Evaluation of water quality in lowland Ramsar Wetlands: Insights on hydrochemistry analysis-sustainable development goals nexus

Wetlands are increasingly threatened by human activities and climate change globally. This study provides the first comprehensive assessment of water quality in Nepal's lowland riparian Ramsar wetlands. It focuses on Jagadishpur Reservoir (JR) and Nakrori Lake (NL), chosen for their ecological significance and contrasting artificial and natural features. The research examines seasonal water quality changes, identifies key hydrochemical processes, and evaluates suitability for drinking and irrigation. During pre- and post-monsoon periods, 156 water samples were collected from both lakes. Samples were analyzed for physicochemical parameters, including total dissolved solids (TDS), and major ions (Ca²⁺, Mg²⁺, HCO₃⁻), using standardized laboratory techniques. Statistical analyses and hydrochemical diagrams, such as Piper and Gibbs plots, revealed that both lakes exhibited similar physicochemical profiles. Ca²⁺-HCO₃^- was the dominant water type, indicating that carbonate and silicate weathering, along with cation-anion exchange, were key determinants of water chemistry. TDS levels averaged 182.7 mg/L in NL pre-monsoon and declined to 154.3 mg/L in JR post-monsoon, reflecting the effects of evaporation and monsoonal dilution. Water quality consistently met standards for both drinking and irrigation, with water quality index (WQI) and Sodium adsorption ratio (SAR) < 50 and 10, respectively. These findings underscore the challenges in maintaining standard water quality and highlight the implementation of a sustainable action plan (SAP) that advances Sustainable Development Goal (SDG) 6 by 25 % and SDG 13 by 40 % through targeted pollution mitigation and climate resilience measures. This research can provide a transferable framework for wetland conservation and policy development in similar ecosystems worldwide.