AbstractsBusiness Management & Administration

Over the last centuries, Dutch rivers such as the Rhine have been heavily trained for the purpose of the safe discharge of water, sediment and ice, and navigability. After the notorious flood events of 1993 and 1995 along the Rhine, new large-scale river works were initiated, such as the Room for the River (RfR) programme, to increase flood conveyance capacity. For a better navigation, in 2006 the minimum guaranteed depth on the Waal has been raised from 2.50 m to 2.80 m (relative to the Agreed Low Water level). It is inevitable that the measures of the large-scale works (depending on the type and magnitude of the measure) and changes in the minimum guaranteed depth will influence the morphology of the river and the dredging effort. Three schematisations are distinguished in this research, namely maintenance dredging in the situation with a minimum guaranteed depth of 2.5 m (‘Ref – 2.5 m’), the situation with a minimum guaranteed depth of 2.8 m (‘Ref – 2.8 m’), and the situation after the implementation of the Room for the River programme (‘RfR’, with a minimum guaranteed depth of 2.8 m). The aim of this research is to determine the impacts of the increase in the minimum guaranteed depth and the Room for the River programme on the maintenance dredging in the river Waal using the deterministic approach (traditional) and a stochastic approach, and to determine the potential of a stochastic approach with respect to the deterministic approach in river management practice. Currently, morphological calculations are being executed using a deterministic approach. The deterministic approach appears to be an effective tool to provide a quick expression of the physical morphodynamic processes. However, to fully acknowledge these morphodynamic processes and to derive a precise illustration using a deterministic model is very complex. By ignoring the complexity of the morphodynamic processes, the involved uncertainties are not made explicit. Identifying the uncertainty in morphodynamic predictions is necessary in order to come to grips with system behaviour of the Waal. Therefore, it is important to not only look at the deterministic calculation, but also to perform stochastic calculations. In this study, numerical calculations with a 2D depth averaged Delft3D model are performed using a deterministic and stochastic approach to determine the bed level changes, navigability, and dredging effort. For the deterministic approach a representative discharge hydrograph is used and for the stochastic approach 75 different discharge time series. From the present research it follows that the maintenance dredging volume in the ‘Ref – 2.8 m’ situation is twice as much as in the ‘Ref – 2.5 m’ situation. It increases drastically with 196%. The increase in the maintenance dredging volume in the ‘RfR’ situation compared to the ‘Ref – 2.8 m’ situation is approximately 10 times lower than the increase in the maintenance dredging volume in the ‘Ref – 2.8 m’ situation (which is related to the dredging effort in the ‘Ref – 2.5 m’ situation).…