Climate modeling and Groundwater: the key role of the water table in the terrestrial water cycle

Monday, 15 December 2014: 3:25 PM
Gonzalo Miguez-Macho1, Ying Fan2, Alberto Martínez de la Torre1,3, Breogan Gomez1 and Yadu N Pokhrel4, (1)Universidade de Santiago de Compostela, Santiago de Compostela, Spain, (2)Rutgers Univ, Piscataway, NJ, United States, (3)NERC center for Ecology and Hydrology, Wallingford, United Kingdom, (4)Michigan State University, Department of Civil & Environmental Engineering, East Lansing, MI, United States
The incorporation of groundwater processes in land surface models has improved the representation and our understanding of terrestrial water cycles. We discuss here how the consideration of the water table as a dynamic lower boundary for the vadose zone and the inclusion of lateral flow driven by gravitation, which redistributes groundwater horizontally, create a persistent underlying pattern on soil moisture conditions linked to topography, with wetter valleys and drier hilltops. The long scales of evolution of groundwater induce soil moisture memory, and groundwater-surface water exchanges are fundamental for wetland, river and floodplain dynamics. One step further, this reshaping of the land-surface hydrology by groundwater has an important impact on climate and ecosystems, via evapotranspiration and sensible heat fluxes. We will show some examples of the key role of groundwater on the terrestrial water and energy cycles using a fully coupled groundwater-soil-vegetation-atmosphere model.