Water Resources Research Act Program

Details for Project ID 2008TX306B

Effect of grid sizes as subbasins on SWAT model hydrologic and water quality predictions

Institute: Texas
Year Established: 2008 Start Date: 2008-03-01 End Date: 2009-02-28
Total Federal Funds: $5,000 Total Non-Federal Funds: $16,962

Principal Investigators: Sivarajah Mylevaganam, Raghavan Srinivasan

Project Summary: The uncertain nature of Hydrological Responsive Units (HRU) definition that consists of homogeneous land use, management, and soil characteristics in a hydrological model is pronounced in the literature. Presently, there are no standard protocols for deciding what decomposition scheme to adopt to capture the spatial variability through HRU concept. SWAT, a basin-scale, continuous-time model that can be used to simulate a variety of watershed problems, too suffers in its prediction due to imprecise definition of HRU. ArcSWAT, the GIS interface of SWAT, implemented algorithm in sub-watershed delineation may attribute in preventing to come up with an appropriate size of HRU. Compounding this matter, most of the observed hydrological parameters in the market are gridded. This proposed study demonstrates a square shaped sub-watershed delineation tool in SWAT required format, developed in GIS environment using Arc Object and Structural Query Language, to come up with an optimum size on HRU definition and to demonstrate the predictability of SWAT using square shaped sub-watershed network. Principle of Maximum Entropy (POME) and Principle of Maximum Information Preservation theories are applied to define the optimum HRU size while preserving the information hidden with in the SWAT input datasets at the maximum. Few watersheds/basins of hydrologically mixed nature are used to demonstrate the applicability of the algorithm.