Africa rolls - Mystery floods in Namibia

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Mystery floods in Namibia

Tsumeb ‑ Floodwaters, suspected to be coming from underground lakes, have destroyed huge sections of roads between Tsumeb and Oshivelo in northern Namibia and ravaged some five farms in the area.

In an interview with The Southern Times last week, the Oshikoto Police Deputy Regional Commander, William Peter, who is also a member of the region’s emergency response team, said the waters suddenly appeared around February 25.

The most severe flooding in Namibia historically occurs in Oshikoto, Oshana, Ohangwena and Omusati.

Peter said a group of emergency officers were attending to affected areas in Oshikoto.

“When we got there we found out that the road, just 40 km to Tsumeb, was completely destroyed by water and there were also three vehicles that were involved in accidents around that area due to the flood.

“No deaths were reported,” said Sergeant Noongo Thomas of the Namibian Police.

Sgt Noongo said at least five farms were under water, including one belonging to the head of the Namibia Defence Forces, Lieutenant-General Epaphras Denga Ndaitwah.

Police Regional Deputy Commander Peter added, “We were astonished to discover that some of this water was coming from underground and it wasn’t rain water as we thought.

“This water was swift flowing and there was nothing we could do to stop it.”

He said people had been relocated to higher ground.

Asked if the water could be coming from the nearby Otjikoto and Guinas lakes, he said there had been heavy rains and the picture was not yet clear.

“I am not a hydrologist, but … I think the two lakes have something to do with this flood because the flooded farms are situated between the two.

“There are underground lakes and they appear at some points but never in this magnitude.”

Peter said experts were investigating and their report would be made public.

He advised people against erecting barriers  around their properties, as that would merely divert the water elsewhere.

One of the affected farmers, Apie Smith, said, “We don’t know where this water is coming from ... it cannot be rain water.

“Some people are saying it’s coming from (the nearby) Arab River...

“Last week I flew to my farm to relocate my livestock to high ground but this morning I was just told that the grazing is getting finished and that some of the cattle have lost weight.”

Police Regional Deputy Commander Peter said there was need for the government to prepare roads for floods.

Guido van Langenhove, the head of Namibia’s National Hydrological Services, said they were still investigating.

He said the last time flooding occurred in the area was in 1970s.

“First we were informed about this by the Red Cross.

“When I passed by I saw lots of water and I thought maybe some underground pipes had burst.

“But there are no underground pipeline routes across that area.”

He said his office had been informed that the Omiramba Omuthiya-Owambo River that is 30km away, was also flooding, which was out of character.

Van Langenhove said the Tsumeb Sub-Basin is defined by the drainage of surface and groundwater from Otavi in the south and towards the Etosha Pan in the north.

The boundary in the south is defined by the geological contact between the basement rocks and the dolomitic arc of the Damara Sequence, which represents the recharge area of the Kalahari Aquifer underlying the Etosha Basin.

He said the groundwater in the sub-basin was used for large-scale stock farming but also for crop irrigation.

Some people have superstitious interpretations for the flooding.

However, Petrus Angula Mbenzi, a lecturer at the University of Namibia, and author of books on local cultures, said this was highly unlikely.

“Water is good, even if it causes damage to people’s properties; water is known to be used for good purposes.

“It’s known for cleansing and for fighting bad luck and not for bringing bad luck.

“For example, in our culture if people are about to fight you just pour water between them and they will stop,” he said.

Otjikoto and Guinas lakes are situated on the Northern Platform of the Damara Orogenic Belt, which consists predominantly of shelf carbonates that geologists say are some 700 million years old. Carbonic acid-rich groundwater percolating on fracture planes caused dissolution of the rock and the formation of cavities, growing into huge, usually water-filled, caverns.

The resulting system of underground caverns and tunnels may become unstable and collapse, leaving behind a circular sinkhole, which ‑ with its almost vertical sides ‑ looks like an impact crater. Thus, Otijkoto and Guinas lakes represent “windows” to the surface of the groundwater flowing from the Otavi Mountain land towards the north.

Lake Otjikoto lies 20km northwest of Tsumeb along the main road to the Etosha National Park.

The lake is one of the few places in Namibia where underground water comes to the surface.

According to tradition, humans who entered such water would disappear forever.

Earliest inhabitants believed the lakes to be bottomless and connected to each other by a system of subterranean tunnels.

