在日本冲绳县那霸市南约300km的宫古岛上,世界最大的地下水库——砂川水库已开始正式施工。砂川地下水库截水墙(坝)长835m,墙高49m(最大施工深度65m),总库容950万m~3,其中有效库容680m~3。目前在进行第一期工程的施工,从去年9月开始在右岸60m长的地段建造面积约4000m~2的截水墙。 On the Miyako Island, about 300 km south of Naha, Okinawa, Japan, the world’s largest underground reservoir, the Xichuan River reservoir, has started construction. The dam of the Xuanchuan underground reservoir is 835m long and 49m high (maximum construction depth is 65m) with a total storage capacity of 9.5 million m 3, of which the effective storage capacity is 680 m 3. Construction of the first phase of the project is currently under way. From September last year, a cutoff wall of about 4,000m 2 in area has been constructed on the right bank of 60m.