Spatiotemporal soil water storage variation comparison between newly formed and untreated gully land sites under a land restoration project and associated implications on land management

Soil water storage (SWS) can effectively be used as an important indicator to manage soil water resources in water-limited ecosystems, being strongly linked to land-use and land management changes. The Government of China launched the Gully Land Consolidation (GLC) project in 2011 to reclaim landforms and resolve land scarcity and food shortages in the Chinese Loess Plateau (CLP) without endangering the environment. Corollary effects of this project were alterations to original landscapes and associated hydrological processes. However, temporal dynamics in available soil water of the newly formed land for cultivation purposes remain unclear. Accordingly, this study measured SWS to a 5 m soil depth over a 5-year period at two gully sites, one newly formed under the GLC project (i.e., the experimental site) and the other left untreated (i.e., the control). SWS exhibited similarly weak temporal variation at both gully sites (coefficient of variation [CV] = 6% at the experimental site; CV = 11% at the control site). Although SWS always negatively correlated to mean temperature and wind speed (p < 0.05) with no observable hysteresis, SWS responded to precipitation at both sites with obvious hysteresis (experimental site = two month hysteresis; control site = three months hysteresis). Seasonal SWS characteristics confirmed the lag response to precipitation. Moreover, spatial SWS patterns differed distinctly at both sites. The mean proportion of available SWS to the available water holding capacity was 69% at the experimental site, indicating that stored soil water was available for crop cultivation without the threat of water shortages. Our results provide new insight into spatial and temporal SWS variation in newly formed land engineered by restoration projects. Furthermore, clarifying SWS temporal dynamics and spatial distributions based on long-term monitoring is essential to evaluate, model, and manage water resources in areas affected by anthropic activities.

Automated summary

Soil water storage (SWS) is an important indicator for managing water resources, and it is closely related to land use and management changes. The Gully Land Consolidation (GLC) project in China has altered landscapes and hydrological processes, but the temporal dynamics of SWS in newly formed land remain unclear. This study found that SWS had weak temporal variation and responded to precipitation with hysteresis. The spatial distribution of SWS also differed between sites. The results provide new insights into SWS variation in restored land and highlight the importance of long-term monitoring for water resource management.