GROUND WATER INPUT TO A RARE FLOOD EVENT IN AN ARID ZONE EPHEMERAL RIVER IDENTIFIED WITH ISOTOPES AND CHEMISTRY

摘要

Various isotope studies in temperate climates have shown that the shallowgroundwater component feeding perennial rivers during rainfall events can be moreimportant than surface runoff. We report here on possibly unique isotopic and chemicalevidence of groundwater contributions to a rare flood event of the ephemeral AuobRiver during the exceptional rains of 1999/2000 in the arid/semi-arid Kalahari of south-easternNamibia. The recognition of this process was enabled by a detailed knowledgeof the isotope hydrology of groundwater in the area and provided insights into aspectsof the palaeo-hydrology of the Auob River catchment.