Dredging
Dredging is the removal of sediments, debris, and other materials from the bottoms of water bodies such as rivers, harbors, lakes, and oceans using specialized machinery to maintain or deepen navigation channels, facilitate port operations, and support maritime infrastructure.[1][2] This process counters natural sediment accumulation driven by erosion, river flows, and coastal dynamics, which would otherwise render waterways impassable for commercial vessels.[3] Employed globally to sustain over 25,000 miles of U.S. navigation channels and hundreds of ports, dredging underpins economic activities reliant on waterborne transport, including the movement of bulk goods like grain, coal, and containers.[4] Historical records indicate dredging practices originated in ancient civilizations, such as Mesopotamian and Egyptian efforts to clear irrigation canals and harbors, evolving through manual labor to mechanized systems in the 19th century with steam-powered bucket dredges and suction technologies that enabled efficient large-scale excavation.[5] Modern dredging employs two primary categories: mechanical methods, which use grabs, buckets, or excavators to physically scoop material, and hydraulic methods, which suction sediment as a slurry for pumping via pipelines or hoppers, with subtypes like cutter suction dredgers for cutting into hard seabeds and trailing suction hopper dredgers for mobile operations in deeper waters.[2][6] Beyond navigation, applications include beach nourishment, land reclamation, mineral extraction, and environmental remediation, such as removing contaminated sediments, though these activities can generate turbidity plumes that smother benthic organisms, resuspend pollutants, and alter habitats, prompting regulatory frameworks to balance economic imperatives against ecological costs.[7][8][9] Empirical studies show recovery of affected ecosystems varies by site conditions and dredging intensity, with some benthic communities rebounding within months while others face prolonged disruption, underscoring the need for site-specific assessments over generalized prohibitions.[10][11]