Natural Resources and Control Processes

Abstract

Sedimentation is a serious threat to long-term water resource management worldwide. In particular, reservoir sedimentation is becoming more serious in Taiwan due to geological weathering and climate change in watersheds. Large amount of sediments transport to reservoirs during storm events at hyperpycnal concentration. Full-event monitoring of sediment transport in a reservoir plays an important role in sustainable reservoir management. This chapter begins by reviewing existing surrogate techniques in need for monitoring suspended-sediment transport in reservoirs with high concentration range and wide spatial coverage. More commercially available techniques suffer from particle-size dependency and limited measurement range. This chapter introduces a relatively new technique based on time-domain reflectometry. It possesses several advantages, including particle-size independence, high measurement range, durability, and cost-effective multiplexing. This chapter describes a modified TDR technique for better field applicability and demonstrates its application in an extensive SSC monitoring program for reservoir management through a case study in Shihmen Reservoir, Taiwan. Monitoring stations were installed at the major inflow river mouth and outlet works with fixed protective structures to provide inflow and outflow sediment-discharge records. To capture the characteristics of density currents, a multi-depth monitoring station was designed and deployed on floating platforms in the reservoir. Some of the data collected during typhoons are presented as an example to demonstrate the effectiveness and benefits of the TDR-based monitoring program.