Satellite-based monitoring of contrasting characteristics of suspended sediment discharged from the Red and the Ma river systems along the northern coast of Vietnam

作     者：Yoshimitsu Tajima Kavinda Gunasekara Hung Thanh Nguyen 

作者机构：Department of Civil Engineering Graduate School of Engineering The University of Tokyo Geo-Informatics Center Asian Institute of Technology Key laboratory of River and Coastal Engineering Vietnam Academy of Water Resources 

出 版 物：《International Journal of Sediment Research》 (国际泥沙研究(英文版))

年 卷 期：2019年第34卷第3期

页      面：191-204页

核心收录：

学科分类：08[工学] 081502[工学-水力学及河流动力学] 0815[工学-水利工程] 

主　　题：Turbidity River mouth Coastal erosion MODIS 

摘      要：The northern coast of Vietnam has accumulated a significant amount of sediment discharged from the multiple distributaries of rivers such as the Red River and Ma River. While recent decreases of the sediment supply appears to have a significant impact on coastal erosion, the complex network of these distributaries makes it difficult to determine the overall spatiotemporal characteristics of sediment discharges and related topographic changes. The goal of the current study is to develop a satellite-based monitoring system for observation of turbidity discharged from the multiple rivers and to investigate the applicability of the developed monitoring system through a case study on the northern coast of Vietnam. Based on the in-situ observed data, a formula was determined for estimation of the surface water turbidity as a function of the red band reflectance of Moderate Resolution Imaging Spectro-radiometer(MODIS) images. The formula was then combined with a newly determined threshold for cloud-masking to obtain maps of the nearshore turbidity patterns. These maps capture the spatiotemporal water surface turbidity along the entire coast of the Red River Delta and the coast around the Ma River mouth over the past sixteen years with frequency of twice a day. Finally, long-term trends of the turbidity patterns from multiple rivers were compared with the in-situ observation data and it was found that the Red River and the Ma River showed clearly contrasting characteristics, which reasonably explain the recent coastal shoreline changes and characteristics of sediment sampled along the coast.