Vertical and lateral soil moisture patterns on a Mediterranean karst hillslope

Abstract

Abstract:The need for a better understanding of factors controlling the variability of soil water content (θ) in space and time to adequately predict the movement of water in the soil and in the interphase soil-atmosphere is widely recognised. In this paper, we analyse how soil properties, surface cover and topography influence soil moisture (θ) over karstic lithology in a sub-humid Mediterranean mountain environment. For this analysis we have used 17 months of θ measurements with a high temporal resolution from different positions on a hillslope at the main recharge area of the Campo de Dalías aquifer, in Sierra de Gádor (Almería, SE Spain). Soil properties and surface cover vary depending on the position at the hillslope, and this variability has an important effect on θ. The higher clay content towards the lower position of the hillslope explains the increase of θ downslope at the subsurface horizon throughout the entire period studied. In the surface horizon (0-0.1 m), θ patterns coincide with those found at the subsurface horizon (0.1-0.35 m) during dry periods when the main control is also exerted by the higher percentage of clay that increases downslope and limits water depletion through evaporation. However, in wet periods, the wettest regime is found in the surface horizon at the upper position of the hillslope where plant cover, soil organic matter content, available water, unsaturated hydraulic conductivity (K unsat ) and infiltration rates are higher than in the lower positions. The presence of rock outcrops upslope the θ sampling area, acts as runoff sources, and subsurface flow generation between surface and subsurface horizons also may increase the differences between the upper and the lower positions of the hillslope during wet periods. Both rock and soil cracks and fissures act disconnecting surface water fluxes and reducing run-on to the lower position of the hillslope and thus they affect θ pattern as well as groundwater recharge. Understanding how terrain attributes, ground cover and soil factors interact for controlling θ pattern on karst hillslope is crucial to understand water fluxes in the vadose zone and dominant percolation mechanisms which also contribute to estimate groundwater recharge rates. Therefore, understanding of soil moisture dynamics provides very valuable information for designing rational strategies for the use and management of water resources, which is especially urgent in regions where groundwater supports human consume or key economic activities.

Response of soil water movement to rainfall under different land uses in karst regions

“…In karst areas, the processes of rainfall in ltration on hillslopes are mainly affected by rainfall characteristics (Gregory et al 2009), vegetation coverage, and soil properties (Canton et al 2016). Rainfall characteristics such as amount, intensity and frequency signi cantly affect the depth of soil water migration (He et al 2012;Yaseef et al 2009).…”

Temporal Soil Moisture Variations in Different Vegetation Cover Types in Karst Areas of Southwest China: A Plot Scale Case Study

“…Fu et al [22] found that soil texture was one of the main influence factors of soil moisture content, which was consistent with the result of this study. Canton et al [30] found that clay content, surface cover had effect on soil moisture on a Mediterranean karst hillslope, and high clay content could explain the increase of soil moisture content. In conclusion, soil texture and natural vegetation cover type could influence each other, such that different vegetation cover types are related to different soil texture and the vegetation cover type could influence soil moisture content by influencing soil texture.…”

Soil moisture responses under different vegetation types to winter rainfall events in a humid karst region

“…Soil moisture plays an important role in the growth of vegetation (Brantley et al 2017;Laio et al 2001). Vegetation can affect soil moisture and its response to precipitation via many complex and interacting hydrological processes (Canton et al 2016;Chen et al 2007;Daly and Porporato 2005;Rivera et al 2014). There are differences in the characteristics of the canopy and root distributions of different vegetation types, and these differences affect the response of soil moisture to rainfall (G ehrels et al 1998).…”