for sustainable development


Forecasting future water demands: planning-security for water suppliers

For local water suppliers it is often hard to forecast the future water demand for urban supply areas because it is not only influenced by demographic developments and weather-related fluctuations but also by the behavioral patterns of various user groups as well as changing technologies. Modelling this complex interaction with scientific methods provides the necessary planning and supply security for water suppliers. ISOE – Institute for Social-Ecological Research has developed a suitable forecasting model.


Water suppliers depend on reliable predictions since investments into the infrastructure require long lead times. So far, suppliers have drawn on nationwide average values providing per capita use, on data dealing with population growth and on information concerning expected technological innovations. With these kinds of data, small-scale analyses are impossible, though. Fortunately, detailed information on socio-economic, settlement-related and technical factors is now available as well as data on user behavior. Information like this is important for a spatially specified planning of water infrastructures in urban supply areas. ISOE’s integrated forecasting model includes all relevant influencing factors and enables specifications for single town districts and even smaller units given the respective data. By always using the latest data at hand, the model enables a continuous update of the prognosis.

Less water usage despite population growth

Why is there a declining water demand in an urban area even though the population has been increasing for decades? This trend has for example been prevailing in Hamburg since 1976. The water supplier HAMBURG WASSER not only had to face decreasing revenues but also a lack of planning reliability. Using the integrated model, ISOE’s water experts were able to find the causes of the decrease in consumption on behalf of the Hamburg water supplier: more efficient household appliances that are using continuously less water as well as modern sanitary equipment and domestic water meters.

But now, the possible saving potential is mostly exhausted and a further decline in water demand is therefore not to be expected. ISOE’s water researchers suggest that from now on, the population development and the related economic progression will again increasingly decide about the expected water demand. Extreme weather patterns are another factor that will lead to fluctuations: up to four percent more during years of drought and two percent less during so-called runoff years.

ISOE-water research: long-standing expertise in creating water demand prognoses

“Now, the water supplier has a precise idea which factors have to be taken into consideration when it comes to future demand”, says ISOE’s water researcher Stefan Liehr who was involved in developing the model. “The flexible model allows a comparison between initial estimates and current data. Thus, the development of the water demand can be much better updated than before.” The data are based on spatially divided consumption statistics and on data that provide information on the population, housing, settlement and economic structure combined with analyses done by a geographic information system (GIS) as well as user and expert surveys.

ISOE has a long-standing expertise in the integrated modelling of water demands: In 2007 the first water demand forecast was developed for HAMBURG WASSER which was then updated in 2014. “As soon as the data basis is established, the water supplier can independently continue to work on the Excel-based model”, says Stefan Liehr. “Because of the flexible combination of methods, it is also possible to transfer the forecast model to other supply areas.”


Schulz, Oliver/Stefan Liehr/Jörg Grossmann (2017): Das integrierte Prognosemodell für den Wasserbedarf von Hamburg - Szenarien, Fortschreibung und Perspektiven. energie/wasser-praxis (8), 58-63

Liehr, Stefan/Oliver Schulz/Thomas Kluge/Georg Sunderer/Johann Wackerbauer (2016): Aktualisierung der integrierten Wasserbedarfsprognose für Hamburg bis zum Jahr 2045 - Teil 1: Grundlagen und Methodik. gwf-Wasser/Abwasser 157 (2), 156-165

Liehr, Stefan/Oliver Schulz/Thomas Kluge/Georg Sunderer/Johann Wackerbauer (2015): Wasserbedarfsprognose für Hamburg und Umland bis 2045. ISOE-Studientexte, 24. Frankfurt am Main: ISOE - Institut für sozial-ökologische Forschung



Nicola Schuldt-Baumgart

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