Soil matters: Evaluating soil texture and irrigation impacts in Earth system simulations

Soil texture characteristics play an important role in determining the amount of soil moisture and the availability of water for evapotranspiration. As a result, they might affect the components of the water and the surface energy balance. An anthropogenic practice that also influences these components is irrigation, enhancing soil moisture, which subsequently leads to an increase in latent heat flux. Moreover, in some irrigation parameterizations, soil texture characteristics such as field capacity and permanent wilting point determine the irrigation amount, potentially affecting the overall impact of irrigation on surface variables. Some studies evaluated the impact of different soil texture maps globally and regionally in climate models, while other studies investigated the impact of irrigation on surface and atmospheric variables. However, the combined effect of soil parameters and irrigation on Earth system modeling, particularly in the context of uniform soil texture maps, has not been investigated yet.

 

In this study, we assess the impact of two uniform soil texture maps on the surface energy and water budget components over the EURO-CORDEX domain during the years 2017–2018, both in isolation and in combination with irrigation. We choose uniform loam and sand soil type maps to evaluate the potential extent of change in the interactions between soil, climate and irrigation. Moreover, these soil textures are more common in agricultural land. We conduct a set of five simulations with the ICON-nwp model at 3 km resolution, a control run and four experiments. The control run includes the default soil map and no irrigation. Then, we perform two sets of experiments utilizing uniform soil maps, one representing loam and the other sand, both with and without irrigation. The surface energy balance decomposition (SEB) method (Thiery et al., 2017) allows us to determine which components of the surface energy balance influence any temperature changes. Some preliminary results indicate that the uniform sandy soil experiment intensifies the heat wave of 2018. In the same year, experiments with irrigation show that the temperature cooling is stronger over the uniform sandy soil experiment in the Alps, East Europe and Mid-Europe. In contrast, the temperature cooling is stronger over the uniform loamy soil experiment in moisture-limited regions such as the Iberian Peninsula and the Mediterranean. The SEB identifies the variables that mostly influence the temperature changes across different prudence regions.