How Does the Formation of a Natural Levee Impact Flooding?

Introduction

Hello, Reader nawafnet! Welcome to this journal article about the formation of a natural levee and its impact on flooding. A natural levee is a raised bank formed beside a river due to the repeated flooding of its banks. Natural levees are crucial in reducing the impact and severity of flooding. In this article, we will discuss in-depth how the formation of a natural levee affects flooding, its strengths, weaknesses, and impact on the environment.

According to the UN, floods are the most frequent and costly natural disasters, affecting millions of people worldwide. In 2021, the world has already witnessed 23 major floods, leaving behind deaths, displacements, and economic losses. A natural levee acts as a wall resisting the flow of floodwater, creating a separation between the river and floodplain. When the river breaches its banks, the floodwaters spread out over the surrounding area. The building up of a levee, therefore, allows the river to flow higher without inundating the floodplains, thus reducing the impact of flooding.

Now, let’s delve deeper into how the formation of a natural levee impacts flooding.

The Formation of a Natural Levee

When a river overflows its banks, it deposits sediment along the edges of the channel, creating a raised bank of soil, sand, and gravel. This overflow happens when the volume of water in the river exceeds the capacity of the channel to carry it.

The top layer of the levee dries out and hardens to form a barrier, while the lower layers maintain the soil characteristics of the surrounding floodplain. The next time the river overflows, it deposits more sediment on top of the existing levee, increasing its height and strength. Over time, repeated floods cause the levee to grow higher and wider, eventually creating a natural barrier between the river and floodplain.

Strengths of Natural Levees

Here are the strengths of natural levees:

1. Protection Against Flooding

The primary benefit of forming a natural levee is its ability to protect against flooding. The levee acts as a physical barrier to block and control floodwaters from overflowing the river. By providing a resistance, it directs water back to the river channel, reducing the floodwater’s impact and severity.

2. Protection of Ecological Systems

Natural levees help protect and sustain nearby ecosystems. The deposit of the river sediment on the floodplain causes it to become fertile, allowing plants and animals to thrive in the area. The reduction in flooding also reduces soil erosion, which can negatively impact the health of the environment. A well-formed natural levee maintains a balanced ecosystem that thrives and helps keep nearby areas safe.

3. Cost-Effective and Accurate

The formation of natural levees is inexpensive as it occurs naturally and does not require much assistance from humans. After placement, they require minimal maintenance and can last for centuries as long as they are not overloaded. Unlike man-made structures, natural levees have a much higher degree of integrity and can withstand extreme weather conditions, making them an effective and economical option to protect against floods.

4. Preventing Floodwater Damage

Because natural levees redirect floodwaters back to their source, they help prevent damage to downstream properties and other infrastructures. Land and properties located near the floodplains are less likely to experience severe water damage when a natural levee protects them.

Weaknesses of Natural Levees

Here are the weaknesses of natural levees:

1. Limited Capacity

Natural levees have limited capacity in terms of controlling more significant and intense flooding events. They can only reduce the severity of moderate floods, and when floodwaters exceed the levee’s capacity, they can break, fail and even worsen flooding.

2. Erosion Pressure

The formation of a natural levee increases water velocity within the channel, which can cause erosion due to increased pressure. This erosion has the potential to weaken the levee and cause it to break, exacerbating flooding problems.

3. Periodic Maintenance

Natural levees require periodic maintenance, which involves inspecting the levees to ensure that they are not structurally compromised and that any potential vulnerabilities are addressed. This maintenance can be expensive and time-consuming.

4. Land Use Restrictions

Natural levees limit land development near the floodplain, which may impact certain industries like real estate and agriculture. The strict land use restrictions limit economic growth in these areas and can prove challenging for those communities.

The Impact of Natural Levees on Flooding

Natural levees have a considerable impact on flooding in several ways, some of which are:

1. Floodwater Confinement and Routing

Natural levees confine and route floodwaters, preventing the flood from spreading over the floodplain. The bank acts as a physical barrier, preventing the water from overflowing and spreading into neighboring communities, reducing the effect of flooding.

