Abstract
This paper aims to investigate the relations among reservoir sedimentation, rainfall and deforested area in the Omaru River watershed. For this purpose, land-covers of four dams in the Omaru River watershed are classified by using Landsat Thematic Mapper images in 1989-2004 and deforested areas are estimated by Geographic Information System. The relations are analyzed by using statistical regression approaches.
The remote sensing image analyses reveal that the deforested areas of the Dogawa Dam and Matsuo Dam catchment areas are increasing from 1989. Simple regression analyses show that the sedimentations in both dams have positive correlations with the deforested areas. And the results of multiple regression reveal that the deforestations significantly affect the amounts of the sedimentation. These results suggest that the control of deforested area is required in order to reduce the sedimentation in this watershed.
