Relationship between Increase in Sand Supply from Tenryu River and Beach Erosion of Enshu-nada Coast

Abstract

Long-term beach changes after the completion of sand-bypassing project in the Tenryu River, which takes 10 years from the present, were predicted using the contour-line-change model. Even if beach nourishment of 5×10⁴m³/yr is continued in front of Nakatajima sand dune, and 3×10⁵m³/yr of sand is additionally supplied to the river mouth as the effect of sand bypassing at the dam reservoir, supplied sand is only effective for recovering the river mouth terrace severely eroded in the past, and newly supplied sand is ineffective to nourish further downcoast. To conserve the Enshu-nada coast, further overall comprehensive management of sand movement is required.