WATER STATISTICS UPDATE

According to the latest council minutes, the Director of Engineering Services reported on January 23 2015 that the amount of water in the dams was currently 63.25% of the overall storage capacity and the total volume was 262,247,374m3. The usable volume was 245,662,266m3. 

During the same period last year, the operational dams contained 190,648,166m3 of water (i.e. 45.98%), that was, 17.27% less than the current storage.

Insiza dam (Source: https://images.search.yahoo.com/images/view)

a) Net Inflow and Drawdown.

The rate of storage drawdown for the month of January was 0.58%, whereas in December the drawdown rate was 0.16% which was about 648,128m3. An amount of 204mm of rainfall had been recorded in January at the dam sites. The cumulative rainfall to date was 354.6mm of rainfall received during the month and hence a cumulative net inflow of 5,148,732m3. 

The cumulative inflows over the same period the previous year was 43,989,129 m3. The current inflows were 854% less compared to the same period in 2014. The average rate of drawdown in 2014 had been 1.59% and at this rate the anticipated storage by year end would be 212,210,548m3 of which the usable volume would be 195,625,440m3.

 (b) Abstraction

Abstraction from supply dams in the month of January 2015 totaled 3,595,078m3.

Water received from Mtshabezi to Mzingwane for the month totaled 492,499m3.

Locations hillside dams Bulawayo (
www.zimbabweflora.co.zw)

(c) Drawdown and Depletion Period

With a total water storage of 262,247,374m3 in supply dams, the usable volume in all dams was 245,662,266m3 (excluding dead water). The monthly average drawdown calculated using the period 2012-2014, when there were no inflows was 7,908,827m3/month. 

 Using this figure for drawdown and usable storage, the expected theoretical depletion period translated to 31.0 months. Abstraction from Mtshabezi and Insiza dams were limited by pipeline capacities, which at present were 17 and 45 Ml per day respectively. 

Umzingwane Dam intake tower (Source:
www.thezimmail.co.zw)

The director noted It was important to note that while there was 31 months supply, continuity of supply could not be guaranteed after January 2016 as it was projected that Umzingwane Dam would be decommissioned in January 2016 and followed by Lower Ncema in March 2016. 

(Source of Information: Bulawayo City Council)