Research on earth-and-sand control of the artificial reef installed near the mouth of a river

泥土和沙子来自一条河。当海边的沙子被海浪移到海岸时，它就得以维持。它变成了一种动态平衡。然而，海滩侵蚀在以下情况下进行。这是减少河流流量和泥沙。在海岸线附近必须安装大量的混凝土块，并保护海岸。此外，当土砂供应被切断时，消波工程前沿的水深变深。本研究在河口附近设置人工鱼礁，目的在于探讨更有效捕捉河川泥沙的方法。人工鱼礁的安装会产生局部的海岸水流。使用该方法检查合适的设置位置、方法等。在河口附近安装人工鱼礁时，必须了解水流的外观和泥沙运动。特别是，有必要澄清从河口排放的土和沙的拦沙效果。海岸线也有前移的趋势。然后，对日本海某海岸人工鱼礁的地形变化特征进行了整理，并应用扩展型Boussinesq模型对人工鱼礁口周围的时间序列波浪场进行了计算。此外，还比较了不同输沙量计算公式引起的地貌变化量和当地实测水深变化量。通过设置人工鱼礁群，它可以减少河流中百分之十的泥沙排放量。

Earth and sand are supplied from a river. The sands of the seashore are maintained when it moves to the shore by sea waves. It becomes a dynamic equilibrium. However, beach erosion progresses in the following case. It is reduction of a river discharge and sand. A lot of concrete blocks must be installed near shoreline, and the seashore must be protected. Moreover, when earth-and-sand supply is cut off, the depth of water of the front of wave absorbing works becomes deep. And it will be scattered about with subsidence one after another, and maintenance will take much cost.This research installs an artificial reef near a mouth of a river; the method of capturing the earth and sand from a river more effectively is the purpose. Installation of an artificial reef will produce a local seashore flow. A suitable setting position, method, etc. are examined using this. When installing an artificial reef near a mouth of a river, it is necessary to get to know about current appearance and earth-and-sand movement. In particular, it is necessary to clarify the sand trapping effect of the discharge earth and sand from a mouth of a river. It is observed that there is also an advance tendency of shoreline. Then, the geographical feature change characteristic of the artificial reef installed in certain seashore in the Sea of Japan was arranged.Moreover using the application of the extended type Boussinesq model, we calculate for the time series wave field around the opening. Furthermore, we compare the amount of geographical feature change using the various amount calculation formulas of sediment transport and the amount of local measured depth change. By installing an artificial reef group, it has ten percent of the amount of discharge earth and sand from a river.