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On a yearly average, the world loses more than 40 billion dollars in damage caused to crops, houses, and public utilities due to floods. Between 1998 and 2017, floods affected around 2 billion people worldwide. Devastating floods are almost an annual occurrence in many parts of the world. Flood management is becoming increasingly critical with the anticipated sea-level rise and other climate change impacts. But human-made hazards such as stormwater runoff, levee instability, and the development of floodplains are making effective flood management difficult.
Keeping in mind these issues, flood management involves increasing the breathing room for constricted rivers by reducing development on floodplains, setting back levees, and considering environmental and economic factors while making management decisions.
Flood management involves making efforts to reduce the risk of flooding. Rivers are mighty and unpredictable forces of nature. Completing stopping rivers from creating floods is impossible. However, there’s a lot we can do to reduce the impacts of flooding on vulnerable people and communities.
There are three main approaches to flood management. They are:
1. Officials need to assess flood risks and map areas to identify flood-prone zones. Mapping and assessment help them estimate the probability of a flood occurring in an area, the depth and speed of the flood waters, and the duration for which floods might submerge an area. Data like this helps prevent flood damage by guiding land use and urban development. It guides officials in developing hospitals, schools, and power plants in areas not at risk of flooding. It also reduces flood damages by advising officials which buildings need flood-proofing and guiding the design of new buildings.
2. Improved and efficient flood warning systems and forecasts can constantly monitor weather patterns. They can reduce damages to life and property by alerting people to evacuate an area or ready themselves for flooding events. This way, people can protect their belongings and flood-proof their residences.
3. City officials and planners can use flood management structures to protect urban and agricultural communities, homes, and areas of economic importance. Flood management structures include:
a. Reservoir dams for delaying and abating floods by storing excess water and protecting areas downstream.
b. Protecting and rejuvenating natural channels, reservoirs, lakes, and wetlands to divert the flow of water away from an area.
c. Preventing inundation of areas along floodplains and coasts by building spurs, levees, and seawalls.
d. Preserving and increasing the flow capacity of riverbeds and canals through riverbank protection, monitoring and maintaining riverbeds, and channel stabilization.
e. Protecting and rebuilding forests. Forests act as a barrier against floods and also help prevent soil erosion. The presence of soil is necessary for the percolation of flood waters.
Flood management structures reduce the damage to physical infrastructure by keeping water out through natural or man-made structures. It ensures that communities can go on with their social and economic activities.
We can summarize most of the challenges facing flood management in the following points:
1. A growing population needs more space to live, socialize, and work. This increases the construction of infrastructure on floodplains. Floodplains are important natural barriers against floods. Their porous surfaces quickly soak up floodwaters. Additionally, they provide us with fertile lands to grow our crops. Development on floodplains increases the risk of an area flooding.
2. The poorest and most vulnerable people are often the ones exposed to the risks of floods. Their poverty and financial situation leave them no choice but to settle in areas most at-risk.
3. The rise in population has left most of the world with a shortage of land for economic activities. This means that people abandoning flood-prone areas is not a sustainable option for flood management.
4. Urbanization has led to impervious surfaces like concrete and cement covering porous, permeable soils. These impervious surfaces lead to increased surface runoff accentuating downstream floods.
5. Deforestation driven by increased farming, mining, and urban activities increases the events of flooding. Forests can protect us from flood waters and stop soil erosion, allowing water to seep down.
The challenges of current flood management methods and the shortcomings of traditional measures tell us that we need new approaches to flood management. The new approaches must balance development with the environment. We have to find ways of making life easy in floodplains and flood-prone areas.
Climate change is causing sea levels to rise by melting glaciers and expanding warm seawater. The rise in sea levels will increase the risk of tidal inundation and coastal erosion. Coastal storm surges will worsen as climate change increases the intensity of hurricanes, typhoons, and cyclones.
Experts have predicted that climate change will also increase the intensity and frequency of extreme rainfall events. More intense and frequent rainfall events mean that rivers will flood more often. In coastal environments, river floods may combine with coastal floods and high tides. The combination of these phenomena will increase the depth and extent of flooding.
The climate change consequence of most concern to scientists is that weather conditions will change. That means that the flood management structures that officials built for present weather conditions will no longer be appropriate and relevant in the future. Present flood management structures may become ineffective and fail. Their failure may cause more damage than if they did not exist.
Designers will also face problems while designing new flood management structures. If they cannot rely on past weather patterns to predict future flooding events, how will they come up with structural designs effective against future floods?
National governments must provide adequate flood protection for people and infrastructure in developing countries since these regions are the most vulnerable to flooding events intensified by climate change. This can happen through adequate funding via private and public investments. Governments need to make appropriate decisions on the appropriate planning, design, operation, and maintenance of flood management structures. While making these decisions, they must consider the local hydrology, topography, rainfall patterns, and existing infrastructure.
However, most importantly, they need to consider the extent and nature of climate change and the impacts it will have on new and existing flood management structures. For example, the structural design of a seawall may be resilient, but it can become ineffective as sea-level rise causes its frequent overtopping.