土器川流域の土地被覆の変遷と流出の経年変化

抄録

Land cover change and discharge fluctuation for the past 12 years in the Doki River catchmentwere examined using multi-temporal satellite data. This catchment is composed of mainly forest andsome agricultural fields along the streams, the ratio of which is more than 10% of the total area. Usingthe multi-temporal satellite data, Landsat TM, in 1986 and 1990, approximately 3% of the total area hadchanged from forest to the agricultural fields during this period. From the water budget from 1981 to1992 in the catchment, evapotranspiration decreased and runoff ratio increased. Short-term waterbudget led to monthly evapotranspiration before and after 1986, which showed the evapotranspiration in April and October decreased. Such change means agricultural activities, seeding and harvest. Moreover, statistical tests for hydrological data before and after 1986 showed that runoff ratio increasedsignificantly with its significant level of 0.05. Therefore, one of the factors that caused the increase ofrunoff ratio in the catchment should be the land cover change from forest to agricultural fields.