RUNOFF AND SOIL-EROSION FROM AREAS OF BURNT SCRUB - COMPARISON OF EXPERIMENTAL RESULTS WITH THOSE PREDICTED BY THE WEPP MODEL

The effects of burning on runoff and soil erosion from scrub-bearing h illslopes in northwest Spain were investigated by monitoring of experi mental plots over a 4-year period. At the beginning of this period, tw o plots (BP1 and BP2) were subjected to low-intensity controlled burns , and two plots left as controls; in the year following the controlled burns, however, one of the control plots (plot WF) was burnt in a wil dfire of higher intensity than the controlled burns. Runoff and erosio n losses from the BP plots were only slightly higher than from the con trol plot, with the loss in no case exceeding 300 g m(-2) yr(-1). Eros ion losses from plot WF were considerably higher (1314 g m(-2) over th e 1st year post-burning, 8.5 times higher than from the control plot). These results were compared with those predicted using the Water Eros ion Prediction Project (WEPP) hillslope model (Version 95.7). In gener al, WEPP predictions of total runoff volume over the study period were acceptable: coefficients of determination for the regression of predi cted on observed values were 0.41, 0.68, 0.66 and 0.57 for the control plot and plots BP1, BP2 and WF, respectively. Erosion losses were lik ewise predicted with reasonable accuracy, though the model showed a co nsistent tendency to under-estimate, particularly with plot WF. (C) 19 98 Elsevier Science B.V.