逕流運行時間分佈對運動波－地貌瞬時單位歷線影響之初步研究

晚近所發展之地形性逕流模式，能有效地反應集水區地文因子對水文歷線的影響。此類地形性水文模式中較完備者，則爲運動波－地貌瞬時單位歷線模式。該模式可經由水力學觀點配合集水區河川網路特性，推衍時變性與非線性之水文反應函數，且已漸成爲目前集水區逕流模式之主流。然而，模式中有關逕流運行時間分佈之假設，前人研究未有一致定論，致使模式之參數無法適切地反應集水區之物理意義。本文之目的即在於探討不同逕流運行時間分佈，對運動波－地貌瞬時單位歷線之影響。本研究將集水區中漫地流與渠流階段逕流運行時間，分別假設爲指數分佈、均匀分佈以及此二分佈的褶合分佈，並利用一假想之試驗集水區，進行不同逕流運行時間分佈之數值試驗。研究結果發現，運動波－地貌瞬時單位歷線形狀與尖峰到達時刻主要由漫地流逕流運行時間分佈所掌控，而漫地流與渠流逕流運行時間分佈則共同影響歷線尖峰流量。研究中進一步探討不同地文因子與降雨條件情況下，利用不同逕流運行時間分佈所推求得之運動波－地貌瞬時單位歷線的差異，並進行參數之敏感度分析。

關鍵字

運動波－地貌瞬時單位歷線；逕流運行時間分佈

並列摘要

The recently developed kinematic-wave based geomorphic instantaneous unit hydrograph model (abbreviated as KW-GIUH) is a time-variant and nonlinear runoff model based on watershed geomorphology and hydraulics. In this model, runoff travel times in overland-flow and channel-flow states were assumed to be different probability distributions, and the mean value of the travel time distributions were estimated using kinematic-wave approximation. Although various travel time distributions were proposed by previous researchers, the adequate distribution in the KW-GIUH was not definitely ratified. Therefore, it may raise a question that if the values of the calibrated model parameters, the overland and the channel roughness coefficients, can well represent the physical phenomena of the watershed. The objective of this study is to investigate the influences of different runoff travel time distributions on the KW-GIUH model. The overland-flow and the channel-flow runoff travel time distributions were assumed to an exponential, a uniform, or the convolution of an exponential and a uniform distribution, respectively. Numerical tests were conducted on a conceptual watershed. The results show that the shape and the time to peak of the IUH are dominated by the overland-flow travel time distribution; on the other hand, both of the overland-flow and the channel-flow travel time distributions affect IUH peak. Furthermore, sensitivity analyses for watershed geometry, rainfall intensity, and roughness coefficients were conducted. The results can provide useful information while applying the KW-GIUH model in ungauged watersheds.

並列關鍵字

Kinematic-wave based GIUH ； Runoff travel time distribution

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