Contribution of event water to soil water content using specific conductivity as a tracer under different land covers

How precipitation recharges the soil water is essential for managing water resources of semiarid rangeland ecosystems. This research assessed the soil water content (SWC) dynamics at soil depths of 0.05 m, 0.25 m, 0.5 m, and 1 m over an annual cycle under four vegetation types—shrubs, tussock grass, meadow, and dwarf heath shrub. In addition, the specific conductivity was measured at each location and used as a tracer in a simple two-component mixing model.

The time series analysis indicates that the SWC response to precipitation differs in different land covers. Shrubs exhibited higher SWC at shallow depths, while tussock grass showed lower SWC compared to other vegetation types in the upper layers. Instead, meadow and dwarf heath shrubs had a similar temporal variability and amplitude which dampened towards deeper soil layers. The temporal variability of new water varied among the different vegetation types.  Shallow soil layers in the meadow had a high temporal variable but where stable in deeper layers.

These findings provide insights into the connectivity and interplay between the atmosphere, vegetation and different soil layers. These first findings offering a better understanding of ecohydrological processes at locations with different landcover and will help to improve our understanding of rainfall-runoff processes at catchment scale to develop water and landscape management strategies for these delicate semiarid ecosystems.

Acknowledgements: P. H-F thanks SIA 85220121 and FONDECYT N°1240314 for funding. While, R. M-A and S. R-S thank FONDEF ID22I10139.