• Studying simulations at CESGA highlights the importance of including the groundwater dynamics in climate models.
• The groundwater reserve plays an essential role to properly simulate the climate of regions with limited water resources and arid features, like the interior of the Iberian Peninsula.

The atmospheric and hydrologic simulation to study the influence of groundwater in the hydrological cycle and climate is one of the lines of work of the Group of Nonlinear Physics in the Department of Condensed Matter Physics at the University of Santiago de Compostela. The results of the work done by researchers Gestial Lucia Souto, Alberto Martinez de la Torre and Alexandre Rios Entenza, provide some of the results of their research, which among other things show that groundwater is able to save the memory of climatic episodes.

According to Alberto Martinez de la Torre, "Simulations performed with a hydrological and soil model in which we include an implementation that simulates the dynamics of groundwater and its interaction with the surface areas of the ground." With these simulations, which are performed using the computing power of the Supercomputing Center of Galicia (CESGA), "We can study the influence of the phreatic layer and its position in the flow of water and the heat between earth and atmosphere, as well as the influence in the climate when we adjust our model to the meteorological models commonly used for climatic prediction."

Comprehensive climate models

Martinez de la Torre recalls that "Normally this influence is not included in climate studies and our results point to the importance of including groundwater dynamics in climate models."

"Most of the climate models used today do not include the dynamics of subterranean groundwater in their representations. Nevertheless, this reserve of groundwater plays an essential role when properly simulating the climate of regions with limited water and features of dryness, as in the case of large areas inside the Iberian Peninsula, where the water table is near the surface and decisively affects the water and heat flows established between the soil and the atmosphere."

In particular, says the physicist, "Focusing on the Iberian Peninsula, we find areas where the water table is near the surface, where groundwater soil holds moisture in dry seasons. Furthermore, this memory of weather events is stored in groundwater, whether mitigating effects on soils in dry years by accumulating rainfall in previous years, or for the long term effects of dry spells. As an example, this report found that the water table took three years of heavy rainfall to recover after the drought in the depression of Guadiana between the years 1992-1995, only reaching in the winter of 1998 the level prior to the drought."