Land development changes runoff characteristics, and it usually makes floods larger. To deal with larger flood, flood control facilities must be constructed, when the river don't have capacity for larger discharge. One of flood control facilities is a storage facility of rainfall, retarding basin, and other is a infiltration facility of rainfall, drainaging to underground by infiltration.
The former reduces pea k discharge, but cannot reduce runoff volume. And covering large area isn't effective from the developing point of view.
The latter doesn't only reduce peak discharge for in f i ltration rate, but also reduces runoff volume and recharges groundwater. It makes effective land use possible because it is constructed under ground. But it isn't sure quantitative effect and its life.
Yatabe experimental field was established in Tsukuba Science City to study runoff changes due to development and to evaluate infiltration facilities. This is a report on evaluation of infiltration facilities.