摘要
The impact of large scale land use changes such as afforestation on the hydrological system behaviour of river basins is of major interest to water resources managers. Particularly in semi-arid areas, where water is strongly limited, the continuous assessment and monitoring of the hydrological system components are necessary. Their analysis and prognostic hydrological modelling requires both the determination of updated land use patterns and an estimation of their spatial dynamics over time. In this study optical remote sensing data were used in order to provide such hydrological model input parameters at different scales. Therefore, Landsat TM data from 1995 to 1999 have been utilized for various scale depended land use maps within the semi-arid Umzimvubu catchment, South Africa. The classification results were compared due to the temporal changes as a consequence thereof the afforestation. Based on an complex accuracy estimation during all processing steps, significant changes of the land use patterns could be quantified. In addition, the Leaf Area Index (LAI) distribution has been calculated for the Mooi river subcatchment based on the transformation of the normalized difference vegetation index derived from Landsat TM data to LAI utilizing an empiric equation.