Role of water absorbing polymer for adaptation to climate change impact on the urban green infrastructures

Background and Aims: Rapid urbanization and climate change intensify water stress, threatening urban green infrastructure (UGI). Water-absorbing polymers (WAPs) are a promising solution to enhance soil water retention and plant drought resilience. This review applies the Soil–WAP–Plant–Atmosphere (SWPA) framework as an analytical tool to conduct an in-depth assessment of the mechanisms among soil hydraulic behavior, WAP properties, plant physiological responses and atmospheric factors. This comprehensive analysis reveals previously unrecognized mechanistic gaps and provides a roadmap for interdisciplinary research and development of water-efficient urban green infrastructure strategies. Methods: The synthesis examines studies on WAP applications, analyzing soil hydraulic properties, plant growth parameters, and environmental interactions. Emphasis is placed on the integrated soil–WAP–plant–atmosphere framework to evaluate system-scale impacts. Results: WAPs significantly improve soil water-holding capacity and modify the soil–water characteristic curve, enhancing plant water availability. The presence of WAP can promote better root development, stomatal conductance and photosynthetic efficiency under abiotic stress condition in plants. In addition, by maintaining soil moisture availability, WAPs can regulate evapotranspiration (ET) dynamics for better plant growth. However, key uncertainties remain regarding optimal application rates, long-term stability, salinity tolerance, environmental impacts, and large-scale economic feasibility. Conclusions: The findings confirm WAPs' potential to boost drought resilience and water efficiency in UGI. They also highlight the necessity for further interdisciplinary research integrating soil physics, plant biotechnology, and urban climatology. This review offers practical insights for developing sustainable strategies while noting unresolved challenges in environmental impact and scalability.