Journal of Natural Disaster Science

SIMULATION ANALYSIS OF URBAN STORM DRAINAGE

Yoshiaki IWASA
Professor, Department of Civil Engineering, Kyoto University
Masato NOGUCHI
Associate Professor, Department of Civil Engineering, Nagasaki University
and
Takehiro NAKAMURA
Research Associate, Department of Civil Engineering, Nagasaki University

(Received 27 October, 1988 and revised form 2 February, 1989)

Abstract

Heavy rainfall may produce flush flows that result in severe damage to urban areas. In the past 30 years, such flooding has happened twice in Nagasaki Prefecture, at Isahaya in 1957 and at Nagasaki in 1982. The former flood was caused by a daily rainfall of 1,109 mm, and the latter by an hourly rainfall of 187 mm, records for the long-and short-period rainfall at that time. To avoid or mitigate flood disasters, well devised rescue and relief systems are needed in addition to projects to prevent flooding.

A simulation analysis of urban storm drainage that involves the interaction of river and overland flows is described to show in detail the behavior of flush flows. Because the model deals simultaneously with one and two-dimensional flows, the accuracy of the calculations for both is improved. We etsted this method of analysis by applying it to a real drainage basin. A comparison of our calculated results with those of other methods shows that the boundary condition markedly affects computation, especially in urban areas. Finally, we also show that the method of warning with inundation maps illustrated on a Cathode-Ray-Tube will be available for a refuge action of flood disaster.

Key words