Why have dam levels not risen dramatically?

Moderate to heavy rainfall received over the past 84 hours has had little impact on the levels of the major dams in the area.

Umgeni Water spokesperson, Shami Harichunder said the amount of rainfall that fell at Midmar, Mearns and Spring Grove dams was the highest recorded in six months, yet the levels of these and Hazelmere Dam have remained relatively unchanged.

Harichunder gave a number of possible explanations for unchanged dam levels:

• Large dams take longer to fill and the rainfall run-off that makes it to these dams is relatively small makes no noticeable difference. He said a lot more rain was needed over a short period of time to make a clear difference to the levels of large dams.
• Much of the rain was absorbed into parched ground, consequently there was very little or no run-off into dams through river systems.
• It takes at least 72 hours for the bulk of run-off water to make its way into a dam. It is estimated that on average only between ten and 20 per cent of rain makes it into a river system. Because of this, a clearer picture of the impact of the rainfall on dam levels will only emerge in the next day or two.

The following amount of rainfall was received at Umgeni Water dams over the past 48 hours:

• Hazelmere Dam got 120 millimetres and the level increased by two per cent to 45.71 per cent
• Nagle Dam got 59.2 millimetres
• Inanda Dam got 87 millimetres
• Albert Falls Dam got 52.2 millimetres
• Midmar Dam rainfall was not supplied but the dam level has stabilised at 45 per cent
• Mearns Dam’s (a small dam) rainfall was not supplied but the level increased by four per cent to 54.14 per cent

It is important to remember that small dams like Mearns fill up as quickly as it empties out and that these smaller dams are used to augment water resources in Midmar Dam through transfers.

All water restrictions still apply, including 50 per cent for the Ilembe district, Hazelmere, and Ixopo dams, 15 per cent for the entire Mngeni system, Umgungundlovu, Pietermaritzburg and large parts of Durban.

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