Shihmen Reservoir suspended sediment concentration vertically layered monitoring technique development and field evaluation
|關鍵字:||分層;異重流;水庫; ;Layer-integrated;Density Current;Reservoir;|
To assess the best reservoir siltation prevention strategy, reservoir runoff sediment characteristic is the key to flood monitoring. This feature was monitored in various reservoirs but only Shihmen, Zhengwen and Nanhua reservoirs retained much more and complete monitoring information. Incomplete data and monitoring issues existed in other reservoirs, thus constructing a complete reservoir sediment database is the fundamental work in reservoir siltation prevention strategy. According to the preliminary planning in “Reservoir suspended sediment concentration monitoring technique and desiltation operation strategy research project”, suspended sediment monitoring equipment setup mainly begins from establishing monitoring stations at the flow buffer area of turbid water open channel flow and each outlet. This is mainly due to the reservoir management unit would wish to understand the inflow suspended sediment concentration to master the total sand inflow amount, and by knowing suspended sediment concentration variation of each discharge outlets or water, reservoir operation of water discharge or intake could be adjusted accordingly. Luofu monitoring station in Shihmen reservoir upstream had vertical layered water sampling equipment and automated suspended sediment concentration installed at the slope of the right embankment. Although there was relatively evidence-based sediment inflow estimation available currently, side boundary effect may induce substantial variation in river suspended sediment concentration measurement. Methods to gather representative sediment concentration at specific cross-sections are very important but yet lacking for river sediment transportation monitoring. This study is hence a successor of previous research outcome, to evaluate the differences between current Luofu river bank monitoring station and newly established observation pole in main channel, to accurately acquire inflow sediment concentration historical data, to establish reservoir sediment migration pattern during flood events, to effectively master optimal timing of reservoir desiltation operation and enhance desiltation efficiency. While at the same time, this study investigates relationship between landslide area within catchment region and amount of inflow driftwood and sediment, which would assist in cross-border coordination between forestry authorities and soil-water conservation authorities to jointly prevent debris flow disaster, and to compile all sources of earth and soil and forest resources management as reference. Control station monitoring the end inflow boundary could master catchment area water and soil resources, which could enhance reservoir water supply stability and siltation prevention, integrating catchment area management related authorities, in turn to master main sand source and achieve collaboration between soil management and forestry resources fields.