Irrigation scheme under threat
16 January 2020 | Disasters
The company's acting chief of water supply for the South, Andries Kok, told Namibian Sun that by Monday the Hardap Dam now contained only 19.58 million cubic metres of water.
The dam's capacity is 294.5 million cubic metres. This time last year the dam was 33.3% full.
According to Kok, water supply to the irrigation scheme will be stopped when the dam reaches 4.8%, which is equivalent to 14 million cubic metres of water.
“Originally it was planned to stop supply to the irrigation scheme by the end of December last year, but due to saving measures implemented by producers the date will most probably be extended to the end of January,” he said.
Kok said a new depletion analysis will be done within the next week to determine the final date.
He said once supply was stopped to the irrigation scheme, there would be sufficient water for Mariental until the end of March 2021.
“This is when the dam reaches 1.5%, which is equivalent to 4.3 million cubic metres of water. This means we still have two rainy seasons available to get inflow into the dam, from the current season as well as the 2020/2021 rainy season,” said Kok.
At a level of 1.5% the dam reaches the so-called “dead storage” area where the water level is lower than the ordinary abstraction points, he explained.
“Water will still be available, but should be abstracted by means of additional pumps that need to be installed into the dam basin.”
Kok added that once water supply to the irrigation scheme was stopped, more stress would be put on the potable water system.
He said NamWater was therefore installing a booster station on the potable water system which would be able to supply more potable water than normal.
This booster station will not be finished by the end of January, though, meaning that the next few months will be tough for residents.
“There is a little bit of river flow at the moment, which might result in very little inflow at this stage, but still insignificant,” he added.
The chairperson of the Hardap Farmers' Association, Dawie de Klerk, dismissed it as a “myth” that NamWater would stop providing water to the irrigation scheme at the end of this month.
De Klerk said the cut-off point for raw water delivery to the irrigation scheme was at 4.5% of the Hardap Dam's capacity. According to him if the dam reaches 4.5% there will still be enough potable water until March 2021 in case there is no inflow.
De Klerk further said that local farmers in November last year committed themselves to stop production on 40% of their irrigated land to mitigate the situation until February when the main rainy season starts.
According to De Klerk only 60% of the about 2 100 hectares is therefore under irrigation.
“The bit of good news that I can give is that there is some inflow currently into the dam,” De Klerk said.
Kok, on the other hand, said it was a fact that water supply to the irrigation would be stopped if there was no inflow and that it had been discussed with all stakeholders.
“This is why producers agreed to cut production by 40% to stretch the water in the dam to the end of January.”
It was reported last year that about 3.5 billion litres of water released in August 2017 from the Hardap Dam to feed the N$5.7 billion Neckartal Dam, 123 kilometres away, evaporated before reaching the intended destination.
When NamWater announced in 2017 that the Hardap sluices would be opened to release water for the Neckartal Dam, it said that in the event of insufficient inflow into Hardap during the 2017/2018 season, the situation would be addressed with stakeholders after that rainy season.
Meanwhile, in the central area of Namibia the Swakoppoort Dam has had an inflow of 0.104 million cubic metres, raising its level to 5.5% from the previous week's 5.3%. Last season the level of the dam was 22.2%.
The Omatako Dam has had an inflow of 3.9 million cubic metres and the dam is now at 23% of its capacity, up from last week when it was 14% full. Last season the dam was at 1.1%.
The average level of the dams in central Namibia currently stands at 22.6% in comparison to last season's 27% full.
In the Gobabis area the average dam level is 13.5% compared to 3% last season.
In the South, which has some of the country's largest dams, the average stands at 22.8% compared to last season when it was 40.1%, while in the north the average is 3.6% compared to last season when the dams were empty.
The average of Namibia's dams by Monday stood at 21.5%, which is equivalent to 148.4 million cubic metres of water. Last season the average was 32.8%.