The topography of inland deltas : observations , 1 modeling , experiments

The topography of inland deltas is influenced by the water-sediment bal-3 ance in distributary channels and local evaporation and seepage rates. In this 4 letter a reduced complexity model is applied to simulate inland delta forma-5 tion, and results are compared with the Okavango Delta, Botswana and with 6 a laboratory experiment. We show that water loss in inland deltas produces 7 fundamentally different dynamics of water and sediment transport than coastal 8 deltas, especially deposition associated with expansion-contraction dynam-9 ics at the channel head. These dynamics lead to a systematic decrease in the mean topographic slope of the inland delta with distance from the apex fol-11 lowing a power law with exponent α = −0.69 ± 0.02 where the data 12 for both simulation and experiment can be collapsed on a single curve. In 13 coastal deltas, on the contrary, the slope increases toward the end of the de-14 position zone.