Development of Integrated Sediment Delivery Systems throughout a River System

本研究的目的在于：1）仅利用降雨、泥沙特性和地形条件，预测沿着河系输沙量; 2）利用开放式沙堡坝有效控制泥石流; 3）利用大型水库排沙。提出了一种将运动波洪水径流分析与泥沙输移分析相结合的数值模拟方法。一个特殊的设计采取的沉积物供应从裸露的斜坡包括在内。应用该方法对Takase水库流域的泥沙径流和委内瑞拉一次强降雨引发的泥沙灾害进行了解释，验证了该方法的有效性和实用性。对于主题2），介绍了泥石流中的孤石堵塞格状坝的随机模型。将该模型与泥石流颗粒分离过程模型相结合，对格构式沙堡坝控制泥石流进行了数值模拟。针对课题3），设计了一种新的水库排沙系统。在水库内靠近上游端的地方修建了一个小水坝，产生的泥沙只在这个子坝的上游堆积。在洪水退水期间，子坝上游的水和泥沙通过旁路洞排到主坝下游的泄洪河段。如果子坝背堆积的三角洲存款冲刷不充分，则引入主水库的回流冲刷存款。通过室内实验和数值模拟验证了该系统的可行性，证明了该系统的可行性。

This research aims to develop the methods 1) to predict the sediment delivery along the river system by giving only rainfall, sediment characteristics and topographic conditions, 2) to effectively control debris flow using the open type sabo dams, and 3) to flush sediment from a comparatively large reservoir.Concerning with the theme 1), a numerical simulation method that combines the kinematic wave flood runoff analysis with the sediment entraining and detraining analysis is developed. A special contrivance to take the sediment supply from bare slopes is included. This method is applied to explain the sediment runoff within the watershed of Takase reservoir and the sediment disasters triggered by a severe rainfall in Venezuela, and it is proved valid and useful to examine the efficiencies of various countermeasures.As for the theme 2), a stochastic model for the clogging of grid-type dam by boulders contained in debris flow is introduced. This model is combined with a particle segregation process model to numerically simulate the debris flow control by grid-type sabo dam. This method is proved valid by experiments.Concerning with the theme 3), a new system to flush sediment from reservoir is invented. A small dam is constructed inside of the reservoir near the upstream end, and the yielded sediment accumulates only upstream of this sub-dam. During flood recession period, water and sediment stored upstream of the sub-dam are emptied through a bypass tunnel to the rfirer reach downstream of the main dam. If erosion of the delta deposit accumulated the backside of sub-dam is not sufficient, reverse flow from the main reservoir is introduced to scour the deposit. The feasibility of this system is examined by both laboratory experiments and numerical simulations, and it isproved feasible.