A systematic review of climate change impacts on water quality in transitional environments from a multi-hazard perspective

Abstract

Climate change-induced hazards and their impacts on the socio-economic and ecological system are a major global concern, particularly significant in transitional environments with high susceptibility to modifications, and exposure to multiple land, marine, and atmospheric hazards. These factors can lead to the deterioration of water quality and the ecosystem services they support. Despite the availability of studies that link climate change hazards with water quality parameters, this is the first attempt to provide a literature review that synthesizes these impacts from a multi-hazard perspective. Therefore, the present review provides an analysis and synthesis of publications of the last 20 years that analyzed climate hazard-induced alterations of water quality in transitional environments with a particular focus on eutrophication processes. The analysis revealed that multiple climate change hazards (including flood, storm surge, drought, tidal flooding and variation in wind regime) can influence the quality of transitional waters with flood and drought being the most prominent ones investigated in 74% and 44% of the studies respectively. These hazards and their interactions can alter the dynamics of water quality constituents through their influence on the hydrodynamic, morphodynamic, and biogeochemical processes of transitional ecosystems. This involves a variety of mechanisms and interdependent processes such as the mobilization and transport of sediments, nutrients, and other pollutants, the interaction of water masses with different characteristics, and the changes in water residence time. Nutrient concentration, salinity, turbidity, water temperature, and Chlorophyll-a (Chl-a) and primary productivity are the principal eutrophication-related parameters altered by different hazards. Besides, the interactions among different water quality indicators play a significant role in determining the overall water quality dynamics and the tendency of eutrophication. To illustrate these complex interactions, a conceptual framework was developed which can assist the understanding and analysis of climate change multi-hazard impacts on transitional waters. Finally, this work highlights that innovative observational and modeling tools are crucial for addressing the complex and dynamic interactions among climate change-related stressors, ecosystem processes, water quality constituents, site-specific morphological features and management interventions. Hence, the advancement of methodologies capable of integrating high-resolution remote and in-situ data collection technologies, alongside advanced physics-based and AI-driven models, leveraging their combined strengths, are required to deepen the understanding of complex system dynamics under multiple pressures, providing critical insights for informed decision-making on adaptation strategies.