• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.28-33
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• 2008

From the 1997 to January, 2004, a groin 156m long was constructed at the mouth of the Heoya river-mouth as a protection and barrier. To understand the changes to Jinha beach from the blockade of the river mouth, several aerial photographs, etc., were compared, which showed that the changes were significant. Comparing these results to the state of the area before construction of the groin, the blockade of the river was relaxed, but the formation of the tombolo, in the middle groin area was accelerated and the total Jinha beach erosion and especially the erosion of the southern part of Jinha beach was developed. But according to statements by residents and some current documents, the blockade of the Heoya-river mouth is still underway at the surrounding areas of the groin and chronic dredged sand has been used for littoral nourishment at the northern part of the middle groin and on Jinha beach. The result of numerical simulation based on the present state shows that if this sort of dredging is stopped, the sand accumulation will progress near the river mouth groin and the existing tombolo at the middle groin will progress to the north and severe erosion will occur at the southern coastline near the middle groin and the farthest southern part of Jinha beach, and Jinha beach itself will experience a gradual erosion. The main reason for these erosions should be the typhoons that are happening during the summer season. To provide protection from these kinds of undesirable erosions, a total of 23 numerical simulations have been done. It has been shown that submerged breakwaters at the front area of the beach will be efficient to protect from main beach erosion, but there should be alternative proposals for the influence of the river mouth blockade.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.477-486
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• 2014

Integrated sand control including sediment discharge from hinterland rivers is necessary to maintain coastal sand resources over a long term. In this regard, the following subjects should be considered; efficient ways to transfer discharged sand from a river to the neighboring coast, measures to improve storage efficiency of the discharged sand at the river delta and/or river terrace, measures to prevent the sand resources from being discharged into the deep sea during flooding. From the 1997 to January 2004, the jetty of 156 m length was constructed the Heoya-river mouth to protect the blockade of river mouth. Several tests were carried out to investigate the characteristics of sediment transport and morphological change due to the construction of the jetty at the Heoya-river mouth. Firstly, The sand discharge from Heoya river is quantified by one-dimensional numerical analysis assuming the mixed sand of three different particle diameters. Also the numerical mode system, which predicts the sea bed changes obtained from the Bailard's energy model(1981), was combined with the wave, wave-induced currents and sediment transport models. Then, to understand the changes to the blockade of the river mouth, several aerial photographs were compared, which showed that the changes were significant.