COASTAL SEDIMENT BUDGET WITH FLUVIAL AND LITTORAL SEDIMENT TRANSPORT SYSTEM BY GIS ANALYSIS WITH THE TERADOMARI－NOZUMI COAST, NIIGATA, JAPAN

Abstract

 The development of a coastal sedimentary features are affected by the fluvial and littoral sediment transport system. It is necessary to understand the sediment budget between the fluvial sediment supply and littoral drift to predict the long-term topographical changes due to the coastal conservation. However, the actual state has not been quantitatively clarified. This study aims to investigate the sediment budget at the Teradomari-Nozumi Coast located in the estuary of the diversion channel of the Shinano River. As a result, the total sediment volume of littoral drift in this coastal area is estimated 160 Mm³, and the volume of sediment supply from some small streams are totaled 84 Mm³ .Then, it assumes that there are only two sources of sediment supply to the coast: sediment discharged from small streams and the diversion channel. The fluvial supply by diversion channel is calculated 76 Mm³ as the difference between the volume of littoral sediment (160 Mm³) and the sediment supply from small streams (84 Mm³). Ministry of Land, Infrastructure and Transport’s research pointed out that the sediment discharge rate is 0.7~0.8 Mm³/yr and which in the period between 1922 and 2018 (for 96 years) is 70~80 Mm³. The result of this study is in good agreement with MLIT’s data and indicate the validity of the sediment budget analysis based on wide-area and long-term geomorphological changes.