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Sensitivity Analysis of Flood Runoff Models according to Watershed Characteristics and Project types in Disaster Impact Assessment

재해영향평가 개발사업과 유역 특성별 홍수유출량 산정 모델의 민감도 분석에 관한 연구

Changjae Kwak1
,
Kwangjin Jang1
,
Jungsoo Kim2*
곽 창재1
,
장 광진1
,
김 정수2*
1Research Officer, National Disaster Management Research Institute, UIsan 44538, Korea
2Associate Professor, Department of Civil Engineering, Bucheon University, Buchoen 14632, Korea
1국립재난안전연구원 방재안전연구사
2부천대학교 부교수
*Corresponding Author
30 September 2026. pp. 147-168
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Abstract

This study aims to propose an optimal flood runoff calculation method tailored to the geometric characteristics and types of development projects, addressing the limitations of current standards in Disaster Impact Assessment (DIA). Based on 63 years (1961–2023) of hourly rainfall data from the Ulsan Meteorological Station and a 50-year return period rainfall, a sensitivity analysis of key parameters (basin area, shape factor, and channel slope) was conducted across 300 virtual watershed conditions and actual project sites (land development, road construction, and quarry/mountainous development) using four runoff models: the Clark unit hydrograph, Time-Area, Rational Formula, and NRCS unit hydrograph methods. The results revealed that the NRCS method exhibited extremely low parameter sensitivity, while the Time-Area method showed inconsistent trends. The Clark method was sensitive to basin area changes but lacked sensitivity above certain shape factors. Conversely, the Rational Formula displayed the most stable and consistent sensitivity across all parameter variations. In actual project applications, the Rational Formula best reflected structural changes caused by road and mountain developments. However, since the Rational Formula only estimates peak flows and cannot generate hydrographs required for flood retention storage design, this study highlights the necessity of developing a modified rational formula or a specialized runoff model optimized for DIA projects.

Keywords
Clark unit hydrograph
Development project types
Disaster impact assessment
Flood runoff
Rational formula
Sensitivity analysis

본 연구는 재해영향평가 협의 시 적용되는 홍수유출량 산정방법의 현행 한계를 극복하고, 개발사업의 유역 특성 및 사업 유형에 적합한 유출모형의 채택 방안을 제안하고자 수행되었다. 울산관측소의 63개년(1961~2023년) 시우량 자료와 50년 빈도 확률강우량을 바탕으로, 가상유역 300개 모의 조건과 실제 개발사업(택지개발, 도로, 산지개발) 사례에 적용하여 4가지 주요 유출모형(Clark 단위도법, 시간-면적법, 합리식, NRCS 단위도법)의 매개변수(유역면적, 형상계수, 유로경사) 민감도를 비교 분석하였다. 분석 결과, NRCS 모형은 매개변수 변화에 대한 민감도가 매우 낮았고, 시간-면적법은 매개변수 변화에 따른 일정한 경향성을 보이지 않았다. Clark 단위도법은 면적 변화에는 민감하나 특정 형상계수 이상에서는 민감도가 소실되는 한계를 나타냈다. 반면, 합리식은 면적, 형상, 경사 변화 모두에서 가장 일정하고 안정적인 민감도를 나타냈다. 실제 사업 유형별 적용에서도 도로 및 산지개발과 같이 형상계수나 경사 변화가 지배적인 경우 합리식만이 유역 특성 변화를 충실히 반영하였다. 다만 합리식은 수문곡선 및 저류지 용량 산정에 한계가 있으므로, 향후 개발사업의 지형·공학적 특성을 반영할 수 있는 수정합리식 도입 또는 재해영향평가 전용 홍수유출 모형 개발이 필요함을 제안한다.

키워드
Clark 단위도법
사업 유형
재해영향평가
홍수유출량
합리식
민감도 분석
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Information
  • Publisher :Korean Society of Ecology and Infrastructure Engineering
  • Publisher(Ko) :응용생태공학회
  • Journal Title :Ecology and Resilient Infrastructure
  • Journal Title(Ko) :응용생태공학회 논문집
  • Volume : 13
  • No :3
  • Pages :147-168
  • Received Date : 2026-07-31
  • Revised Date : 2026-08-14
  • Accepted Date : 2026-08-14
  • DOI :https://doi.org/10.17820/eri.2026.13.3.147
Journal Informaiton Ecology and Resilient Infrastructure Ecology and Resilient Infrastructure
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