A preliminary investigation of water storage in check-dams across China's Loess Plateau using electrical resistivity tomography

Check dams are typical deposition sites that trap and store eroded sediments from uplands and are widely constructed on China's Loess Plateau (LP) as an effective soil and water conservation practice. Compared with slope land (SL), check-dam land (DL) may store more water resources and play an important role in food production and water regulation in watersheds. However, little is known about the water distribution characteristics and driving factors of DL. In this study, we investigated seven DLs in different regions of the LP and four SLs under different land uses using the non-invasive electrical resistivity tomography (ERT) technique and established a nonlinear model correlating electrical resistivity (rho) and soil water content (theta(v)). The results showed that theta(v) can be successfully estimated by rho using the power function model according to the coefficient of determination (R-2 = 0.77) and root-mean-square error (RMSE = 0.035 cm(3)/cm(3)), indicating that ERT is applicable for estimating water resources in the loessal region. Generally, the distribution of DL water resources can be divided into three types: (i) unsaturated throughout the entire profile, (ii) unsaturated in the top but saturated in the lower profile and (iii) approximately saturated throughout the profile with minimal spatial variation. The different water distribution characteristics among the DLs may be related to the soil texture, land use type and drainage facility. The total mean water storage in the 0-4 m profile of DL for different land-use types was 1.5-2.0 times higher than that of SL. Therefore, DL water stores should not be ignored when assessing hydrological cycles and the water budget in a watershed in the LP. Future research should be implemented to understand the hydrological processes and ecological effects of both DL and SL to optimize water management strategies with sustainable ecosystem functions in the loessal region.