Assessment of upstream flood risk in the Rhine Basin (HSGR02)
This research aimed at developing a uniform flood risk methodology to assess current and future flood risks in the upstream German part of the Rhine basin. The methodology was used to evaluate the impact of climate change and socio economic scenarios, as well as different adaptation strategies on basin wide flood risk. The results of the project can be used to facilitate cooperation between upstream and downstream stakeholders, inform the population about flood risk, and help with planning of flood control measures and cost-benefit analysis of these measures.
This research showed that the risk from extreme flood events along the Rhine will not be stationary and might increase considerably during the coming decades. It was found that the annual expected damage in the Rhine basin may increase by between 54% and 230%. The highest current potential damage can be found in the Netherlands (110 billion €), compared with the second (80 billion €) and third (62 billion €) highest values in two areas in Germany. Additional flood defence measures, such as retention basins and dike heightening, might prevent the increase in flood probability.
Data from a survey among households along the Rhine in Germany showed that direct disaster experience is an important trigger for the implementation of flood mitigation measures. As far as the current implementation level of flood mitigation measures is concerned, it was found that a considerable share of respondents did not implement a single flood mitigation measure, despite a high vulnerability of the surveyed households to floods.
The damage-reducing effect of flood mitigation measures was examined by comparing the precautionary behaviour and damage suffered of households that were affected by two severe floods in 1993 and 1995. This comparison demonstrated that the substantial damage reduction observed in 1995 can indeed be attributed to an improved preparedness of the flood-prone population during the latter event.
In order to effectively stimulate flood precautionary behaviour, better knowledge about the factors that influence individual’s decisions to protect themselves against flood impacts is essential for risk communication. Workshops offered to flood-prone households by civil society and international river basin organisations, which emphasise the need for precautionary behaviour, can also be a successful mechanism to increase the level of preparedness of flood-prone households.