Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run-off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially delivered within the soil profile. However, run-off was not observed until soil water content of the profile reached field capacity, and the apertures of surface-connected cracks had closed >60%. Electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport, even in wet conditions. Likewise, single-ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values, despite apparent surface sealing. Overall, although the wetting and sealing of the soil profile showed considerable complexity, an emergent property at the hillslope scale was observed: all of the plots demonstrated a strikingly similar threshold run-off response to the cumulative precipitation amount.
|Title||Hillslope run-off thresholds with shrink–swell clay soils|
|Authors||Ryan D. Stewart, Majdi R. Abou Najm, David E. Rupp, John W. Lane, Hamil C. Uribe, José Luis Arumí, John S. Selker|
|Publication Subtype||Journal Article|
|Series Title||Hydrological Processes|
|Record Source||USGS Publications Warehouse|
|USGS Organization||OGW Branch of Geophysics|