新住宅地の不浸透面率

Abstract

It is important to estimate impermeable coverage in a residential district in order to predictthe effect of urbanization on flood runoff, but we can hardly know the coverage without long spellsof and laborious investigation.A simple formula is proposed in this paper for estimating the impermeable coverage in aresidential district. The formula is composed of three terms such as the coverage in housinglots, the coverage by roads and the coverage in other lands, but the last one is negligible in manycases. The impermeable coverage in housing lots, which is the most important factor, is closelyrelated to the density of housing lots, but may be estimated considering the land use classificationwith slight loss of the accuracy. By the use of the formula, the impermeable coverage is able to beestimated in future, too.