The 2022 drought in the Netherlands – is it over yet?
The meteorological drought in the Netherlands was within the 5% most extreme years (based on precipitation minus potential evaporation). But there were strong regional differences with most severe dry conditions in the east and some locations in the southwest and northwest.
Both river levels and groundwater levels were extremely low, with impacts on agriculture and restrictions on water withdrawal (mostly in the higher parts of the Netherlands, in the south and east) and impacts on water quality (saline intrusion) and restrictions on navigation (mostly in the low lying parts of the Netherlands, in the north and west).
River discharge Rhine river April to August 2022 compared to 2018 (another drought year) and historic percentiles, and salinity levels April to August 2022 compared to salinity thresholds (source Niko Wanders)
A national drought emergency was declared and all relevant authorities worked on drought crisis management during the summer. Many measures were implemented, including withdrawal restrictions, additional pumping capacity, checking of peat dikes.
On 21 September the drought emergency was declared over. The rainfall deficit had fallen below the 5% driest years due to some rain, but the most important reason was that the water demands were lower since the agricultural season was over. The “drought season” in the Netherlands runs between 1 April and 1 October, which means that outside of that season there is no monitoring of the meteorological drought situation and the drought committee is dissolved.
|7 Dec 2022||13 Jan 2023||1 Feb 2023|
But… the 2022 drought is not completely over! The groundwater drought portal shows that on 7 Dec 2022 many groundwater monitoring points still had below normal groundwater levels, especially in the east and south. Withdrawal restrictions were still in place in some regions until 14 December 2022 (water board De Dommel). In January 2023 some wells show recovery (and even above normal levels) due to prolonged winter rainfall, but most are still lagging. In February 2023 heavy rainfall has increased groundwater levels significantly, but in the east and south many wells still show moderate to extreme drought. At the same time, the lack of snow in the upstream part of Rhine basin is worrying and could affect summer low flows in 2023 (see here).
In the drought research group at the Institute for Environmental Studies at VU Amsterdam we do research to understand the hydrological aspects of drought and the effects of human interactions. We investigate:
- how the drought propagates from meteorological (lack of rain) to hydrological (low soil moisture, river flow and groundwater) conditions
- what the long-term effect is of consecutive droughts (is there an influence of the 2018-2020 period?)
- how abstraction, land use change and other human activities influence the drought development
- what the impacts of the drought on society are and how these can be related to drought hazard indicators
- what the effects of restrictions are on the drought and on societal impacts
- and how the drought recovers and the management is adapted based on the drought
Source: UNDRR GAR Special Report on drought (2021)
Here we show some insights into our research with the 2022 drought in the Netherlands as example case.
Propagation + impacts
In order to understand the impacts of droughts in the Netherlands and act accordingly, the propagation of the drought signal within the hydrological cycle (from meteorological to soil moisture to hydrological drought) needs to be studied and linked to existing drought impacts. This will enable impact prediction and hindcasting, leading to a more resilient and prepared society. The summer of 2022 was a particularly dry one in the Netherlands amidst the heat waves experienced in the rest of Europe and the ongoing global climate crisis.
The northern and southern regions of the Netherlands experienced a critical lack of precipitation. At the end of July 2022, the Netherlands was severely affected by moderately low measured flows of the Rhine (indicated by the low flow index), as its highly interconnected water system mainly relies on the Rhine as a water resource. In addition, the discharge of the Rhine was influenced by a very dry winter in the Alps with little snow and a dry spring and summer with below-average precipitation and above-average temperatures.
Low-Flow Index (LFI) at the end of July 2022. A Low-Flow Index of 0 corresponds to no drought and a value of 1 to the highest drought hazard. Circles represent low flow situation at Rhine gauges provided by ICPR – International Commission for the Protection of the Rhine , through the Undine Information Platform . Data are classified by low flow, based on return periods
The number of measured water points with below-average values shows the severity of the 2022 drought in the Netherlands.
