant differences with respect to metal distribution in sediments were observed between the two basins of the lake, despite the experimental acidification of one of the basins from pH 6.1 to 4.6. The concentrations of most elements in the lake sediments were generally similar to soil concentrations in the area and were well below sediment quality criteria. Two exceptions were lead and zinc, whose concentrations in July 1990 exceeded the criteria of 50 μg/g and 100 μg/g, respectively, in both littoral and pelagic sediments. Concentrations of some elements, particularly Cu, Pb, and Zn, increased along transects from nearshore to midlake, following a similar gradient of sedimentary organic carbon. In contrast, Mn, Fe, and alkali/alkaline‐earth elements were at maximum concentrations in nearshore sediments. These elements are less likely to partition to organic particles, and their distribution is more dependent on mineralogical composition, grain size, and other factors. Element concentrations varied among different sediment grain‐size fractions, although a simple inverse relation to grain size was not observed. Fe, Mn, Pb, and Zn were more concentrated in a grain‐size range 20–60 tm than in either the very fine or the coarse fractions, possibly because of the aggregation of smaller particles cemented together by organic and Fe/Mn hydrous‐oxide coatings.
MONITORING SUSPENDED PARTICULATE MATTER IN PUERTO RICO: FIELD MEASUREMENTS AND REMOTE SENSING1
Authors: Miller R. L. , Cruise J. F. , Otero E. , Lopez J. M.
Published: June 2007

ABSTRACT: The spatial distribution of suspended particulatematter (SPM) was estimated in Mayagüez Bay on the west coast of Puerto Rico by using traditional ship board measurements and remotely sensed data acquired over four days during January 1990. This effort was part of a joint project between NASA and the University of Puerto Rico to develop techniques to monitor the water quality of a Caribbean coastal zone. This paper presents the methods and algorithms developed to map and analyze short term changes in the source and spatial distribution of SPM in Mayagüez Bay by using remotely sensed data acquired by the Calibrated Airborne Multispectral Scanner (CAMS). A PC‐based data acquisition system was developed to record continuous ship measurements of select in‐ water variables. Spectral reflectances derived from CAMS red and near‐IR data were corrected for atmospheric effects and then used to generate maps of SPM. These maps displayed SPM plumes associated with the mouths of the bay's three river systems. Significant day‐to‐day differences in the spatial characteristics were observed, suggesting that changes in river discharge occurred. However, an analysis of estimated river discharge, sediment yield, local wind field, and thermal river plume indicates that observed sediment plumes result primarily from wind‐driven resuspension events.
ESTIMATING PROBABLE MAXIMUM FLOOD PROBABILITIES1
Authors: Shalaby Ahiam I.
Published: June 2007

ABSTRACT: Methods of computing probabilities of extreme events that affect the design of major engineering structures have been developed for most failure causes, but not for design floods such as the probable maximum flood (PMF). Probabilities for PMF estimates would be useful for economic studies and risk assessments. Reasons for the reluctance of some hydrologists to assign a probability to a PMF are discussed, and alternative methods of assigning a probability are reviewed. Currently, the extrapolation of a frequency curve appears to be the most practical alternative. Using 46 stations in the Mid‐Atlantic region, the log‐gamma, log‐normal, and log‐Gumbel distributions were used to estimate PMF probabilities. A 600,000‐year return period appears to be a reasonable probability to use for PMFs in the Mid‐Atlantic region. The coefficient of skew accounts for much of the variation in computed probabilities.
A MODELING APPROACH FOR OPTIMUM SEDIMENT DETENTION POND DESIGN1
Authors: Tiyamani C. , Shanholtz V. O. , Younos T M. , Thomson S. J.
Published: June 2007

ABSTRACT: A design procedure to determine optimum size for a sediment detention pond is presented. The procedure is based on simulating the sediment removal efficiency of the pond in conjunction with temporal variations in rainfall and potential land use and/or management options. The simulation procedure is based on a combined probabilistic‐deterministic modeling approach. The probabilistic model generates daily rainfall with hourly increments for a selected site. The deterministic model simulates sediment yield and concentration for drainage area (pond inflow) and sediment trapping efficiency of the pond. The sediment yield and concentration in pond effluent is estimated from the difference between sediment inflow to the pond and sediment trapped by the pond. As an example, the procedure is applied to determine optimum design for a sediment detention pond in a surface mined area using several pond design options and alternative mining operation/land reclamation strategies.
RESOLVING INTERSTATE WATER CONFLICTS IN THE EASTERN UNITED STATES: THE RE‐EMERGENCE OF THE FEDERAL‐INTERSTATE COMPACT1
Authors: Sherk George William
Published: June 2007

