Abstract
The Yangtze River Delta (YRD), as China's socioeconomic core, faces compound pressures from water scarcity, pollution, and ecosystem degradation, with water ecological security emerging as a critical bottleneck for sustainable development. This study aims to construct a comprehensive evaluation system and identify key constraints to provide scientific guidance for urban agglomeration water security management. We innovatively established a four-dimensional evaluation framework encompassing water resource security, water environment security, water ecosystem health, and economic benefit management, employing the TOPSIS model with entropy-CRITIC combined weighting to assess water ecological security across four YRD provinces from 2010 to 2023. Results reveal a three-phase evolutionary pattern with provincial gradient distribution, exposing a "high economic-low ecological" resource curse effect in megacities; water resource security subsystem holds the highest weight (35.23%), indicating the synergistic role of economic regulation and natural restoration in system resilience; and dominant obstacles have shifted from industrial pollution to compound pressures including ecological water deficit, agricultural non-point pollution, and lagging water-saving technologies. This study proposes differentiated zoning strategies and cross-regional collaboration mechanisms, providing theoretical and methodological references for water security management in high-density urban agglomerations with global implications for analogous regions.