The Influence of Remotely Sensed Leaf Area Index (LAI) on the Estimation of Evapotranspiration from SLURP Model

Abstract

Evapotranspiration (ET) is an important state variable while simulating daily streamflow in hydrological models. In the estimation of ET, for example, when using FAO Penman Monteith equation, the LAI (Leaf Area Index) value reflecting the conditions of vegetation generally affects considerably. Recently in evaluating the vegetation condition as a fixed quantity, the remotely sensed LAI from MODIS and NOAA satellite data is available, and the time series values of spatial LAI coupled with land use classes are utilized for ET evaluation. Four years (2001-2004) of MODIS LAI, MODIS NDVI and NOAA NDVI data were prepared for the evaluation of ET in the continuous hydrological model, SLURP (Semi-distributed Land Use-based Runoff Processes). The model was applied for simulating the dam inflow of Chungju watershed (6661.3 km2) located in the upstream of Han river basin of South Korea. For 4 years (2001-2004) dam inflow data, the model was calibrated and verified using MODIS LAI data. The average Nash-Sutcliffe model efficiency was 0.66. To identify the vegetation effect of two other cases (LAI from MODIS NDVI and LAI from NOAA NDVI), the model was run and the results were compared based on the MODIS LAI result.