Abstract
There is a freshwater lens which is stored in porous Pleistcene Ryukyu Limestone aquifer at Tsuken island in Okinawa prefecture. The volume of the freshwater lens were estimated approximately 97, 000m3 in this study.
In order to avoid the intrusion of saltwater during pumping, a radial well type intake facility with vertical pit (14m in depth and 3.5m in diameter) and four horizontal collector pipes (each 25m in length) was designed and constructed. After that the continuous pumping test during 31 days was proceeded.
As the result, amount of the freshwater yields by the intake facility are 7, 000m3 which correspond to 3.4 times larger than that of a vertical pipe well (150mm in diameter and 27m in length) where located close to the intake facility.
