Water blindness continues as well, supported by the conceptual shortcuts between atmosphere and ecosystems that characterise not only Agenda 21, but also the various UN Conventions and Principles. The perceptions of our political and economic world leadership are water blind and are built on false assumptions regarding globalisation, free trade, etc. No attention is paid to the undermining of the resource base through the hidden action of water - the creeping destroyer. A useful starting point is shown in Figure 1 which visualises human interaction with the water cycle. Grey squares symbolise rural and urban land use, respectively.
Water is drawn from aquifers and water bodies and conveyed through the urban system.
One branch supplies the rural system with irrigation water. The precipitation over land is partitioned between the vertical green water branch of vapour and the semi-horizontal blue water branch of liquid water, wherever a precipitation surplus goes to recharge aquifers and rivers. Food production is based on green water taken up in the root zone and takes place as part of rural land use. Societal production in households and industry is based on blue water, withdrawn from aquifers and water bodies, and seen as part of urban land use. Finally, food production may be intensified by irrigation, based on withdrawn blue water, which is then redirected into green water.