How does deforestation affect rivers? Everything you need to know

Deforestation is a global problem that is affecting every area of our ecosystem.

When you cut down trees you rob the soil of nutrients and stability and you deprive the air of oxygen and moisture.

This also has a significant impact on waterways and rivers, including the root networks and animals and humans who depend on river systems to survive and thrive.

How does deforestation affect rivers? Everything you need to know

When you cut down too many trees you dirty and dry up rivers.

Here’s why this happens and how to change it.

1) Deforestation creates droughts and floods

When you cut down trees you do two main things:

You increase how much carbon is in the air and you interrupt the cycle of rainfall.

In other words, the air becomes more toxic and warm, and rain becomes more unpredictable and extreme.

Trees breathe in carbon and breathe out oxygen. They also absorb water through their trunks and breathe out what they don’t need. This is then breathed out through the leaves and absorbed into the clouds. It then falls back down later as rain.

When large areas of trees are cut down, less rain falls and climate change worsens.

This leads to a cycle of drought and floods, as these areas dry out and nearby areas produce water that floods into the dry areas and the parched and weakened river systems.

The simple truth is that large-scale deforestation is a disaster for rivers because it interrupts the rain that feeds them.

As Jean-Michel Martinez of the Hybaum National Observation Service warns:

“If you gradually cut down the forest, you take away the engine of evaporation and you’ll completely destabilize the ecosystem.”

It’s worth noting that in the past century there have been six major floods in the Amazon rainforest. Four of them have been in the past decade. There’s a reason for that: deforestation.

2) Deforestation erodes riverbanks

When you cut down trees and interrupt rainfall patterns, you also erode the riverbanks and root systems that reinforce rivers.

Tree roots act like a network of straws, bringing water where it’s needed when it’s not falling from the sky and keeping soil quality strong.

When those roots die off, the soil cracks and dries out, leading to erosion, desertification, and unstable soil conditions.

This also leads to not enough water for animals and nearby communities, killing off life and starving out entire areas that formerly depended on a fresh and plentiful supply of river water and flowing current.

Barbara Lyra and Daniel Rigo noted in a study of the Doce River in southeast Brazil, that deforestation causes a worsening of problems “such as floods and water shortages.”

This boom and bust cycle is awful for all forms of life that depend on rivers for sustenance, irrigation, and clearage of waste, including humans.

4) Deforestation kills river-reliant animals

When you cut down forests and starve rivers of their root networks and rain, you also harm the animals that rely on them.

Animals come to drink at rivers and feed from them as well.

When rivers dry out or become stagnant and stop flowing, the water gets fetid and toxic and the animals die of thirst and disease.

This is why deforestation leads to the killing off of local animals and the interruption of their trail networks as well.

One irony is that clearing of forests including slash and burns agriculture is often done to make a place for cattle and other livestock to graze, in order to feed the global meat demand.

This, however, kills off many other animals and weakens biodiversity and the biome as a whole, turning the world into an increasingly dry wasteland prone to sudden flooding and soil collapse.

Monica Bleich of the National Institute of Amazonian Research explains this really well, concluding that deforestation causes a:

“loss of variability in headwater stream habitat structure across hydrological periods, making habitat conditions more homogeneous and simplified throughout the year.”

In other words, animals that drink from rivers and are sustained by their ecosystem die off and cease existing in high numbers.

5) Deforestation decreases drinking water quality

For communities that rely on river systems for drinking water, deforestation also decreases drinking water quality and hikes up the price for treating water that is available.

For example, take a look at the African nation of Malawi, where increased runoff into rivers and pollution from unclean water has gone up directly proportional to deforestation.

The more that trees are chopped down in the southern African country, the dirtier water gets and the less houses have access to clean and safe drinking water.

The more that forests are cut down, the less rain there is, and the more that rivers stop providing enough water that is clean enough.

As currents dry up and the soil becomes unstable and full of more runoff and toxins from agricultural products and other uses, the availability of drinking water and sufficient water for communities begins to decreases.

The implications of this are very large indeed.

This is a giant problem, especially in countries which are not wealthy enough to easily treat large volumes of dirty water or come up with alternate, energy-intensive ways to procure clean water which rich nations like Saudi Arabia have done.

6) Riparian vs. non-riparian

It’s key to note that not all forests are riparian.

Riparian means anything next to a river or related to a river system. Some forests exists in dry scrublands, next to the ocean or in areas that are not directly riparian.

However, it’s also worth noting that even non-riparian forests can impact river systems.

When you cut down a forest in Africa, for example, it can lead to decreased rainfall in the United States, and so on.

This is because interrupting the global fall of rain and rain currents in the sky leads to droughts and floods in unexpected places.

That’s why even if you cut down a non-riparian forest in one area, it can devastate a river in a totally different area, flooding, eroding or drying it out at various times and harming all who depend on it.

7) Deforestation damages aquatic ecosystems

Aquatic ecosystems including fish, bugs, and smaller life forms get killed when rivers dry up or become stagnant.

When you dry or dirty streams and rivers, or cause them to change course and flow in a different way over time, it does huge damage.

Repairing that damage takes a lot of attention, time and money and is not easy to do by any means.

Reforestation by planting trees also takes a huge amount of time and is very expensive.

It’s not like anyone can just click a button and get forests replanted and doing what they were doing before.

And with deforestation accelerating, particularly in places like Brazil and areas of Africa and Asia, this is an increasingly dire and immediate concern.

8) Clearcutting kills rivers

When clearcutting is done and large areas of forest are removed, it dirties, dries, and disturbs riparian systems.

When too many tries die, eventually rivers die.

Take the Brazilian state of Mato Grosso, for example, which had 8 million hectares of forest cut down between 2001 to 2012, especially as a result of mineral exploration and clearing land for cattle to graze.

The result of clearing a fifth of its forest in the past decades has been that Mato Grosso’s rivers are in deep trouble.

Initiatives are being launched to protect its headwaters and springs for that reason, including by the World Wildlife Federation (WWF).

As a study on the issue showed, “an area that provides 30% of the waters of the Pantanal floodplain and guarantees a constant supply of water to at least three million people who live and work in the region is under high ecological risk.”

Protecting our rivers

Rivers aren’t just under threat in Brazil and Africa. They are being compromised and harmed all over the world.

Furthermore, as noted, damage to forests in one area of the world harm’s the entire globe’s hydrologic cycle and rivers all over the place.

Protecting our rivers isn’t just a matter of environmental initiatives, charities and regulations: it’s well known that large corporate interests have a way of finding loopholes in regulations or paying fines after they’ve already expanded where they want to go.

Instead, the key to protecting the world’s rivers going forward will have to be changing the way that society lives, grows, builds, disposes of waste and treats our forests.

Continuing to cut down forests is going to drive up the cost and energy to produce clean water, which in turn will worsen climate change.

Continuing to deforest the planet is going to dirty and collapse riparian systems and make it harder for humans and animals to exist healthily and in large number.

Continuing to use wood products and non-sustainable models of farming and community is going to become an increasing impossibility if we wish to have a future worth living in with clean water and air.

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Paul Brian

Paul R. Brian is a freelance journalist and writer who has reported from around the world, focusing on religion, culture and geopolitics. Follow him on and visit his website at

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