Technological Tools for Planning and Development of Dredging Studies and Projects
WODCON XXIII - Dredging is changing - The Practice. The Science. The Business.
M. Torronteguy, J.J. Menegucci, M. de Lorena
"The planning and development of dredging projects and studies took a technological leap in recent decades, with the continuous increase in computational power and the efficiency and accuracy of survey systems, providing higher quality information regarding bathymetry, oceanography, sedimentology, geophysics, geotechnics, hydrology, meteorology, etc. In parallel, numerical computational models promoted a real technological improvement allowing a detailed representation of the hydrodynamic and sedimentary behavior of dredging sites, as well as making short, medium, and long-term forecasts of the environmental impacts caused by dredging and material disposal. Furthermore, such models made it possible to precisely estimate sedimentation rates in waterways, to determine the range and dispersion of turbidity plumes, defining the efficiency of dredging works overtime, estimating the support capacity of material disposal sites dredged, among several other analyses. Thus, computational modeling became a fundamental technological tool in studies and projects involving dredging. Through the years, ship maneuvering simulators were created allowing testing and optimizing the dredging designs for ports and terminals before the execution of the dredging works, also becoming essential technological tools in the post-construction phase, when the training of the pilots that will operate in the dredged waterways (channels, basins, berths) is necessary. This article discusses how these new technological tools, numerical computational models, and maneuver simulators, have contributed to the planning and development of dredging studies and projects using the authors experience during real cases in Brazil. Computational modelling applied to dredging projects The implementation of computational numerical models, especially in the last two decades, has made possible to carry out different kind of studies as a subsidy for dredging design and planning. The use of computational models makes it possible to represent a handful of processes associated with dredging, such as: i) impacts in hydrodynamic and sedimentary processes resulting from dredging excavations, ii) turbidity plumes dispersion generated during dredging and dredged material disposal in water bodies, iii) estimation of sedimentation rates in channels and dredging frequencies, iv) efficiency analysis of silt curtains in suspended solids control, etc. There are different computational models in the market, but just a few present a complete solution for simulations applied to dredging, an example is Delft3D, a suite of applications developed by Deltares, which involves a set of algorithms capable of high accuracy simulation fluid flows and mass transport in water. This model simulates flows in two or three dimensions, as well as waves, water quality, ecology, sediment transport and morphodynamic. This model has been successfully implemented around the world in dredging for different kinds of environmental settings (estuaries, coasts, lagoons, rivers, deltas, dams, etc.). Figure 1 shows a morphodynamic simulation result using the Delf3D to determine sedimentary trends in a port area in the northeast coast of Brazil, where the blue colors show erosion, and the yellow-red colors are related to sediment deposition. Based on these, and other modelling results, the annual volumes of dredging and planned the future dredging for the site could be estimated. Figure 2 below shows the result of sediment transport simulation using Delf3D, which estimated the dispersion of the generated turbidity plume during the dredging of a hydroelectric power plant in southeastern Brazil, where the blue colors represent low"
Keywords: Numerical modelling; Dredging; Technological tools, Simulators