Revitalizing traditional tank systems: case study insights from Sri Lanka's village tank cascade systems for climate resilience and water governance

Village tank cascade systems (VTCS) are a long-established form of water management in Sri Lanka's dry zone. However, their role in groundwater recharge, climate adaptation, and water governance remains insufficiently recognized in policy and planning. In this study, we examine the hydrological and institutional functions of VTCS in Sri Lanka's dry zone, with a focus on Vavuniya District. Using field validation, GIS-based cascade mapping, tank status assessment, and correlation analysis between tank water levels and nearby wells, the study identifies a strong hydrological relationship, most notably at Vavuniyakulam, where a correlation coefficient of 0.88 was observed. These findings highlight the significance of tanks in sustaining groundwater availability, especially during dry periods. However, decades of neglect, socio-political conflict, and fragmented institutional mandates have led to widespread degradation of tank systems and erosion of community-based governance structures. The study shows that VTCS offer critical ecosystem services beyond irrigation, including groundwater recharge, domestic water supply, climate buffering, and livelihood support. Drawing from the Vavuniya case, the paper argues for repositioning village tanks within national water policy and climate resilience frameworks. Revitalization efforts need to combine scientific assessment, participatory governance, local ecological knowledge, and institutional coordination to restore the multifunctional role of VTCS. The Vavuniya case offers wider lessons for dryland and postconflict regions where small-scale water systems remain central to groundwater security, rural livelihoods, and climate-resilient water governance.