Comparison of the flood extent on the River Meuse: 1993, 1995 and 2021

Major flooding occurred on the Meuse River in 1993, 1995 and 2021, causing significant damage to regions in NL, BE, DE. The flood events of 1993 and 1995 occurred in the winter, while that of 2021 occurred in the summer. There are large differences in the characteristics of these floods separated by nearly three decades; not only the seasons differ, but the topography of the river bed and the shape of the flood wave have also changed. Since 1995 dikes and flood-routing measures have been constructed along the river. Although all these projects are not yet completed, the flood event of July 2021 indicates that the Meuse projects are producing the expected results. This research aims to understand the effect of the shape of the flood wave during a high-discharge event, the impact of the different types of flood protection along the river and the interaction between the main river and its tributaries. The main research question is: what are the hydrodynamic differences between the high-waters levels on the Meuse in Limburg in 1993, 1995, and 2021, and how can these differences be explained?The first step to complete this research was to gather the needed information. The second step is to identify the differences between the different flood events and assessing the impact of the different flood protection measures. The third step is to assess the impact of the different flood protection measures.After an analysis comparing inundation maps, five flood prone areas were identified and investigated, namely: Maastricht, Bunde and Meerssen, Maaseik-Roosteren, Roermond and Venlo. Flood wave characteristics play an important role: the width illustrates the duration of the event, while the height indicates the maximum water level that can be expected. Theoretical predictions of flood wave behaviour derived by scenario-based simulations with hydraulic models (i.e., report of peak attenuation, evaluation of the Grensmaas and the tool Box of building blocks) were compared with measurement data, water levels, discharges and inundation maps in order to assess if intended effect of certain measures correspond with the measured effect of the flood events of 2021.The flood event of July 2021, the amount of water already in the river system, before the heavy rainfall in the southern part of the Netherlands, Ahr-Eifel region in Germany, Luxemburg and Eastern part of Belgium, was only approximately 200 m3/s instead of the 600-700 m3/s in 1993 and 1995. This means that there was a large buffer, before the water level increased to dangerous levels. Secondly, the short duration of the flood event in 2021 compared to 1993 and 1995 the increased role of peak attenuation. The flood routing-measures have helped to increase this effectivity due to the fact that more water could be stored in floodplains, high-water channels and retention areas. For this event it can be concluded that the duration of the flood event in combination with the already executed flood-routing measures have prevented further flooding. Civil Engineering | Hydraulic Engineerin