Back to: Jss3 Basic Science
Topic: Environmental Hazards
WEEK: 3 & 4
An environmental hazard is any action that can hurt the natural environment or harm people’s health. Soil erosion, flooding, bush burning, cutting down trees (deforestation), creating deserts (desertification), and so on are all examples of an environmental hazard.
Soil erosion is when rain and wind wear away at the surface of the soil. This is caused by activities that individuals do, like building roads, burning down forests, building houses, farming, and so on.
Types of Erosion
Based on the cause of erosion, we have:
Water erosion This is what happens when a lot of rain or a flood washes away the soil on a slope. Over a long time, gullies are made by the constant flow of water. When it rains on the muddy ground, the water runs off, washing away a lot of soil and breaking up rocks through a process called “weathering.”
Wind erosion You can stop wind erosion by planting trees in the path of the wind. These trees help block the wind.
Human Activities That Cause Erosion
i. Building roads: Before roads can be built, trees need to be cut down and bushes need to be burned. This leaves the surface of the soil open to erosion. During these steps, heavy machines are also used, which wear down the surface of the soil.
ii. Bush burning: When bushes are burned to get rid of them, the topsoil is shown. This lets the soil be worn away by rain and wind.
iii. Building houses: Just like with building roads, trees need to be cut down and bushes need to be burned before houses can be built. This leaves the surface of the soil open to erosion.
iv. Farming: Before farmers can plant new crops, they have to till the land. Soil erosion is made worse when land is tilled.
Effects Of Erosion
- It makes the soil less fertile
- It harms the surface of roads and soil.
- It affects farmlands and the food they grow.
- It could cause people to lose their homes.
- It causes accidents and building collapses that kill people.
Control Of Erosion
The following things can be done to stop soil erosion:
i. Planting grasses and trees with deep roots can stop soil from washing away by reducing the force of rain and wind on the soil.
ii. Planting cover crops like Mucuna not only makes the soil better but also stops it from washing away.
iii. Making ridges on farmland to slow the flow of rainwater and reduce soil erosion.
iv. Sloping land is more likely to have soil erosion. This effect can be lessened by building ridges on the slopes that look like stairs to slow the flow of rainwater down the muddy areas. This is known as terracing v. Soil erosion can also be stopped by alternating cover crops and other crops on muddy land.
Methods Of Preventing Soil Erosion
- Wind erosion can be stopped by planting wind-blocking cover crops, grasses, and a belt of trees.
- Erosion and flooding can be stopped by making sure that water flows into rivers through canals and drains.
- Small dams made of rocks and sticks can be built along the edges of gullies to hold the soil that is being washed away.
- To stop erosion, a terrace should be built. Terraces are walls that are built along the slopes of the land to slow the flow of water downhill.
When too much water flows over normally dry land, this is called flooding. Floods not only ruin land and property, but they also kill people and ruin crops.
Causes of flood
Some of the reasons for flooding are:
- Amount of rain: When it rains too much, water runs off the land in such large amounts that it can’t be carried by stream channels.
- Establishment of settlements along river channels: Some parts of rivers and other bodies of water, like flood plains, are sometimes filled with sand and used for building.
- Strong tidal waves: Depending on the time and season of the year, tides can be low or high.
- Dumping of refuse may block culverts or water channels.
- Presence of steep slopes in an area.
- Not enough or bad planning for cities.
- Dams and berms are falling apart.
- When it rains hard, rivers overflow into neighbouring lands. When the sea overflows into rivers, the rivers then overflow into neighbouring lands.
- Clay-like soil keeps water in. So, when it rains on clayey land, it fills up with water and causes flooding
Effects of Flooding
- Sands and some harmful substances that are deposited during flooding can cause water pollution in bodies of water like rivers, streams, and seas. Therefore, this could cause the death of living things (plants and animals) that are present in that area.
- It might result in the destruction of property, lives, etc.
- It may throw off an ecosystem’s normal balance.
- Food crops may be ruined by flooding.
- The fertility of the land can be lost.
Prevention of Flooding
- Flooding can be stopped by educating the public about what happens when it rains too much.
- Building dams and levees to hold water in case of a flood.
- Building gutters or culverts that are wider.
- Keeping waste from being dumped anywhere.
- Drainage channels need to be cleaned out regularly so they don’t get clogged.
- Keeping buildings from going up in swampy areas or along waterways.
- Cleaning out gutters and drains to make water flow better through them.
- Building dams next to rivers.