This study investigates water resource management strategies in sustainable agriculture amid climate change, focusing on innovation adoption, regional disparities, and policy effectiveness. Using a combination of field surveys (covering 2,500 farms across 12 countries), remote sensing data (2020–2023), and policy analysis, we identify key challenges: erratic rainfall (reducing surface water availability by 35% in arid regions), groundwater over-extraction (lowering aquifer levels by 1.2 m/year in semi-arid areas), and limited access to advanced irrigation technologies (adopted by only 22% of smallholder farms globally). We evaluate innovations such as drip irrigation, rainwater harvesting, and AI-based water monitoring systems, finding that drip irrigation reduces water use by 40–50% while increasing crop yields by 20–25%. Regional case studies (India, Spain, Sudan, and Japan) highlight context-specific solutions: community-managed rainwater harvesting in India, desalination-integrated agriculture in Spain, solar-powered irrigation in Sudan, and precision water management in Japan. The study concludes that policy support—including subsidies for water-saving technologies and capacity-building programs—can increase innovation adoption by 38%. These findings provide a roadmap for enhancing water resilience in sustainable agriculture under climate change.