Morphodynamics Suriname River: study of mud transport and impact due to lowering the fairway channel

Morphodynamics Suriname River: study of mud transport and impact due to lowering the fairway channel

Loose, M.

De Vriend, H.J. (mentor)
Winterwerp, J.C. (mentor)
Van Maren, D.S. (mentor)
De Groot, J.K. (mentor)
Quist, A. (mentor)
Van Banning, G. (mentor)

Hydronamic BV

Civil Engineering and Geosciences

2008-09-04

inland transportation of goods. The artificial fairway channel provides entrance to the port of Paramaribo and Paranam. The motivation for this thesis project is the intention of lowering the fairway channel to increase the navigable depth, to create a cost-effective fairway for the bauxite and alumina transport activities. To obtain the navigable depth, the fairway has to be dredged at the shallow locations in the fairway channel. For the investing companies and the contracting companies it is important to know in advance what the amount of sedimentation rate will be in the lowered fairway after capital dredging. The sedimentation rate of the lowered fairway channel will define the feasibility of the whole dredging project on the long term. This study focussed on the mud dynamics in the Suriname River and the effect of lowering the fairway to increase the navigability. This study will focus only on a particular section of the Suriname River Estuary, between Nieuw Amsterdam (km 42) and Paranam (km 87). To achieve the goal of this thesis project, the available measurement data is used to describe the physical elements of the Suriname River Estuary, which are considered important for the sediment transport. To classify which processes influence the mud concentrations and which processes dominate the mud transport in a numerically way, first measurement data of the tidal movements, velocity measurements and salt concentrations are analysed. Analyzing the data resulted in recognizing several hydrodynamic processes, which are potentially dominant for the mud transport in the Suriname River Estuary. The computer tool Delft3D is used for further analysis of the hydrodynamic and morphodynamic processes, plus the estimation of the morphological development of the present situation and the effect of lowering the fairway. According to the Delft3D model results it is clear that the effect of the sediment and salt density on the fluid mixture in the Suriname River Estuary is important for the cumulative sediment transport. The four most important processes that influence the cumulative sediment transport are: tidal asymmetry, gravitational circulation, damped turbulence and the residual river discharge. These processes are included in the simulation within the model, resulting in a balance in sediment transport during one spring-neap cycle of 15 days. Extreme conditions such as extraordinary high tidal amplitude (extreme spring condition), very low river discharges or extreme supply of muddy sediments from the Ocean side could be a reason for an occasional import of sediment in the study area. Lowering the fairway channel hardly influences the balance of the sediment transport processes. The change of the cross section is too small to impact the sediment transport balance on the long term. The width of the fairway channel compared to the width of the entire river is negligible small. The consolidation of the settled sediments was not able to be simulated with the Delft3D-FLOW module. The settling and consolidation strongly influences the erodibility of the sediment bed. Implementing the consolidation process should significantly improve the erosion and sedimentation pattern of the muddy river estuary simulation. Implementing the consolidation process should also include the presence of fluid mud at the bed of the river estuary. Possible density cross current of fluid mud could be an explanation for the dispersion of mud over the entire cross section in stead of deposits at the shallow sections at the river banks.

Suriname
river
estuary
mud
fairway

http://resolver.tudelft.nl/uuid:3a8a8469-944f-42b6-95aa-20d2c2c6c329

TU Delft, Civil Engineering and Geosciences, Hydraulic Engineering

Student theses

master thesis

(c) 2008 Loose, M.