토지이용변화에 따른 제주도 도심하천의 홍수유출 변동 분석

Abstract

For the Hancheon basin of Jeju island, flood soil outflow by change in land use and event of heavy rain were analyzed as 5-year cycle from 1980 to 2005, and the effects of the change in land use on flood outflow amount were examined. From 1980 to 2005, the urban area and agriculture cultivation area of Hancheon basin in Jeju island have increased 5 times, and 28% forest area has decreased. As a result of analyzing the outflow coefficient by utilizing land cover data and soil statistical data, averagely 2.2% outflow coefficient has increased in every 5-year cycle, particularly 11.6% in 2005 to 1980. Results of flood outflow change analysis in each heavy rain event with regard to the change in land use indicated that peak flowrate has increased 9.9 to 33.67%, while outflow total amount is 12.53 to 30.21%, and the arrival time of peak flowrate has decreased by 10 minutes in each heavy rain event. It was confirmed quantitatively that land use of Hancheon basin in Jeju Island switched from forest area to urban area and agriculture cultivation area, and the amount of flood outflow increased.