Hydraulic analysis of overland flow

Abstract

Because of the urban development, surface roughness and permeability decrease. This phenomenon leads to the decrease in time of concentration and the increase in surface runoff, and also make the frequency and scale of floods in downstream areas increase. For this reason, the prediction of change of the overland flow due to rainfall has become an important issue. In this study, the diffusion wave model is used to carry out the hydraulic analysis on a mild slope. The generalized integral transformation technique is employed in the model. The results are compared with previous research, and acceptable. In this study, the overland flow under different rainfall intensities is simulated with consideration of the effect of infiltration. Considering natural soil and pervious pavement makes the results more realistic. It is hoped to achieve the purpose of disaster prevention and control.

由於都市開發減少地表的粗糙度與滲透率，造成集流時間減少且逕流量增加，進而使下游 地區洪水發生的頻率與規模增加，所以預測降雨造成漫地流流況的變化成為一項重要的課題。 本研究以擴散波模式對地表較緩之坡面進行水理分析，採用廣義積分轉換法進行解析，並與前 人研究所得之結果作比較，藉此模擬出不同降雨強度下產生之漫地流。接著，將入滲所造成之 影響納入考量，以自然土壤及透水性鋪面為案例進行模擬，使所得結果較符合實際現象，期望 能達到災害防治的目的。