Improved picture of soil moisture during dry summers in the Netherlands

Published: 31 January 2020

Droughts have had a major impact on agriculture and nature in recent years. During the last two summers, many small watercourses were dry, groundwater levels were low, and soils dried out. Water authorities have little up-to-date information about the water in the soil. That makes it difficult to make an assessment of the management measures in place when there are either water shortages or water surpluses.

A researcher from the University of Twente, Michiel Pezij, developed methods in collaboration with Deltares to provide water managers with information about soil moisture. Satellite images and algorithms play a vital role. Pezij received his doctorate for this research at the University of Twente on 30 January.

Drought in the summer of 2019, Dwingelderveld National Park, Drenthe NL

New methods

Researcher Pezij developed two new methods to provide water managers with information about soil moisture. He conducted his research in close collaboration with Deltares. The first method combines soil moisture information from satellite images with the existing geohydrological numerical models (www.openda.org). Changes in soil moisture can be simulated and predicted better by integrating all the information from the models and satellite images in the best possible way. The second method merges satellite images of soil moisture with radar data. A machine learning algorithm is then used to produce predictions of precipitation and evaporation. This method simulates changes in soil moisture efficiently.

Learning more about soil moisture

Both methods deliver charts and predictions that provide a spatial picture of the current status of, and changes in, soil moisture. The advantage of the first method is that it also improves other model results, such as groundwater level data. The drawback is that it requires a relatively large amount of compute capacity and costs more computing time. The second method, on the other hand, is simple and quick.

Better management information for water authorities

This new information helps water authorities to assess the severity of drought conditions and to respond with measures such as retaining water in ditches and introducing an irrigation ban. The new data about soil moisture can be used not only during droughts; it is important to know how wet the soil is during periods of intense rainfall as well. Is the soil saturated or can rainwater still be stored in the subsurface? This type of information can help water managers to reduce the risk of flooding and take timely measures to mitigate the impact.

Irrigation of agricultural land near Dwingelderveld, Drenthe (Photo: Dimmie Hendriks)

Michiel Pezij succesfully defended his doctorate thesis ‘Application of soil moisture information for operational water management‘ at the University of Twente on Thursday, 30 January 2020.