HomeOpinion & AnalysisWhy Byo dams are not filling up

Why Byo dams are not filling up



THE fact that Bulawayo and Matabeleland South province have been receiving torrential rains since January is evident to everyone.

The fact that most dams nationally are full and spilling (including the largest inland waterbody — Tugwi-Mukosi), is very clear to all and sundry.

But the biggest question is: why are Bulawayo supply dams still tottering at half to below half capacity?

According to the Zimbabwe National Water Authority (Zinwa) update of February 4 2021, Upper Ncema was 52,5%, Lower Ncema 20,2%, Inyankuni 51,5%, Mzingwane 29,6%, Insiza 63% and Mtshabezi 42,1%.

This is a serious cause for concern considering that most dams nationally are above 70% and some are 113% full.

On February 2, 2021, Matabeleland Institute for Human Rights sent a petition to Zinwa, key among the issues residents of Bulawayo sought answers for was why the Bulawayo supply dams were not filling up.

On February 7, another petition was handed to Bulawayo City Council (BCC) as the residents continued to seek answers to the same question.

The only attempt closer to a response came from some BCC officials who said that because it’s raining in Bulawayo, it doesn’t mean in the supply dams catchment areas it’s also raining. However, there is evidence that the catchment areas are also receiving rains.

So where is the problem?

In this opinion article, I will, therefore, seek to point out some issues that may be the contributing factors which need to be quickly investigated:

Catchment oversubscription

There is need to quickly investigate if the catchment areas of our supply dams are not oversubscribed with weirs and smaller dams that are affecting the receiving capacity of our major supply dams.

Once the catchment areas are oversubscribed with smaller dams and weirs, it means the dams downstream will suffer as less water will reach

Catchment management

How the catchment is managed may also be a key contributing factor.

Are the streams and tributaries within the main river basin not blocked or illegally diverted into private dams?

Are they not affected by streambank and river cultivation and illegal artisanal mining activities?

Are there no agricultural activities that are flattening the basin areas and thus limiting the scale and speed of runoff?

Are there no illegal (consciously or subconsciously) runoff arrest or diversion activities happening in the river basin?

Disused mineshafts

The authorities need to investigate if there are no disused mineshafts that are now collecting water underground where instead of the runoff or streams flowing to the river, they now flow into these disused shafts.

These shafts may also have the net effect of reducing water runoff into dams as they will need to fill up first and then only when they are spilling will the water flow into dams.

Underground syphoning

There is also need to investigate if there are no disused or active mineshafts that are syphoning water underground.

Once the mineshafts are dug towards the dam sites, they also have the ability to syphon water from underground through leakages or leaching.

This also has the capacity to continually deplete dam levels.

Bulawayo storm drain direction

The authorities also need to investigate where the Bulawayo storm drains are channelled.

Bulawayo is a watershed area.

From Bulawayo, Matabeleland North rivers flow westwards and Matabeleland South rivers flow eastwards.

Our Bulawayo supply dams are in the east.

If the Bulawayo storm drains are channelled towards the west, that means they are not aiding our supply rivers, but are aiding the rivers that flow westward which do not assist our supply dams at all.

A joint operation involving Zinwa, the Environmental Management Agency and BCC is very important in addressing these critical questions.

Finally, an honest and objective examination of these factors may be the solution to the question why Bulawayo supply dams are taking ages to fill

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