序率串聯集塊降雨－逕流模式應用於石門水庫集水區之流量預測

本文旨在以石門水庫上游集水區之颱洪事件說明序率串聯集塊降雨－逕流模式之應用。首先根據地形地貌上之區隔及流量站控制範圍，將集水區分割爲兩個次流域，在每個次流域內之地表覆蓋及降雨分佈均假設爲均勻，而兩個次流域之間則不相同，並以串聯方式構成降雨－逕流之串聯集塊系統；每個次流域即爲一集塊系統，各有其降雨輸入及流量輸出，而一個次流域流量輸出亦可為另一個次流域之輸入。在降雨輸入部份，因為實際上降雨在空間的分佈並不是真正的均勻，加上氣象的擾動，使得降雨輸入並不真正符合理論上之假設，換言之，即有誤差存在；串聯集塊模式的特色，就是將流域複雜的氣象、水文及地文因子擾動所產生的序率性，代入模式中，求輸出流量第一階及第二階動差方程式，以模擬具有統計意義之輸出流量。模擬結果顯示，以第一階動差方程式模擬逕流歷線，在合適性的評估有尚佳之表現，而以第二階動差方程式對降雨擾動項變方之檢定，尚需改進。

關鍵字

集塊系統；序率性；合適性評估

並列摘要

To apply the stochastic series lumped model with typhoon events for predicting runoff in the upstream watershed of Shihmen Reservior is the subject of this paper. First, using the characteristic of topographic feature and the control area of the stream flow station as a guide, the area of the watershed is divided into two subwatersheds, each of which is assumed to be approximately uniform in terms of rainfall excess and geographic conditions. But, there exist the difference of the characteristic of topographic feature and the distribution of rainfall excess between two subwatersheds. Then the subwatersheds are interconnected according to the drainage pattern of the watershed in series. Each model subwatershed unit is composed of two elements: one for converting rainfall excess on the subwatershed area into outflow at the subwatershed outlet and the other is converted outflow of the subwatershed into inflow at another subwatershed inlet. The measurements of rainfall are regarded as input of rainfall-runoff model and the distribution of the measurements which are not uniform practically in the space. Furthermore, the meteorological perturbations that make the change of rainfall is not consistent with the assumption of theory. In other words, that have errors between the output of rainfall-runoff model and the realizations of runoff. The characteristic of the stochastic series lumped model is that contain the stochasticity of the meteorological perturbations and the change of the geographical condition, and substituted into the water balance differential equation then derive the first order and the second order momenent equations. The moment equations are used to simulating the runoff process with statistic properities. The results of simulation exhibit that the first order moment equation simulate the runoff process well by acceptable evalution, but the verification of the rainfall variance with the second order moment equation must be improved.

並列關鍵字

Lumped system ； Stochasticity ； Goodness-of-fit asscess

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