Future water demand forecast by integrating climate and socio-economic scenarios

Climate change, demographic development, increasing urbanization and growing tourism pose complex challenges for the water supply. To address these challenges, this study carried out a scenario analysis for a case study in Austria. For this purpose, different scenarios were derived that consider different trends in climate change, population growth, urban development, and tourism development. To estimate the change in peak water demand due to climate change, a random forest regression model was derived. The model uses climate indices such as hot days and mean air temperature as explanatory parameters for varying water demand. The model was trained and tested using historical water demand records. The quality of the modeling approach was evaluated using common methods such as the mean absolute percentage error. To predict the future water demand under climate change, climate projections for Austria from the RCP4.5 and RCP8.5 climate change scenarios were used. Different population trends were considered for the scenarios, ranging from a decline to a scenario with strong growth. In the tourism sector, a range from minimal growth in the number of overnight stays to a significant increase was assumed. For the industry, a range from minimal growth to a significant increase in the future was also considered. Various scenarios were developed that take into account the different developments of the individual factors and their range. By including the range of factors, the uncertainties in their future development are also represented. For each scenario, changes in peak water demand were derived for the period 2031-2060. The scenarios provide a variety of outlooks, ranging from minimal to significant changes in peak water demand. The results show a range of possible water demand developments for each scenario, given the uncertainties in the underlying factors. Several factors have been identified as critical to the development of future peak water demand. These include population growth, climate change, and, in some areas, seasonal tourism. The development of the housing situation is also an important factor, as water consumption differs significantly between residents of single-family homes and those of apartment buildings. Depending on the development of the housing situation, water demand can fluctuate considerably. Depending on the scenario, the future average water demand in one study site may increase by 3% to 15%. Population growth combined with urban development and the effects of climate change have been identified as the key factors for demand increase. By considering a variety of possible developments, the analysis provides a good basis for long-term water supply planning and can be used to raise awareness in a region for sustainable housing development