International Commission on B14 Irrigation and Drainage 1st Asian Regional Conference Seoul, 2001 REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM IN RUNOFF COEFFICIENT ESTIMATION FOR IRRIGATED REGIONS

Fast economic development and population growth has been the major impression in Taiwan for the past twenty years. However, the development has put pressure on the agriculture and overall hydrology of the nation. For example, peak runoff increases significantly in the urbanized area due to the increase of runoff coefficient, which was caused by the over-development of neighboring farmland, the construction of new houses, roads, factories, nursery and plastic-mulched farms. Furthermore, the drainage system has not been upgraded accordingly and, as a result, poor drainage and severe floods have occurred. A runoff and drainage estimation model should be developed. Major parameters in the model should include hourly rainfall (maximum hourly rainfall, daily rainfall, etc.), land use change, soil characteristics, irrigated area, and drainage facilities. The rainfall records in the weather stations can be used to model rainfall parameters at first. Later, real-time information from radar, lightning data and satellite cloud imagery can be used to model more reliable rainfall parameters. Soil characteristics can be derived from existing data. The land use/cover change and actual irrigation area, if based only on traditional gathering and analysis methods, will b