More recent tales tell of the ghost of a German soldier haunting Lake Otjikoto and of an incredibly rich German war chest reposing in its depths.

Today the lake water is used for irrigation, but its abstraction is strictly regulated.

During colonial times, Lake Otjikoto was also a popular recreational site but that ended with the start of World War I.

After hostilities between South African and German troops near Otjikoto, the Germans disposed most of their military equipment into the lake rather than surrender it to the enemy

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http://photos.nj.com/star-ledger/2012/04/4-4-12_the_star-ledgers_ph...

Kenyan rescue workers retrieve the body of a man a victim of a massive boulder that crashed onto houses on April 4, 2012 in Mathare slum of Nairobi, killing at least six people and trapping many underground after a night of heavy rains. The Red Cross said more than 40 houses were destroyed in the sprawling slums in the north of the capital when huge boulders came crashing onto them early on April 4. Teams of rescue workers used hoes and axes in an attempt to break up boulders that towered over their heads as crowds of onlookers stood perilously close.

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Another sinkhole closes Walvis Bay traffic artery

One of Walvis Bay’s main traffic arteries, Rikumbi Kandanga Avenue, has been partially closed for the second time in less than a month after a giant sinkhole was recently detected in the westward bound lane close to the intersection with Sam Nujoma Avenue. In mid-March a sinkhole closed the entire section of Rikumbi Kandanga between the Hage Geingob and Sam Nujoma Avenue intersection, less than a hundred meters from where the current sinkhole appeared.

“We are working as fast as we can so that traffic flow can be normalised again”, a municipal worker told Informanté this week. Sinkholes forming near manholes in the town’s sewer reticulation system have drastically increased over the past few years, according to a retired plumbing expert who conducted major sewerage network works for the Municipality of Walvis Bay many years ago.
The expert, who wishes to remain anonymous, explained to Informanté that many parts of Walvis Bay are situated below sea level. When the sewer pipes rupture, it causes underground water and sand to seep into the system and it is this phenomenon that causes the giant sinkholes. In many instances these sinkholes can swallow a small vehicle and could cause serious injuries and even death in the event of a moving car driving over such a sinkhole and the asphalt street surface giving way. The asphalt surface usually never gives way and therefore causes the problem to remain undetected, until it becomes too late.
When asked about the possible remedies to reduce the problem of sinkholes, the plumbing expert consulted said that he differs with the Municipality of Walvis Bay’s explanation in recent months that entire stretches of sewer-lines are to be replaced once a rupture occurs.  He is of opinion that the problem is only fixed at the rupture and said in many instances the town’s sewer pipes are aged or very close to its guaranteed lifespan.
He is of the opinion that the repairs only buy time and that at some stage the Walvis Bay Municipality will have to face the music and embark upon an extensive replacement program of its sewer network, especially in the older parts of Walvis Bay. He agreed that some parts of the network can still be regarded as “new”, but said with a twenty year lifespan on some of these “new” lines it is only a matter of time before these parts also become part of the prevailing problem.

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Other news Re Africa rolls - 

Kenya: 'Residents trapped' in Nairobi slum landslide

A policeman at the rescue effort said he could hear trapped victims calling for help

A landslide has killed at least six people and trapped others in a slum in the Kenyan capital Nairobi, officials say.

Huge boulders reportedly crashed into houses in the Mathare area at dawn, following torrential rain.

Several people are still thought to be buried under the rubble, residents say.

At least four people have been pulled out alive, but the rescue operation is being hampered by rain and mud, the Kenya Red Cross says.

Earlier, police spokesman Matthew Iteere said four people had died; several hours afterwards the Kenya Red Cross said another two bodies had been retrieved.

A Red Cross official said more than 40 houses were destroyed by the landslide, the AFP news agency reports.

"The main challenge at the moment is accessibility thus the appropriate machinery for rescue cannot access the scene of the tragedy. At the moment rescuers are using hoes and axes in the rescue efforts," the Kenya Red Cross said in a statement.

Another police official, Aphiod Nyagah, said he could hear trapped victims calling for help, but that it would be difficult to rescue them.

"There is no road to lead the emergency teams here. People are trapped and the vehicles cannot access the scene. We have to demolish some houses to enable the teams here," he told the Standard newspaper by phone.