Field Experiment on Beach Nourishment Using Gravel at Jinkoji Coast

Abstract

Beach nourishment using 87,000 m3 of gravel with grain size between 2.5 and 13 mm was experimentally carried out until April 2008 at the Jinkoji coast, which faces the Pacific Ocean and is surrounded by artificial headlands. Monitoring surveys, a boring test and core sampling on the beach were carried out to investigate the mechanism of the formation of gravel layers and their effect on protecting the foot of the seawall. It was found that the nourishment gravel was deposited with a slope of 1/8 at the foot of the seawall, thus providing some protection to the seawall, and that the nourishment gravel was stably deposited without offshore discharge.

Influence of particle shape on pebble transport in a mixed sand and gravel beach during low energy conditions: Implications for nourishment projects

“…In this perspective is very important to better understand how gravel fill material evolves over time when deployed on a native sandy beach surface. Several project have been made choosing gravel as nourishment material to counteract erosion processes on native sandy beaches (Takagi et al, 2001;Cammelli et al, 2004;Kumada et al, 2010;Bertoni and Sarti, 2011;Ishikawa et al, 2012), but no considerations are made on shape nor shape evolution of fill material. The real issue of gravel nourishment is the supply of coarse gravel (pebbles and cobbles), thus many coastal managers chose to replenish using fine gravel or sand-gravel mixes (Williams, 2005;Moses and Williams, 2008).…”

“…Nourishment projects with coarse material (i.e. gravel or shingle) started in England in small scales and occasionally already in the 1950s and began to proliferate in the 1970s (Hanson et al, 2002;Moses and Williams, 2008); currently they are not only used to contrast erosion on natural coarse-grained beaches but also as an attempt at stabilizing originally sandy beaches (Takagi et al, 2001;Cammelli et al, 2004;Kumada et al, 2010;Bertoni and Sarti, 2011;Ishikawa et al, 2012). However, an issue often present is the availability of coarse material from sea-bed reservoirs, as this type of sediment is only available in continental shelf seas, where large fluvio-glacial deposits are available, like in the North Sea.…”

Introductory Chapter: Morphodynamic Model for Predicting Beach Changes Based on Bagnold’s Concept and Its Applications

“…This model then was improved to predict the temporal and spatial changes in the grain size of bed material [41][42][43]. The authors applied this model to many coasts in Japan to work out the countermeasures against beach erosion [2,[44][45][46][47][48][49][50][51]. However, this model has weak points.…”

Monitoring of Gravel Nourishment on Makuhari Beach in Tokyo Bay

“…In recent years, gravel nourishment has been widely carried out in Japan because of the high stability of the gravel beach against storm waves and its effectiveness as a measure against scouring as a result of the deposition of the gravel at the toe of the seawall. Kumada et al (2010) investigated the effect of the beach nourishment using 87,000 m 3 of gravel with the grain size ranging between 2.5 and 13 mm at the Jinkoji coast originally composed of fine sand. They found by an excavation test that alternate layers of sand and gravel were formed instead of the uniform deposition of nourishment gravel, and they assumed that the deposition of fine sand over the gravel layer was caused by shoreward sand transport under calm wave conditions.…”