Dam Synchronisation and Flood Releases - agriwaterpedia.info

DAM SYNCHRONISATION AND FLOOD RELEASES IN THE ZAMBEZI RIVER BASIN: ANNEX 4 OF FINAL REPORT
if suitable, some could be defined as flooding areas whose use would be limited to activities with
low economic value. When a flood wave comes, the peak is reduced by diverting some of the
flood waters away from the channel into a local depression. An example, of diversion of floods
can be found at Marromeu where flood waters are diverted into Marromeu Buffalo Reserve of
the Zambezi Delta would improve the ecological conditions in the marsh and reduce the impact
of flooding in surrounding areas of the delta that are populated. Costing of this measure is very
site specific and cannot be done here. In this regard it is also worthwhile mentioning the idea of
diverting the Ruo River flood through the Elephant Marsh on the Shire River, as discussed in
Chapter 3.
Storage reservoirs
Storage reservoirs can be used in flood control. To this end, some of (or all) the reservoir
effective storage capacity is allocated to flood control in order to decrease and delay the flood
peak in the river reach downstream of the reservoir. This option has been discussed in Chapter
5.
Site specific for Chobe plains; adjustment of Ngoma bridge
The Department of Water Affairs in Namibia (2004) identified a possibility of flood protection
measures at the bridge of Ngoma Gate to avoid back water of the Zambezi coming up the
Chobe. The idea would be to control flow by means of gates under the bridge and to partly
retain floodwater in order to form an artificial open water body. Besides flood control for the
downstream area, this would provide continued opportunities for fishing at the time when Lake
Liambezi is drying out, and also be beneficial for wildlife and tourism. Moreover the measure
would benefit both riparian countries (Botswana and Namibia) according to the report. Further
details of this idea are unknown and it is therefore not further discussed here.
7.4 Decision stage of investments
In literature examined and interviews conducted, it emerged that none of the governments of the
region have any plans for structural flood protection measures, apart from an elevated school
near Marromeu.
For Malawi a new study will start on a flood and drought management plan for the Shire River
Basin subsystem, comprising but not limited to infrastructure development (Call for expressions
of interest advertised January 2011 on UN Development Business).
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