Innovative Approaches to Freshwater Restoration and Management Under Changing Climatic Conditions

Presently, there are multiple factors threatening the function and services provided by freshwater systems, such as rivers, wetlands, and lakes throughout the world. These include hydrologic variability due to climate change, thermal stress, invasive species, and increasing human development uses of freshwater systems. This research aims to assess alternative restoration and adaptive management strategies that have been utilized across five freshwater sites in Tamil Nadu, South India (with varying ecosystem types and climate stressors). Monitoring was conducted prior to and following restoration intervention for a 24-month period utilizing a multi-indicator monitoring framework (i.e., hydrology, physiochemical, and biological measures) to assess pre- to post-intervention ecological trends. All locations showed statistically significant results for all sites and yielded positive results for all sites. The average improvement of each water quality indicator, namely dissolved oxygen (12.3% - 34.1%) (p<0.01), total suspended solids (28.6% - 52.1%), and biotic integrity scores (BMWP, IBI), was one quality class better than at least four of five tested locations. Nature-based solutions (including riparian buffer restoration, eco-flow regime reinstatement, construction of wetland habitats) performed best when implemented as adaptive, site-specific portfolios versus stand-alone interventions. Modeled climate change scenarios (using CMIP6 RCP 4.5 and RCP 8.5) indicate that proactive integration of green infrastructure with hydrological forecasting will extend the functional resilience of restored systems by 15 to 30 years under moderate climate change scenarios. These findings demonstrate the urgent need for governance frameworks that incorporate ecosystem-based adaptation into regional water resource management plans, in order to secure freshwater biodiversity and human water security into the middle of the 21st century.