Some effects of afforestation on streamflow in the Western Cape Province, South Africa
Abstract
This paper reports results of a multiple catchment experiment in the South Western Cape Province of South Africa where the influence of afforestation with Pinus radiata on streamflow was monitored from 1940 to 1980. Afforestation resulted in reduced streamflow. In the case where 98% of the catchment was afforested streamflow decreased by 313 mm from an initial 663 mm to an average of 350 mm/a over a period between 12 and 32 years after afforestation. Streamflow stabilised at this level. In the catchment with 57% afforestation, streamflow declined by 200 mm/a from an initial 593 mm/a over the period 16 to 40 years after afforestation. Here streamflow stabilised at about 20 years. Percentage of area afforested, total biomass and rainfall appear to have influenced the magnitude of reductions in streamflow.