Effect of Clearfelling and Reforestation on Runoff and Peak Rates in Small Watersheds

Abstract

Two small forest (brush) Watersheds W₁F (1.45 ha) and W₂F (0.87 ha) were calibrated for 8 years (1961-68). During calibration period W₁F gave 18% more runoff and 63% higher peak rate of runoff as compared to W₂F. In the year 1969, W₁F was clearfelled and reafforested with Eucalyptus species. The post calibration relationship indicates that W₁F (treated) after afforestation gave 10% less runoff and peak rates of runoff as compared to W₂F (untreated). The total reduction of 28% in runoff and 73% in peak rate is due to afforestation resulting in fully stocked plantation and a dense undergrowth. The study has quantitatively indicated the effectiveness of afforestation for flood control purposes by reducing runoff (28%) and of drastically reducing the peak rate of runoff (73%).