The Effects of Riparian Clearing and Clearfelling of an Indigenous Forest on Streamflow, Stormflow and Water Quality

SYNOPSIS The paired catchment method was used to measure the effects of riparian zone clearing and clearfelling on streamflow, stormflows and water quality. The forested riparian zone of a 39,6 ha, humid Northern Province catchment, amounting to 10 % of the catchment area, was cleared and kept clear of vegetation. Two years later the entire catchment was cleared by bulldozing and burning its cover of indigenous evergreen forest and scrub forest, and replanted to Eucalyptus grandis seedlings. The riparian clearing resulted in a small 55 mm (9 %) increase in streamflow in the first year, and mean increases per storm in quickflow volume of 2,32 mm (71 %), in stormflow volume of 4,60 mm (76 %) and in storm response ratio by 2,37 % (a 50 % increase). By the second year these effects were diminished, and total flow was reduced by 56 mm (19 %) below expected flow. Clearfelling and replanting of the catchment had similarly small effects on streamflow and stormflows. This could be ascribed partly to a serious drou...