In natural systems, floods play an important role in ecosystem functioning, such as by recharging groundwater systems, filling wetlands, and the promotion of breeding, migration, and dispersal of numerous species . In natural ecosystems, there is a lot of resiliency to the majority of flood events.
In contrast, in areas that have been developed by humans where the natural resiliency of ecosystems has been lost, floods can be very destructive. They can destroy homes and other infrastructure, and can lead to a loss of crops, to the spread of waterborne diseases, and to a loss of human life. Floods can also disrupt industry, water supplies, wastewater treatment, transport, education, and healthcare, essentially forcing many local economic activities to be halted until rebuilding has occurred .
While there are naturally caused floods that would have occurred from time to time that natural systems could mostly handle, our development of a lot of the world’s landscape and our consumptive lifestyles have led to an increase in floods.
The following is a list of some of the human causes of floods.
Common causes of man-made floods
Floods can be caused by a breaking or failure of infrastructure that can cause large quantities of water to flood a local area.
One example is when water mains break such as the one that occurred in July of 2014 on the UCLA campus in the United States that caused water to gush out into the surrounding area at 75,000 gallons per minute.
Another example is when dams break due to faulty construction or maintenance, or when they are overwhelmed due to heavy precipitation.
Development and infrastructure in flood-prone areas
The development and building of infrastructure in flood-prone areas, such as along rivers, near ocean shorelines, or near river deltas, has led to an increase in vulnerability to flooding because the natural resiliency of these ecosystems has been compromised.
When deforestation occurs in a particular area, there are no more trees to help soak up precipitation and reduce waterflow over the landscape. Without these natural protections, there is an increased risk of flooding and erosion whenever it rains.
In developed areas, such as in urban areas, there is commonly a large amount of impermeable surfaces like roads and other concrete structures that do not allow water to permeate back into the soil.
When large amounts of rain falls on these impermeable surfaces, the water can accumulate and lead to flooding in low-lying areas if it is not directed properly.
Sometimes, bridges that have been built over rivers can slow the discharge of water and reduce the river’s capacity to hold more water .
Flood embankments that are intended to increase the water-holding capacity of rivers can potentially prevent flood water from draining back into the rivers during large precipitation events .
Due to an increased level of human-produced greenhouse gases in the atmosphere, the world’s climate is changing and getting warmer. Among many other climate change impacts, some regions are now experiencing increased precipitation and flooding.
As melting of the the world’s glaciers occurs due to warmer global temperatures, sea level rise is occurring around the world, also leading to an increased risk of flooding in low-lying coastal regions and in heavily urbanized floodplains such as the Nile, Mississippi, and the Ganges-Brahmaputra.
These flooding risks are predicted to increase if greenhouse gas emissions continue unabated.
Examples of measures that help us prevent flooding
While we as humans have certainly altered much of the natural landscape of the planet, leading to an increase of floods, we can also help to reduce the risks of flooding.
- By restoring natural ecosystems, such as wetlands and coastal ecosystems such as Mangrove forests, we will restore some of nature’s capacity to deal with flood events.
- By planting trees and reforesting areas that have been deforested, we can restore the landscape’s ability to take up and store precipitation. We can also restrict the development of infrastructure within flood-prone areas, such as next to rivers and coasts.
- By moving forward with a sustainable future where only clean energy is used, and by working with Nature’s limits in our own daily lives, we can ultimately help to reduce the risk of flooding as greenhouse gases are reduced and we strive to turn the tide of a warming planet.
- We can plant trees in urban areas and intentionally develop parks and reserves for natural ecosystems that retain the ability to take up rainwater and other precipitation.
- When we engage in development, our development must incorporate permeable surfaces that allow water to recharge groundwater supplies, instead of simply allowing precipitation to runoff and flood vulnerable areas.