Survey of the Subject

An open question in soil physics and hydrology, namely the quantification of water and solute movement in larger voids, something one could live with reasonably well until now, is rapidly becoming urgent and calls for an answer. What has brought this development about? In short, it is mankind immediate need for more nutrition and more life space. Officials in adminstrative entities and financing organizations worldwide know that by the year 2000, it will be very difficult to close the gap between growing world population and food supply. The “green revolution”, which was based on successful high-yielding varieties of some important food crops, can probably not be repeated based on new varieties or crops developed by successes in gene technology. Thus, the increase in production which one can expect realistically from production areas under irrigation in arid zones by improving water management becomes one of our great hopes. In humid zones, landscape management to preserve water resources — always intimately linked to water management — becomes increasingly necessary to preserve quality and quantity of life space, protection of the ecology not being a separate aspect of this. In semi-arid and semi-humid zones, loss of food production potential and environmental quality shows itself in various forms. Nearly always, water is involved. Thus, more precision in the analysis of the water balance and in the active control of water quantities has become a topic that is of relevance to everybody everywhere. One million cubic meters of water in many situations are not a “rounding quantity” in calculations any more. Willingly or not, in many cases society will be prepared to pay as much for the preservation of adequate quantities and qualities of components of water balances as they do presently for medical care. As in medicine, there will be competition between solutions of different price, and good solutions will have a market even if they are expensive.