Study on water infiltration characteristics in Gotjawal (forest on lava flow) wetland area

Gotjawal is forest that was formed by the lava flow along the slopes as a result of the volcanic activity of the parasite volcanoes which distributed over Jeju Island, the Republic of Korea. Since Gotjawal has very shallow soil layer and wetland in Gotjawal does not have water for a long time, infiltration characteristics are very important. Study wetland is 48m in diameter and 2.2m in depth and water level change with respect to time was measured in 2019. The results showed that annual rainfall in this area was measured to 2,748mm and 5 rainfall events with daily rainfall more than 100mm were recorded in 2019. When the wetland was full of water, the period of drainage was 12 days. Water level started to change when the rainfall was 43~70mm taking 10~15 hours and this seems to vary depending on the period of no rainfall. This result will be helpful for estimating groundwater sources in lava flows area and for developing conservation plan of Gotjawal.