Distribution of dried soil layers on the dividing waterline in the gully area of the Loess Plateau

The northern Loess Plateau is characterized by dense gullies and fragmented topography. The status of soil water shortage in this region is complicated under the combined effects of topography and vegetation. In this research, we designed 15 observational sites on 3 dividing waterlines in the gully area of Liudaogou catchment in Shenmu country. Based on long-term observation with neutron probe, we studied the spatial-temporal distribution of deep soil moisture as well as the characteristics of dried soil layer. The specific results were showed as follow:① Soil moisture was in deficit in 0-3 m soil layers in the growing season, then it was recharged above 1.2 m depth. Soil moisture under 1.2 m depth did not recover and soil water deficit was serious in 2.6-6.4 m soil layers. ② The profile distribution of soil water content and relevant depths of extreme values as well as the occurred range of dried soil layers were inconsistent among different observational points. Moreover, the profile distribution of dried soil layers along the dividing waterline was discontinuous. ③ The thickness of dried soil layers varied within the range of 0.4-8 m, the average formed depth of dried soil layer and mean soil moisture within the dried soil layer were 2.03 m and 9.03%, respectively. The former had negative linear correlations with the latter two quantitative indices. Compared with the average status of the Loess Plateau, dried soil layers in the gully area was more prominent. These results were expected to provide help for comprehensively evaluating the function and status of soil water reservoir in gully area.