Sustainable Reservoir Sediment Management

The terrain of Taiwan is steep with high mountains and short rivers. Due to the uneven spatial and temporal distribution of rainfall, droughts and floods have caused disasters in many areas. Therefore, water resources are collected through reservoir construction. However, during typhoons and heavy rains, floods brought a large amount of sediment into the reservoir area. Besides, traditional methods of reservoir sediment management did not consider sustainable use, which affected the normal operation and service life of the reservoir. Therefore, a sustainable sediment management strategy for the reservoir was required, to extend reservoir life.

To achieve sustainable use, the reservoir must adopt an appropriate sediment management strategy, and the need for water supply to the reservoir must also be taken into account during desilting. In addition to the operation of the reservoir itself, monitoring the amount of sediment and its discharge is also necessary. Therefore, with proper desilting operations, the reservoir can be used continuously while meeting the water supply requirements. At the same time, it is hoped that by understanding the erosion and deposition of sediment drainage in the downstream river channels, it will be included in the decision-making considerations to reduce the impact of desilting to downstream river channels.

We focused on Agongdian Reservoir in southern Taiwan, one of the few currently conducting sediment flushing operations and Techi Reservoir in central Taiwan, one of the Dajia River series hydropower plants. The objectives of our research are to understand the desilting efficiency of the current practices based on monitoring data and propose better operational strategies for future practices by water supply evaluation, numerical simulations and economic analyses to maximize the potential to preserve long-term capacity and inform decision making.

Multiple sediment management strategies (Morris, 2015)