An alternative procedure to evaluate the dechannelling correction for the extraction of disorder depths distributions, particularly for high levels of disorder, in channelling-backscattering studies is described. It involves the use of experimentally determined values of dechannelling and was used for the extraction of damage distributions in a study of disorder generated by 40 keV N+, P+, As+and Bi+and 20-200 keV Sb+bombardment of (100) GaAs at 40°K. As a result the method appears applicable at least when thermal annealing of disorder is absent. A comparison with various models of small angle scattering is also made.