ABSTRACT: As population growth occurs in regions of the eastern United States that do not have abundant water supplies, new transbasin diversions may be required. Such diversions are exceptionally politically divisive and are at the core of most of the interstate water conflicts that presently exist in the eastern states. This study examines alternative means by which these conflicts might be resolved. The strengths and weaknesses of these alternatives are examined. The study concludes that the federal‐interstate compact should be the preferred alternative by which interstate water conflicts in the eastern United States are resolved.
WATER BUDGET ANALYSIS FOR THE EVERGLADES AGRICULTURAL AREA DRAINAGE BASIN1
Authors: Abtew Wossenu , Khanal Nagendra
Published: June 2007

ABSTRACT: Water budget studies are essential for water resources and environmental management. In this study, a water budget analysis is presented for the Everglades Agricultural Area (EAA) in South Florida for the period from 1973 to 1991. The EAA is a highly productive irrigation/drainage basin that has a high water table and organic soils. Water quality problems are associated with the drainage discharge from the basin. During dry periods, supplemental water is used for irrigation and in rainy periods excess water with relatively higher phosphorus content is pumped out of the basin to Lake Okeechobee and the Everglades ecosystem. Elevated concentrations of phosphorus in the runoff/drainage that is discharged from the EAA basin have created water quality problems. The mean surface water inflow to the basin was 63,990 ha‐m, and the outflow was 131,447 ha‐m per year. On the average, supplemental surface water use was 47,411 ha‐m, and runoff/drainage was 114,816 ha‐m per year. The mean annual basin rainfall was 120.9 cm. A general trend in the decline of the wet season rainfall is observed.
ECONOMIC INCENTIVES FOR AGRICULTURAL NONPOINT SOURCE POLLUTION CONTROL1
Authors: Malik Arun S. , Larson Bruce A. , Ribaudo Marc
Published: June 2007

ABSTRACT. The limited success of command‐and‐control policies for reducing nonpoint source (NPS) water pollution mandated under the Federal Water Pollution Control Act (FWPCA) has prompted increased interest in economic incentive policies as an alternative control mechanism. A variety of measures have been proposed ranging from fairly minor modifications of existing policies to substantial revisions including watershed‐wide polices that rely on economic incentives. While greater use of economic incentive policies, such as environmental bonds and point/nonpoint source trading is being advocated in the reauthorization of the CWA, the expected effects of individual proposals will be modest. The characteristics of NPS pollution, namely uncertainty and asymmetrical information, underscores that there is no single, ideal policy instrument for controlling the many types of agricultural NPS water pollution. Some of the usual incentive‐based policies, such as effluent taxes, are not well suited to the task. Individual incentive policies proposed for the reauthorized CWA, such as pollution trading or deposit/refund systems, are not broadly applicable for heterogeneous pollution situations. Economic incentive policies may be appropriate in some cases, and command‐and‐control policies will be preferable in others and may in fact complement incentive policies.
MODELING CONCENTRATION VARIATIONS IN HIGH‐CAPACITY WELLS: IMPLICATIONS FOR GROUNDWATER SAMPLING1
Authors: Gosselin David C. , Ayers Jerry F , Zhang You‐Kuan
Published: June 2007

ABSTRACT: High‐capacity wells are used as a convenient and economical means of sampling groundwater quality. Although the inherent limitations of using these wells are generally recognized, little has been done to investigate how these wells actually sample groundwater. A semi‐analytical particle tracking model is used to illustrate the influence of variable vertical contaminant distributions and aquifer heterogeneity on the composition of water samples from these wells during short pumping periods. The hypothetical pumping well used in the simulations is located in an unconfined, alluvial aquifer with a shallow water table and concentration gradients of nitrate‐nitrogen contamination. This is a typical setting for many irrigated areas in the United States. The main conclusions are: (1) high‐capacity wells underestimate the average amount of contamination within an aquifer; (2) shapes of concentration‐time curves for high‐capacity wells appear to be governed by the distribution of the contaminant and travel times to the well; (3) variables such as well construction, pumping rate, and hydrogeologic properties contribute to the magnitude of the concentration‐time curves at individual high‐capacity wells; and (4) a sampling strategy using concentration‐time curves based on the behavioral characteristics of the well rather than individual samples will provide a much better framework for interpreting spatial contaminant distributions.
ESTIMATING THE PROBABILITY OF EXCEEDING GROUNDWATER QUALITY STANDARDS1
Authors: Ahlfeld David P , Islam M. Shafiqul.
Published: June 2007

ABSTRACT: A model for estimating the probability of exceeding groundwater quality standards at environmental receptors based on a simple contaminant transport model is described. The model is intended for locations where knowledge about site‐specific hydrogeologic conditions is limited. An efficient implementation methodology using numerical Monte Carlo simulation is presented. The uncertainty in the contaminant transport system due to uncertainty in the hydraulic conductivity is directly calculated in the Monte Carlo simulations. Numerous variations of the deterministic parameters of the model provide an indication of the change in exceedance probability with change in parameter value. The results of these variations for a generic example are presented in a concise graphical form which provides insight into the topology of the exceedance probability surface. This surface can be used to assess the impact of the various parameters on exceedance probability.