Morphometry of river deltas

Abstract

The modern morphometry of deltas of numerous rivers of the world was studied using cartographic and satellite data. The deltas were subdivided into two groups: bayhead deltas of sea bays, limans, lagoons, and estuaries and protruding deltas on open coasts of seas and lakes. The morphometric parameters measured for both delta types include delta length along its main branch, the length of its marginal coastline (sea, lake, liman, and lagoon), delta area, and the number of mouths of main branches; some morphometric parameters were calculated. Regression analysis was used to study the relationships between the morphometric delta parameters taken in pairs as well as between these parameters and the values of external factors responsible for delta formation (first of all, water and sediment river runoff). The closeness of the calculated empirical relationships was assessed. Considerable differences were revealed in the obtained relationships for the two types of deltas. Based on the calculations, two geometric models of typical deltas were proposed: bayhead delta and protruding delta. The obtained results can be used for approximate assessment of possible changes in river deltas under the condition of variations in river water and sediment runoff and in the sea level.