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Development and Application of L-THIA 2009 System for Accurate Direct Runoff Estimation in Doam-dam Watershed

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010  1000012.(doi:10.13031/2013.29601)
Authors:   Jonggun - Kim, Bernie A Engel, Won-Seok Jang, Younshik Park, Junho Park, Dongseok Shin, Seong Joon Kim, Kyoung Jae Lim
Keywords:   CN2s, Direct runoff, HRU, Land use change, L-THIA 2009 system

The Long-Term Hydrologic Impact Assessment (L-THIA) model has been widely used in estimating the long-term impacts of land use change because of its ease-of-use interface. However, the current L-THIA 2.3 is developed in the ArcView 3.x platform. Thus, there have been requests for enhanced version in ArcGIS platform because of computer processing capacity and model execution time. Also, the current L-THIA 2.3 calculates CN values based on average field slope for the whole watershed to estimate direct runoff. However, when it is applied to steep mountainous areas, the CN values should be adjusted based on subdivided field slope. For these reasons, the ArcGIS-based L-THIA 2009 system was developed for ease and accurate evaluation of the L-THIA performance in this study. This enhanced system was applied to Doam-dam watershed to evaluate the accuracy of the estimated direct runoff, considering CN2s value based on slope of each HRU. As shown in the results, it is strongly recommended the CN2s values should be adjusted based on slope of each HRU, especially in steep sloping watershed. The enhanced L-THIA 2009 system has been proven as an efficient tool for various land use change studies because of it ease-of-use interface in ArcGIS platform and built-in base-flow separation module for direct runoff comparison.

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