Science Interviews


Sun, 28th Feb 2010

WATCHing Water and Global Change

Dr Richard Harding, Centre for Ecology and Hydrology

Listen Now    Download as mp3 from the show The Science of Water Security

Helen -   Another priority is for us to understand how people actually use water, and how climate change and the way we use land will affect the availability of water in the future.  Dr Richard Harding is from the Centre for Ecology and Hydrology and one of the co-ordinators of the European network of researchers called WATCH, and that’s short for WATer and global CHange, and he’s with us now.  Hello, Richard.

Richard -   Hello.  Good evening.

Helen -   Thanks for joining us on the Naked Scientists.

Richard -   Hello.

Helen -   Now, as we’ve just heard from Eugene Cloete, having clean, fresh water is something that many of us take for granted.  But it’s certainly not the case that everywhere on the planet, they have access to healthy, safe water.  So, what are the main problems linked to the availability of water, and our uses of it?

Richard -   Well, there’s many problems linked to the uses of water and we’ve heard a lot about them just now.  But we have to realize that the majority of the water that’s used across the world is actually used for agriculture.  Something like 90% of the water that is extracted in these dams and from the aquifers, the underground aquifers, are used for irrigating crops.

Helen -   So nine out of ten litres of water we use is for food essentially?

Richard -   Yes, that’s right.  That’s obviously an essential purpose.  Particularly at the moment, we’re having to feed something like 6 billion people.  There are many, many people, particularly in developing countries who don't have enough to eat.  In the future, we’re going to have to feed perhaps 9 billion people by the midpart of this century.

Helen -   Se we're looking at needing a lot more water to be able to feed all those people.  So, if water for agriculture is such an important and huge part of the global water cycle, is that what you at WATCH are focusing on?

Richard -   Yes.  What we’re trying to do in WATCH is firstly to identify exactly how much water we have.  And quite surprisingly, it’s quite difficult to get a picture across all the world that we trust of what the rainfall is, what the evaporation is, and what the runoff in the rivers is.  Then beyond that, we have to look at what the consumption patterns are now for agriculture, for domestic water use, for industry, and what they might be in the future, and what the consequences of that might be.

Helen -   And those are all things I assume that you're looking at, trying to collect more of that data and bring it altogether?

Richard -   Yes.  What the WATCH program is and actually, what many of the researchers at the Centre for Ecology and Hydrology do, is we’re trying to bring together the experts on the climate, the experts on hydrology who know about what happens to the water when it falls on the ground, and then there’s another group of scientists, the water resource engineers, who understand how you store water, how the population uses water, and how it’s supplied to the where it’s needed.

Helen -   And we’ve talked already about agriculture and I presume that as we change the way we use land and do different things with it, this must have a significant impact on water availability as well.

Richard -   Yes.  There’s a lot of issues in that.  Certainly, different crops use water in a different way.  Some crops use more water than other crops and certainly as you change [land use] - for example, as is increasingly happening, natural vegetation is cut down, and crops are put in - that again changes how much water is used and referring back to the scientist from Colorado, that in itself has an impact on the local and actually the regional climate.  We have to take all these factors into account, if we’re to make a good assessment, a realistic assessment of how much water we’ll need in the future, and where we should be growing food.

Helen -   Increasingly, many of us are living in huge cities.  Presumably, as we heard already from South Africa, providing fresh water for all those people is a huge issue and presumably, simply by building on the land and changing the way water behaves, we’re also changing the availability of the water for us to use elsewhere and in the cities?

TokyoRichard -   Yes, we are.  In fact, the concrete of cities uses a lot less water than plants.  So, on one hand, by concreting over large areas of farmland, you're actually using less water but there’s a whole load of other issues.  For example the rainfall. particularly in areas where it had a very heavy rainfall, will runoff city areas and concrete areas very quickly, and actually, that water is sort of lost to the soils in the surrounding groundwater.  There are sort of pluses and minuses to the local water resources, and that’s obviously before we consider the quality of the water that is in the cities and underneath the cities.

Helen -   We’ve already touched on the idea that we’ve got to feed lots of people, we’ve got to provide them with water, and that’s already straining our current resources, and that’s only likely to get worse as the population increases.  And then we’ve got climate change as well, to make things even more tricky.  Is that something else presumably that you've got to take into account?

Richard -   Yes, I think so.  As you referred, there’s actually many places in the world where we’re already using water unsustainably.  There’s many places in the world for example where the groundwater levels are dropping quite alarmingly because water is being pumped out to grow crops.  In the future, climate change is going to have an impact on that.  We’re actually quite uncertain about what rainfall patterns are going to be in the future.  We’re quite certain the temperatures will increase, and that will have an effect on increasing the amount of evaporation into the atmosphere.  But it’s much, much more difficult to predict what will happen to rainfall patterns because they're much more dependent on the patterns of depressions and circulations in the atmosphere.  But there is general agreement from all the climate models that the dry areas are going to tend to get drier and the wet areas are going to get wetter.  Of course, that’s pretty bad news because dry areas like the Mediterranean, like the Midwest United States, like South Africa, and Australia are all predicted to get drier.  Now we’re quite uncertain, so we’re not absolutely certain about that, but it is looking that climate change will be an additional stress on what is already I think quite a serious situation.

Helen -   Well thanks, Richard and just to finish things off, is WATCH going to be providing solutions or are you basically handing your information onto someone else to come up with an idea of what we can do to increase the sustainability of water use?

Richard -   Yes.  I'm afraid we’re probably unlikely to provide many solutions.  I think the solutions were very well summed up by your previous contributor from South Africa who was essentially, in essence, saying that we have to use water much more efficiently, much more cleverly, and make best use of the resources we have.  What WATCH can do is give us our best estimate of what we have at the moment, and what we’re going to have in the future.   This will help us to make plans and identify critical points and hotspots where we need, perhaps to put additional resources in, maybe to build more dams, maybe to improve the distribution of water, or even maybe change the land use practices in some of those areas.


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