University of Twente Student Theses


Influence of inland shipping on sediment transport in the Waal river

Spoolder, Bastiaan (2023) Influence of inland shipping on sediment transport in the Waal river.

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Abstract:The objective of this Master thesis was to investigate the effects of inland shipping on sediment transport in the Waal river. Inland shipping plays a crucial role in the transportation of goods, particularly in regions with extensive river networks. The Waal river, situated in the Netherlands, serves as a vital waterway for transporting cargo between major cities and industrial middle points. Rijkswaterstaat, the Dutch governmental body responsible for managing waterways, currently maintains daily communication with shippers to ensure navigable depths in the Waal river. As vessels navigate the river, their cargo capacity is directly influenced by the water depth and width, which can vary considerably. When the load of a vessel exceeds the capacity of the river, leading to insufficient keel clearance, the riverbed is directly affected. The study aimed to achieve a better understanding of the processes involved in sediment transport resulting from inland shipping activities. Specifically, the focus was on investigating the magnitude of the return flow velocity caused by propeller jets and backflow from inland shipping near the riverbed. This was examined through utilizing the data obtained from CoVadem between Deest and Druten. CoVadem is a platform that monitors the under-keel clearance of a vessel to predict the navigable depth based on real time data, ensuring a comprehensive and reliable dataset. With the found jet velocity and return currents, the study analysed and evaluated the relation between inland shipping activities and sediment transport by using the values from the propeller jets and backflow. For the determination of the sediment transport, several formulas were used. Eventually, the formula by van Rijn (1993) has been picked as the most suitable one. To show the results, a Python model has been used. The Python model included a script with formulas and parameters for the calculations of the propeller jets and backflow. The results of the propeller jets and backflow led to return current velocities near the riverbed. These velocities were used to calculate the sediment transport for a vessel. The sediment transport has been calculated for three selected vessel types which represented the annual bulk transport in the Waal river. Furthermore, a sensitivity analysis was conducted to examine the effects of various variable parameters on sediment transport in the Waal river. The sensitivity analyses examined the power efficiency rate, keel clearance, vessel width, and vessel velocity. Reducing the power efficiency rate, vessel width, and vessel velocity all have a significant impact on reducing sediment transport in the Waal river. Increasing the keel clearance also led to a reduced sediment transport. Within the sensitivity analyses also the effect of an extreme dry event was tested with regards to the sediment transport. As a result of a lower water depth in dry periods the sediment transport increased significantly due to inland shipping. Eventually, feasible measures were proposed for Rijkswaterstaat and the users of the Waal to manage sediment-related issues in the future. Since determining the influence of inland shipping on sediment transport is a relatively new subject a few limitations and assumptions are included in this research. One key limitation lies in how the sediment transport is calculated according to return flow velocities near the bed. Specifically for propeller jets and the backflow of a vessel, turbulent accelerations also must be considered. Incorporating these turbulent accelerations requires the use of complex models and significant amount of time. The effect of the annual bulk transport on sediment transport within the Waal river is determined by classifying all shipping categories into three main groups. For each group, a reference vessel was selected as a simplification for the calculations. The resulting total sediment transport caused by the entire bulk transport was quantified to be 1.23*105 m2/year.
Item Type:Essay (Master)
Rijkswaterstaat, The Netherlands
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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