The present paper characterizes the distribution of sediments and geo-forms in a tidal channel within the Guadiana River Mouth using Side Scan Sonar techniques. This work presents a map of bed distribution in terms of sedimentary lithology and geomorphological features. Trom a Hthological point of view clean sands, muddy sands and sandy muds can be distinguished. Trom a dynamic perspective, each Hthological type can present accumulative or erosional features. The dominant flow regime in the sandy beds can be deduced from the morphology and asymmetry ofbedforms