Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Identification of unit hydrograph peak behavior according to changes in precipitation scale in a virtual watershed

가상 유역의 강수 규모 변화에 따른 단위유량도 첨두치의 거동 규명

  • Yoo, Ju-Hwan (Department of Drone Application, U1 University) ;
  • Kim, Joo-Cheol (International Water Resources Research Institute, Chungnam National University)
  • 유주환 (유원대학교 드론응용학과) ;
  • 김주철 (충남대학교 국제수자원연구소)
  • Received : 2023.07.31
  • Accepted : 2023.10.06
  • Published : 2023.10.31
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Abstract

In this study, unit hydrographs are calculated when precipitations of 10 scales instantaneously occurs in a virtual watershed with a constant slope and roughness. Then, the relationship between the peak flow rate and the peak occurrence time of the unit hydrograph was calculated for the precipitation scale, respectively. At this time, the virtual watershed simplified with a rhombic shape, a constant slope, and a flow condition with a certain roughness was applied instead of a natural watershed in order to understand the effect the precipitation scale has on the peak value of the unit hydrograph. And it was assumed that the precipitation in the basin was effective rainfall and the runoff was direct runoff, and the runoff flowed in a straight, uniform flow from the drop point to the outlet. The relationship between the peak flow and the peak occurrence time of the unit hydrograph was calculated in the case of 10 types of precipitation scales of 10 mm, 40 mm, 90 mm, 160 mm, 250 mm, 360 mm, 640 mm, 1,000 mm, 1,210 mm, and 1,690 mm of effective precipitation. A noteworthy achievement of this study is that, even without the storage effect of the watershed, as the scale of precipitation increases, the depth of runoff increases, so the flow rate in the watershed increases and the distance per unit time increases, so the peak flow rate increases and the peak occurrence time increases. This is a nonlinear characteristic of watershed runoff.

본 연구에서는 일정한 경사와 조도를 갖는 가상 유역에서 10가지 규모의 강수가 순간적으로 발생할 때 단위유량도를 산출하였다. 그런 다음 강수 규모에 대하여 단위유량도 첨두유량의 관계와 첨두발생시간의 관계를 각각 산출하였다. 이때 강수 규모만이 유역의 단위유량도 첨두치에 주는 영향을 파악하기 위해서 자연 유역을 대신하여 마름모 형태, 일정 경사, 일정 조도의 유로 환경 상태 등으로 단순화한 가상 유역을 적용하였다. 그리고 유역에 내린 강수는 유효우량이고 유출은 직접유출이고 낙하지점에서 출구 방향으로 직선적인 등류로 유출된다고 가정하였다. 강수 규모를 10가지로 유효강수 10 mm, 40 mm, 90 mm, 160 mm, 250 mm, 360 mm, 640 mm, 1,000 mm, 1,210 mm, 1,690 mm의 경우로 하여 단위유량도의 첨두유량과 첨두발생시간을 각각의 관계를 산출하였다. 본 연구에서 주목할 만한 성과는 유역의 저류 효과가 없어도 강수 규모가 커질수록 유출 깊이가 커져서 유역의 유속이 빨라지고 단위 시간당 유하 거리도 커지므로 첨두유량은 커지고 첨두발생시간은 빨라진다는 것이었다. 이는 유역 유출의 비선형적 특성이다.

Keywords

Acknowledgement

본 연구는 2017년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행한 이공학개인기초연구(2017R1D1A3B03035695) 및 2022년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업(NRF-2022R1I1A1A01056269)의 일환으로 수행되었음.

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