**7. Conclusions**

Beach changes after the construction of artificial reefs and the increase in the amount of sand blown from the foreshore in the lee of the artificial reefs to inland were investigated, taking Kimigahama Beach in Chiba Prefecture, Japan, as an example. Then, a numerical simulation of these topographic changes was carried out using the combination of the BG model for predicting beach changes caused by waves and a cellular automaton method for predicting the windblown sand. In the field

observation, it was found that salients were formed after the construction of two artificial reefs and the amount of sand blown from the widened foreshore in the lee of the artificial reefs increased. Not only was fine sand transported in front of the seawall but also part of sand was further transported inland. The formation of salients in the lee of the artificial reefs and the deposition of windblown sand in the hinterland as observed in the field were numerically predicted well.

As an application of the prediction of beach changes, the effect of beach nourishment at the opening of the artificial reefs was predicted using the same model. When beach nourishment was carried out while maintaining the present condition of the reefs as they are, sand was further transported inland by wind. Instead, if artificial reefs were removed and then beach nourishment was carried out, nourishment sand was distributed on the entire sandy beach, and loss of sand toward the hinterland became minimal. From this, the construction of a facility with a wave dissipating function such as a detached breakwater or an artificial reef in the nearshore zone on a coast composed fine and medium-size sand must be carefully carried out. It is important for a coastal engineer to sufficiently consider not only the effect of the movement of sand due to waves but also the management of windblown sand when shore protection facilities are constructed on a coast composed of fine and medium-size sand.
