서서귀수역 동부지역 하천의 홍수량 및 토사유출량 산정

Abstract

Recent weather changes are resulting in increased damages from heavy rains and typhoons. Downstream regions of rivers, where flood and soil erosion are especially concentrated, are causing reduction in flood arrival and increase in peak runoff due to urbanization. Accordingly, it is necessary to estimate or analyze causes of disasters, to compute runoff of rivers in accordance to meteorological and topographical characteristics, and to establish measures to reduce such disasters. In this study, Hoesu stream, Daepo stream, Donghoesu stream, Icheonjangmul, and Golse were selected among rivers of West Seogui in Jeju Province based on rivers shown in national base map. Weather and geographic data on these rivers were collected and analyzed to compute appropriate flood runoff and sediment. Probability of precipitation for target regions was computed using daily precipitation data between 1974 and 2008. Geographical data and effective precipitation were computed with consideration on DEM data, land coverage, and land usage. When computing flood runoff, six methods were compared and the result obtained using Clark unit hydrograph and rational formula was selected. Soil runoff was deduced using RUSLE method. As a result of study, flood runoff of 14~16.3 ㎥/sec (frequency for 30 years) for two sub-rivers and 43~91 ㎥/sec (frequency for 50~80 years) for four local rivers. Soil runoff was 122~36,589 ㎥/storm (frequency for 100 years) on average. Such study results can be used as basic data to provide directivity for appropriate response to damages from river disasters. Future studies are deemed necessary on comparison and analysis using actual measurements instead of past data.