Topography of inland deltas: Observations, modeling, and experiments

Abstract

The topography of inland deltas is influenced by the water‐sediment balance in distributary channels and local evaporation and seepage rates. In this letter a reduced complexity model is applied to simulate inland delta formation, and results are compared with the Okavango Delta, Botswana and with a laboratory experiment. We show that water loss in inland deltas produces fundamentally different dynamics of water and sediment transport than coastal deltas, especially deposition associated with expansion‐contraction dynamics 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 following a power law with exponent α = −0.69 ± 0.02 where the data for both simulation and experiment can be collapsed onto a single curve. In coastal deltas, on the contrary, the slope increases toward the end of the deposition zone.