Hong, WY; Park, MJ; Park, JY; Park, GA; Kim, SJ (2010). The spatial and temporal correlation analysis between MODIS NDVI and SWAT predicted soil moisture during forest NDVI increasing and decreasing periods. KSCE JOURNAL OF CIVIL ENGINEERING, 14(6), 931-939.
Soil moisture is an important hydrologic state variable to affect the plant and crop actual Evapotranspiration (ET), storage capacity for surface runoff and subsurface flow, and recharge to groundwater. The variation of soil moisture is highly dependent on the land surface condition and its vegetation vitality. Thus, this study is to identify the degree of how much the status of soil moisture can be elucidated by vegetation canopy. For this purpose, the MODIS (MOD erate resolution Imaging Spectroradiometer) NDVI (Normalized Difference Vegetation Index) was used for vegetation canopy and the corresponding soil moisture was prepared from the SWAT (Soil and Water Assessment Tool) model result respectively. For a 6,661.6 km(2) dam watershed, seven (2000-2006) years MODIS NDVIs were compared with the simulated soil moistures simulated from the model. Before the analysis, SWAT model was calibrated and verified at two locations (Chungjudam watershed outlet and Yeongwol water level gauging station) of the watershed using daily streamflow data of 7 years (2000-2006). The average determination of coefficient (R-2), Root Mean Square Error (RMSE) and Nash-Shutcliffe model Efficiency (NSE) for calibration period (2003-2006) at two stations were 0.89, 1.82 mm, and 0.89, and the R-2, RMSE and NSE for validation period were 0.76, 1.50 mm, and 0.72 respectively. The spatial correlation between SWAT soil moisture and MODIS NDVI were evaluated during the forest NDVI increasing and decreasing periods.