From the muddy Ría de O Burgo in Coruña to the degradation of the Mar Menor in Murcia, passing through the water hyacinth-infested Guadiana river in Badajoz, the eroded coast of the southern Portuguese Algaravia or the loss of depth in many Mediterranean ports, without forgetting the accumulation of toxic sludge resulting from mining or industrial activities -as in the Flix reservoir-, environmental homework is stocking up in the Iberian Peninsula. And be it because of technical complexity, ineffectiveness of a fragmented and uncoordinated administration, politicization -and corruption- of the academic and management environments, shortage of agents with the required operational capacity or budget cuts trailing from the crisis, after many years since their identification and characterization, these environmental projects remain awaiting for effective solutions.
Because when it rains, it pours, everything seems to indicate that these problems will tend to worsen, as the effects of global warming and globalization make their mark on the sea level, changes in weather patterns, ocean acidification, coastal erosion, the proliferation of invasive species or eutrophication. Fortunately, a series of tools have been developed in recent years for the carrying out of regeneration projects, not only in a respectful and environmentally sustainable manner, but at much lower costs than with traditional techniques. All those tools generally included under the concept of environmental dredging are especially important for the successful implementation of this type of projects.
Environmental dredging operations are carried out for the removal of sensitive or toxic sludge and sediments from the environment, thus reducing environmental impact risks. Five features define this type of operations: environmental responsibility, precision, monitoring, efficiency and transparency. In terms of environmental responsibility, these projects must have a perfectly defined scope and required authorizations, including a preliminary assessment that appropriately characterizes the environment in which they are to be carried out (oceanography, limnology, fauna and flora, ecosystems of littoral, etc.). They must also typify the type of target sediments: organic matter, heavy metals, chemical compounds, macro / microplastics, fertilizers, hydrocarbons, biotoxins, pesticides, etc.
Among the new tools facilitating precision in these projects, those allowing for the exact delimitation of areas such as geolocation, satellite mapping, geographic information systems (GIS), photogrammetry, coastal topography and digital visualization and modeling can be cited. Also those equipments on which modern bathymetry is based, such as submarine georadar, sonar, the construction of transversal cuts by means of towed videography, etc. These techniques are currently complemented by a wide range of software for precise geo-positioning, such as Novatron, TopCon, Sultan Hawk, MMGPS +, etc.
The monitoring strategy during environmental dredging operations must be considered not only for water, but also for algae, bottom or benthic fauna and coral communities. During the execution of the works, the monitoring of particles in suspension and turbidity is particularly important, which can be done with satellite assistance, recently improved for the Iberian Peninsula with the entry into operation of the new Hispasat 30W6, PAZ and SEOSAT systems. The use of aerial or submarine drones, as well as smart buoys for the mapping of submersed areas, the collection of samples or the continuous monitoring of water quality parameters has been implemented more and more frequently as effective strategies to reduce costs in environmental restoration operations.
Efficiency maximization in these types of projects requires a clear approach on three issues: an adequate management structure, including sufficient staffing and qualified supervision, as well as external advisors, observers, coordinator, subcontractors, etc. Clear technical protocols, defining equipment to be used, methodology and logistics, specifying volumes and coordinates to be dredged etc. And a viable strategy for the handling and management of the waste generated during dredging, which specifies the methodology to be used in each case, location, inertization, transport, reprocessing, valorization, etc.
The combination of the Watermaster ecodredge with the geotubes technique has allowed the successful implementation of difficult cleanup and environmental regeneration projects, both in fresh water and in marine environments. This compact Finnish dredger operates with great efficiency and precision, which together with its mobility – it is able to move on land and water without cranes, tugs or support vessels -, functionality – with a powerful cutting and suction crown allowing it to pump up to 900 m3 / h of sludge, discharging it at a maximum distance of 1.5 km from the point of dredging – and versatility – capable of aspiration dredging, navigation, excavation, raking vegetation or pile driving with a single machine- have deservedly converted it in the tool of choice for shallow works from dry ground up to 6 meters deep.
This ecodredge already operates in more than 70 countries, carrying out projects for the prevention of floods, cleanup of urban canals, the elimination of invasive vegetation or operational maintenance work in ports and waterways. It is often used for discharging dredged sediments on geotubes, which are large, prefabricated sacks made of geotextile membranes allowing for the retention and dehydration of solids for further processing under biosecure conditions. The flexibility and robustness of these structures make their use possible in coastal protection projects, the removal and immobilisation of toxic sludge or the recovery of valuable materials, enhancing cost control during environmental regeneration works.
Finally, the successful implementation of this type of projects requires a working strategy capable of guaranteeing the transparency of the process, involving the affected communities, promoting open, proactive, responsible and receptive management, facilitating interaction between the parties involved, as well as the auditing and evaluation of results at the end of the project.