Development of Watershed Rainfall-Runoff Model Based on the Partial Contributing Area Concept (III)

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Project title

Code/計畫編號

NSC92-2211-E019-012

Translated Name/計畫中文名

應用部分集水面積觀念建立集水區降雨逕流模式(III)

Project Coordinator/計畫主持人

Kwan-Tun Lee

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Harbor and River Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=827678

Year

2003

Start date/計畫起

01-08-2003

Expected Completion/計畫迄

31-07-2004

Bugetid/研究經費

503千元

ResearchField/研究領域

土木水利工程

傳統水文模擬方式將集水區內地表逕流與地表下逕流之水流運行機制視為相同，並假設在降雨逕流過程中，集水區內每一個位置點均有地表逕流產生，以直接逕流之概念進行集水區降雨逕流模擬。然而，由於地表下逕流為水體入滲至地面下後，經上層土壤流動至河川，其水流運行機制與地表逕流並不相同；並且在實際降雨逕流過程中，集水區內地表逕流往往僅發生於河川附近，地下水位較高且土壤水份達飽和之區域。因此，若以傳統方式進行集水區降雨逕流模擬，將因無法反應集水區內水流之真實流況，而造成逕流模擬之誤差。本研究應用地表逕流僅發生於部分集水面積之觀念，藉由地形指數模式推算部分集水面積分佈範圍，將集水區內水流之運行區分為地表逕流與地表下逕流兩種不同機制。研究中並應用運動波-地貌瞬時單位歷線模式與分佈式運動波逕流模式，以運動波理論配合曼寧公式與達西公式，分別模擬地表逕流與地表下逕流之運行，以推衍集水區降雨逕流關係，建立以部分集水面積觀念為基礎之半分佈式與全分佈式降雨逕流模式。本研究以臺灣北部大漢溪流域橫溪集水區與三峽集水區為模式應用集水區，藉由數值高程模式推求半分佈式模式與全分佈式模式中，所需之各項地文特性因子，並以實際颱洪事件進行逕流模擬分析。研究結果顯示，應用本研究所建立之降雨逕流模擬方式，不論尖峰流量或逕流歷線上升段與退水段之模擬，皆能得到良好的模擬結果。研究中並探討部分集水面積範圍對逕流推估之影響，以供水文工程師進行降雨逕流模擬之參考。 In conventional watershed rainfall-runoff modeling, the entire watershed was assumed to contribute overland flow to the main drainage network. However, field investigation showed that only the area near channel or those areas with high groundwater level contribute overland flow. Therefore, rainfall-runoff analysis based on conventional hydrologic concepts cannot adequately simulate field hydrologic phenomena. The discrepancy between the conventional simulation method and the field hydrologic phenomena results serious errors in further design work of water resources engineering. In this study, the partial contributing area (PCA) concept was employed. The influence factors of the PCA phenomena were investigated. The size of the PCA during storm was derived based on TOPMODEL theory and estimated by using a digital elevation model (DEM). The PCA concept was then combined with a kinematic-wave based geomorphic instantaneous unit hydrograph model (KW-GIUH) and a distributed kinematic-wave grid routing model (KW-G) for rainfall-runoff simulation. In the KW-GIUH and KWG runoff simulation considering the PCA concept, the surface runoff mechanism was simulated by Manning’s formula, and the subsurface runoff was approximated by Darcy’s law. The Heng-Chi watershed and San-Hsia watershed in northern Taiwan were used to demonstrate the capability of the proposed model. The required geomorphic factors of the distributed runoff model were obtained by using a DEM. Storm records were used to verify the model performance. The results showed that significant improvements were found in the simulation of the rising and recession limbs hydrographs. The ratios of the PCA in the study watersheds were detail discussed to provide information for hydrological engineers in practical applications.

Keyword(s)

部分集水面積
地形指數模式
運動波-地貌瞬時單位歷線模式
分佈式降雨逕流模式
運動波理論
達西公式
數值高程模式
Partial contributing area
TOPMODEL
KW-GIUH model
Distributed runoff model
kinematic-wave theory
Darcy’s law
Digital elevation model

DSpace CRIS

Development of Watershed Rainfall-Runoff Model Based on the Partial Contributing Area Concept (III)

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