Soil-Temperature Survey and Ground-Water Prospecting in a Crystalline-Schist Landslide

Abstract

An underground-temperature survey was carried out in summer time and a ground-water prospecting was carried out after a typhoon in a crystalline-schist landslide. Drainage drillings were executed towards lower-temperature zones inferred from the underground-temperature survey. During a typhoon in the next year, the drainage flow rate was 40-720 1/min, which rate was from 4 to 50 times as great as that of low-water flow. At the period of the rain, the ground-water level decreased from one meter to nine meters. The lower temperature zones seem to be caused by high ground-water velocity, while the higher temperature zones by low ground-water velocity. But there was a high temperature spot, where ground water flowed rapidly. The velocity ranged between several cm/sec and 100cm/sec. The intermittent ground-water flow is suggested at two points in the landslide area.