IMPLEMENTATION OF HIGH RESOLUTION SATELLTE IMAGES FOR AGRICULTURAL LANDUSES MAPPING AND PLANNING OF RETENTION POND IN THAILAND: YOM RIVER BASIN, SUKHOTHAI

摘要

The case study of Yom River Basin are located at Sukhothai province, where is coverage by 4,596 sq.km (square kilometers) which estimated to 99.7% of the provincial area. It estimate to only 26.9% of the whole area of the Yom Basin. The Yom River Basin is located in the lower northern region of Thailand with 23,616 sq.km or about 4.6% of the basin. Yom is a main river with the total length of 735 km and flow throughout the basin via several provinces including Sukhothai, it via Sukhothai 170 km. The mean annual rainfall of 1,195 mm and the river flow of 3,657 million cubic meters (MCM) was produced from the basin via Sukhothai were reported. However, there were not any large reservoirs in the upstream as in many large river basins yet. Therefore, flood problem caused by heavy rainfall and overflow from the Yom River in lately of rainy season at the floodplain area had occurred year-by-year. Efficiency flood management in Sukhothai Province was studied; the delineation of existing farmlands and flood extents with each return period of flood event should be carried out by using of existing aerial maps and satellite images. A case study in lowland floodplain of the lower Yom River Basin namely Thung-Thaleluang are located at Muang District in Sukhothai Province. The commanded area of 25 sq.km was chosen to study for flood extent and its impacts. The cases including before and after the construction of the retention pond were simulated by using hydrodynamic model. The application of IKONOS high resolution satellite images were used to identify agricultural farmlands mapping and flood delineation in 2005 in order to produce flood area and depth data as for the boundary and initial condition in floodplain model. The results from the model showed that flood depths will be reduced to 0.20-0.40 m from previous flood peak level. These prevent to flooding about 20% to the agricultural farmlands in Sukothai with shorter retention pond were done with the capacity of 32 million cubic meters combined to a diversion channel inundated period, if the construction of the by the discharge of 86,400 cubic meters per day.