LARGE-SCALE RAINFALL SIMULATION EXPERIMENTS ON JUNIPER RANGELANDS

The effects of shrub clearing on surface and subsurface water movement in the Edwards Aquifer region were investigated using two large-scale rainfall simulation plots. Multiple replications of a large (168 mm) rainfall event were applied at an ashe juniper covered plot before and after shrub removal and at a plot with longstanding herbaceous cover. The study sites were equipped for monitoring of throughfall, stemflow, surface runoff, and soil water. Lateral subsurface flow was measured in a trench at the downhill end of each plot. The canopy plot produced high lateral subsurface flow during rainfall but no surface runoff, even for high rainfall intensities. In contrast, hydrologic response at the inter-canopy plot was dominated by rapid surface runoff. Following shrub removal at the canopy plot, water movement beyond the soil layer increased due to reduced canopy interception. Soil water storage capacity at the shrub plot remained small for both conditions, with much water apparently bypassing the litter and soil layers via macropore pathways. This additional water could move off site as macropore flow or remain on site as matrix and conduit storage. Differences in surface runoff and subsurfaceflow are attributable to vegetation and geologic differences. 2008 American Society of Agricultural and Biological Engineers.

LARGE-SCALE RAINFALL SIMULATION EXPERIMENTS ON JUNIPER RANGELANDS Academic Article