River monitors were used on inland waterways such as rivers, estuaries, deltas and lakes. Alluvial fan deltas in this region have shallow slopes. The Dalmatian pelican is found in lakes, rivers, deltas and estuaries. Most of their population is concentrated in the country's alluvial deltas and coastal plains. Mostly unnavigable, many originate as swift highland streams, meander in valleys, and form coastal deltas. This reservoir was deposited as a complex amalgamation of fan deltas and alluvial fans. The Okavango Delta, one of the world's largest inland deltas, is in the northwest. Pygmy cormorants like pools with plenty of vegetation, lakes and river deltas. The mangal is particularly prevalent in the deltas of large Asian rivers. The river must carry enough sediment to layer into deltas over time. It also appeared on Convair's next two deltas, the F-106 Delta Dart and B-58 Hustler. Researchers have found a number of examples of deltas that formed in Martian lakes. Distributaries are most often found in river deltas. They also occur on peneplains and some of the larger river deltas. Distributaries are a common feature of river deltas.