Vertical distribution of soil saturated hydraulic conductivity and its influencing factors in a small karst catchment in Southwest China

Abstract

Saturated hydraulic conductivity (Ks) is one of the most important soil hydraulic parameters influencing hydrological processes. This paper aims to investigate the vertical distribution of Ks and to analyze its influencing factors in a small karst catchment in Southwest China. Ks was measured in 23 soil profiles for six soil horizons using a constant head method. These profiles were chosen in different topographical locations (upslope, downslope, and depression) and different land-use types (forestland, shrubland, shrub-grassland, and farmland). The influencing factors of Ks, including rock fragment content (RC), bulk density (BD), capillary porosity (CP), non-capillary porosity (NCP), and soil organic carbon (SOC), were analyzed by partial correlation analysis. The mean Ks value was higher in the entire profile in the upslope and downslope, but lower value, acting as a water-resisting layer, was found in the 10-20 cm soil depth in the depression. Higher mean Ks values were found in the soil profiles in the forestland, shrubland, and shrub-grassland, but lower in the farmland. These results indicated that saturation-excess runoff could occur primarily in the hillslopes but infiltration-excess runoff in the depression. Compared with other land-use types, surface runoff is more likely to occur in the farmlands. RC had higher correlation coefficients with Ks in all categories concerned except in the forestland and farmland with little or no rock fragments, indicating that RC was the dominant influencing factor of Ks. These results suggested that the vertical distributions of Ks and RC should be considered for hydrological modeling in karst areas.

Combined deep sampling and mass-based approaches to assess soil carbon and nitrogen losses due to land-use changes in karst area of southwestern China

“…In the karst area, most early reports have focused on the top soil layer (e.g., ≤ 30 cm) to assess the SOC stocks changes Fu et al, 2015;Liu et al, 2015b;Zhang et al, 2012). These above-mentioned works and other superficial studies on how land use changes may alter SOM dynamics (Post and Kwon, 2000;West and Post, 2002), may lead to erroneous results.…”

“…We hypothesized that the ecological resettlement program may deplete SOM stocks, and thus cause soil degradation. Recently, some researchers have paid more attention about the effect of land use change on the soil physicochemical properties and soil quality in this karst region (Fu et al, 2015;Hu et al, 2014;Xie et al, 2015;Xu et al, 2008). However, studies on soil C dynamics were mainly focused on the surface layers (e.g., ≤ 30 cm), and the FD method is utilized to assess SOC stocks Fu et al, 2015;Liu et al, 2015b;Zhang et al, 2012).…”

Analysis of soil moisture condition under different land uses in the arid region of Horqin sandy land, northern China

“…3). This is because the "dry" sequence appeared (Fu et al, 2003). In arid land, the soil moisture content often reached its highest value after a heavier rain, and when the rain had stopped for a couple of days, the soil moisture content decreased sharply due to evapotranspiration, absorbed by roots or runoff etc.…”

“…Therefore, spatial and temporal variations of soil moisture have always been the critical issues in vegetation restoration and water resource management, especially in the semi-arid and arid ecosystems (Brevik et al, 2015;Yu et al, 2015). Additionally, land use change contributes to the variability of soil moisture, resulting in soil deterioration, agricultural productivity decline and land degradation (Biro et al, 2013;Fu et al, 2003;Leh et al, 2013;Parras-Alcántara and Lozano-García, 2014).…”

“…It is the feedback between the infiltration of water from precipitation and the water use characteristics of the particular vegetation community that ecologically predominates in an area that determines the moisture state of the soil in the root zone (Sandvig and Phillips, 2006). Some studies have shown that plant biomass and productivity increased significantly with increasing soil infiltration rates, which have close relationships with covered vegetation types (Benegas et al, 2014;Finley and Glenn, 2010;Fu et al, 2015;Zhang et al, 2014;Zheng et al, 2015). In addition to types and coverage degrees of vegetation (Cerdà, 1998;Molina et al, 2007), precipitation patterns , antecedent soil water content (Guo et al, 2014) and soil properties (Neris et al, 2012) also play the influential role in the water infiltration process.…”