¿Water Resources Utilization and Sustainable Development Research ¿takes the paradigm integration of "water system sustainability science" as its central theme. In response to complex challenges such as water scarcity, aquatic ecosystem degradation, and water pollution risks arising from the combined impacts of climate change and human activities, it emphasizes expanding the research object from the traditional "single hydrological system" to a "hydrology-ecology-socioeconomic coupled system." From a systems perspective, the book elucidates the mechanisms and evolutionary logic underlying water-related problems, and elevates research objectives from a simple balance between supply and demand to a coordinated improvement in sustainability across multiple goals, including ecological security, economic efficiency, social equity, and effective governance. Methodologically, the monograph advocates an interdisciplinary approach, integrating observational experiments, model simulation, big-data analytics, scenario analysis, and multi-objective decision-making tools to develop a comprehensive methodological system oriented toward real-world governance needs. It further proposes an overarching framework comprising "theoretical foundations-core issues-research methods-practical pathways-support mechanisms," thereby linking theoretical understanding with practical regulation and management. In terms of application, the book underscores problem orientation and practical usability, focusing on systematic combinations of key regulation measures and governance solutions for sustainable utilization, and providing a conceptual framework for assessing, comparing, and optimizing watershed- and regional-level water resources management.