Estimation of peak runoff impact from land use change using remote sensing and GIS in Keduang sub-watershed

Changes in land use in watersheds and climate change have a dominant influence on watershed hydrology. One of the important aspects of watershed hydrology related to land use change and climate change is runoff. Land use changes in the watershed area from non-built areas to built areas or vegetated areas to non-vegetated areas will increase runoff. Because vegetation helps absorb rainwater optimally into the soil. Thus, rainwater that falls to the ground will become more runoff. For this reason, it is necessary to conduct a study to determine the land use changes and impact on the runoff, as has been done in the Keduang sub-watershed, Wonogiri District, Indonesia. Land use change and peak runoff were estimated using remote sensing and Geographic Information System (GIS). Remotely sensed images from the Landsat satellites were used to develop land use maps of the study area in 2009 and 2020. The peak runoff was computed by the Rational Method. The land use map between 2009 and 2020 shows an increase in built areas and dryland agriculture and a decrease in the vegetated area such as a forest and mix garden. The impact of land use change increases the coefficient runoff value in the study area from 0.22 to 0.24. The results showed that peak runoff for 2009 was 358.73 m³/s and in 2020 was 363.38 m³/s there is an increase of 4.66 m³/s.