Coastal areas have always been a favourite place for people to settle. Living near the sea and other types of open water, such as rivers, estuaries and lakes, offers many benefits. These areas often have a more moderate and comfortable climate, as well as allow access to maritime food sources, and facilitate trade and transport.
For many centuries, the popularity of living in coastal areas didn’t pose a problem from a density point of view. However, the exponential growth of the world’s population over the past century has put rising pressure on coastal zones.
Depending on how it is defined, the United Nations now estimates that up to 60% of the world’s population lives in coastal areas and this figure is only expected to rise. With the increasing population density and economic activity, remaining land is scarce, or in some places non-existent, leading to prices rising to sky-high levels.
The Port of Rotterdam in The Netherlands was one of the first to do exactly that. Once the largest port in the world during the 1960s and ’70s, it has become increasingly confronted with a growing demand for port infrastructure and the need for expansion.
Wedged between urban areas in the north and precious rural areas, the only option was to expand seaward. Subsequently, one of the first large-scale land reclamations was achieved: the Maasvlakte.
Vital tools for accomplishing this project included trailing suction hopper dredgers (TSHDs) that dredged the necessary sand out at sea and brought it back to the project site. The introduction, several years earlier, of swell compensators on board hopper dredgers has also played a major part in increasing the efficiency of the dredging process in offshore sea conditions.
The example set by Rotterdam would soon be followed by other places in the world that were also struggling with a shortage of available land. Three famous reclamations have been realised for new airports in Asia: Changi in Singapore; Chek Lap Kok in Hong Kong; and Kasai in Japan.
Similarly, TSHDs played a vital role, as well as the deployment of cutter suction dredgers (CSDs). Where appropriate sand sources could be found nearby, CSDs were able to pump the material directly into the reclamation site.
Joint operations between both types of dredgers have also occurred. In these instances, a TSHD will dredge the sand offshore and dump it in front of a stationary CSD, which subsequently pumps it on land.
Two major developments with regards to the design of TSHDs started during the latter stages of the 1980s and came to fruition during the 1990s. These had a substantial influence that lowered the cost price of land reclamations. Up to this point, most hopper dredgers were only able to unload by dumping. However, during this period, TSHDs were increasingly designed and built with the added capability to empty the hopper utilising the pumping equipment.
Combined with the added installation of bow couplings and rainbow nozzles, it became possible to pump sand directly into the reclamation site, either by pumping ashore or by rainbowing.
The second development saw the gradual introduction of dredgers that became categorised as jumbo TSHDs, with capacities of over 30,000m3. At present, the largest existing hopper dredgers measure an impressive 46,000m3.
By achieving such capacities, it is now cost effective to carry out land reclamations at places where no sand is available nearby and it has to be sourced at larger sailing distances.
Every size matters
The introduction of jumbo-sized hopper dredgers doesn’t make the role of small and medium size vessels any less significant. Achieving a land reclamation in a cost-efficient way involves making optimal use of each type and size.
Dumping sand is still the least costly method, but this can only be applied for the underwater basis of the land reclamation and is restricted by draft limitations. The next level is rainbowing, but the draft of the dredger still plays a significant role in this process. For both operations, small and medium size dredgers are indispensable.
Although large land reclamations in the marine environment are the most eye-catching, the significance of small-scale reclamations in more inland locations, along estuaries, rivers, river deltas and lakes, should not be underestimated. On a local level, these projects are often of the utmost importance.
For the realisation of such reclamations, no seagoing dredgers are required. They can be carried out with the help of inland hopper dredgers and/or small CSDs, such as the IHC Beaver®.
Besides dredgers, additional land-based equipment is needed to accomplish reclamation projects. These include earth moving machines, such as bulldozers, hydraulic excavators and loaders, and equipment for the consolidation of the new land, for instance to install vertical drainage.
Over the past 15 years, land reclamations have been carried out all over the world for many different purposes. Besides the expansion and building of new maritime ports and airports, land has also been created for housing projects, tourism and waterfront development.
Countries where important land reclamations of this type have been realised or are still ongoing, include The Netherlands, the United Arab Emirates, Nigeria, Panama, as well as the tiny Principality of Monaco.
Furthermore, reclamation projects are increasingly being carried out to compensate for and/or anticipate the loss of land due to rising sea levels. In particular, for low lying countries and archipelagos, for example the Maldives, land reclamation projects are of vital importance.
In the near future, it is expected that land reclamation will also be carried out on behalf of the energy sector, for example to create special energy and offshore islands to interconnect different wind farms.