Beneath the groundwater-rich Pingtung Plain there is an underground "water corridor" known as "Twin Peak Ditch" built during the Japanese occupation. For more than 80 years groundwater has been extracted using this "underground weir" and it has continuously provided water for local irrigation. Its yearly average output of almost 30 million tons is more than that of Tainan's Paiho Reservoir.
地下水豐沛的屏東平原就有一座日據時代興建的「二峰圳」，八十多年來一直以「地下堰」方式取用地下水，持續供應當地農業灌溉，平均一年出水量近三千萬噸，比台南縣的白河水庫供應量還大。