Barchan-dune movement in Imperial Valley, California

The movement of 47 barchan dunes on the west side of Salton Sea, California, ranged from 325 to 925 feet over the 7 years between 1956 and 1963, an average of 82 feet per year. During the 15 years between 1941 and 1956, the movement of 34 of these dunes ranged between 350 and 1200 feet, an average of 50 feet per year. This difference in average movement during the two intervals is attributed primarily to increased sand supply. Movement (D) plotted against height of slip face (H) for the Salton dunes fits reasonably well with Finkel's reciprocal curve (1/D = n + k H) or with a law of the type D = Pe^rH. Factors other than height affect the rate of movement, one of the more important being the state of the dune, whether growing or steady state. Barchan shape, whether fat or slim, may also influence the rate of movement of growing dunes. None of these dunes needs be more than 300 years old.