STUDY ON RIVER FACILITIES HARMONIOUS WITH ENVIRONMENT

没有洪水破坏的河流开发造成了自然河流环境的严重破坏。为了修复河流环境，必须建设具有防洪和环境保护双重功能的设施。本文对丁坝的作用进行了探讨。丁坝具有护岸作用，丁坝周围形成的局部冲刷适合鱼类的栖息地。本文由三个部分组成。第一部分建立了二维河床演变的数值模拟方法，并通过曲流河河床演变的数值模拟验证了该方法的有效性。然后，将该方法应用于现场数据。预测了枯水时水池的位置和曲流河的形成。第二部分，利用该方法对丁坝的护岸作用和丁坝周边局部冲刷(塘)剖面进行了评价。如果不考虑非平衡输沙，局部冲刷剖面不能被模拟。最后，通过对仙台河的观测，探讨了池塘适宜鱼类栖息地的条件。由各种粒度的底质组成的较深的池塘可供鱼类栖息地。

The development of rivers free from flood damage has resulted in serious ruin of natural river environment. In order to rehabilitate the river environment, we should construct the facilities with both functions on the flood control and the environmental protection. In this paper we have discussed the functions of spur dikes. The spur dike is effective in the protection of bank and the local scour formed around the spur dike will be suitable to the habitat of fishes. This paper is composed of three parts. In first part, the numerical method for 2-dimensional bed evolution is developed and the validity is verified by the simulation of bed evolution in the meandering channel. Then, the method was applied to the field data. The place of the pool and the formation of the meandering streams at the low water were predicted. In second part, using the method the function on the protection of the bank and the profile of the local scour ( pool ) around the spur dike are evaluated. The profile of local scour is not simulated without considering the non-equilibrium sediment transport. In last part the conditions on the pool suitable to the habitat of fishes are discussed from the observation in the Sendai river. The deeper pool composed of the bed material with wide-ranging grain sizes is available for the habitat of fishes.