Monitoring and communication lie at the very heart of modern water management, from the assessment of available resources to early warning of disasters. There has been some dismay at the loss of many ground-based monitoring systems over the last 40 years. The number of raingauges has declined on every continent. The number of stations measuring river discharge increased dramatically in North America and Europe during the 1980s, but has shown a slight decline since. Numbers have remained almost static elsewhere, but the total number of river gauging stations in all the rest of the world is only around half the total in Europe and North America. The contrast in the deployment of water quality stations is even starker: the rest of the world has only around a tenth of the number in Europe and North America. The contrast in water quality measurements swelled in the 1980s as Europe and North America introduced environmental legislation, but has levelled off since. Evaporation and evapotranspiration are hardly measured at all, and normally only calculated from data collected at meteorological stations or agricultural research stations (Jones, 1997).