동화지구 설계 수문량 재추정

Abstract

The fundamental study of hydrologic redesign of Donghwa area located in a second tributary of Seomjin river was performed. The amounts of hydrologic design were estimated using the available cumulated hydrology data provided by Korea Agricultural and Rural Infrastructure Corporation (KARICO). The management status of the water resources in Donghwa area was also widely surveyed. The probability rainfalls, probable maximum precipitation (PMP) and probability floods were estimated and subsequently their changes analyzed. The amount of 200 year frequency rainfall with 1 day duration was 351.1 ㎜, 2.5 % increased from the original design value, and the PMP was 780.2 ㎜. The concentration time was reestimated as 2.5 hours from existing 2.4 hours. Soil Conservation Service (SCS) method was used to estimate effective rainfall. The runoff curve number was changed from 90 to 78, therefore the maximum potential retention was 71.6 ㎜, 154 % increased from the original value. The flood estimates using SCS unit hydrograph showed 8 % increase from original value 623 m3/s to 674 m3/s and the probable maximum flood was 1,637 m3/s. Although the flow rate at the dam site was increased, the flood risk at the downstream river was decreased by the flood control of the Donghwa dam.