Soil water response to precipitation in different micro-topographies on the semi-arid Loess Plateau, China

Abstract

Soil water is an important factor restricting afforestation on the semi-arid Loess Plateau. The micro-topography of the loess slope has changed the distribution pattern of soil water on the slope. To improve water utilization efficiency and optimize afforestation configuration patterns, the relationship between soil water and precipitation at micro-topographic scale must be studied. We used time series analysis to study the temporal variation of soil water and its response to precipitation in four kinds of micro-topographies and undisturbed slope on loess slopes. Micro-topographies significantly influenced soil water distribution and dynamics on the slopes. Soil water stored in the platform, sinkhole, and ephemeral gully influenced subsequent soil water for 4 weeks, whereas soil water stored in the scarp and undisturbed slope could influence soil water for 2 weeks. It took 12 weeks, 10 weeks, 18 weeks, 6 weeks, and 12 weeks for precipitation to reach the deeper soil layer in the platform, sinkhole, scarp, ephemeral gully, and undisturbed slope, respectively. These soil water characteristics in different micro-topographies are vital factors that should be taken into consideration when undertaking afforestation on the Loess Plateau.