Supply
Three sets of general circulation model (GCM) results were used to provide scenarios of future supply. These came from the HadCM2 (developed by the UK Hadley Centre for Climate Prediction and Research), from ECHAM4 (from the German Climatic Research Centre, and developed from the ‘ECmwf’ atmospheric model and a comprehensive package); and from CGCM1 (the ‘Canadian Global Coupled Model’, from the Canadian Centre for Climate Modelling and Analysis). All the data were obtained via the Climate Impacts LINK Project, from the Climatic Research Unit, University of East Anglia, UK.

Demand
There are a variety of different water demands to consider. These are divided into the follwoing categories:

• domestic: rural and urban water supply, all uses;
• industrial;
• agricultural: irrigation and livestock.

The Water Balance Model