Simulation models are powerful tools in support of watershed analysis and assessment of management scenarios at the watershed scale. This paper integrates geographic information systems (GIS) and agricultural nonpoint source pollution model (AGNPS) to analyze the effect of land use change on nonpoint source pollution in a study watershed. ArcView nonpoint source pollution modeling (AVNPSM), an ...

Several best management practices (BMPs) have been implemented through Water Quality Management Plans (WQMPs) in the West Fork Watershed of Trinity River Basin in Texas, USA, where nonpoint source pollution is a serious concern. Major sources of pollution are sediment erosion and nutrients. The objective of this study was to evaluate the long-term impact of implementation of WQMPs on nonpoint s...

[1] The focus in the search for more reliable predictions in ungauged basins (PUB) has generally been on reducing uncertainty in watershed models (mainly their parameters). More recently, however, we seem to remember that the ultimate objective is not to define the parameters of a specific model but to understand the watershed: What behavior do we expect the ungauged watershed to exhibit? And w...

Suspended sediment resulted from distributed soil erosions facilitates nutrient transportation and influences soil depletion. Phosphorus (P) is one of the major limiting nutrients controlling eutrophication of surface water. Irregular P load pulsed by heavy rainfall may damage the ecological quality of downstream waters. P transport study during rainfall events is important in both predicting a...

Soil depth is an important input parameter in hydrological and ecological modeling. Presently, the soil depth data available in national soil databases (STATSGO, SSURGO) is provided as averages within generalized land units. Spatial uncertainty within these units limits their applicability for spatially distributed modeling. This work reports a statistical model for prediction of soil depth in ...

A validation study has been performed using the Soil and Water Assessment Tool (SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW), which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a previous study with nested modeling for the UMRW that required both the Agricultural Policy EXtender (APEX) model and SWAT. In the nested modeling appr...

Soil depth is an important input parameter in hydrological and ecological modeling. Presently, the soil depth data available in national soil databases (STATSGO, SSURGO) is provided as averages within generalized map units. Spatial uncertainty within these units limits their applicability for spatially distributed modeling. This work reports a statistical model for prediction of soil depth in a...

CASC2D is a physically-based, distributed model that simulates the response of a watershed to precipitation. Basic processes in the model include: precipitation, interception, infiltration, surface runoff and channel flow, and erosion and deposition of upland soil and channel bed sediment. Model performance is demonstrated by applications to numerous sites such as Goodwin Creek, MS. This waters...

The paper presents applications and models which are beneficial to watershed management in various areas. The intention is to inform about the current capabilities of soft computing, hydrologic analysis modules, and distributed hydrologic models, and to provide an initial guide on implementing soft computing. Watershed is not simply the hydrological unit but also socio-political-ecological enti...

Watershed nutrient management is essential in minimizing the eutrophication rate of reservoirs. A shortcoming in nutrient management of watershed-reservoir systems has been the lack of successful linking of watershed and water body models to evaluate impact of watershed management options on reservoir water quality. The objectives of this research were to 1) calibrate and validate a Soil and Wa...