2003 Volume 16 Issue 6 Pages 631-639
The groundwater in the Kanto Loam Formation, Tokyo, was influenced the peripheral topography, structures on soil surface, and geological features. It was shown that groundwater conservation system was different by the number of precipitation. Results were follows.
The Kanto Loam Formations includes fine/macro pores with much quantity. In this soil layer, water permeability of rainwater was high. The change of annual groundwater level was low in February of the winter season. It tended to become high during the rainy season with the typhoon and the summer season. The appearance time of minimum/maximum groundwater level was similar, too. There was a property in characteristics of increase/decrease of groundwater level. Then, a method was suggested to estimate groundwater level by precipitation and soil characteristic. A change of rise speed of groundwater level was explained that the precipitation supported soil macropore and the falling speed of groundwater level supported a quantity of evapotranspiration. An annual change of groundwater level was examined and the sign of groundwater level suddenly decreased was not appear. The function of groundwater conservation was maintained constantly. Sudden groundwater level decrease after rain stop. Then it was estimated that groundwater outflow occurred from the groundwater maintenance district to the peripheral non-maintenance district. This investigation district has the soil physical properties to include a characteristic of the Kanto Loam Formations and urban precious groundwater is kept in good condition. These superior conditions must be maintained continuously.
