Colin Green, University of Middlesex
“Practical challenges for scarcity management
What we can be confident in knowing is that water management is always fundamentally about food production because plants both require enormous quantities of water – depending on diet, 1-4 tonnes of water a day are required to grow the food for one person – and because plant growth is the principle necessarily consumptive use of water. Secondly, that water is heavy and incompressible means that water management is capital intensive and lifting it is energy intensive.
For agriculture, there is a true scarcity of water: increasing global food production requires more water (Molder 2007). For urban uses, the problem is not a scarcity of water, since we get most of the water back after use and many cities export more water than they import, but the scarcity of resources such as capital, and also technical. This means that the short cut to looking at water scarcity is to focus on plant demand, evapotranspiration needs, versus local precipitation. Where the former significantly exceeds the latter, importing water is necessary to grow food.
Unfortunately, this is only part of the problem; a large part of the problem is the variability in the availability of water. Averages are of little use in water management; it is the variabilities that matter, both the intra-year variability across the seasons and more especially between the years. It is these variabilities that make water management difficult, and hence much more difficult in some regions than in others. Balancing supply and demand depends largely upon the availability of storage; the greater the variability of water availability, the greater the requirement for storage.
How to deal with the challenges: The tools
The three primary functional challenges in considering WRM are:
- Raising and servicing the capital sums necessary to finance water management approaches.
- Whereas historically water management focused upon modifying the environment to match anthropogenic needs, we are now focusing upon changing people’s behaviour to live with the environmental constraints. Appropriate and effective means of changing behaviour are therefore a necessity.
- Water management is always a transboundary problem; national boundaries are only the most obvious example of those boundaries. Hence, we need means of bridging in various ways across those boundaries.”