Abstract:The seasonal rainfall and corresponding variations of groundwater status due to rainfall are important factors that can induce collapse,debris flow and landslide hazards at Ryukemitsu area,Kakoshima,Japan. The average annual precipitation is around 2 000 mm in the study area;and several collapse and debris hazards occurred due to the influence of groundwater,making a great damage to the surrounding roads and railways. Based on many years of observation data of rainfall and water level,the tank model of the study area has been established to provide a powerful data support for the monitoring and early warning systems.