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Okavango’s Resurgent Floods Test Disaster Management

MAUN, Botswana, Oct 16 2010 (IPS) - Despite early warnings about higher-than-usual flooding of the Okavango Delta in 2010, homes, fields, latrines and boreholes in the delta were flooded.

Beginning in May, gradually rising waters destroyed crops, disrupted the water supply and sanitation facilities, threatening public health with increased incidence of malaria and diarrhoea.

The flooding marks a return to high water levels last seen thirty or forty years ago, and even with advance notice, local government’s disaster management strategy proved inadequate to the task.

Dr Piotr Wolski, Associate Professor at the Okavango Research Institute (ORI) of the University of Botswana in Maun, who is an expert in hydrology, says he warned government already in April of the risk of severe flooding in the area, but nobody paid heed to his advice.

Wolski was able to predict the advent of the flood because he had been studying the delta’s weather patterns for years. He says the flood was caused by cyclic weather patterns and not by – largely unpredictable – climate change.

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“It looks like there is a lot of flooding this year, but when you look back 30 years, these floods are not exceptional,” he notes.

According to Wolski, the flooding in the delta is based on a 30-year cycle of flooding and drought which has been occurring for the past 800 years. After having experienced drought for three decades, the delta is now likely to enter a 30-year-period of flooding, he reckons.

Wolski says the phenomenon correlates to the Pacific Decadal Oscillation, a shift between phases of warmer and cooler surface temperatures half a world away in the Pacific Ocean. “Pacific Decadal Oscillation affects temperatures over the Pacific and this [in turn] affects rainfall in Botswana,” he explains.

“There has been no cyclicity change,” Wolski further notes. “A change in climate would be a modification of the cycle, and so far we have not seen that.”

It’s a reminder that while the broad predictions of increasing drought for Southern Africa are valid, they don’t simply translate into reduced rainfall in every locale. Careful study and interpretation of data is vital to guide planning.

Government officials – and indeed hydrologists – long assumed the decades-long dry spell in the Okavango was a permanent effect of climate change and were caught by surprise when the floodwaters began rising higher.

“There has been no water for the past number of years,” confirms Olebeng Balapi, head of hydrology at the provincial Department of Water Affairs in Maun. “Only the past two years have seen a tremendous amount of water, particularly this year. Because of the dryness, we have seen people built in the middle of the river where they have been allocated land

Wolski’s study of the data meant he was the amongst the first to recognise the error; his April predictions for 2010’s record flooding were remarkably accurate.

But relatively little could be done to prepare the community in line with Wolski’s warning. For one thing, limited availability of funds blocked local government from effectively dealing with the situation.

“No assistance was provided because of [lack of] money. Money is a factor, and we don’t have much,” said Balapi.

Wolski agreed with Balapi that local government’s hands are often bound by red tape and lengthy tender processes. For example, he predicts it will take a long time before the boreholes submerged by the flood will be fixed or new ones will be built: “Construction of more boreholes could take months or years due to tender procedures.”

Also complicating a comprehensive response is the very broad nature of the problem. Over the decades of dryness, the local population has grown and low-lying land had been allocated for use on the assumption that it would remain above the flood line.

People have made private investments in properties that now seem set for regular inundation; public works such as boreholes and sewage infrastructure are inappropriately sited; disaster management will need thoughtful, long-term intervention from numerous departments.

Responding to the upturn in the annual flooding of the Okavango is clearly not one day’s work – or even one months-long flood season, as the challenges of 2010 demonstrate.

Yet the return of high waters is welcome, accompanied as it is by returning fish and fowl, and economic opportunities. The data and analysis by hydrologists like Wolski, as well as the evidence-based scenarios put out by the river basin’s coordinating body, the Permanent Okavango River Basin Commission, will be vital to designing immediate and long-term plans for the entire Okavango delta.

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