Climate Change and Water Supply - Consequences of Climate Change and Potential Adaptation Strategies

 Dr. Claudia Castell-Exner1, Dr. Daniel Petry1


1 JDVGW German Association for Gas and Water Technical and scientific association; Josef-Wirmer-Str. 1-3, D-53123 Bonn, Germany; e-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it , This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Climate change and its impacts have been in the focus of public attention for many years. In the recent past the UN World Water Development Report and the World Water Forum have drawn worldwide attention to the questions of how climate change will affect the availability and quality of water and how human beings may adapt to this challenge. The European Commission’s White Paper on “Adapting to Climate Change” and the report by the European Environmental Agency on the dangers of water scarcity and droughts have addressed these issues at the European level. According to present knowledge climate change impacts in Central Europe are likely to be moderate compared to other parts of the world. Nevertheless, it will affect water supply directly, i.e. in terms of raw water availability and quality as well as with respect to the operation of the supply infrastructure. Given that water suppliers are used to long-term planning and investment periods and know how to cope with changing parameters, they should - in cooperation with researchers, politicians and other stakeholders - be expected to succeed in adapting to the consequences of climate change. In the following, the focus is on climate change impacts in addition to ways and means to adapt to these changes. The water supply industry is nevertheless fully aware of its responsibility for climate change mitigation, i.e. to reduce greenhouse gas emissions from water supply.

Keywords: climate change, water availability, water quality, impacts on water supply, indirect consequences, adaptation options



Climate change in Germany

Across Germany, annual average temperatures will go up, resulting in warmer and drier summers and milder and wetter winters. There are, however, large regional differences within Germany and in some areas contrary to the general trends observed across the country. As seasonal and spatial climate variabilities increase, the reliability of projections on future water management parameters decrease. Extreme weather events such as hurricanes, rain storms, and dry periods are generally more likely to occur. These, in a nutshell, are the climate changes most studies expect to occur before the end of the 21st century. However, regional projections for concrete quantitative parameters are still uncertain and can be made only within relatively wide boundaries. The degree of uncertainty is higher still if we want to determine on the basis of various climate factors (e.g. precipitation, temperature, evaporation) the changes of parameters like, for instance, groundwater recharge or runoff regimes in river catchments.

Climate change may also affect some of the familiar, fixed parameters that serve as a basis for planning and investment decisions, since the parameters derived from long-term time series, that describe the availability of resources, have ceased to be a reliable basis for information helping to assess future conditions. Increasing climate variability creates a wider range of potential weather conditions and may be part of future climate conditions. This requires precise analyses and monitoring of the development of all climate-related conditions that are relevant for water utilities in order to facilitate an early response to emerging trends. Long-term operating and investment decisions should take into account the expected range of climate changes which may impact the operation of water supply facilities and networks.

Impacts on water supply

Climate change may result in the more frequent or intense occurrence of familiar phenomena that may also spread to other regions. This may include more frequent or intense periods of drought, heat waves or rain storms in regions that, so far, have been affected by these phenomena either not at all or only rarely. In other words, the water supply industry will not be confronted with vague unknowns, but mainly with phenomena it is experienced in coping with. This is not supposed to be construed as an all-clear, but rather meant to encourage a proactive and unemotional discussion of the effects brought about by climate change.