Fluvial-tidal interactions, coastal erosion, and human modifications dominate the northwestern region. Dam construction near the head of Caņo Manamo, a large distributary channel, has greatly reduced the annual discharge and has led to local channel infilling. On the Atlantic shore east of Caņo Manamo, rapid shoreline retreat has exhumed late Holocene salt marsh peat.

The Atlantic shore of the central third of the delta is prograding. Mud capes and sandy spits are forming in response to sediment supplied by large distributary channels and northwesterly directed longshore currents. The currents transport large volumes of suspended sediment from the Orinoco, Amazon, and other rivers and deflect the channel courses of large Orinoco distributaries to the northwest.

The southeastern third of the delta is dominated by the flow of the main channel of the Orinoco River, the Rio Grande, and by semidiurnal tidal processes. This interaction produces an anastomosing channel pattern of bifurcating distributaries and intervening islands that are stabilized by mangrove forests. Longshore transport is negligible because the Guyana headland shelters this part of the delta from longshore currents that flow across the subaqueous delta platform. Geomorphic evidence indicates that Rio Grande, the main channel of the Orinoco River, has remained confined to the southern part of the delta during the Holocene, whereas distributary channels of the northern delta have avulsed frequently.