Author(s): Koichiro Ohgushi; Yoshiaki Tsuruta; Hiroyuki Araki
Linked Author(s): Koichiro Ohgushi
Keywords: Runoff; Pollutant load; GIS; Ariake Sea; Non-irrigation period
Abstract: This study is aimed to build a runoff and pollutant load model of the Ariake Sea catchment area using GIS. The runoff of the main rivers flowing into the Ariake Sea is analyzed by tank model and GIS. The pollutant load model for these rivers is obtained by using relationships between pollutant load and river discharge through field investigations. As water qualities'indices of the pollutant, such as COD, TN, TP are considered as well as some other nutrients indices. Because the Ariake Sea has the most tidal range in Japan, wide area of coastal zones are affected by tide. In order to estimate the runoff and pollutant load from this area which is affected by the tide, additional field investigations in the east Saga Plain are executed with classification of existing data by GIS. A long term change of a relationship between the pollutant load and the river discharge is also considered. By GIS classification of the river basin, a good runoff and pollutant model to reappear hydrological phenomena are obtained. By estimating the unit load appropriately, point and non-point pollutant loads to the bay are estimated successfully.