Sedimentation Processes Following the Construction of Waterway Tunnels in Sun Moon Lake, Taiwan

Abstract

Lake bottom topography and sedimentation rate measurements were used to study sedimentation processes following construction of artificial waterway tunnels in Sun Moon Lake, a natural lake that was transformed into a reservoir for a hydroelectric power plant. The sediment inflow rate from the waterway tunnels is influenced by the artificially controlled water inflow rate, and the sediment concentration associated with precipitation in the Zhuoshui River. Low sediment inflow rates were observed during winter and spring, and large rates were observed during the East Asian rainy season and typhoon season. Low sedimentation rates were observed during winter/ spring, and high sedimentation rates were observed during summer and autumn corresponding to the changes in the rate of sediment inflow. Results from a 1-dimensional sedimentation model suggest that the sediment deposition rate in Sun Moon Lake decreases exponentially with distance from the tunnels and erosion in shallow areas near the tunnels.