R&D highlights edition 2019

Water and subsoil resources 33 T he drought was caused by long periods of no rain and low water levels in the rivers, ditches and lakes. As a result, groundwater levels in a large part of the Netherlands were also much lower than normal. In many places, groundwater levels actually fell below the previous record lows in the summer of 2003. The consequences for the various water users were also clear to see. Farmers in one third of the country were no longer allowed to irrigate their land and their crops were drier. Drinking water companies monitored their inlets closely to ensure that chloride levels in water taken from the river were low enough. Shipping was forced to reduce cargo sizes to navigate the shallow rivers. Water authorities in the eastern part of the Netherlands had to intervene to save fish from ditches that were drying up. Additional routes were used to distribute water to the regions and water was allocated to different areas of the country using the national and regional priorities for water use. The 2018 drought has been rated as an event that will occur once in thirty years. Given this relatively low probability, it is not a situation often encountered by the operational water managers. The national and regional water authorities managed the water system well and they had a strong tool: the RWsOS FEWS forecasting system, a forecasting system developed and maintained by Deltares over many years. At critical times during this period, the Ministry of Infrastructure also asked Deltares for a rapid response to a number of questions to support their decision-making about a number of imminent interventions needed to cope with the unique drought situation. Deltares delivered tailor-made advice in a very short time frame covering areas ranging from hydrological forecasting scenarios to interventions such as bubble screens for preventing salt intrusion. Multi-disciplinary teams engaged in research and the development of new knowledge under high pressure. Examples include advice on the risks on saltwater intrusion in the southwest delta, the design of different water allocation strategies, and advice on land subsidence issues. The close collaboration between Rijkswaterstaat and Deltares experts in the Dutch Delta Freshwater Programme also paid off since many experts from both organisations have worked closely together to develop the knowledge in recent years. These are elements that will be valuable in the future since drought events are expected to be more frequent as a result of climate change. C ontact: Judith ter Maat, Judith.terMaat@deltares.nl , t +31 (0)6 1070 5417 Tony Minns, Tony.Minns@deltares.nl, t +31 (0)6 1037 6218 DROUGHT IN 2018 – THE DELTARES EMERGENCY RESPONSE q Measures due to drought in the Netherlands: additional ship locking, smaller shipping cargoes, extra pumping for water supplies. Knowledge development for drought management in the Netherlands The summer of 2018 was extremely dry, not only in the Netherlands but throughout Europe. Deltares provided the Ministry of Infrastructure and Water Management, and others, with specialist advice to support operational water management targeting the extreme drought situation. Research and develop­ ment of new knowledge were conducted under high pressure but Deltares was able to meet the challenge effectively. Photo: Adobestock

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