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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #322127
Title: Impact of DEM and soils on topographic index, as used in TopoSWAT

Author
item Collick, Amy
item Veith, Tameria - Tamie
item WELD, JENNIFER - Pennsylvania State University
item LAMBA, JASMEET - Pennsylvania State University
item FUKA, DANIEL - Pennsylvania State University
item BEEGLE, DOUGLAS - Pennsylvania State University
item Kleinman, Peter
item EASTON, ZACHARY - Virginia Polytechnic Institution & State University

Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Abstract Only
Publication Acceptance Date: 4/23/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: A topographic index (TI), comprised of slope and upstream contributing area, is used in TopoSWAT to help account for variable source runoff and soil moisture. The level of precision in the GIS input data layers can substantially impact the calculations of the topographic index layer and affect the ability to correctly analyze the subsequent hydrological and water quality results from TopoSWAT. This sensitivity is seen especially in the small watersheds and landscapes of Northeastern US where GIS input layers are seldom publicly available at finer resolutions than the spatial units of interest (e.g., field or hillslope). In this study, DEMs from the National Elevation Dataset (NED), which has a resolution of 1/3 arcsecond (roughly 10m), were compared against 10-m DEMs that were resampled from 1-m LiDAR data to assess differences in the resulting TI layers. Similarly, modified FAO and SSURGO soils were distributed spatially across TI classes and the corresponding characteristics were compared. A better understanding of the sensitivity of the TI to input resolution is necessary to improve the modeling predictions of hydrological movement, and together with a more precise association with soil characteristics, the relation to the transport of nutrients.