bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
USE AND MISUSE OF COMPLEX MODELS: EXAMPLES FROM WATER DEMAND MANAGEMENT1
Authors: Parker Michael , Thompson James G. , Reynolds Robert R. , Smith Michael D. 
Published: June 2007

ABSTRACT: The power of computers has increased in recent decades, and one might expect improved management to result because decisions can be made with understanding available only via models. However, there is potential for quite the opposite: poor decisions due to unrealistic model output generated by users without access to appropriate training in the use of models. We discuss and, by reference to water demand models (IWR‐MAIN, MWD‐MAIN), illustrate three areas in which unintended errors of judgment by untrained personnel may cause difficulty:

Attributes of management models; if output from any type of model has no measure of confidence, then results may be over‐ or undervalued
Input data; with complex models, problems here typically will be difficult to detect.
Calibration and history‐matching (verification); if these steps or data are combined, then users should be less trustful of model output than otherwise.

Because all models have weaknesses and because there always is uncertainty about output from any model, we end with suggestions for coping with complex models. Monitoring programs play a central role in such efforts because they can identify discrepancies between model predictions and actual events and because they can ensure time is available to develop solutions for problems unanticipated in the modeling effort.
RUNOFF AND SEDIMENT YIELD UNDER GRAZING IN FOOTHILLS FESCUE GRASSLANDS OF ALBERTA1
Authors: Anne Naeth M. , Chanasyk David S. 
Published: June 2007

ABSTRACT: Grazing can have a profound impact on infiltration and thus runoff and erosion. The objectives of this study were to quantify the effects of select grazing systems on rainfall and snowmelt induced runoff and sediment yield from sloped areas of the foothills fescue grasslands of Alberta, Canada. The effects of two grazing intensities (heavy and very heavy) for two durations (short duration and continuous throughout the growing season) were compared to an ungrazed control between June 1988 and April 1991. Runoff was measured using 1‐rn2 runoff frames and collection bucket systems. Sediment yields were then determined on samples from the collected runoff.Snowmelt was the dominant source of runoff. Snowmelt runoff was higher from the heavily grazed areas than from the very heavily grazed areas, due to the higher standing vegetation which accumulated snow in the former areas. Sediment yields as a result of snowmelt were generally low in all areas. Only a few summer storms caused runoff. Runoff volumes and sediment yields from summer rainstorms were low, due to low rainfall and to generally dry antecedent soil moisture conditions. The greatest risk of summer runoff, and thus sediment yield, appears to occur in August.
SWMHMS ‐ SMALL WATERSHED MONTHLY HYDROLOGIC MODELING SYSTEM1
Authors: Allred B. , Haan C. T. 
Published: June 2007

ABSTRACT: SWMHMS is a conceptual computer modeling program developed to simulate monthly runoff from a small nonurban watershed. The input needed to run model simulations include daily precipitation, monthly data for evapotranspiration determination (average temperature, crop consumptive coefficients, and percent daylight hours), and six watershed parameter values. Evapotranspiration was calculated with the Blaney‐Criddle equation while surface runoff was determined using the Soil Conservation Service curve number procedure. For watershed parameter evaluation, SWMHMS provides options for both optimization and sensitivity analysis. Observed runoff data are required along with the model input previously mentioned in order to conduct parameter optimization. SWMEIMS was tested with data from six watersheds located in different regions of the United States. Model accuracy was generally found to be very good except on watersheds having substantial snowfall accumulation.In having only six watershed parameters, SWMHMS is less complex to use than many other computer programs that calculate monthly runoff. Consequently, SWMHMS may find its greatest application as an educational tool for students learning principles of hydrologic modeling, such as parameter evaluation procedures and the impacts of input data uncertainty on model results.
WETLAND DESIGN METHODS FOR RESIDENTIAL WASTEWATER TREATMENT1
Authors: Sauter Gregory , Leonard Kathleen 
Published: June 2007

