Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 34 for “"Agricultural watersheds"”.
-
Estimating Bacterial Loadings to Surface Waters from Agricultural Watersheds
Fecal bacteria and pathogens are a major source of surface water impairment. In Virginia alone, approximately 73% of impaired waters are impaired due to fecal coliforms (FC). Because bacteria are a significant cause of water body impairment and existing bacterial models are predominantly based upon …
-
Legacy Nutrient Management and Remediation in Diverse Agricultural Watersheds
Excess nutrient loading from agricultural landscapes remains a primary driver of freshwater eutrophication in the United States, despite decades of conservation investment. In many watersheds, water quality impairments persist due to the accumulation of legacy nutrients—phosphorus (P) stored in …
-
Suspended sediment and total phosphorus loadings from small agricultural watersheds in western Illinois
… substantially within a day. In five small, rural watersheds in western Illinois, the collection and analysis of data during runoff events was done on a sub-daily time step. To have accurate load estimates, the selected load calculation method should correctly characterize loading behavior during …
-
Erosion and nutrient loading characteristics of two small agricultural watersheds in Piedmont Virginia
… erosion process was characterized on two small agricultural watersheds in Piedmont Virginia. Rainfall and runoff were measured for all storms at both watersheds over a two year monitoring period. Although the data base was relatively short, the data covered a wide range of rainfall and runoff …
-
Modeling phosphorus transport in surface runoff from agricultural watersheds for nonpoint source pollution assessment
… Numerous studies have indicated that, for many watersheds, a few critical areas are responsible for a disproportionate amount of the nutrient and sediment yield. Consequently, if pollution control activities are concentrated in these critical areas, then a far greater improvement in downstream …
-
Fractal and Multifractal Analysis of Runoff Time Series and Stream Networks in Agricultural Watersheds
… of runoff and stream network morphometry in agricultural watersheds has not been previously reported. In the present study, fractal and multifractal scaling of daily runoff rate in four experimental agricultural watersheds and their associated sub-watersheds (32 in total) were investigated. …
-
Response of Soil and Water Quality to Winter Manure Application from Small Agricultural Watersheds in South Dakota
… that manure spread near the outlets of the watersheds would lead to an increased loss of nutrients as compared to the manure spread away from the watershed outlets. A paired watershed study was established near Colman, South Dakota, in which two watersheds were used as treatment watersheds …
-
Effects of Perturbations by Agricultural Land Use on Structure and Function of Stream Ecosystems
The effects of agricultural land use on headwater stream ecosystems were assessed. Three factors were examined: (1) the role of physical and biological processes in terrestrial, riparian, and aquatic portions of agricultural watersheds as regulators of water quality, (2) the changes in fish c
-
The Sorption of Roxarsone, an Organoarsenical Animal Feed Additive
… the fate of roxarsone once it is introduced into agricultural watersheds. Using batch experiments, I investigated the sorption characteristics of roxarsone to Ap and Bt soils of the Frederick series, common in the Shenandoah Valley of Virginia, an area of intense poultry production. Results …
-
Land use drives the physiological properties of a stream fish
… zone can alter the abiotic properties of watersheds and stream reaches, potentially resulting in abiotic conditions that are stressful for resident fishes. The inability of fish to cope physiologically with stressful abiotic conditions can have deleterious effects on individuals, and could …
-
Urban Erosion Potential Risk Mapping with GIS
… focus primarily on estimating erosion from agricultural watersheds. Methods are needed to predict areas with high erosive potential (EP) in urban watersheds. Highlighting highly erosive areas in urbanized watersheds allows for the prioritization of maintenance and installation of Stormwater …
-
Perspectives on the Geomorphic Evolution and Ecology of Modified Channels and Two-Stage Ditches in the Agriculturally-Dominated Midwestern United States
… and a persistent eutrophication problem in agriculturally-dominated watersheds, such as the Gulf of Mexico and the Great Lakes, which have led to examination of managing agricultural drainage ditches for ecosystem benefits. Work by dissertation collaborators on alternative ditch designs has …
-
A comprehensive modeling approach for BMP impact assessment considering surface and ground water interaction
… changing land use management practice in an agricultural watershed and 2) interaction between surface and ground water over the entire system. A user interface and Dynamic Agricultural Non-point Source Assessment Tool (DANSAT) were developed to achieve this goal. DANSAT is the only …
-
Development of a continuous, physically-based distributed parameter, nonpoint source model
… runoff, sediment, and nutrient losses from agricultural watersheds. The Holtan's infiltration equation used in the original version of ANSWERS was replaced by the physically-based Green-Ampt infiltration equation. Soil evaporation and plant transpiration were modeled separately using the …
-
Application of multi-state financial data for use with the USDA Agricultural Conservation Planning Framework
… with regards to excess nutrient pollution. Agriculturally dominated landscapes are one of the major contributors to impairments in waterways at both local and regional scales. As Iowa and other US Corn Belt states continue to navigate water quality issues, spatially targeted conservation and …
-
Understanding the role of scale in assessing sediment and nutrient loads from Coastal Plain watersheds delivered to the Chesapeake Bay
Urban and agricultural runoff is the principal contributor to non-point source (NPS) pollution and subsequent impairments of streams, rivers, lakes, and estuaries. Urban and agricultural runoff is a major source of sediment, nitrogen (N) and phosphorus (P) loading to receiving waters. Coastal …
-
Understanding Streamflow Change at the Scale of a Major City: Chicago
… that have been observed in urban, suburban and agricultural watersheds in and around the Greater Chicago area. A novel statistical method, the Procedure for Change Pattern and Signi ficance (PCPS), is developed to detect non-stationarity and identify the timing and duration of these shifts in …
-
Simulation of Runoff and Pollutant Loss in Urbanizing Watersheds
The effect of urbanization on previously agricultural watersheds is an increasingly important issue for watershed planners. Urbanization increases runoff and pollutant loadings to the watershed outlet. Watershed planners in areas that previously had little impervious cover must now consider the …
Page 1 of 2