Effects of clay content distribution on soil hydrothermal responses in the Lake Chad region: Numerical investigation

Understanding water dynamics under the effect of climatic conditions is important to improve water sustainability over the medium- and long-term. Clay content can affect soil hydrothermal properties, and hence modify water and heat exchange between soil and atmosphere, e.g. evapotranspiration and infiltration. This work aims to develop a numerical approach to explore the influence of clay content on soil hydrothermal response to the timely climatic conditions in the Lake Chad region, Sahel Region of west-central Africa. The meteorological information at the studied points, i.e. points A and B with a clay content of 8.3% and 25%, during the year 2008 is collected from ERA5-Land hourly data. The numerical results allow for understanding the effect of clay content on the hydrothermal response of the surface soil layer. Specifically, the soil surface temperature under point A is lower than that under point B during the dry season due to the dominant effect of heat conduction. However, the converse tendency is observed during the wet season because of the combined effect of heat conduction and latent heat. The variations of soil volumetric water content are closely related to the timely interaction between the soil and atmosphere, in addition to the hydrothermal properties of soil. Moreover, the outcomes of this work improve the understanding of the heat and water dynamics under the effect of climatic conditions and clay content, and provide further insights into the potential water protection in arid and semi-arid regions in the future.