ABSTRACT: Constructed wetlands have recently gained popularity as an alternative method for wastewater treatment. This paper compares two design methodologies currently used for constructed wetlands; Tennessee Valley Authority (TVA) and the Environmental Protection Agency (EPA) methods. A discussion of parameters for both methods is given and a wetland treatment system is designed for an individual residence with typical BOD5 loads and flow rates.Calculation results revealed significant discrepancies in the required constructed wetlands volume, and thus detention time, stemming from inherent differences in the design methodologies. The EPA method relies heavily on plug flow kinetics, and is therefore sensitive to changes in the reaction rate constant and media porosity. Conversely, TVA determines the surface area by sizing in accordance with a recommended hydraulic loading criterion and is affected only by the hydraulic flow rates. This study concluded that a constructed wetland is a viable option under design considerations that are not favorable for traditional on‐site wastewater treatment methods. However, it is recommended that conservative values for flow and loading rates be assumed to assure complete treatment for either of the design methods.
SELECTED CHALLENGES IN RUNOFF GENERATION RESEARCH IN FORESTS FROM THE HILLSLOPE TO HEADWATER DRAINAGE BASIN SCALE1
Authors: Bonell Mike 
Published: June 2007

ABSTRACT: When faced with practical forest land management issues such as the impacts of logging or forest conversion to other land uses, planners ideally require a comprehensive understanding of within drainage basin hydrological processes to determine the most vulnerable areas to increased storm runoff and erosion. Land managers in particular need to know the source areas and magnitude of inputs to the storm hydrograph, in terms of water quantity, sediment and solute transport; and the routing of such hydrographs from headwater to larger drainage basins. The latter includes an overall assessment at various scales of the impacts of forest disturbance and conversion on the water balance.This paper will focus on runoff generation in terms of identifying the various pathways and source areas. Such aspects will be linked with the need for a more comprehensive effort towards the field testing of so‐called ‘physically based’ models of runoff generation. Some of the controversial issues arising from the difficulties in reconciling results from hydrochemical investigations with complementary hydrometric studies will be highlighted. Subsequently, attention will be given to topographic‐wetness models, which have promising applications in forestland management. In addition, alternative simple models for application at the catchment scale will be assessed. The latter is in recognition that at smaller scales, heterogeneity both in time and space of soil hydraulic properties demand a greater number of parameters in modelling. Such considerations can even prove an obstacle in terms of the confident application of ‘physically based’ models.
RELATIONSHIPS BETWEEN WIND VELOCITY AND UNDERWATER IRRADIANCE IN A SHALLOW LAKE (LAKE OKEECHOBEE, FLORIDA, USA)1
Authors: Hanlon Charles G. , Miller R. L. , McPherson B. F. 
Published: June 2007

ABSTRACT: Relationships between wind velocity and the vertical light attenuation coefficient (K0) were determined at two locations in a large, shallow lake (Lake Okeechobee, Florida, USA). K0 was significantly correlated with antecedent wind conditions, which explained as much as 90 percent of the daily variation in K0.Sub‐surface irradiance began to change within 60 to 90 minutes of the time when wind velocity exceeded or dropped below a threshold value. Maximum one hour changes in K0 were > 50 percent, however, 20 to 30 percent changes were more common. The magnitude of change in K0 varied spatially based on differences in sediment type. K0 never exceeded 2.8 at a location where bottom sediments were dominated by a mixture of coarse sand and shells. In comparison, K0 exceeded 9 during episodic wind events where the bottom sediment was comprised of fine grain mud.Underwater irradiance data can be used to determine threshold wind velocity and account for the influence sediment type has on K0. Once a threshold velocity has been established, the frequency, rate, and duration of expected change in underwater irradiance can be evaluated. This is critical information for scientists who are studying algal productivity or other light‐related phenomena.
EFFECTWENESS OF INTEGRATED STORMWATER MANAGEMENT IN A PORTLAND, OREGON, WATERSHED1
Authors: Hottenroth Dawn , Harper Craig , Turner James 
Published: June 2007

ABSTRACT: The City of Portland's stormwater management program, winner of EPA's Environmental Excellence Award for 1996, is committed to partnership‐based, cost‐effective, “green” approaches to healthy neighborhoods and water quality. The stormwater program encourages innovative, non‐structural pollution reduction techniques like native landscaping, stormwater pollution reduction bioswales and ponds, and public involvement and education.Effectiveness of stormwater best management practices (BMPs) has been difficult to determine on a citywide basis. Recognizing this problem, the City of Portland launched the Parkrose Pilot Project in 1994 to test the effectiveness of a wide range of BMPs in a small watershed in north Portland, the Parkrose catchment, and monitor the results prior to citywide implementation. This catchment was selected because of its small size (144 acres), its representative mix of land uses, and an extensive record of water quality monitoring data.This paper examines the City's strategy in selecting the Parkrose study area as a pilot watershed, the BMPs chosen for use in the watershed, and the results of the program to date. Final success of the Parkrose project will be gauged by the attainment of measurable pollution reduction within the catchment while providing opportunities for meaningful participation by the local community in achieving water quality. Involvement by private citizens in the community is crucial to the success of the project and to ensure compliance with the federal mandate to reduce pollutants to the maximum extent practicable.
OPTIMUM DESIGN OF BORDER IRRIGATION SYSTEM1
Authors: Khanjani M. J. , Barani G. A. 
Published: June 2007

