Land reclamation refers to the process of creating new land by altering the topography of existing bodies of water such as seas, rivers, lakes, or marshes. This is done most commonly along coastlines but can also occur inland, often involving the conversion of wetlands or other types of water bodies. The procedure has been used historically to expand coastal areas for agricultural and industrial purposes.
Traditional Vs Modern Land Reclamation
Traditionally, land reclamation involved building a series of dikes around tidal marshes or shallow offshore waters. These enclosures would then be drained to create dry land. Sometimes, streams were redirected to carry extra sediment into the diked areas. Soil and stone could also be excavated from the mainland and dumped along the shore, progressively expanding the land into the sea.
In contrast, modern engineering projects are more extensive, involving the construction of kilometres-long offshore concrete barrier walls filled with substantial amounts of sand, earth, clay or rock. The reclamation site is often filled with soil dredged from the nearby seafloor mixed with water, in a process known as hydraulic reclamation.
Current Landscape of Land Reclamation
A recent study examined satellite imagery of coastal cities with populations of at least 1 million. It found land reclamation projects in 106 cities worldwide had created around 2,530 square kilometres of coastal land. Almost 90% of this new coastal land was generated in East Asia over the last two decades, primarily to accommodate industry and port facilities catering to the globalised economy. From 2000 to 2020, China alone added around 350 square kilometres of reclaimed land.
Problems Arising from Land Reclamation
While land reclamation has proven economically beneficial, it comes with significant environmental challenges and potential risks. Most of the land created in the past couple of decades is in low-lying areas that are at high risk from coastal flooding due to global warming and land subsidence. Moreover, using materials like sand, which are obtained from marine and river environments, can destroy habitats and spawning grounds of organisms. Some countries have banned the export of sand for land reclamation due to this reason.
Ecological Impact of Land Reclamation
Land reclamation often involves draining or filling wetlands, leading to their destruction or alteration. Coastal wetlands such as mangroves, salt marshes, and estuaries provide numerous ecological benefits. Their loss disrupts the natural balance of coastal ecosystems, affecting water quality, fish nurseries, and shoreline resilience.
Proposed Solutions and Future Directions
Addressing the challenges and risks posed by land reclamation requires strategic coastal planning and innovative engineering techniques that minimise the impact on coastal ecosystems. Comprehensive coastal zone management plans should consider the long-term effects of land reclamation and balance economic development with environmental sustainability. Soft engineering solutions such as permeable structures, floating islands, and sand-filled geotextile containers can help minimise disruption to coastal processes. Additionally, artificial intelligence and remote sensing techniques can be used to monitor coastal changes, predict erosion hotspots, and assess the effectiveness of coastal management interventions.
Last Modified: February 20, 2024