*Numerical Simulation on Sand Accumulation behind Artificial Reefs and Enhancement… DOI: http://dx.doi.org/10.5772/intechopen.107014*

area is located near the east end of Honshu Island and faces the Pacific Ocean, as shown in **Figure 1**, which is a pocket beach of 1070 m length bounded by a rocky headland on the north end and Point Inubo on the south end. At present, two artificial reefs of 50 m in width and 200 m in length with a crown height of 2.0 m below the mean sea level (MSL) are constructed in the central part of the study area. A shallow zone covered with exposed rocks extends in the vicinity of the rocky headland and Point Inubo, whereas a sandy beach composed of fine and medium-size sand extends along the shoreline with salients being formed in the lee of the artificial reefs.

The wind and wave conditions of this area are as follows. The wind conditions of the area predicted by NEDO Neo Winds [28] are shown in **Figure 2**. The predominant wind direction of the study area ranges between NE and NNE in winter and is SSW in summer. In **Figure 2**, the direction of the mean shoreline at transect No. 3 located at the central part of the pocket beach shown in **Figure 1** is indicated by a dotted line. Because there is no predominant wind direction at the central part of the pocket beach between the rocky headland and Point Inubo, wind can be assumed to blow from the direction normal to the shoreline.

We referred to the forecasting results offshore of Chiba Prefecture predicted by the Japan Meteorological Agency [29] for the wave characteristics in this area. **Figure 3** shows the probability of occurrence of waves in each direction: the predominant wave

**Figure 2.** *Probability of occurrence of wind direction and mean shoreline orientation.*

**Figure 3.** *Probability of occurrence of wave direction offshore of the study area.*

direction is E. As for the wave conditions of this coast, an average significant wave height is 1.9 m with a wave period of 8.6 s, and a tidal range is approximately 1.5 m.
