The accuracy of agricultural nonpoint source pollution models depends in part on how well model input parameters describe the relevant characteristics of the watershed. The spatial extent of input parameter aggregation has previously been shown to have a substantial impact on model output. This study investigates this problem using the Soil and Water Assessment Tool (SWAT), a distributed-parame...

climate change is a natural phenomenon that occurs in the long time scale. the most important factors that intensify climate change are changes in reflected radiation from the sun, changes in earth's orbit, greenhouse gases and continents drift. in this research the barandoezchay watershed in west azerbaijan province with an area of 1088 km2 was investigated. due to the lack of synoptic st...

Streamflow hydrographs represent the integrated effects of hydrologic processes operating over a wide range of spatial and temporal scales. Constant-parameter transfer function models have been shown to represent the relationship between effective rainfall and streamflow adequately in many cases, but are limited in ability to reveal detailed behaviour by their aggregation of watershed dynamics ...

This paper describes estimation of stream channel geometry with multiple regression analysis of GISderived watershed characteristics including drainage area, catchment-averaged precipitation, mean watershed slope, elevation, forest cover, percent area with slopes greater than 30 percent, and percent area with north-facing slopes greater than 30 percent. Results from this multivariate predictor ...

assessment of watershed management activities is one of the main subjects for future planning of practical projects and natural resources management. due to the lack of any tool for assessment of watershed processes in many cases, distributed hydrological models can be useful. the purpose of this study was evaluation of watershed management activities in kan watershed by hec-hms (hydrologic mod...

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 ...

Protecting is the sources of drinking water is the first barrier of contamination of drinking water. The Feitsui Reservoir watershed of Taiwan supplies domestic water for around 5 million people in the Taipei metropolitan area. Understanding the spatial patterns of water quality trends in this watershed is an important agenda for management authorities. This study examined 7 sites in the waters...

Determination of river runoff is essential in design and construction of most hydraulic structures including dams. In rivers with no measurement stations, the hydraulic models can be used for data estimation.  SWAT is one of the most widely-used numerical models. In this model, input influential meteorological data as precipitation, temperature, wind speed, solar radiation and relative humidity...