Tuesday, May 1, 2012

So There's a Lot of Groundwater in Africa?

Dear All
 I really enjoyed  reading  the news in several media about an incredible discovery:

 Apparently there are aquifers below the soil of Africa ………………..!!!!!!  and there is WATER in the  aquifers…..

Who would have suspected that?
That short email, sent to me and a hundred or so other hydrogeologists last week, oozed...no, gushed like a spring from a karst aquifer - with sarcasm from a hydrogeologist who knows the African hydrogeological landscape. Like the rest of us on the list, the sender was not surprised by size of Africa's groundwater reserves, but surprised that it was making news now.

The sender also referenced this Reuters article from 20 April 2012. The BBC originally broke the story although a colleague of mine said the original press release came from DFID. Here is an informative blog post by Roger Calow.

Fig2e5sIt's been known for some time that much of Africa - primarily the northern part of the continent where there are thick sequences of sedimentary rocks - is underlain by a lot of groundwater. The western and southern part of the continent contain some rocks that generally are not productive aquifers, but can supply small boreholes fitted with handpumps. 

The best-known of the northern aquifer systems is the Nubian Sandstone Aquifer System (NSAS), underlying Egypt, Sudan, Chad, and Libya. It's reputed to be the largest 'fossil' - very old (perhaps a million years or so) groundwater and non-recharging - groundwater system in the world. One estimate (of which I am somewhat skeptical) pegs its water storage at 373,000 cubic kilometers - that is something like 300 billion AF. Want some perspective? That is over 16 times the volume of water stored in the North American Great Lakes. Whether or not it is that large, suffice it to say that the NSAS contains an incredible amount of groundwater.
Ever heard of the late Col. Gaddafi's Great Man-Made River project? It brings about _41462932_libya_water3_map416 6,500,000 million cubic meters per day (almost 2 million AF per year) to coastal regions from about 1000 wells in Libya's interior tapping the NSAS. Oil drilling in the 1950s identified the groundwater reservoirs.
Two of my early (late 19070s) grad students were Libyans working on the groundwater in the deep interior of Libya. I later realized that at least one of the theses probably was a component of the GMMR project.

So what's the big fuss? Beats me! The international hydrogeological community was surprised at the publicity received by the revelation of  something that was not news to many hydrogeologists who have some knowledge of African regional hydrogeology. Some criticism seemed to be directed at the authors; at least one person suggested that not enough credit was given to those who helped lay the groundwork and that gave the impression that this was 'something new'. Another suggested that the media accounts were a bit too optimistic. So whose fault is that? 

Here is an email from the paper's senior author, Alan MacDonald of the British Geological Survey (reprinted with his permission):
I thought I should give you some background on the media coverage about the "groundwater in Africa story" which broke originally in the BBC on Friday. Not often we see groundwater so prominent.

We published a paper in Environmental Research Letters last week where we  attempted to quantify groundwater resources in Africa in terms of storage and also potential borehole yields. It was building on previous mapping from WHYMAP, BGR, BGRM, BGS, country maps and also a review of about 300 aquifer studies.   The research was part of a larger project funded by DFID who saw a strong need to translate groundwater information into something more easily accessible in terms of resilience and water supply investments for CC adaptation and food security.

The journal decided to put out a press release -  I've published more than 50 papers that have not had much response from the media (apart from one linking farmers in Scotland to nitrate pollution!) - so was not expecting the story to go far. In fact I was working in a remote part of Iceland on groundwater/glacier interactions when the story broke, and had to hastily get to somewhere with decent web access.

It's a bit unsettling when the media take hold of something and simplify the messages, but I think most of the coverage has not been too outlandish and on the whole the BBC and others (beneath the headlines) have done a fair job of ensuring that the caveats and subtleties have been left in and discussed.   Many thanks to some of you for your help in getting the balance right in the other articles and coverage.  Some have also used the coverage to help discuss the broader issues of sustainability, lack of investment and broken handpumps, etc. I hope it has been useful to help groundwater get out a bit more in the open!

In our interviews and discussions we are trying to take the opportunity to get the main messages from the maps across:

1. Groundwater storage is a much larger water resource than any other in Africa - so should be considered in any water scarcity assessments

2.  There is a great variety of groundwater conditions across Africa

3. Generally groundwater can meet the demands of rural communities and small scale irrigation economically and relatively easily if accompanied by appropriate investigation

4. The demands of large scale irrigation or large urban centres is much more problematic and will require detailed investigations and favourable conditions to be successful

Not startling news to many of us, but seemingly news to a lot of people.

Here are: 1) the links ot the paper and also to the home page of the larger research project of which it is part; 2) the PDF of the paper and the URL of supplementary data; and the quantitative groundwtaer maps for Africa page.

I earlier commented on the BGS CC study and its effort to make 'grey data' available.

My sense is that some of the criticism directed at MacDonald et al. can be attributed to Fig3a the 'I Could've Done That!' or 'My Kid Could Do That!' syndrome. You see a piece of abstract art or a simple device that's selling millions of copies and proclaim, 'I could've done that! C'mon - maps of Africa?'

But many hydrogeologists are genuinely concerned that this information could easily be misinterpreted or misused. I can see it now - some well-meaning NGO or government agency drills a bunch of wells in an area that the maps indicate has a lot of groundwater. Bingo! Dry holes! Damn! The BGS misled us!

The situation described above can happen any time technical information makes its way into the popular realm. This time it was information from a scientific journal. The popular press took up the cudgels and spread the word. Some will make inferences that the authors would not condone.

The information presented by MacDonald et al. gives a very broad overview of Africa's groundwater. They are essentially condensing a lot of information from a continent-sized region onto a few maps. Generalizations have been made, and must be interpreted with care by someone who knows the significance of the maps and the uncertainties involved in their construction. 

As the authors indicate in their paper, there are issues with sustainability of the groundwater resources and that the amount of water in storage does not mean that can it all can be recovered. And let's not forget water quality.

MacDonald et al. have done a great service by partly lifting the veil from 'mystery' surrounding Africa's groundwater. Their article will help people utilize groundwater where it was thought not to exist.

And it will help to get groundwater 'out there' so that 98% of the world's available freshwater assumes its proper place in water resources planning and management.
Of course, I could have done this, too. If only....

"[Science] is not perfect. It can be misused. It is only a tool. But it is by far the best tool we have, self-correcting, ongoing, applicable to everything. It has two rules. First: there are no sacred truths; all assumptions must be critically examined; arguments from authority are worthless. Second: whatever is inconsistent with the facts must be discarded or revised. ... The obvious is sometimes false; the unexpected is sometimes true." - Carl Sagan

From Michael E. Campana great blog WaterWired

1 comment: