Impacts of land use and land cover change on blue and green water resources availability

Ongoing anthropogenic climate change and other human interventions increasingly interfere with freshwater availability and its distribution. Land use, land management, and land cover change (LULCC), in particular, shapes water resources by altering the partitioning of precipitation into green and blue water. Yet, a comprehensive understanding of how LULCC influences global precipitation partitioning is lacking. We address this gap by employing the Blue-Green Water Share (BGWS) metric, which quantifies water partitioning dynamics using monthly precipitation data, while monthly runoff and transpiration data serve as proxies for blue and green water flows. Using simulations from the Land Use Model Intercomparison Project (LUMIP), a component of the Coupled Model Intercomparison Project Phase 6 (CMIP6), we evaluate how LULCC impacts precipitation partitioning. Historical land use change impacts are isolated using simulations without land use change (hist-noLu). Additionally, we assess the effects of different land use scenarios on the BGWS under the Shared Socioeconomic Pathways (SSPs) 1-2.6 and 3-7.0 (ssp370ssp126Lu and ssp126ssp370Lu). Regression analysis and variable importance computations are performed to identify key drivers of BGWS trends, comparing the relative contributions of LULCC and climatic factors to shifts in green and blue water flows. Our results highlight the critical need to understand green and blue water dynamics for sustainable water resource management in the face of changing climatic and land use conditions. By advancing our knowledge of the hydrological consequences of LULCC, this research provides actionable insights to inform land-based climate mitigation and adaptation strategies.