Decision-makers in low-lying coastal zones are confronted with uncertain developments around flood risk.These drivers are surrounded by large uncertainties, which requires delta management to be adaptive. This research offers insights about adaptive delta management for the Rhine-Meuse estuary from three perspectives: a physical, a socio-political and a integrated perspective. In the physical perspective, the effect of pump capacity on the water system of the Rhine-Meuse estuary is quantified; one of the adaptation options against sea level rise. To assess the adaptation potential of pumps, the case study Delta21 is used; a plan to construct an artificial lake with an area of 35 km2 next to the Maasvlakte 2 in combination with a pump capacity of 10 000 m3/s. The Rhine-Meuse estuary is divided into four sub-areas depending on the
dominant hydrodynamic process: storm surge dominant area, flood storage dominant area, discharge dominant area and transition area. For each sub-area, the effects of Delta21 are computed on 1) water flows, 2) hydraulic loads and 3) failure probabilities. Delta21 succeeds in lowering the hydraulic loads and corresponding failure probabilities. At the same time, reductions are disproportionately over the Rhine-Meuse estuary leading to low reductions in some sub-areas. In the socio-political perspective, the focus is on decision-making and learning processes in management in delta management. The Rhine-Meuse estuary is characterized by a network structure, which means that knowledge and decisions do not belong to one single actor, but those decisions come about during interactions between various groups of actors. Not only the decisions need to be adaptive to cope with uncertain circumstances, but the learning process itself must also become adaptive. To achieve this aim, a conceptual mode is developed. Two case studies are used; the Delta Program and Knowledge Program Sea Level Rise. A longitudinal analysis of the Delta Program resulted in different narratives over time and various learning types. Subsequently, the Knowledge Program Sea Level Rise is analyzed with semi-structured interviews, process-tracing and the conceptual model. Observations and challenges are translated into a roadmap of learning activities. Moreover, the DEALTa learning handbook is developed, to support actors in designing learning activities. The physical and socio-political perspective are united in the integrated perspective. On the level of technical studies, insights are shared about the relation between both aspects and how the integration can be improved in the future. ... Read more

The city of Barranquilla can play an important role in the establishment in a multi-modal network. Currently however, issues with navigable depth in the river mouth (Bocas de Ceniza) make it difficult for the larger vessels to enter the port area. Resolving these issues will increase the navigability of the Magdalena river which in turn will help Barranquilla bloom as a port city. The aim of this research is to analyse the various sedimentation processes and to explore the possibilities for mitigation measures.
In order to gain more insight into the processes which affect the sediment transport in the first 38 km of the Magdalena river a morphological model is developed using Delft3D software. However, to understand and capture the essence of the issue also the socio-political context is researched. This is done by analysing both the stakeholders and the previous unsuccessful Magdalena recovery project. The combination of both the physical and more organisational aspects formed the input to come up with multiple intervention ideas to solve navigability issues. To evaluate these interventions a multi-criteria analysis (MCA) is conducted witFh both technical and managerial criteria. Finally, also an engagement plan is constructed as a guideline to have successful stakeholder management in a future river project.
From the exploration of the physical part of the issue it can be concluded that there are both natural and anthropogenic aspects which influence the river system, hence the sedimentation issue. With regard to the natural aspects, high discharge variability, stratification and wave action are selected to be further investigated with the Delft3D model. Model results show that sedimentation and erosion rates increase in the access channel above a discharge of around 5000 m3/s. For discharges below this value, the salt intrusion length increases faster than for higher discharges. This salt intrusion leads to a low flow velocity at the bottom that is directed upstream, making the reach over which salt intrudes susceptible to sedimentation. Waves mainly influence bar formation in the river mouth and are not important further upstream.
The analysis of the non-physical aspects leads to a few important conclusions as well. First of all it is concluded that the stakeholder network, in which this problem exists, is a fairly complex one. Therefore stakeholder and process management are key elements in making a future river project successful. Furthermore hypotheses on the success factors of setting up a public private partnership (PPP) in Colombia are formed based on research by Koppenjan (2003), cultural differences between the Netherlands and Colombia and interviews with important stakeholders. These hypotheses are that corruption, political stability and openness for change are also important factors in setting up a successful PPP in Colombia.
Possible interventions to mitigate the sedimentation issues in the first 38 km of the Magdalena river have been assessed separately for three different sections. For the first section (reaching from 0 km to 8 km), the most promising intervention resulting from the MCA is water injection dredging. This would efficiently improve the navigation conditions, capital investments are relatively low and it is also an adaptable solution. For the next section (from 8 km to 22 km), a fixed bottom layer is considered a promising intervention since it will lead to erosion of the relatively shallow inner bend and therefore increase the navigable width. As for the last section (from 22 km to 30 km) it can be concluded from the MCA that none of the assessed training works score better than the current situation.
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Historically, the Magdalena river has been important for inland transportation in Colombia. However, the Magdalena river has ceded its importance as a mode of transportation to the road over the last decades. This is largely due to the difficulty to navigate the river ... Read more