2. Reduction in Flood Damages

Natural levees help reduce the damage caused by flooding. When floodwaters are routed away from developed areas, the water doesn’t cause damage to houses, infrastructure, and other exposed objects. Natural levees also keep infrastructure like bridges, roads, and railways safe, reducing the cost of repair and preventing disruptions in transportation.

3. Changes in the Landscape

Repeated flooding and building up of a natural levee can lead to changes in the landscape. The dependence on flooding creates a conducive environment for the formation of fertile soil, perfect for agriculture and other vegetation. The ecosystem of the area may change due to the regular flooding, creating habitats for different organisms.

4. Reduction in Erosion

Natural levees help reduce soil erosion by confining floodwaters to the river channel. This reduces the possibility of soil erosion away from the bank, which makes the area more fertile and less prone to erosion by flooding.

The Impact of Natural Levees on the Environment

Natural levees have significant environmental impacts, some of which include:

1. Habitat for Wildlife

Natural levees create habitats for a variety of wildlife in the area. The deposited sediment creates a fertile environment, making it attractive to different types of plants and animals.

2. Soil Conservation

Natural levees help conserve the soil by reducing erosion in the nearby area. This helps prevent soil loss and degradation and retains nutrients in the soil, which is essential for agriculture.

3. Reduced Carbon Emissions

By reducing the impact of flooding, natural levees reduce the release of carbon from nearby areas. During floods, carbon-rich soil and vegetation are washed away and transported downstream, releasing carbon into the atmosphere. Without flooding, carbon emissions are reduced, making the environment more balanced.

The Formation of a Natural Levee Table

Aspects	Factors
Construction	Deposition of sediment, raised embankment, layer hardening, and increased width
Strengths	Protects against flooding, protects ecological system, cost-effective, and prevents floodwater damage
Weaknesses	Limited capacity, erosion pressure, periodic maintenance, and land use restrictions
Impact on Flooding	Floodwater confinement and routing, reduction in flood damages, changes in the landscape, and reduction in erosion
Impact on Environment	Habitat for wildlife, soil conservation, and reduced carbon emissions

FAQs

1. What causes flooding?

Flooding occurs when water overflows from a watercourse or drainage system. This happens when there’s heavy rainfall, when natural watercourses cannot carry the water, or when man-made structures like dams fail.

2. How do natural levees form?

Natural levees form when sediment accumulates along the edges of the channel during the repeated flooding of a river. Slowly, this sediment gets packed tightly together to form a small ridge or embankment gradually becoming bigger with each flooding cycle.

3. How do natural levees reduce the impact of flooding?

Natural levees resist the flow of floodwater, directing it back to the river channel. This reduces the amount of water that overflows the river’s banks, preventing flooding from inundating the floodplain.

4. Are natural levees better than man-made levees?

Natural levees are long-lasting and cheap to construct compared to man-made levees. In contrast, man-made levees require extensive maintenance, are expensive to build, and can break under extreme conditions.

5. What is the difference between a natural levee and a man-made levee?

Natural levees are formed due to the frequent flooding of a river, while man-made levees are structured to contain floodwaters and protect nearby properties and infrastructures.

6. Do natural levees have any weaknesses?

Yes, natural levees have some limitations, like limited capacity, erosion pressure, periodic maintenance, and land use restrictions.

7. What are the benefits of natural levees?

Natural levees protect against flooding, conserve the soil by reducing erosion, help create habitats for wildlife, and reduce carbon emissions.

Conclusion

In conclusion, natural levees are an essential component in reducing the impact of flooding. As we have seen in this journal article, it acts as a physical barrier that directs water back to the river channel, reducing flooding’s impact and severity. Natural levees also have environmental impacts, as they provide habitats for wildlife, reduce soil erosion, and help reduce carbon emissions. Although natural levees have limitations, their benefits cannot be ignored. We encourage everyone to play a role in ensuring that natural levees are well-maintained and preserved to help minimize the impact of flooding for generations to come.

Closing Words and Disclaimer

We hope that you enjoyed the article on how natural levees impact flooding. Please note that while the content of this article is accurate to the best of our knowledge, it is subject to change. The purpose of this article is educational and should not be taken as a definitive guide on natural levees or flooding. Please consult with appropriate experts in the field before making any decisions or taking any action. Thank you for taking the time to read this article.