Quantitative Assessment of Coastal Geomorphological and Ecological Damage Risks: A Case Study of Sheyang Coast

Dong Liang¹Na Gao^1*Mingli Zhao^1*Mianrun Chen¹Dongmei Li²Haobing Cao³Zhaoyuan Zhang²Huamei Huang¹Huaguo Zhang²

• ¹South China Sea Development Research Institute, Ministry of Natural Resources, Guangzhou, China
• ²Second Institute of Oceanography Ministry of Natural Resources, Hangzhou, China
• ³The National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, China

As critical zones of land-sea interaction, coastal areas serve as core regions for dense populations, developed economies, and social sustainability. However, coastal erosion poses significant challenges in China, with a notable lack of quantifiable classification standards for coastal risk management. This study analyzed data spanning two decades from the Sheyang estuary, including shoreline changes, nearshore mean wave height, nearshore mean current velocity, salt marsh vegetation area, mudflat area, and coastal slope. By applying game theory to reconcile conflicts between subjective and objective weights of evaluation indicators, final combined weights were derived to quantify the risk values of the Sheyang coast over the past 20 years. Critical thresholds demarcating coastal status from "excellent" to "poor" were identified as follows: Shoreline siltation, shoreline stability, shoreline erosion coupled with disappearance of salt marsh vegetation, and steep slope formation with near-complete loss of mudflat. These thresholds corresponded to low, moderate, and high risk levels, respectively. Using a cloud transformation algorithm, the risk values