The Impact of Sea Level Rise on Coastal Drainage Systems

Seascape change is inevitable. As the salt water rises, sea level rise has significant implications for coastal areas. It increases the rate at which groundwater is being pulled into the ground by gravity, threatening to further degrade groundwater quality and cause saltwater intrusion in drinking water aquifers. Increased erosion, flooding and impact on infrastructures such as roads and buildings can occur as these effects compound each other.


If I Live Near a Coastline, What Should I Do?

If you live near a coastline, it’s important to know how climate change affects your home and community: you need to know what areas are at risk for flooding and what steps you can take to protect yourself and your family from rising seas.


What Is Sea Level Rise?

Sea level rise is a global phenomenon that threatens human and environmental health. Sea level rise occurs when the ocean water warms up and expands because of global warming. The oceans are warming faster than land areas because of increased greenhouse gas emissions from burning fossil fuels. This warmer water expands as it warms up and displaces colder water from around the world’s coastlines.


Causes of Sea Level Rise

Rising sea levels are a result of climate change and they have been accelerating in recent years due to melting ice sheets, thermal expansion of seawater, and other causes. The effects of sea level increase on coastal drainage systems comprise flooding, erosion, saltwater intrusion into freshwater aquifers, increased storm damage, and decreased property value.


Impacts of Sea Level Rise

The impact of sea level rise on coastal drainage systems is complex, and has been described as a “multi-faceted problem”. The impacts of sea level rise on coastal drainage systems include:


Saltwater intrusion

Saltwater intrusion will be more common as the ocean water rises. When the tides are high, saltwater can flow into storm sewers and other pipes in coastal areas. This can cause corrosion of metal pipes, which could lead to leaks or breaks in water distribution systems. It also increases the salinity levels in groundwater aquifers, leading to higher nutrient levels that can affect drinking water quality.


Frequency Increase and magnitude of flooding events

As sea levels continue to rise, flooding events will become more frequent and intense due to increased storm surges from tropical storms and hurricanes, as well as increased rainfall from hurricanes and tropical storms. In addition to causing property damage and loss of life, these events can damage roads, bridges and utilities such as power lines and water lines (which are often buried under roads or sidewalks) that run along the coast.

Sea level rise also increases the frequency and magnitude of flooding events by increasing storm surges. Storm surges can be caused by hurricanes or tropical storms, though they also occur during nor’easters or winter storms when there is no storm activity offshore. Storms with high wind speeds (100 mph or greater) can cause significant damage inland along rivers.


Inundation of coastal stormwater pumping systems

Coastal communities are often built in low-lying areas. As seas continue to rise, it may become necessary for some communities to pump their wastewater into nearby rivers or oceans instead of using existing drainage systems. This can cause problems, including high water costs and decreased availability of water.


Reduced groundwater recharge

The same changes in sea level also affect the amount of groundwater that enters coastal aquifers. As seas continue to rise, groundwater levels will likely fall under some circumstances. This can have significant implications for coastal communities that rely on this resource for their drinking water supply.


Water quality degradation

As the ocean continues to rise, saltwater will be able to invade coastal aquifers. Saltwater intrusion occurs when salts from seawater enter shallow aquifers that were once freshwater sources. The higher salinity increases the risk of contamination and reduces the aesthetic appeal of coastal areas.


Ecosystem changes

Sea level rise has been linked to ecosystem changes across many marine habitats including sea-grass beds and coral reefs. The results of this study suggest that climate change may have significant impacts on marine ecosystems. For example, it is possible that some species could become extinct if their habitats become too salty or too shallow due to rising seas.


Increased maintenance costs

In order to maintain existing drainage systems, there are additional costs involved in maintaining them. The cost of maintaining drainage systems increases as the sea level rises, which makes it more difficult to maintain these systems. If there were no change in sea level, then these costs would be minimal and easy to handle. However, as the sea level rises, the cost increases significantly due to the increased maintenance required by the system to prevent damage from flooding and erosion.


Reduced water supply availability

The amount of water that flows into coastal areas depends on the amount of rainfall received by those areas and how quickly it can be absorbed into these systems. When sea levels rise, it will cause problems for flood prevention because less water will be available for absorption into these systems due to higher volumes of water entering them from rainfall instead of being absorbed by them. This means that there will be less capacity available for flooding during storms or other natural disasters.


Effects on infrastructure, such as roads and buildings

The 2017 National Climate Assessment (NCA) identified climate change as a major threat to infrastructures such as roads and buildings along coasts, particularly in areas with high population densities. The NCA predicts that by 2050 more than half of the nation’s coastline will experience some type of infrastructure damage due to rising seas (e.g., airports with runways less than 1 meter above current sea level).


Factors that need to be considered

The impact of sea level rise on coastal drainage systems can be significant. A number of factors need to be considered when determining the effect that sea level rise will have on your drainage system.

The first thing to consider is how much water your drainage system can handle before it begins to overflow or back up into your property. The size of a pipe and the velocity of its water flow determine how much water it holds before it overflows. The larger the diameter of the pipe, the more volume it holds.

If you live in an area where there are no major rivers or streams nearby, then you may not experience any problems with flooding due to sea level rise. However, if you live near a river or stream, then it’s likely that you will see some changes as a result of rising sea levels over time.

The second factor that needs to be considered is whether or not there are any man-made structures near your property that could be affected by rising sea levels as well. If these structures include roads or bridges, then they could become flooded if they aren’t properly maintained over time.


Final Thought

Sea level rise is almost certainly going to present significant challenges and offset costs for coastal communities, which will have to adapt in a number of ways. In the case of this specific example, the cost-benefit analysis leads to the conclusion that environmentally sound solutions are worth pursuing, but, as with all proposed solutions, such should be considered on a case-by-case basis, taking other factors into account.

As leading drainage and environmental specialists, RWB Group UK delivers innovative solutions nationwide. If you have a project near the coastline and you think it may be susceptible to the impacts of the rising sea level, get in touch with our team today on 0800 488 0658 or email us at