Spatiotemporal development of the 2018–2019 groundwater drought in the Netherlands: a data-based approach

Abstract

Abstract. The 2018–2019 drought in northwestern Europe caused severe damage to a wide range of sectors, and has made clear that even in temperate-climate countries adaptations are needed to cope with increasing future drought frequencies. A crucial component of drought management strategies is to monitor the status of groundwater resources. However, providing up-to-date assessments of regional groundwater drought development remains challenging due to the limited quality of available data. This limits many studies to small selections of groundwater monitoring sites, giving an incomplete image of drought dynamics. In this study, a time series modelling-based method for data preparation was developed and applied to map the spatiotemporal development of the 2018–2019 groundwater drought in the southeastern Netherlands, based on a large set of monitoring data. The data preparation method was evaluated for its usefulness and reliability for groundwater drought quantification and prediction. The analysis showed that the 2018–2019 meteorological drought caused extreme groundwater drought throughout the southeastern Netherlands, breaking 30-year records almost everywhere. Drought onset and duration were strongly variable in space, with especially higher elevated areas remaining in severe drought well into 2020. Groundwater drought development appeared to be governed dominantly by the spatial distribution of rainfall and the geological-topographic setting. The time series modelling-based data preparation method was found a useful tool to enable a detailed, consistent record of regional groundwater drought development. Applying a validation step before analysis turned out to be important for good results. The time series simulations were generally found to be reliable; however, the use of time series simulations rather than direct measurement series can bias drought estimations especially at a local scale, and underestimate spatial variability. Finally, time series modelling showed to be a promising tool for regional-scale drought nowcasting and prediction. Further development of time-series based validation and simulation methods, combined with accessible and consistent monitoring data, will be valuable to enable better groundwater drought monitoring in the future.

Different drought types and the spatial variability in their hazard, impact, and propagation characteristics

“…Bakke et al, 2020;Brunner et al, 2019). Our study further revealed a multi-year nature of the drought of 2018 that made the event more impactful, which is in line with findings for the groundwater drought in the Netherlands (Brakkee et al, 2021). Hydrological droughts for part of the catchments and wells persisted far into 2019.…”

Large increases of multi-year droughts in north-western Europe in a warmer climate

“…Soil moisture and runoff responded to the meteorological drought with a slight delay (Fig. 1e, f), it is this hydrological response that caused the widespread negative impacts of the drought on ecosystems and society (Ecorys et al 2018;Peters et al 2020;Brakkee et al 2021).…”

“…1c-f). In many regions the recovery of ground water tables was not completed in the subsequent winter (Brakkee et al 2021), making ecosystems and different societal sectors more vulnerable to dry conditions in the following summer (pre-conditioning, . The summer of 2019 was again drier than normal, which magnified existing drought impacts in vulnerable ecosystems and societal sectors.…”

“…The severity of drought conditions and impacts varied widely between regions, for example due to differences in soil characteristics and topography, which lead to differences in the temporal disconnect between precipitation and groundwater levels (Van Loon et al 2014;Brakkee et al 2021). Therefore, in some locations ground water tables and ecosystems recovered fully every winter, meaning that those droughts could maybe be analysed as individual droughts.…”

“…We limit our analysis to the large-scale meteorological processes leading to MYD, and because of that refer to this study as 'exploratory'. It is however important to note that local meteorological and hydrological processes influence drought development (Van Loon et al 2014;Brakkee et al 2021), further study of local hydrological MYD processes is therefore warranted.…”