GIS-Based Design Flood Estimation of Ungauged Watershed

논문 - GIS기반의 미계측 유역 설계홍수량 산정

  • 홍성민 (건국대학교 사회환경시스템공학과) ;
  • 정인균 (건국대학교 사회환경시스템공학과) ;
  • 박종윤 (건국대학교 사회환경시스템공학과) ;
  • 이미선 (건국대학교 지역건설환경공학과) ;
  • 김성준 (건국대학교 사회환경시스템공학과)
  • Published : 2011.12.30

Abstract

This study is to delineate the watershed hydrological parameters such as area, slope, rain gauge weight, NRCS-CN and time of concentration (Tc) by using the Geographic Information Sytem (GIS) technique, and estimation of design flood for an ungauged watershed. Especially, we attempted to determine the Tc of ungauged watershed and develop simple program using the cell-based algorithm to calculates upstream or downstream flow time along a flow path for each cell. For a $19km^2$ watershed of tributary of Nakdong river (Seupmoon), the parameters including flow direction, flow accumulation, watershed boundary, stream network and Tc map were extracted from 30m Agreeburn DEM (Digital Elevation Model) and landcover map. And NRCS-CN was extracted from 30m landcover map and soil map. Design rainfall estimation for two rainfall gauge which are Sunsan and Jangcheon using FARD2006 that developed by National Institute for Disaster Prevention (NIDP). Using the parameters as input data of HEC-l model, the design flood was estimated by applying Clark unit hydrograph method. The results showed that the design flood of 50 year frequency of this study was $8m^3/sec$ less than that of the previous fundamental plan in 1994. The value difference came from the different application of watershed parameter, different rainfall distribution (Huff quartile vs. Mononobe) and critical durations. We could infer that the GIS-based parameter preparation is more reasonable than the previous hand-made extraction of watershed parameters.

Keywords

Acknowledgement

Grant : 자연 하안 창출 및 하안변화 유도기술개발

Supported by : 환경부