Study on Suspended Sediment Concentration Measurement in Rivers and Reservoirs

了解冲刷量对流域上游和下游的泥沙综合管理具有重要意义。河流或水库悬浮泥沙浓度测量一般采用连续浊度测量和瓶采样两种方法。然而，由于浊度是用光学方法测量的，因此存在着一个长期不稳定的问题，对于瓶子采样，在小流域径流时间很短的情况下，很难在流量峰值时采集不丢失的样品。本研究旨在开发一种新型的差压变送式悬浮泥沙浓度测量系统(以下简称SMDP)。该方法通过差压变送器直接利用水的密度来测量悬沙浓度，不依赖于传统的光学方法来解决这一问题，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。为了弄清该系统的基本性能，分别在天龙江、米窝坝和黑河进行了室内和野外试验。取得的结果如下：(1)在米洼大坝的野外试验中，天然洪水通过水库时的悬沙测量稳定，潜水式SMDP可用于水库悬沙监测，具有实时、高含沙量测量的优点。(2)在黑河现场试验中，对水库冲沙作业中的悬沙进行了测量。而水循环式SMDP可用于天然河流中难以持续保证足够水深的水体悬浮物监测。

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.