Some characteristics of river morphology depends on flow and relations have been established (Cristofaletti, 1981). Besides this, the flow is influenced by the basin physical conditions, such as drainage area, topography, ground cover and use. Furthermore, the basin area is one of the most important factors on the data transfer of regional flow hydrological studies (e.g. Chow, 1964; Tucci, 1993).

Based on streamflow station field surveys and cartographic data analysis, this works presents relations derived for two morphological river parameters (main river length and cross section width) as a function of basin drainage area for different regions of Bahia. The relation between flow and drainage area is also presented.

As a results equation like Y= a A^b showed good fit to the data. The relation between main river length (L) and drainage area (A) was the best one. For different regions a and b have changed. For example, the Paraguaçu River that runs to the Ocean and has headwaters in Chapada Diamantina resulted in the equation L = 1,175A^0,555, while the Corrente River Basin, which runs over a sedimentary plateau, left margin of São Francisco River, resulted in L= 16,44 A^0,287

The relations between the maximum discharge and drainage area were best fit to perennial rivers rather than intermittent ones.