市街地域の雨水流出特性

Abstract

In this paper, runoff characteristics in an urban area are discussed on the basis of observeddata in the Tenjin Basin. Outline of the results are as follows:It seems that there exists a functional relation between peak diseherge, Qp, of flood runoff andits concentration time, tpc, such as tpc ∽ Qp-c ∽ re-c in which r, means the effective rainfallintensity and c constant. This suggests to us of usefulloess of the kinematic wave method for theurban runoff analysis, and the value of c must be near to but smaller than 0.4, generally. Theweight of river channel on concentration time is regarded as 10～20% in a mountain river, but theone is 50～60% in the Tenjin Basin.Runoff percent for heavy rainstormes is almost 100% and the peak runoff coefficient 0.7～1.0.In the Tenjin Basin. The value of equivalent roughness, N(m-1/3. Sec), defind in the kinematicwave method for slope surface, seems to be 0.01 in the detail model, and 0.004-0.006 in the roughmodel for the basin.