How the Flood Damage Bill Will Increase With Climate Change
Why is climate change increasing the threat of flooding? What impact Why is climate change increasing the threat of flooding? What impact does this have on communities? And what are the economic repercussions?
The effects of climate change are being felt around the world, and unfortunately we’re seeing an increase in both the frequency and severity of natural weather related disasters such as floods. The devastating impacts of these events are creating problems for communities and governments globally, as they struggle to mitigate and adapt: not only is there a human cost to climate-related events such as flooding, there’s a resulting economic impact too.
👉 Why is climate change increasing the threat of flooding? What impact does this have on communities? And what are the economic repercussions?
First up, what causes flooding?
Flooding is an overflow of water that submerges land that would usually be dry. They are the most common and widespread type of natural disaster - and unfortunately due to climate change they’re becoming more and more frequent.
The term flooding actually covers a variety of different types, and can refer to anything from a few inches of submersion to water that’s many feet deep. Before we take a deep dive into the causes of flooding, let’s first take a look at the different types of floods that can impact a community:
River floods usually occur when the water levels within the river breach the top of the river banks. This type of flooding can happen in any river or stream channel (from the smallest brooks to the largest mainstream). The causes of this type of flooding are usually excessive rainfall over land, persistent thunderstorms, combined rainfall and snowmelt, or ice jams (when large chunks of ice block the flow of a river).
If a large river with a significant catchment area is affected, the flooding tends to be slow and low-rising. Sudden river floods are more likely to occur in smaller rivers, rivers with steep valley sides, or those that flow over impermeable terrain (ie. ground that doesn’t soak up any of the moisture).
Coastal flooding occurs when dry and low-lying land is submerged by seawater. It’s often caused by tidal surges, high winds, and barometric pressure resulting from weather events such as cyclones, tsunamis and higher than average tides. However, the topography of the area may also influence the likelihood of flooding - for example the height of land above sea level, the amount of erosion, and the removal of vegetation can all make an area more susceptible to coastal flooding.
Inland flooding occurs when the volume of water on land exceeds the capacity of natural and man-made drainage systems. This type of flooding is often referred to as urban flooding and is usually caused by short term, intense rain or rain over several days.
Urban areas are particularly susceptible to this type of flooding as they tend to have low capacity drainage systems and poor ground soil quality due to low amounts of vegetation and green space.
Flash floods are an extremely dangerous type of flooding that occurs in a especially short timeframe (ie. under 6 hours). Usually they are caused by heavy or excess rainfall and areas near rivers or lakes tend to be the most susceptible to this type of flooding, however it can also occur in areas with no water bodies nearby.
Urban areas are also vulnerable to flash flooding as their impervious surfaces mean that the water can’t drain into the ground properly, meaning that the water has nowhere to go and so levels rise quickly.
The speed of this type of flooding is what makes it so dangerous - communities are given little time to react or evacuate.
What are the main causes of flooding?
Now that we’ve outlined the different types of flooding that exist, let’s take a closer look at the main causes behind it.
Heavy or prolonged rain
Heavy rain is the most common cause of flooding and can be caused by a number of different weather conditions. The amount of rain, the intensity, the duration, and the area affected by the rainfall all influence the runoff of water that reaches streams and rivers, as well as the land's ability to absorb the water.
Overflowing rivers and bodies of water aren’t just caused by heavy rainfall. Flooding may also occur when debris in rivers or dams block the normal flow of water resulting in a build-up.
When snow melts this results in water saturating the ground or soil. When snow melts in large quantities the ground may reach a point of saturation meaning that it is unable to absorb any more water, this leads to surface runoff which then enters nearby rivers and streams, increasing their water levels.
Deforestation is the removal of trees to convert the land for non-forest use. Clearing land of trees and vegetation reduces the volume of water that the soil can absorb and retain, which in turn leads to increased surface runoff, and increased flow of water into rivers and streams.
👉 Note that forest fires also have the same effect as man-made deforestation and reduce the volume of water that the soil is able to hold.
The building of structures such as roads, pavements and buildings means that permeable soil is replaced with impervious materials such as asphalt and concrete. This means that the ground is no longer able to absorb excess water which increases the risk of excess surface runoff and makes the area more vulnerable to flooding.
How is climate change affecting flooding?
Climate change affects weather systems and our environment in a multitude of different ways: from increased storms, to more intense rainfall, to periods of drought resulting in dry, arid soil, to the melting of snow and glaciers. There is no corner of the world and no weather system that is unaffected by rising global temperatures. In this next section we’ll explore how the effects of global warming are increasing the risk of floods in countries and communities across the world.
Why is global warming creating more rain? Well, a warmer atmosphere holds and therefore releases more water. In fact, as climate change heats the Earth’s atmosphere, the air is able to hold 7% more water vapor for every 1℃ rise in temperature. When this air cools quickly, water vapor turns into water droplets which combine to form heavy rainfall.
What does this mean? Well, due to global warming heavy precipitation events are projected to increase, with some scientists predicting that we could see three times the historical average in rainfall by the end of the century.
Why is this a problem? Increased intensity of rainfall, or rainfall that is prolonged can saturate the soil and lead to increased volumes of water in our rivers and streams, which means that flooding is more likely to occur.
