In 2020, the water balance in the Dutch sandy soil is still recuperating from the dry summers of 2018 and 2019, which affected the water balance all over the country. Many small waterways were completely empty, soil layers were dried out, and groundwater levels were low. UT researcher Michiel Pezij developed methods for making soil moisture data available to water management bodies, using technologies such as satellite imaging and algorithms. Pezij obtained his doctoral degree at the University of Twenty on 30 January.
The impact of drought on agriculture and nature has been considerable in recent years. Regional water boards have little access to up-to-date information about the water levels in the upper layers of soil, making it difficult to estimate what control measures are suitable for periods of either drought or excess water.
Together with research institute Deltares, researcher Pezij (University of Twente) developed two methods to better provide water management organisations with information about soil moisture. The first method involves integrating soil moisture information from satellite images with existing geohydrological calculation models. Optimally combining the data from calculation models and satellite imaging allows for better simulations and predictions of changes in soil moisture. The second method combines satellite images of soil moisture with radar data of precipitation and evaporation by means of a machine-learning algorithm. This tool efficiently mimics (future) changes in soil moisture.
Both methods result in accurate maps and predictions that provide a spatial insight into the state and changes of soil moisture. The advantage of the first method is that it also allows for the improvement of other model results, such as groundwater levels. The disadvantage is that this method takes a relatively large amount of time and computer capacity, while the second method can be applied quickly and easily.
This new data helps water boards assess the severity of drought conditions and respond with adequate measures, such as retaining water in ditches and streams and introducing watering bans. The new data on soil moisture can be used not only during droughts, but also during periods of heavy precipitation when it is important to know how wet the soil is. Is the soil saturated with water or is there still room to store rainwater in the subsoil? This kind of information will help water management bodies reduce the risk of flooding and take timely measures to reduce the impact.
Michiel Pezij was a PhD candidate working in the Marine and Fluvial Systems research group. His supervisors were Prof. S.J.M.H. Hulscher PhD and D.C.M. Augustijn PhD MSc of the Engineering Technology faculty. His dissertation ‘Application of soil moisture information for operational water management’ can be requested from the contact listed below. His PhD defence was held on 30 January on the UT Campus.