GSSHA 모형을 활용한 미계측 유역 홍수량 산정과 임진강 하류 수리학적 홍수추적 = Hydraulic Routing in Imjin Catchment and Estimating Flood including Ungaged Basin Using GSSHA Model

국문 초록 (Abstract)

최근 우리나라는 기후변화의 영향으로 여름철 집중호우로 인한 홍수규모와 빈도가 점차 증가하고 있는 추세로 침수피해를 예측하고, 대비하는 것은 매우 중요하다. 특히, 임진강은 약 66.7%가 북한에 포함되어있는 유역으로 관리하지 못하는 특수한 상황으로 과거에도 예고 없는 무단 방류로 인해 하류에 큰 피해가 발생한 사례가 다수 있고, 최근 2020년 8월에는 기왕최대강수량이 발생하여 유역 하류부에 큰 홍수가 발생하는 등 치수적인 관점에서 예측과 대비에 대한 불확실성이 크다.
이에 본 연구에서는 북측을 포함한 임진강 전체 유역을 대상으로 기존 확률강우량 산정 방법의 한계점과 개선사항을 분석하여 WMO에서 GTS를 통해 12시간 누적 자료로 제공하는 북측 관측소를 대상으로 시간 자료로 분포시키는 방법을 제시하고, 이를 적용하여 강우 빈도 해석을 실시하였다. 산정된 강우 자료를 바탕으로 분포형 강우-유출 모형인 GSSHA를 활용하여 100년 빈도와 기왕최대홍수량을 비교·검토 하였으며, 2차원 수치 모형인 HEC-RAS 2차원 모형에 미국지질조사국(USGS)의 댐 붕괴기준을 적용시켜 최대 유입 홍수량을 산정하였다. 마지막으로 HEC-RAS 1차원 부정류 모의를 통해 주요지점 댐 붕괴 시나리오에 따른 하류부 홍수위 분석을 실시하였고, 2차원 모의를 통해 침수해석을 실시하였다.
분석결과, 황강댐과 봉래댐, 황강댐 동시 붕괴 조건에서 군남홍수조절지에서 홍수도달시간을 1~4시간 늦출 수 있지만 제방고를 범람하여 임진강 유역에 홍수가 발생하는 것으로 분석되었다. 또한 홍수범람모의 결과, 비룡대교 수위관측소 하류지점부터 한강 합류지점까지 지류인 문산천을 범람하여 파주 도심지역과 사천 상류 지역인 개성공업지구까지 침수피해가 발생하는 것으로 분석되었다.
본 연구에서 제시한 임진강 유역 확률강우량 산정 방법을 적용하고, 분포형 강우-유출 모형인 GSSHA를 활용한다면 미계측 유역에서 정확한 확률홍수량을 산정할 수 있을 것이고, 주요 지점 홍수위 분석과 침수해석을 통해 하천 주요지점의 적절한 치수관리에 기여할 수 있을 것으로 판단된다.

목차 (Table of Contents)

• 제 1 장 서 론 ·················································································································1
• 1.1 연구 목적 ·············································································································1
• 1.2 연구 동향 ·············································································································2
• 1.2.1 남북 공유하천 및 임진강 유역에 관한 연구 ··········································2
• 1.2.2 확률강우량 및 극한 홍수량 추정에 관한 연구 ······································3
• 1.2.3 댐 붕괴파 해석 및 하류부 홍수추적 ························································4
• 1.3 연구 방법 ·············································································································5
• 제 2 장 확률강우량 산정 이론 ···················································································7
• 2.1 지역빈도해석 이론 ·····························································································7
• 2.1.1 지역빈도해석 절차 ························································································7
• 2.1.2 적용 확률분포형 ····························································································8
• 2.1.3 지역구분 방법 ·····························································································15
• 2.2 기존 확률강우량 산정 방법 ···········································································16
• 2.2.1 강우분석 ·······································································································16
• 2.2.2 확률강우량 산정 및 강우강도식 유도 ···················································19
• 2.2.3 강우의 시간분포 ·························································································25
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• 제 3 장 적용유역 현황 및 확률강우량 산정 ························································27
• 3.1 적용 유역 및 하천현황 ···················································································27
• 3.2 강우관측소 및 수리구조물 현황 ···································································32
• 3.2.1 유역 내 기상 및 강우관측소 현황 ·························································32
• 3.2.2 남·북측 수리구조물 제원 및 댐 운영현황 ·········································34
• 3.3 확률강우량 산정 및 검증 ···············································································37
• 3.3.1 강우관측소 선정 ·························································································37
• 3.3.2 확률강우량 산정방법 개선 및 적용 ·······················································39
• 제 4 장 미계측유역의 홍수량 산정을 위한 강우-유출 모형의 구축 ·············53
• 4.1 강우-유출 모형별 특성 ·················································································53
• 4.2 모형의 개요 ·······································································································56
• 4.3 모형의 구축 ·······································································································66
• 4.3.1 모형의 입력자료 ·························································································66
• 4.3.2 모형의 구축 ·································································································67
• 4.4 모형의 검정 ·······································································································76
• 4.5 확률홍수량 산정 ·······························································································82
• 4.6 홍수량 산정 결과 및 고찰 ·············································································86
• 제 5 장 북측 댐을 고려한 임진강 유역 홍수량 산정 ········································87
• 5.1 모형의 개요 ·······································································································87
• 5.2 모형의 구축 ·······································································································88
• 5.2.1 지형자료 구축 ·····························································································88
• 5.2.2 경계 조건 및 댐 운영자료 입력 ·····························································92
• 5.2.3 모의 결과 및 검증 ·····················································································94
• 5.3 황강댐·봉래댐 댐 붕괴 홍수량 산정 ·························································99
• 5.3.1 북측 댐 붕괴 모의 조건 ···········································································99
• 5.3.2 모의 시나리오 설정 ·················································································102
• 5.3.3 시나리오 모의 결과 ·················································································103
• 5.4 댐붕괴를 고려한 홍수량 산정 결과 및 고찰 ··········································115
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• 제 6 장 군남홍수조절지 하류부 수리학적 홍수특성 분석 ······························117
• 6.1 모형의 이론 ····································································································117
• 6.2 모형의 구축 ····································································································118
• 6.2.1 지형자료의 구축 ·······················································································119
• 6.2.2 자료의 검·보정 ·······················································································120
• 6.3 부정류 해석에 의한 하류부 홍수위 검토 ················································123
• 6.3.1 100년 빈도 홍수 조건 ···········································································125
• 6.3.2 기왕최대 홍수 조건 ·················································································135
• 6.4 HEC-RAS 2D에 의한 하류부 침수분석 ················································145
• 6.5 하류부 홍수특성 분석 결과 및 고찰 ························································157
• 제 7 장 결 론 ············································································································159
• 참 고 문 헌 ············································································································ 161
• ABSTRACT ············································································································ 171
• 감 사 의 글 ············································································································ 173