Big questions for water?

Hi all,

Here was my stab at the big questions. The water sub-group cannot answer all (or even most) of these. And there may be other big questions I haven't thought of. So which ones shall our paper focus on? Please discuss...

1. Is there enough water for urban dwellers? What cities are suffering from water shortages?
   
1. How does it vary regionally?
   
2. What proportion of cities are groundwater dependent and is that sustainable?
   
3. What proportion of cities depend on desalinization and at what cost?
   
4. What proportion of cities have water supplies that are of poor quality or are polluted?
2. Assuming urban dwellers take precedence for water allocation, is there any water left?
1. For natural ecosystems? Which freshwater ecosystems are likely to be most affected?
2. For other users, like agriculture and industry? What regions of the world will have the most severe “crunch” between urban needs and the needs of other sectors?
3. Where will the tradeoff and “crunches” between water for food and water for nature be?
3. What is the future trend for cities and water? What cities are projected to suffer from water shortages by 2025?
1. How big will the increase in demand be as access to piped water increases? Similarly, how will wealth increases change water consumption?
2. How big are demographically-driven effects on growth in consumption, from both migration and natural increase?
3. How big an effect might climate change have?
4. What proportion of cities are projected to have water supplies of poor quality or are polluted?
4. Can increases in water use efficiency, both within cities and in other sectors like agriculture and industry, solve any limitations in water availability? Put simply, is efficiency the way out of the “crunch”?
5. What are the current data gaps that prohibit accurate calculation of any of the above?
   

On your questions, I am not sure if I wanted to open my "frontal assault" now or to wait for the meeting. In general, my overall reaction to this whole water shortage question is that on a planet which is covered mostly by water, water resources should not be an issue (as Raphael Brass from MIT argued once privately). I think the question is indeed the trade-off between energy use and water. One can envision a city with minimal water use recycling most of the sewage water. This could also mean that everybody would need to drink bottled water (or beer) since purifying waste water to the level to make it enjoyable drinking water is probably too expensive. Evidently, such a city is likely to have enormous energy use. Since, most of the population live in coastal zones, desalination is definitely an option to many cities. One has to ask the question, which is more expensive, desalination or waste water treatment. Alternatively, one could picture a city which relies exclusively on "ecosystem services", trying to tap into freshwater resources and release waste waters entirely untreated. The question is how cities will be able to exist in the future. I suspect, there will be cities, which won't have enough water without intensive use of desalination. Some cities might be able exist with traditional waste water management. I gues, part of the equation if cities will be able to afford either solutions.

Balazs (posted by Rob)

According to an article I just read today, the only country that invested seriously in desalinization is Saudi Arabia, so I don't think there are much data sets addressing this question. I wonder if we can come up with some rules about the feasibility of various options. As first step, cities would want to use nearby surface waters. If that is insufficient, they need to turn to shallow groundwater. However groundwater is somewhat tricky, but I think, we can make some assumption about groundwater recharge in the surrounding area of the cities to find out sustainable pumping rates. When the city doesn't have enough water, we could make some assumption about the reduced water need as a function of recycling waste water. When the cities are still in short of water after heavy recycling, we could consider pipelines or desalination. I don't think there are data sets for this sort of calculations, but I think there are engineering consideration that we can turn into cost or feasibility.  I am thinking setting up a chain of rules implemented as a series of GIS computations, similar to my attempt to identify locations for future reservoirs in the attached paper. I realize, it is a completely different topic, but I am thinking of working out something similar for our urbanization study.

Balazs (posted by Rob)