Prediction of Floods and Droughts Is an Effective Measure for Adapting to Climate Change

Operational water management based on accurate and reliable hydrological predictions can be an effective means of limiting the economic and social damage caused by an increasing frequency and intensity of summer rainstorms, droughts and wintry precipitation. This will require advanced hydrological modelling and prediction. This was put forward by Prof. Albrecht Weerts, special professor Hydrologic Predictability, during his inaugural address at Wageningen University & Research on 2 March.

During his address, entitled ‘Towards accurate and reliable hydrological predictions for society’, Prof. Albrecht Weerts explained why we need to improve our ability to predict water levels in rivers, creeks and other hydrological infrastructure. “In the past years, insurance companies have reported an increase in claims for damage caused by extreme rainfall from €40 to 90 million, and this is only in the Netherlands. Climate experts predict an increase in both the frequency and intensity of rainstorms. If we do nothing, insurers expect the damage to increase by 140%.”

Investment in hydrological forecasting should be seen as an affordable and effective measure for adapting to climate change. Accurate and reliable predictions that can help us improve the management of our waterways in times of drought, or when floods threat, will have an excellent return on investment, regardless of the extent of the climate change. According to a study by the European Centre for Medium-Range Weather Forecasts (ECMWF), the investment could be recovered in as little as a few months to a year (averaged over several years). “This is why it is interesting for many countries in Europe and elsewhere to invest in accurate and reliable hydrological risk prediction systems,” says Prof. Weerts.

Smart water management

In the Netherlands, cities and municipalities currently lack a system for predicting floods and so the public do not receive timely warnings of such events, while it is expected that this will lead to more and more problems, Prof. Weerts explains. “I propose an accurate and reliable national probabilistic nowcasting & forecasting system for water levels and discharge volumes based on short-term radar precipitation measurements (0-6 hours) combined with high resolution weather forecasting (0-48 hours) that enables smart water management.” Such a system can provide a window of time to warn the public and take local measures. This can help to reduce the risk of floods and improve the regulation of water discharges through sewers and open waterways under normal conditions.

Long-range forecasts

Refining hydrological models to be able to predict smaller scales in space and time (e.g. from daily to hourly and from square kilometers to hectares) will not automatically lead to better hydrological predictions. “This is due to all sort of uncertainties in the model structure, parameters and estimated initial conditions.  Moreover, . before we use the precipitation forecasts  in our hydrological models, it may be useful to apply a correction to the precipitation forecasts first. We should also make better use the real-time available data on discharge or water levels to adjust the initial condition of the hydrological models to increase the accuracy of the predictions. Water management authorities currently hardly  make use of the real-time available data for that purpose at all.”

Prof. Weerts new chair is funded by Deltares and has been brought under Prof. Remko Uijlenhoet’s Department of Hydrology and Quantitative Water Management. Prof. Weerts is Hydrology and Forecasting Expert with Deltares in Delft.