The Lunyangwa Dam is prone to overtopping during the wet season. Raising the spillway crest and/or installing gates on the existing crest will allow an increase in the retention level. In order to determine the height of the redesigned spillway, a flood analysis was conducted for several return periods in HEC-HMS.
The Lunyangwa Dam is the source of water supply for Mzuzu City, Ekwendi Town and surrounding areas. Currently, the yield of the dam is lower than the annual average daily water demand from the dam. A quick intervention for this problem is to raise the spillway of the Lunyangwe Dam.
In order to determine the height of the redesigned spillway, FutureWater conducted a hydrological study for the Lunyangwa Dam Catchment to determine flood extremes for several return periods. HEC-HMS was used for calculating the peak volumes and discharges. The input for the HEC-HMS model was retrieved using satellite-based datasets for rainfall and terrain. Furthermore, the flood routing was simulated with an elevation-storage curve. The output of this study will be used for the redesign of the spillway.