Study on Suspended Sediment Concentration Measurement in Rivers and Reservoirs

从上游到下游流域的综合泥沙治理中，冲沙量的确定具有重要意义。对于河流或水库中悬浮物浓度的测量，一般采用连续浊度测量和瓶样取样两种方法。然而，由于浊度是通过光学方法测量的，因此在很长一段时间内都是稳定的，对于瓶取样来说，在径流时间很短的小集水区，很难在排放峰值时收集样品而不丢失。本研究的目的是研制一种新型的带差压变送器的悬沙浓度测量系统（以下简称SMDP）。该方法使用差压变送器直接通过水密度测量悬浮沉积物浓度，而不依赖于传统的光学方法来解决此类问题。该方法适用于连续测量和高浊度测量。SMDP有两种类型；一种是潜水式，另一种是水循环式。为了明确该系统的基本性能，分别在天龙河、Miwo大坝和黑部河进行了室内和现场试验。所得结果可总结如下。(1)在Miwa大坝的现场试验中，已经稳定地测量了自然洪水通过水库时的SS，潜水式SMDP具有实时、高悬沙测量的优点，可用于水库SS监测。(2)在黑部河的野外试验中，测量了水库冲沙过程中的SS，水循环式SMDP可用于难以持续保证足够水深的天然河流的SS监测。

It is important to know quantity of wash load for the integrated sediment management from upstream through downstream river basins. Generally, both continuous turbidity measuring and bottle sampling are used for suspended-sediment concentration measurement in rivers or reservoirs. However, there is a subject in stability for long time since the turbidity is measured by an optical method and, for bottle sampling, it is very difficult to collect samples without missing at the time of discharge peaks in case for small catchment areas having very short run-off times.This research is to develop a new suspended sediment concentration measuring system with differential pressure transmitter (hereafter, we call SMDP). This method measures suspended sediment concentration by the water density directly with a differential pressure transmitter, without depending on a conventional optical method for the purpose of the solution of such a problem.This method can be applicable for the continuous measurement and the high turbidity measurement. There are two types of SMDP; one is the submersible type and another is the water circulation type. In order to make clear the basic performance of this system, both laboratory and field experiments at the Tenryu river, Miwo dam, and also the Kurobe river have been executed individually.The result that was obtained can be summarized as follows.(1) At the field experiment in the Miwa dam, SS during natural flood flows passing through the reservoir have been measured stably, and the submersible type SMDP can be used for SS monitoring in reservoirs with advantages of real-time and high-suspended sediment measurement.(2) At the field experiment in the Kurobe river, SS during sediment flushing operation from reservoirs have been measured, and the water circulation type SMDP can be used for SS monitoring in natural rivers where enough water depth is hardly secured constantly.