4.10 - Why Coastal Flooding Happens
The impact of climate change on coastal flooding risk
Climate change significantly heightens the risk of flooding in coastal regions through rising sea levels and changing weather patterns. These changes threaten low-lying areas and alter the natural landscape, making flooding a more frequent and severe issue.
Key factors increasing coastal flooding risk
- Rising sea levels - As global temperatures increase, melting ice caps and thermal expansion of seawater cause sea levels to rise, posing a major threat to coastal and low-lying areas.
- Higher tides - Elevated sea levels result in higher tides, which can inundate coastal regions more often and with greater intensity.
- Beach material loss - Higher tides remove more sand and sediment from beaches, reducing their width and leaving the coastline more exposed to the sea.
- Increased cliff erosion - With less beach material to act as a buffer, cliffs face greater erosion as waves directly impact them.
- Expanding coastal exposure - Rising seas extend the reach of water inland, making previously safe areas vulnerable to flooding and erosion.
The effects of increased storm frequency on coastal areas
Climate change contributes to more frequent and intense storms, amplifying the destructive power of the sea. These storms exacerbate erosion and flooding, reshaping coastal landscapes and increasing risks to both natural and human environments.
Consequences of more frequent storms
- Enhanced erosional power - Storms provide the sea with greater energy, accelerating the erosion of coastal landforms.
- Differential erosion rates - Hard rock areas become more susceptible to erosion, while soft rock areas erode at an even faster pace due to their weaker structure.
- Material transport - High-energy waves during storms can carry larger amounts of sediment over longer distances, potentially leaving some coastal areas devoid of protective material.
- Increased vulnerability - Regions starved of sediment face heightened risks of erosion and flooding without natural barriers to absorb wave energy.
- Storm surges - More frequent storm surges, combined with rising sea levels, can push seawater further inland, flooding areas previously unaffected.
The threats posed by coastal flooding to people and infrastructure
Coastal flooding creates significant challenges for communities living near the sea, disrupting daily life, damaging property, and affecting local economies. The impacts are wide-ranging, touching on both personal safety and broader societal functions.
Impacts on human life and infrastructure
- Permanent flooding - Low-lying coastal areas may become permanently submerged or flood so often that they are no longer habitable.
- Damage to industries - Coastal businesses, such as fishing, face losses due to damaged equipment, destroyed boats, and disrupted operations.
- Infrastructure risks - Essential systems like roads and railways, especially those running along the coast, are prone to damage from flooding, cutting off access and communication.
- Weakened flood defences - Storms and repeated flooding can compromise existing flood barriers, reducing their effectiveness over time.
- Tourism decline - Flooding and erosion deter visitors to coastal areas, harming the tourist industry and leading to business closures and job losses.
The environmental consequences of coastal flooding
Beyond human impacts, coastal flooding has profound effects on natural environments, disrupting ecosystems and altering landscapes. The influx of seawater and the physical force of floods can cause lasting damage to both flora and fauna.
Effects on coastal ecosystems and landscapes
- Saltwater intrusion - The high salt content of seawater from flooding can harm or kill organisms unadapted to such conditions, disrupting entire ecosystems.
- Agricultural damage - Flooding reduces soil fertility on farmland by salinisation, making it harder to grow crops.
- Vegetation loss - The force of floodwater can uproot plants and trees, while standing water can drown vegetation, preventing regrowth.
- Threats to conservation areas - Coastal erosion endangers protected sites, such as lagoons separated from the sea by natural bars, which can be destroyed if the barrier is washed away.