Water height as provided by Rijkswaterstaat – Dutch Ministry of Infrastructure and Water Management (5 August 2022).
The low water level may cause problems for commercial shipping on the Lower Rhine, there could be problems with the stability of the dikes (many of the dikes have to be kept wet to maintain their strength), and there is also the problem of salt intrusion and cracking in the polders.
One of our research goals is to understand these impacts and how they relate to drought risk. In the Down2Earth project, we are studying the interactions between drought hazard, hydrology, climate and the societal impacts of drought in the Horn of Africa (Kenya, Somalia and Ethiopia).
Why do we still have to think about past and future droughts during rainy days?
With the arrival of the rainy season, we tend to forget the images of the drought in the Netherlands: from the yellowish Dutch farmlands to the low level of canals and reservoirs. The drought that has gripped the Netherlands and many other European countries was headline-news during the summer months, but on these rainy days, drought seems pretty far from our memory. However, heavy rains and consequent flooding are more connected with past-future drought than we think…
The abundant rain of the last few months have been indeed a great relief for the water sources in the Netherlands, restoring the water levels in the canals and reservoirs… but would the replenished water sources be sufficient to withstand a future drought? Groundwater levels have not yet reached normal condition, indicating that the past drought has not really ended and that we are more vulnerable to the next one. Overexploitation of groundwater sources during dry days can add up to reduced groundwater recharge rates during wet periods caused by prior drought conditions. Increased soil compaction and vegetation degradation are an explosive mix when combined with heavy rainfall, resulting in soil erosion, fast runoff, and consequent reduction in water retention/infiltration in the soil.
But if rainfall and resulting floods can influence drought risk, on the other hand, droughts can contribute to exacerbate flood risk. Peat dikes used for flood protection in the Netherlands tend to shrink when water level drops during drought conditions, reducing their efficiency during flood events.
At IVM, we are currently investigating the interactions between droughts and floods within the PerfectSTORM project. With our research, we show that drought impacts and response influence flood risk and vice versa… emphasizing the importance of thinking about drought and flood risk jointly.
Weather extremes drive important crop yield impacts. Both extreme wet and dry conditions can lead to harvest losses. For instance, extremely dry conditions in 2018 caused large harvest losses in the Netherlands with key crops such as potato and onion severely impacted. On the other hand, extreme wet conditions in 1998 had major negative consequences on crop yields via direct physical damage and proliferation of pathogens.
Lack of rain in 2022 saw farmers release warnings early in the season with fears of a 2018 event repetition in mind. This led to intensified irrigation activities which helped alleviate the impacts of drought. Limited moisture availability also meant lower pathogens. Both these factors contributed to a near average harvesting season at national scale. The outlook looked much more negative at European scale with harvest losses projected across the continent (see below).
Projected summer crop negative impacts linked to hot and/or dry conditions. Source: JRC MARS Bulletin – Crop monitoring in Europe – July 2022 – Vol. 30 No 7
Summer droughts such as in 2022 intensify water demands across sectors. This puts pressure on water boards to accommodate conflicting interests. Finding a balance between multiple parties without proactive adaptation measures can prove increasingly difficult under climate change.
In our research at the IVM, we study the impacts of compound weather on global soybean yields. We show that extreme hot and dry conditions are linked to important harvest losses (up to 30% below expected levels). Additionally, we show that large-scale weather patterns can trigger synchronized droughts in multiple global growing regions therefore increasing stress on global food supply within a single season.
The Netherlands faced four drought events over the last five years, which exposed the limits of the water systems. According to the Royal Dutch Meteorological Institute (KNMI) 2022 was the fifth driest year in the history of their measurements, with a maximum rainfall deficit of 318 mm. For farmers this led to a decrease in crop production and dried up grasslands, especially in higher sandy soil region in the eastern part of the Netherlands. This region has limited access to additional water and is mainly dependent on precipitation. According to the climate predictions of the KNMI drought event will happen more frequently in the future (see below). Therefore, many stakeholders in this region try to adapt to these dry situations, which require changes in water management, infrastructure and mindset.
