Revision of regional maximum flood (RMF) estimation in Namibia

Abstract

Extreme flood hydrology in Namibia for the past 30 years has largely been based on the South African Department of Water Affairs Technical Report 137 (TR 137) of 1988. This report proposes an empirically established upper limit of flood peaks for regions called the regional maximum flood (RMF), which could be associated with an annual recurrence interval of 10 000 years. This paper revisits the Kovacs RMF flood model applicable to Namibia, and incorporates 30 years of additional systematic data as well as palaeoflood data into the model. A revised graphical distribution of the K-value zones for Namibia is presented and is proposed to replace the current model. The results confirm the work previously done by Kovacs and, in some places, increase the bounds of the RMF zones. The proposed new model may also contribute to a South African update of the Kovacs model, providing useful information along the southern and eastern borders of Namibia.