ABSTRACT: Border irrigation systems like most of the other surface irrigation systems, do not need too much energy and special equipment. Thus, many farmers have used this system for a long time. On the other hand, design of surface irrigation systems including border irrigation requires many input parameters, and need intensive engineering calculations. The burden of these requirements probably led the users to experimental design of the systems with low efficiencies. However, accurate design and high quality optimization of the border irrigation system that can result in a highly efficient system is possible.In this study, an optimization model for border irrigation system is presented. The Hook Jeev's pattern search optimization method in conjunction with a general mathematical model of border irrigation is used to maximize the irrigation application efficiency. The border irrigation storage and distribution efficiencies, border slope and length, inflow rate, cutoff time, and the Manning's roughness coefficient are selected as constraints. The model is applied to field‐measured data. The results show that it is possible to select a suitable combination of the border system's parameters (border's length, inflow rate, and cutoff time) to obtain a maximum application efficiency.
A MULTI‐TIER APPROACH FOR AGRICULTURAL WATERSHED MANAGEMENT1
Authors: Rudra R. P. , Dickinson W. T. , Abedini M. J. , Wall G. J. 
Published: June 2007

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

ABSTRACTThis study systematically evaluates residential consumer responses to a utility conservation initiative based on an econometric analysis of a sample of 510 households served by Artesian Water Company, Inc. (New Castle County of Delaware). Using a panel study approach covering the period from 1992 to 1997, this study shows that Artesian's water conservation program has had statistically significant and persistent impacts on residential water consumption.
THE EFFECTS OF CLIMATE CHANGE AND IRRIGATION ON CRITERION LOW STREAMFLOWS USED FOR DETERMINING TOTAL MAXIMUM DAILY LOADS1
Authors: Eheart J. Wayland , Wildermuth Amy J. , Herricks Edwin E. 
Published: June 2007

ABSTRACT: This paper addresses the possible impacts of global climate change on low streamflows in the Midwest, both directly, through lower precipitation, and indirectly, by rendering irrigation profitable in areas where it has found little application in the past. In the analysis presented here, streamflow data are altered to represent the effect of climate change and stream‐supplied irrigation, and then used to estimate new values for two low‐flow criteria, the one‐ and seven‐day‐ten‐year low flows (7Q10 and 1Q10) under 20 climate change and irrigation scenarios. Additionally, the frequencies of violation of these two criteria, and multiple violations in a three‐year period, are determined.Results show that the potential impact of the assumed climate change scenarios on low flow standards is substantial. A 25 percent decrease in mean precipitation results in a 63 percent reduction in design flow, even in the absence of irrigation. With irrigation, the reduction can be as much as 100 percent. The frequency of single violations of low flow criteria is found to increase several fold with irrigation. The frequency of multiple violations of low flow criteria in a three‐year period is sensitive to climate change, increasing from around 20 percent to nearly 100 percent as the climate change becomes more severe.
AFTER THE 1993 FLOOD: A WATER AND SURFICIAL BED SEDIMENT QUALITY SCENARIO ON THE ILLINOIS AND UPPER MISSISSIPPI RWERS1
Authors: Soong TaWei , Ettinger William H. 
Published: June 2007

ABSTRACT: Effects of the 1993 flood on river water and sediment quality were investigated using historical data and data collected from the Illinois River and Upper Mississippi River in a post‐flood period. Overall the post‐flood results showed systematic reductions and individual changes in the water and sediment constituents.The reductions in sediment metals and nutrients were most obvious at the Keokuk and Lock and Dam 26 stations. By analyzing and comparing the physical changes to the changes in water and sediment constituents at each station, it was found that physical processes such as sediment entrainment and, more importantly, the removal of fine sediment to be the main causes for the reduced concentrations in sediment constituents. On the other hand, sediment redistribution and associated secondary contamination could have caused the emergence of several water and sediment constituents that were undetected before the flood.