Capture of overland flow by a tree belt on a pastured hillslope in south-eastern Australia

摘要

We describe a rainfall simulator experiment designed to measure the capture, by a fenced tree belt, of excess water generated as Hortonian flow from a pasture slope. Three rainfall events (48, 49, and 75 mm/h for 13, 30, and 30 min, respectively) were applied, of which 15%, 29%, and 44%, respectively, ran off and drained onto the tree belt. The tree belt captured 100%, 32–68%, and 0–28% of the runoff from the 3 events, respectively. These captured runoff volumes represented 31–39%, 22–45%, and 0–29% increases in water supply to the trees, in addition to incident rainfall. Infiltration rates within the tree belt were up to 46% higher than in the pasture zone. This higher infiltration was mainly attributed to better soil surface conditions in the absence of stock and a 50-mm layer of tree litter. Overland flows within the tree belt formed tree litter into microterraces, which spread and slowed flows and allowed greater time for infiltration.