The available dam sites are not easy to obtain in Taiwan. In recent year, the new reservoirs construction is more difficult to promote due to the public environment protection concept. In addition, most reservoirs are seriously sediment, affecting the water supply function. How to promote the construction of a new reservoir and the reservoir renewal activation for sustainable become the key issue.
The Tien-Hwa-Hu Reservoir and the Shuang-Xi Reservoir projects are under planning in recent years. There are some different problems when promoting both reservoir projects. The reservoir is one of the best storage way for water resources use. Considering the environmental impacts of the reservoir constructions, the publics protest, the lack of available dam sites and sedimentation problem of the reservoirs, we try to have a new planning thoughts. In order to reduce the risk of water shortage in high turbidity and the severity of reservoir sediment problems, the new reservoir will be planned to have by pass tunnel for desilting and different level intakes facilities.
Existing reservoir desilting renewal methods include Sediment Bypassing , Flood Sluicing, Turbid Current Venting/Turbid Water Releasing, etc. Now the renewal reservoirs including Shimen, Zengwen and Nanhua are planned to be operated by combined with the composite desilting method to enhance the desilting efficiency. All the renewal efforts just to maintain the reservoir normal operation and ensure the safety of life and property of the downstream people. Now, there are 13 reservoirs (such as Shimen, Zengwen, Nanhua, Wushantou, Agongdian, Mudan, Renyitan, Chengching Lake, Techi, Wushe, Sun Moon Lake, Mingde and Baihe reservoirs.) under dredging and desiling work since 2014. The implement of Sediment bypassing project in Taiwan reservoir is shown in Figure 1.
The renewal of existing reservoirs are not only reservoir heightening and desilting, but also considers the plan of building artificial lakes in middle and lower reaches of the reservoirs in the future in order to response to the risk of excessive turbidity. Nevertheless, we use smart water management technology to maintain and upgrade the facilities of the existing reservoirs to reach the stable water supply and flood control goal.
Figure.1 The Implement of Reservoirs Desilting Tunnel Project in Taiwan