Not only this, but increased precipitation also speeds up the melting of snow, which means that snowmelt-fed rivers are experiencing higher streamflows and therefore are also at higher risk of flooding.
More frequent storms
Data shows that climate change is increasing the frequency and severity of storms such as hurricanes and cyclones. In the Atlantic basin for example, an 80% increase in category 4 and 5 hurricanes is predicted by the end of this century. What compounds the issue is that these storms are also expected to be wetter with up to 37% heavier precipitation predicted. More frequent storms with more intense rainfall will result in more frequent catastrophic flooding events.
What's even more worrying is that these storms also produce stronger winds and create greater storm surges - something that is especially deadly. Hurricane Katrina for example, produced a 28 foot storm surge in 2005 that resulted in extensive flooding and caused the deaths of nearly 1,500 people. Unfortunately, due to global warming storm surges are not only expected to increase in size but will also penetrate further inland, causing more damage and presenting an even greater threat to human lives.
As air and ocean temperatures rise, the world’s glaciers and ice sheets are melting at a faster rate than ever before. This is causing global sea levels to rise. In fact our oceans are already estimated to be 7 to 8 inches higher than they were in 1990, and scientists believe that future sea levels could rise as much as 5 meters by the end of the century.
Our polar ice caps are also under significant threat. The Antartica has already lost over 3 trillion tonnes of ice over the last 25 years, which has caused global sea levels to rise by 8mm. As the world’s temperatures continue to increase we can expect to see an increased rate of melting and further threat to coastal communities who will be forced to adapt to coastal flooding and permanent loss of land.
What is the impact of flooding?
Flooding not only threatens human lives, but can damage properties and businesses, destroy possessions, cripple vital infrastructure, and prevent access to essential public services. It presents a huge challenge to the communities affected as well as governments who often have to pick up the resulting damage bill. Let’s explore the ramifications of flooding and the economic impacts in more detail:
Immediate loss of human life
Fast flowing and deep flood waters are incredibly dangerous. Even shallow water can knock over children and adults, potentially sweeping them away resulting in drowning or physical harm to the human body. There is also significant danger presented by the debris carried in the flood waters.
While immediate flooding can claim lives through drowning, it can also have a severe impact on human health in the long run too. Flooding can carry with it raw sewage and chemicals, as well as hazardous runoff from waste sites, factories and farms. This can result in contaminated water supplies, which increases the risk of infections and the ingestion of toxic materials.
And even when the water recedes the risk is not gone, bacteria may linger which can increase the rates of respiratory illnesses. Flooding also results in increased psychological stress which can contribute to mental health problems.
Critical health infrastructure may also be affected by flooding, for example flooding may prevent power generation or supply, which can in turn cut off air conditioning, refrigeration, access to the internet and other facilities that are powered by electricity This can result in a variety of different threats to human lives. For example, flooding from Storm Katrina knocked out power to one of New Orlean’s main hospitals (Memorial Medical Center) which meant that patients were forced to endure humid, hot conditions with no AC, and were left without access to lifesaving equipment.
Damage to infrastructure and property
It only takes two feet of water to wash away a car, and the damage doesn’t stop there - flooding can cause significant harm to property and infrastructure. When it comes to homes and buildings, floods can knock out windows and doors, corrode walls and foundations, and litter property with debris. Not to mention the damage to the interiors - ruined floors, walls and furniture.
And it’s not just homes and cars that are damaged: roads, bridges, utilities and a variety of other public infrastructure can be damaged or ruined too. Where flooding knocks out utilities such as electricity, water and gas supplies, households and businesses can also severely suffer.
Damage to communities
The long term impacts of flooding can really take its toll on communities. The stress and trauma of such an event can cause chronic illnesses and long term psychological issues. Additionally the temporary or sometimes long-term loss of access to community services or infrastructures can also cause a wide variety of negative effects - for example lack of access to schools, health facilities and other amenities can severely impact a community's ability to recover from flooding.
Loss of crops
Flooding can damage or completely destroy agricultural land which means that crops and even livestock can be lost. This not only represents an immediate loss of income for the farmers affected, but it can also significantly impact wider food supply chains. Sudden drops in product supplies can result in product price hikes which can impact the cost of goods in countries that are otherwise unaffected by the flooding.
Loss of businesses and livelihoods
It goes without saying that severe flooding can destroy businesses and the livelihoods of entire communities. It might be that their means of creating income has been destroyed (as is the case where flooding destroys a farmer's crops), or it might be that the flooding has destroyed the physical premises of the building meaning that it can no longer operate, or where communities find themselves displaced as a result of the flooding they may have had to leave their entire business behind.
The economic impact of flooding
What’s clear is that the impact of flooding is extensive, and it doesn’t just take a human toll, it has an economic effect too. Damage to infrastructure and property means that money needs to be spent to fix and repair it. Where flooding results in health conditions this is also matched with a corresponding treatment cost. Flooding can also stall or bring an end to people’s livelihoods - business can be destroyed, crops and livestock lost, and entire communities may even find themselves displaced.
What’s most concerning is that climate change is increasing the risk of flooding globally which means that governments and communities around the world must look for ways to mitigate and adapt to the effects of climate change. This is something that will also bring with it a corresponding bill, however, the cost of waiting to act is even greater.
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