Submitted to: Federal Interagency Hydrologic Modeling Conference
Publication Type: Abstract only
Publication Acceptance Date: 4/19/1997
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Accurate prediction of soil water intake and storm runoff is essential in any hydrologic modeling. Factors affecting infiltration rate such as soil surface sealing, macropores, and vegetal cover need to be considered while modeling soil water intake. Darcian soil water flow that treats the soil as a homogeneous medium may not adequately describe infiltration and soil water redistribution in the presence of macropores such as shrinkage cracks. During the 1995 growing season, shrinkage crack patterns, area, and distribution, of a corn field located at the Purdue Agronomy farm with no-till, ridge, chisel and conventional tillages were studied. A relationship between percentage area cracked and soil moisture for each tillage practice was developed. The findings were incorporated into the WEPP computer model. Although the WEPP model hydrology component simulates the effects of vegetal cover, frozen soil and surface sealing while adjusting the saturated hydraulic conductivity for soil surface conditions, the model does not simulate the effect of shrinkage cracks on infiltration. Therefore, the model was modified to simulate development of shrinkage cracks after a tillage practice and flow of water into the cracks. Hydrometeorological, soil, topography, and vegetation data from a pasture and a row-cropped watershed with highly shrinkage cracked Vertisol were used to test the WEPP hydrology component with and without a crack flow routine. The results indicate that the addition of a crack flow routine improved the ability of the model to predict storm runoff on watersheds with Vertisols, near Riesel, Texas.