引 言 在日本,随着它的地质、地形和水文条件的不同,有大量的泥沙产生和输移。此外,由于国土狭窄和人口密度高,侵蚀和沉积已给人类活动带来各种影响。 由于国土利用和水资源,特别是水库建设和沙砾石开采发展的缘故,日本的泥沙环境在最近二十年期间已迅速改变。水库中的泥沙沉积不仅引起水库效益的减少和上游洪水位的升高,而且会大大减少河流下游的泥沙供给。为了获取建筑材料,常常在河中开采沙砾石,特别是1960～1965年期间。 Introduction In Japan, with its different geology, topography and hydrological conditions, a large amount of sediment is produced and transported. In addition, erosion and sedimentation have had various effects on human activities due to their narrow territories and high population density. Due to land use and water resources, especially reservoir construction and gravel mining development, the sediment environment in Japan has changed rapidly during the last two decades. Sediment deposition in reservoirs not only leads to the reduction of reservoir benefits and upstream flood level, but also greatly reduces the supply of sediment in the lower reaches of rivers. In order to obtain building materials, gravel is often mined in the river, especially between 1960 and 1965.