Projected rainfall deficit during the growing season. Source: KNMI Klimaatsignaal ‘21
During the recent dry years farmers became more willing to implement water storage measures and practices, both privately as wells as in a collective, to become more drought robust. However, positive local impacts of such measures can lead to (unforeseen) negative impacts on a regional level, especially when measures are widely adopted. During my research I focus on how small-scale adaptation measures and practices in the agriculture sector will impact water security on different spatial levels, with case study areas in the high sandy soil region of the Netherlands.
Communication, awareness & actions
In the summer of 2022, much of Europe experienced a severe drought. The Netherlands was no exception. Not only was there a severe precipitation deficit, but also historic low river discharge. Additionally, the Dutch water infrastructure is not designed to retain water and climate change is expected to make droughts like these more frequent. Hence, water managers fight an uphill battle to ensure sufficient clean fresh water.
On top of these climate induced drought challenges, if drought risks and measures are not effectively communicated, people can exacerbate the situation. Communicate the drought risks too loudly, people may start stockpiling water. Communicate too softly, people may not save water nor have enough time to adapt. Drought risks also need to be communicated clearly. Misunderstandings about drought forecast uncertainties can break trust- the next time water managers make recommendations, people may intentionally not listen. Effective communication of drought information could help mitigate droughts.
Yet, how exactly people respond to drought information is not well understood, and state of the art literature is scattered. As part of my PhD, I am currently investigating how people respond to drought information. I will do this by collecting and summarising the existing literature and from there, conduct a survey on Dutch water way users. With this, I aim to provide a clearer picture of the human side to droughts.
Drought monitoring and adaptation measures
Not only 2022 was dry in the Netherlands, in the period 2018-2020 water managers were also confronted with extreme drought. During this multiyear event it became clear that information about the propagation of a drought in the system was difficult to find and that, for example, measurements were scattered across many different organisations. For a uniform indication of drought conditions and show the propagation of a drought it was important to change this. A online information portal was developed, www.droogteportaal.nl, with up-to-date drought indicators for precipitation (SPI, SPEI) and groundwater (SGI). During the 2022 drought, this portal provided information about the drought development and was also included in the national drought monitor of Rijkswaterstaat (Dutch Ministry of Infrastructure and Water Management). We are still developing the portal by, for example, improving the modelling behind the calculation of the drought indices and changing the visualisation of the information.
Droogteportaal July 2022
Besides this specific project, I also work on projects related to drought adaptation measures and water availability in general at KWR Water Research Institute. These projects range from specific pilot studies in which measures are tested to general studies about the impact of drought and climate change on the drinking water availability in the Netherlands. Pilot studies are, for example, aimed at studying the effects of the implementation of subirrigation for agriculture or at the effects of a newly developed sport field for which evaporation from artificial turf is accomplished. At a larger scale we focus on the water availability within certain regions to show the potential of water reuse or of other adaptation measures.
Adaptation + feedbacks
Droughts are long-lasting events, which makes it possible for people to act upon it, and therefore increase or decrease the drought risk. For example, farmers can irrigate more, abstracting more water from the river or groundwater and thereby lowering the water levels. During a summer drought people use more water by filling swimming pools or irrigating their lawn. It is important to capture these responses of people, to understand how we can reduce the drought risk. This is especially important in the Netherlands, as the country has been designed to get rid of our water as fast as possible. We will need to actively adapt, since we have been accustomed to having enough water, and use as much as we like. We can adapt to drought by for example storing water in times of heavy rainfall, and using it when it is dry (or slowing down drying process through natural buffers). This can be done in many forms and ways, including blue/green roofs, lakes, urban wadi’s, storage/reservoirs, and forests.
Irrigation of agricultural fields in response to drought. Source: ANP/Flip Franssen
We study these feedbacks and adaptations also in the Horn of Africa, as part of the Down2Earth project. Here we look at how (large-scale) farmers and herders respond to drought impacts and how that influences other water and land users in the area.
