Assessing the Efficacy and Climate Resilience of Traditional Water Harvesting Systems in Jodhpur District, Rajasthan: A Geospatial and Hydrological Modeling Approach

Chandra Prakash Choudhary, Dr. Sarita Kumari, Priyanka Kumari, Ashwini Yadav

Traditional Water Harvesting Systems (TWHS) are critical for water security in arid regions like Jodhpur district, Rajasthan, India, yet their contemporary efficacy and climate resilience remain inadequately quantified. This study comprehensively assesses selected TWHS, primarily nadis and johads, by integrating geospatial analysis for inventory and characterization, hydrological modeling (SCS-CN and water balance) for performance evaluation, CMIP6 climate change projections (SSP2-4.5 and SSP5-8.5) for resilience assessment, and multi-criteria decision analysis (MCDA) for identifying optimal scalability potential. Geospatial mapping identified 450 TWHS (280 nadis, 120 tankas, and 50 johad-like structures) across the Jodhpur district. Detailed characterization of 50 sample structures revealed significant variability in their storage capacities (mean nadi capacity: 18,500 m³ ± 9,200 m³) and catchment characteristics. Hydrological modeling under baseline conditions (1991-2020) indicated that an average nadi captured approximately 65% of its catchment runoff, providing crucial water resources for 4-5 months post-monsoon and enhancing localized groundwater recharge by an estimated 180 mm/year compared to non-TWHS areas. However, climate change projections for mid-century (2041-2070) predict a potential decrease in average annual inflow to TWHS by 8-18% and a reduction in water availability duration by 3-5 weeks, underscoring their vulnerability. Despite these challenges, GIS-MCDA identified that approximately 18% of the district's non-urban area is 'highly suitable' for new TWHS interventions, suggesting substantial scalability potential to harvest an additional 12-15 Million Cubic Meters (MCM) of rainwater annually. This research underscores the enduring hydrological importance of TWHS but emphasizes the urgent necessity for climate-resilient revival, adaptive management strategies, and strategic upscaling, informed by robust scientific assessments and active community participation, to bolster water security and enhance adaptive capacity in arid environments. Policy recommendations focus on integrating TWHS into mainstream water resource planning, promoting climate-smart rehabilitation, and strengthening local institutional frameworks for sustainable TWHS governance.