Evaluating subsurface flow connectivity in a pine-covered hillslope with stemflow infiltration and ground-penetrating radar surveys

The hydrological response of sloping catchments is strongly conditioned by the connectivity of subsurface preferential flows. The objective of this paper is to investigate the role played by stemflow infiltration in subsurface water flow dynamics, focusing on a forested hillslope located in an Aleppo pine Mediterranean forest (Pinus halepensis, Mill.) located at Sierra Calderona, Valencia province, Spain. We combined stemflow artificial experiments with the ground-penetrating radar (GPR) as a non-invasive technique to investigate stemflowinduced preferential flow paths activated by different trees and the related hydrological connectivity at the hillslope scale. Our observations allowed us to identify different dynamics associated with the initiation of stemflow and then lateral preferential flow, including the activation of connected preferential flow paths that received stemflow water from different trees. These observations provided empirical evidence of the role of stemflow in the formation of lateral preferential flow networks. Our measurements also provided estimations for flow velocities, which provided new insight on the magnitude of stem-induced lateral preferential flow paths. The applied protocol offers a simple, repeatable and non-invasive way to conceptualize hillslope responses to rainstorms.

Automated summary

This paper investigates the role of stemflow infiltration in subsurface water flow dynamics in sloping catchments. The study utilized artificial experiments and ground-penetrating radar to examine preferential flow paths and hydrological connectivity on a forested hillslope in a Mediterranean forest. The findings highlight the role of stemflow in the formation of lateral preferential flow networks and provide insights into the magnitude of stem-induced flow paths. The applied protocol offers a simple and non-invasive approach to understanding hillslope responses to rainstorms.