Spatiotemporal assessment of water security in the Dongting Lake region: Insights from projection pursuit method and sparrow search algorithm

The Dongting Lake region (TDLR) is China's essential commodity grain base and inland wetland reserve. Few studies, however, focus on the water security of TDLR. Additionally, as the attributes of water security increase, common methods may not obtain more structural characteristics or make full use of the data, resulting in the evaluation not being comprehensive enough. Hence, based on the vulnerability scoping diagram (VSD) and the coupled model combining projection pursuit method (PP), sparrow search algorithm (SSA), and contribution degree model, this study assesses the water security of TDLR and its three major cities. The result shows that the coupled model may be suitable to assess water security since it obtains a more accurate, comparable, sensitive, comprehensive evaluation more rapidly, intuitively, and stably. The water security of TDLR and three cities all exhibit an overall fluctuating upward trend during 2011–2020, with a significant increase in the comprehensive water security evaluation value (WSV) of TDLR ( p < 0.05). Among the three cities, the water security of Yiyang is the safest, followed by Changde and Yueyang. A summary of the main contributing dimensions and top ten contributing indicators of water security of TDLR illustrates that the effective measures to improve its water security include building embankments and sewage treatment plants through increasing investment; reducing industrial water consumption; improving the ability to convert rainwater to water resources and surface water storage capacity. Additional measures, such as strengthening the integrated management of the Dongting Lake and increasing the use of reclaimed water for ecological replenishment, can effectively improve its water security. This study objectively assesses and summarizes the water security of TDLR and provides a valuable reference for relevant authorities in regional water resources planning and management, as well as for water security assessment of other similar lake regions. • Vulnerability scoping diagram can be used to establish the water security assessment framework based on the water issues and their complex interrelationships. • The coupled model may be suitable to assess water security since it obtains a more accurate, comparable, sensitive, comprehensive evaluation more rapidly, intuitively, and stably. • Water security around the Dongting Lake region has significantly improved during 2011–2020. • The key contributing factors and effective measures to improve water security around the Dongting Lake region are identified.