Linking soil thickness and plot-scale hydrological processes on the sloping lands in the Three Gorges Area of China: a hydropedological approach

The emerging interdisciplinary field of hydropedology promotes synergistic integration of pedology and hydrology to enhance the holistic study of soil–water interactions across space and time. Our study illustrated this integration, exemplifying from plot-scale hydrological processes investigations on the sloping lands with different soil thickness in the Three Gorges Area of China. Our aims were to deal with (i) the watershed scale soil thickness survey, soil profiles description and hydrological processes inferential analysis for the plots with typical soil thickness from the pedological perspective, and (ii) the identification of dominant hydrological processes of these plots based on hydrological monitoring under simulated rainfall (designed as 60 mm h−1) from the hydrological perspective. The main results can be summarised as follows: (i) soil thickness of the sloping lands exhibited a wide range of variability along hillslopes. Thin soils reflected weaker pedogenesis degrees and less intense human intervention as compared with thick soils. (ii) Deep percolation and subsurface flow were the dominant processes in thin soils, whereas in thick soils, surface flow, deep percolation and storage were the dominant processes. (iii) Regarding to the surface flow, the 23-cm plot was mainly in the form of saturated overland flow, whereas the other plots were Horton overland flow. As to the subsurface flow, both 23- and 31-cm plots mainly took the form of preferential flow, the 59- and 76-cm plots mainly in the form of matrix flow regardless of soil horizon and the 45-cm plot displayed mainly the matrix flow in the A horizon and mainly the preferential flow in the AC horizon. Our study suggested that, relative to its parent disciplines of both pedology and hydrology, hydropedology improved synergies between pedology and hydrology in the plot-scale hydrological processes investigations. Copyright © 2011 John Wiley & Sons, Ltd.