Resumen de Hidrología de paleocrecidas en el río Kuiseb (Namibia) y sus implicaciones en la recarga de acuíferos
Gerardo Benito Ferrández, T. Grodek, Y. Enzel, Naomi Porat, J. Jacoby, Ofer Dahan, Gudrun Van Langenhove, Mary Seely, B. Botero
The Kuiseb River floods attenuate along the >100 km bedrock canyon channel, losing by transmission large volumes into a relatively wide (200-400 m) sandy braided alluvial downstream channel (~100 km) and reached the ocean only ~10 times since 1890. Slackwater flood deposition was found at 29 sites along ~120 km of the canyons of the Kuiseb River and its main tributary, the Gaub River and there were documented, dated (14C, OSL), and modeled five sites/reaches. A sequence of 13 flood units since early 20th century and 27 flood units since about >1000 years ago have been described. Step-backwater calculations using HEC-RAS indicate that floods of ~850 m3sec-1 deposited these two sequences. The largest Kuiseb River flood upstream of the Gaub-Kuiseb confluence was estimated in ~1350 m3s-1 based on a line of rotten tree logs on top of thin flood deposited (>5 ka) overlying a much older terrace. The frequency of these large floods is then used in determining the long-term frequency of recharging events along the entire river.
