Land use is fundamentally changing water resources. Water extraction is drawing down water tables and lowering river levels; land use change affects the partitioning of water fluxes; changes in surface runoff and aquifer recharge will affect surface water and groundwater resources; while changes in evapotranspiration may feed back to precipitation regimes. Given the interactions between different hydrometeorological processes, a systems approach is needed. This project is the first to combine both climate impacts on the hydrological regime and hydrological feedbacks on the climate. This is accomplished by using a state-of-the-art suite of data assimilation, new process understanding, and integrated modelling of the atmosphere surface groundwater system. The set-up will be used to evaluate anthropogenic and natural changes in major water fluxes and resources for the Gangetic Plain. The northern Indian plains have experienced land use changes and water exploitation at an unprecedented scale, posing extraordinary scientific challenges to understand, quantify and predict availability of water resources.
We focus on the following questions: (1) To what extent do the large-scale, human-induced land use changes and groundwater depletion that have taken place in India feed back to the hydrological and climate system at a basin scale? (2) How should climate model outputs be disaggregated to provide the boundary conditions needed for hydrological and water resource systems modelling, and do the results of such modelling provide suitable reductions in the uncertainty of projections? (3) Can large-scale modelling studies inform localised, ecosystem-based management decisions to improve water availability and security? The Ganga River is not only crucial for the socio-economic development of the country; it also provides a unique case of large-scale river systems dominated by groundwater resources. The project specifically addresses the scope of the call, especially the themes on interactions between the surface and subsurface, water cycle drivers and mechanisms, and the water cycle-anthropogenic interface.