Prediction and early warning, early actions
It is scientifically proven that action triggered by early warning systems can effectively reduce drought impacts, with benefits often much higher than the costs of actions. Hydrological drought is different in every region, so are the impacts and early actions that can be taken. In the Netherlands, early actions include a reduction of groundwater abstraction prior to the drought, creating water buffers in water bodies or planting drought resistant seeds.
Many African countries currently develop Early-Action Protocols (EAPs) in coordination with the International Federation of Red Cross and Red Crescent Societies. These protocols provide the exact action trigger moments for a variety of different early actions, such as planting drought resistant seeds, borehole rehabilitation, the construction of water storage tanks and food aid.
The distribution of animal feeds is one of the early actions often taken to reduce drought impacts in Africa.
In the Netherlands there is much to learn from the development of these EAPs in African countries. In our country, much is still unknown about proactive drought management, let alone early actions. Currently our approach is mostly reactive with interventions being taken inside the drought season (April-September), while a proactive approach would allow us to take effective actions when a major drought is expected. For example, in case we expect a major drought, the IJsselmeer water levels can be raised to ensure that we start the drought with a strong water buffer (see here).
But we just started to explore these anticipatory actions, which are still surrounded by unknowns. How do we prepare for the next large drought in the Netherlands, and which actions do we take at which stage? Can we use drought early-warning systems, and do these have enough forecast skill in Western Europe? Clear protocols should be developed, grounded by research, to answer these questions.
Drought adaptation and governance
As hydrological extremes such as drought increase in occurrences and severity, there is a need to improve governance processes and adaptation options to ensure that damages and impacts can be minimized. Governance processes can either facilitate decisions that help communities prepare for drought, and enable policies that aim to reduce social vulnerabilities. Moreover, other governance processes such as including communities and other marginalized groups to inform decision-making can also help in designing adaptation options that are contextually-relevant and aimed at specific outcomes.
For my PhD research, I explore how governance processes unfold during droughts and what adaptation strategies communities undertake. These research questions are situated in Iquitos, Perú where droughts exacerbate existing social vulnerabilities by putting pressure on available water resources. As a consequence, water prices increase and communities organize themselves to implement communal water sharing schemes. My research then focuses on how governance processes can help facilitate better adaptation options and on what specific outcomes can be achieved from such actions. In the same manner, governance processes in the Netherlands during droughts can be explored to identify adaptation strategies that can deliver positive outcomes for different stakeholders.
Google searches and academic papers
Search engine reports can help us get a sense of the public awareness and expert and society perception of an issue. For example, Google Trends data, reflecting searches people make on Google every day, is useful for some types of qualitative systematic reviews. Also, a quick review of Google Scholar records reveals how much an aspect is examined from an academic perspective.
We can plot the timeline of searches for certain terms in a specific country. In this graph, we display the monthly interest index that Google Trends assigns to two search words: “droogte” (in Dutch) and “drought” (in English), for searches performed in the Netherlands from 2004 until the present. The two series of the index covariate significantly, and both show two clear recent peaks, one in the summer of 2018 and another one in the summer of 2022, revealing the moments in which it was a hot topic, coinciding with the evolution of the drought indices of physical hazard for the country.
On the other hand, and without the aim of being comprehensive, the searches for academic papers with the keywords “drought in the Netherlands” and “drought”+ “the Netherlands” yielded more than 200 different relevant results for Google Scholar. A rapid exploration of scope and study area in these papers and research reports helped us filter them more, leaving a total of 82. When their years of publication are displayed, it is evident that most of the documents were produced in the last 5 years, confirming that there was a research gap before the last two severe drought episodes, and that there is a growing workstream that kicked off during and after them.
More research on drought is needed, also in wet countries (like the Netherlands) and in wet periods (like winter, when the drought is declared over), to improve drought management and lessen drought impacts on society and ecosystems.
“Rain: because of the long drought he’d forgotten how to use an umbrella” Source: Kamagurka.
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