Pieter Meert

Modular conceptual modelling approach and software for river hydraulic simulations

Numerous applications in river management require computationally efficient models that can accurately simulate the state of a river. This paper presents a reduced complexity modelling approach that emulates the results of detailed full hydrodynamic models. Its modular design based on virtual reservoirs allows users to combine different model structures depending on the river dynamics and intended use. A semi-automatic software tool (Conceptual Model Developer, CMD) was developed to facilitate model set-up. To prevent instabilities during simulations, a highly efficient discrete calculation scheme is presented with a variable time step. To illustrate the effectiveness of the presented approach, the Marke River in Belgium was conceptualized based on simulation results of a detailed model. Results show that the derived conceptual model mimics the detailed model closely, while the calculation time is reduced by more than 2000 times. Finally, several applications are discussed that employ conceptual models built according to the presented approach. A reduced complexity modelling approach for river hydraulic simulations is proposed.Flexible modular framework that incorporates a variety of structures and techniques.A software tool (CMD) was created to speed-up and facilitate model set-up.A discrete calculation scheme was developed with time and space varying time step.A case study and discussion of applications illustrate the approachs effectiveness.

Computationally efficient modelling of tidal rivers using conceptual reservoir-type models

Conceptual reservoir-type models of river systems, that mimic the results of detailed hydrodynamic models, provide a powerful tool for numerous river management applications. Thanks to their computationally efficient model structure they are very well suited for applications that require long term simulations or a large number of model iterations. However, one well-known problem is that conceptual models have difficulties to account for backwater effects. For this reason, their application to tidally influenced river reaches so far was almost non-existent. This paper introduces an extension of an existing grey-box reservoir modelling technique to incorporate tidally influenced river reaches. The methodology is demonstrated for the downstream part of the rivers Zenne and Rupel in Belgium. Results show a minor loss of accuracy when the detailed model is replaced by the surrogate conceptual model. Also, the tidal effects are well represented. A surrogate modelling approach for tidally influenced river reaches is developed.The approach is modular, flexible and compatible with other reservoir-type models.A discrete and explicit calculation scheme that allows for very short calculation times is used.A case study of the rivers Zenne and Rupel in Belgium was used to demonstrate the accuracy of the modelling approach.