Drought in the Pleistocene uplands of Southern, Central and Eastern Netherlands

The summer of 2018 was particularly dry in the Netherlands, which led to water supply problems for agriculture and nature in the Pleistocene uplands. This project focuses on the consequences of the 2018-2019 drought, the recovery from the drought and possible adaptation measures for these sandy regions. The propagation of drought is specifically taken into account. The project includes agricultural and nature areas.

Objectives

The summer of 2018 was particularly dry. In the Pleistocene uplands of the Netherlands this led to water supply problems for agriculture and nature. In this project we (water managers and researchers) are working on a uniform conception and understanding of the relationship between the different drought types (meteorological , soil moisture drought and hydrological drought) at different scale levels, with the aim of:

better understanding and (timely) predicting how different types of systems react to meteorological drought and recover from hydrological drought;
quantifying the effectiveness of (ad hoc and structural) water management and planning measures, so as to limit/prevent the propagation of meteorological drought into hydrological drought (with the associated damage);
and thus providing quantitative guides for the assessment of measures (which measure still makes sense and when?), and defining the elements/building blocks for actions that contribute to lessening the impact of drought for the different actors in the water system.

Method

Our focus in this project is on the southern, central and eastern Pleistocene uplands in the Netherlands, and specifically on the higher, drier sandy regions with agricultural and nature areas. Within the project area we are concentrating on a number of catchments. The analysis of the catchments involves the integrated use of field measurements, water balances, aerial observations using remote sensing, and hydrological model simulations: the study draws on all possible data sources to chart the drought and its effects.

Besides the drought evaluation, model simulations will be performed to study the sensitivity of the system to possible adaptation measures. This involves using scenarios such as reduction of abstractions and increasing surface water levels, and concerns both short-term measures to anticipate and respond to drought, and structural measures for water-system restoration. The measures will be analysed at different scale levels (total study area and selected catchments).

Besides the drought evaluation, model calculations will be performed to study the sensitivity of the system to measures. This involves using scenarios such as the interruption of abstraction activities and the raising of surface water levels, and concerns both short-term measures to anticipate and respond to drought, and structural measures for water-system restoration. The measures will be depicted at different scale levels (total study area and focus catchment area).

Droogteperiodes voor Hupsel gebaseerd op de variabele drempelwaarde methode voor neerslag, bodemvocht en grondwater, waarbij ervanuit wordt gegaan dat alle waarden onder het 20ste percentiel aangeven dat droogte voorkomt.

Drought events for Hupsel catchment, based on the variable threshold level method for precipitation, soil moisture and groundwater, assuming that all levels below the 20^th percentile indicate drought conditions.

Project phases

The current project has three phases. Phase 1 involves the development of a uniform working method for the analysis of drought, and research into how the 2018 drought impacted the Pleistocene uplands. It also involved exploring the possibilities of monitoring drought. Phase 1 has been completed (Van den Eertwegh et al., 2019). Phase 2, which entails more in-depth analysis, is currently underway.