Sediment is a crucial component of natural systems, with socio-economic, environmental, and geomorphological significance. While sediment is found across various terrains, it accumulates predominantly around estuaries, deltas, and coasts, often disrupted by human activities such as damming rivers, port developments, dredging, and pollution. This disruption leads to imbalances in sediment quantity and quality, affecting flood risk, erosion control, habitat, and other functions. Effective sediment management requires understanding sediment dynamics and their impacts on interconnected natural and human systems, as alterations to sediment equilibrium can have substantial consequences.
An overview of ecosystem services and nature-based opportunities within sediment management for varying landscape types, encompassing diverse coastal configurations is presented in Table 4-3. The highlighted approaches center around minimizing the adverse effects of nourishment while offering alternative coastal management strategies. These strategies encompass conserving beaches, fostering dune growth to bolster coastal barriers, and enhancing habitats. Novel techniques like sand borrowing and placement are also introduced to achieve these objectives.
Table 4‑3: Overview of sediment management in different landscape types[1]
Landscape | Key Features | Ecosystem services | NBS Opportunities |
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Sandy Coasts | Commonly found in enclosed bays or as long stretches within beach-dune systems. They host high biodiversity across major taxonomic groups, though diversity varies along the coastal profile. Sediment movement is driven by high-energy agents like wind, waves, and tides, which constantly influence these ecosystems, exhibiting strong variability over time and space. | Provisioning: Fresh water (rain filtrates into the dunes); food (fish, shellfish etc.); construction materials (beach sand, grass, wood); alternative energy resources (derived from e.g., wind, waves, tides, algae). Regulating: Coastal protection (against flooding and erosion through wave attenuation, dunes as barriers and sand buffers); wave regulation; sediment transport (through natural processes). Cultural: Aesthetic value (attractive environment); reflection & spiritual enrichment; tourism and recreational activities; research and education. Supporting: Habitat provision for animals and plants; refuge and forage areas; sediment transport; wave dissipation; soil formation and retention; water cycling.
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Muddy coasts | Productive environments with fine sediment accumulation and limited wave exposure provide vital resources like seafood and timber, while vegetation mitigates flood risks. Being low-lying makes them prone to consolidation and land subsidence, heightening vulnerability to flooding and erosion. Habitat development is influenced by sediment balance in these landscapes. | Provisioning: Fresh water (groundwater); food (agriculture, aquaculture and fisheries); construction materials (timber). Regulating: Coastal protection (against flooding and erosion through wave attenuation by vegetation); sediment trapping; water quality maintenance; carbon sequestration; nutrient cycling. Cultural: Aesthetic value (attractive environment); reflection & spiritual enrichment; tourism and recreational activities; research and education. Supporting: Habitat provision for animals and plants; refuge and forage areas; soil formation and retention; water cycling.
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Lowland Lakes | Naturally formed in areas where sedimentation separates lagoons or estuarine branches, lowland lakes can also result from engineering interventions like dams or dredging. They receive water and sediment from rivers, groundwater, and rain. | Provisioning: Fresh water (surface water for domestic, agricultural, and industrial use); fish production; construction materials (mainly sand). Regulating: Protection against storm surges; flood safety (by providing buffer capacity); water storage; water purification & pollution control (through absorption, filtering and dilution of nutrients and pollutants); soil formation; groundwater recharge. Cultural: Recreational opportunities; spiritual inspiration; serenity and space; landscape aesthetics; cultural heritage and identity. Supporting: Nutrient cycling; habitat formation for a wide range of species; water cycling.
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Rivers & estuaries | Rivers originate from groundwater, precipitation, and snowmelt, carrying sediment, nutrients, pollutants, and waste. Erosion and sedimentation shape alluvial rivers and estuaries, supporting interconnected and evolving ecosystems. Estuaries, transitional zones between fresh river waters and salty oceans, are biologically rich due to the interplay of salt and freshwater flows, fostering high biodiversity. | Provisioning: Fresh water (surface water for domestic, agricultural, and industrial use); fish production; mineable resources (hydropower, clay, sand, gravel); military defence against invasions. Regulating: Pathways (discharge of water, ice, and sediments); flood wave attenuation (floodplains and connected wetlands). Cultural: archaeological (first settlements); spiritual and historical values (cultural heritage); inspiration for art; aesthetics value; recreational opportunities; research and education; tourist activities. Supporting: Sediment transport (to maintain flood conveyance, navigability, and habitats); habitat provision for plants and animals; seed transport for riparian vegetation.
| “Room for the river” concept. Restoration of riparian wetlands Sediment management (e.g., clay ripening, stricter sand mining legislation).
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Cities & Ports | Cities are dynamic environments where water, open space, commerce, living, and leisure converge. Ports are crucial for transport and trade. To address urban demands and pressures, nature development should be multi-functional, offering social and economic benefits to residents, workers, and visitors. | Provisioning: Food (shellfish, fish etc.); construction materials (sand, mud); alternative energy resources (wind, waves, tides, algae); opportunities for industries, transport, tourism. Regulating: coastal protection (flooding, erosion); nutrient cycling; carbon sequestration; water quality regulation (through absorption, biodegradation, filtering and/or dilution of nutrients, pollutants, and other wastes); temperature regulation for city inhabitants. Cultural: recreational activities; research and education; cultural exchange; spiritual, religious and artisan value; aesthetic value. Supporting: habitat provision (animals, plants); refuge and forage areas; resilience to human impact and natural hazards (recovery).
| Sediment management (e.g., clay ripening). Flood protection measures (e.g., mangrove/salt marsh restoration). Combining the creation of opportunities for flora and fauna with improving the spatial quality of the city (e.g., construction of tidal parks).
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Adapted from Landscapes - EcoShape