Professor Wolfgang Kinzelbach

ETH-Zurich, Switzerland

Biography

Prof. Kinzelbach was born in 1949 in Germany. He studied physics at the Universities of Mainz and Munich and environmental engineering at Stanford University. He earned his doctorate from the University of Karlsruhe in 1978. His professional activities have taken him to Maiduguri, Nigeria, the Nuclear Research Center in Karlsruhe, and the Environmental Research Institute of the Academia Sinica in Beijing. After professorships at the University of Kassel and the University of Heidelberg, he has been full professor of Hydromechanics at ETH Zurich since 1996.

His research focuses on flow and transport processes in the environment with practical applications in water resources management, pollution control and remediation. His current main interest is sustainable water resources management in arid and semi-arid regions, mainly in Africa and China. He was awarded the European Research Prize of the Koerber Foundation, the Software prize of the German Federal Minister of Research, the Henry Darcy medal of the European Geophysical Society and the Saudi-Arabian Prince Sultan International Prize for Water. He is a fellow of the American Geophysical Union.

Abstract: Sustainable water resources management: water for agriculture vs. water for ecosystems

Wolfgang Kinzelbach, Institute of Environmental Engineering, ETH Zurich, Switzerland

Sustainability is a difficult concept especially when it is to encompass the triad of environmental conservation, economic efficiency and social justice. It is often easier to define what is not sustainable. In water resources, non-sustainability shows in the depletion of a finite resource, which cannot be substituted, the resource being either water itself, or resources linked to it such as soil and ecosystems. It can also show in the accumulation of waterborne substances - such as salts - to harmful threshold levels. On the socioeconomic side, build-up of conflict potential due to unfair water allocation or bad governance leading to failure of institutions are definitely indicators of non-sustainability.

The most common examples of non-sustainability in the global water sector are the overpumping of aquifers, the excessive consumptive water use in the upstream of rivers leading to insufficient water availability in the downstream especially for wetlands and riverine corridors, the pollution of water bodies with large residence times by persistent or recyclable pollutants, and the salinization of irrigated soils. Of all those problems, the exclusive and competitive demand for water of the two by far largest water users - the natural ecosystems and the manmade agricultural ecosystems - is the most critical and difficult to solve as food security for billions and the conservation of habitats and species are directly confronting each other.

A way to judge, whether a regional water resources management strategy is sustainable, involves the modeling of the system and running the model to time infinity in order to determine whether the system has a solution, which is acceptable in economic, social and environmental terms. Such a solution need not be steady state but could be quasi-periodic or even non-stationary. A difficulty in testing for sustainability is the fact that system parameters and boundary conditions are not constant in time. Population, climate and values keep changing and adaptivity to those changes should be provided for. Another difficulty stems from the fact that parameters and boundary conditions (especially those in the future) are subject to uncertainty, requiring conservatisms and robustness of a strategy. It may well be that for a region no sustainable solution can be designed without a substantial change in system characteristics such as population, land-use, or external inputs (e.g. trans-basin water transfer).

Two examples are discussed to illustrate the above ideas. Both show the conflict between irrigated agriculture and downstream ecosystems. The first case is the Yanqi Basin in China’s arid west, where agriculture adversely affects the salinity of a downstream lake and the survival of a riverine forest corridor. The second case is the Okavango Delta in Botswana, where upstream development threatens the downstream ecosystem.