The construction or designation of detention areas along lowland rivers is considered along many European rivers. Since Croatia accommodates large detention areas, both natural (e.g., Mokro Polje) and controlled (Lonjsko Polje), it serves as an excellent example for planned detention areas elsewhere in Europe. This modelling study focuses on the controlled detention area of Lonjsko Polje. The flooding characteristics of the area are assessed in combination with the vegetation development and the transport and storage of sediment and phosphorus. Results of the modelling show that it is not so much the intake capacity that determines the flood duration time of a detention area, but the drainage capacity. A too long inundation duration following a flood event is shown to lead to major shifts in the vegetation composition. The results further indicate that about 30% of the sediment and adsorbed phosphorus that enters the detention area during an extreme (1:100 years) flood is retained within the area; this is about 10% of the total sediment and adsorbed phosphorus load of the Sava. Results of this study can be used to properly design and manage detention areas along lowland rivers.@en

A few years ago Deltares started a large multidisciplinary project named Next Generation Hydro Software. The main focus of the project is to improve, harmonize and integrate existing hydro software that has been developed throughout the years. Important technological innovations include development of the new computational core D-Flow Flexible Mesh, as well as the user-friendly, open modelling environment Delta Shell. The project involves more than 40 scientists and software engineers. The new integrated system will allow both water managers and modelers to do their work better and faster. The unique characteristic of the project is that it focuses on the possibility of setting up integrated models of the whole aquatic chain from the source to the sea, resulting in complex model configurations. The challenges further increase because of the involvement of experts from many different fields within the aforementioned aquatic chain. Furthermore, the project addresses the complete workflow of a modeler, including model setup, calibration and validation. For this purpose the system includes new scientific visualization, analysis and interactive modeling tools that enable users to improve their understanding of the modelled processes. Applications of the system show the successful integration of 0D (lumped hydrological models and real-time control rules), 1D (river flow and water quality models) and 2D/3D model components (river, estuary and coastal areas). In this paper some of the preliminary results of the project are demonstrated, as well as its current status and a preview of possible future developments @en