EFFECTS OF LAND-USE TYPES AND SPATIAL SCALES ON EVAPOTRANSPIRATION USING REMOTE SENSING TECHNIQUES

摘要

This study focused on the effect of la nd-use types and spat ialscales on the evapotranspiration (ET) using rem ote sensing techniques. The pro cesses included applying hybrid classification to generate a land-use m ap of northern Taiwan using Landsat-5 im age in 1995; using DTM and the SEBAL model to calcul ate the param eters re ferred to ET and to compare the differences a mong different land-use types; and assessing the effects of 2 spatial scales (i.e., northern Taiwan a nd 7 watersheds within norther n Taiwan) on ET using stepwise discriminated analysis. The result indicated that the area of northern Taiw an was classified into 7 land-use types (i.e., forest-land, building, farm-land, baring farm-land, water body, cloud, and shadow). The comparison of ET a mong different types showed that forest area had the highest value and then farm -land, water body, baring farm land, and building sequentially. As for the assessment of spatial scales on ET, the result pointed out that no matter which kind of spatial scales, the required parameters and the number of parameters for discriminating 5 land-use types (excluding cloud and shadow) were not the same , but NDVI and surface tern perarure were the most effective param eters. From above results, obviously E T varied wi th land-use types and spatial scales. Therefore, their effects on ET had to be considered in natural resource or water resource management.