Assessment of derived flood frequency distributions

Derived flood frequency distributions based on the geomorphologic IUH are evaluated in this work. Two existing approaches, the methods of Hebson and Wood (1982) and Diaz-Granados et al. (1984), are evaluated for four catchments in Texas with different climate, geomorphology, soil type, and land use characteristics. The Diaz-Granados et al. technique was modified to use the SCS Curve Number method because the required data are more readily available than the parameters in the original formulation. The extreme value distributions from the three techniques are compared with those obtained from historic records using standard techniques. Sensitivity analysis of the parameters of the model derived in this work were carried out to provide an understanding of the evaluation of the parameters and their impact on the final distributions.