南化水库于1994年开始蓄水营运，其原库容达1亿5 400万m3，为南部重要供水水源。为延缓南化水库淤积速率及提升水库因应气候变迁之防洪能力，经济部水利署南区水资源局正推动南化水库防淤隧道工程。南化水库防淤隧道工程利用底层之进水口吸取随着台风暴雨挟带进入水库坝前之异重流及浑水进行水力排砂，隧道进水口位于设计水位EL.180 m下45 m深之右坝，在营运中水库施作底层进水口困难度相当高。本计划之特殊性包括进水口施工(含水中围堰及水下施工作业)、大型高压闸门制造及安装、大规模地下洞室开挖等。在水库水位EL.180 m之设计流量为1 000 cms，年平均排砂比约24%，即年平均减淤量约72万m3。

When completed in 1994, the storage of Nanhwa Reservoir is 154 million m3. The reservoir is an important potable water supply source in southern Taiwan. The Southern Water Resources Bureau of Water Resources Agency, Ministry of Economic Affairs is undertaking the development of a sedimentsluice tunnel for Nanhwa Reservoir. The purpose of the project is to reduce rate of siltation in the reservoir and to increase flood discharge capacity in light of climate changes. In an operating reservoir, it is very difficult to construct the intake of a tunnel which is 45 m below the design water level in the right abutment for sediment sluicing during storms. Special features of this project include intake construction (including cofferdam an underwater work), fabrication and installation of high pressure large gates, and excavation of a large scale underground cavern. The project is designed to discharge 1 000 cms at reservoir level EL.180.0 m. It is estimated that an average annual silt sluicing of 72×105 m3 can be achieved, or about 24% of average annual sediment inflow.