The Solution to combat desertification


The Great Green Wall


The African Union and other organizations came up with the idea of building the ‘Great Green Wall’. This wall aims to stop the Sahara from reaching the green heart of Africa. This huge new forest will be 8000 kilometers long and stretches from the east- to the west coast of Africa. The mega project aims to create a healthy environment for the millions of people living in the Sahel. Hereby it prevents an invasion of millions of people migrating to Europe.



How to transfer degraded land into fertile land?

The solution to this problem is very easy. We simply have to open the earth crust and make sure that we ‘harvest’ all the water that falls during the rain season. We dig trenches that will catch all the water when it rains. In the trenches we made we will plant young trees and we will seed seeds. When the rain comes the trenches will turn into green areas. The water will be filtered by the vegetation as it sinks deeper into the ground.


What is ‘contour trenching’ and how does it work?

Contour trenching is digging trenches

To process a field of dry land we have to dig trenches. These trenches will be dug every 4 meters. They are 1 up to 1,5 meters deep. In these trenches we put seeds and cow manure. We cover this with a layer of soil to protect it from the sun. We also plant young trees in the trenches to speed up the proces. Young ‘pre-grown’ trees are stronger then the ones that germinate from the seeds. After the first rain the trenches will fill themselves with water. This water will soak deeper into the ground because there is no hard layer of soil anymore. The seeds will germinate, the young trees will root and the groundwater level will rise immediately.



Within one month it will be green

Once the rain has fallen, everything happens very fast. The seeds will germinate and within one month the trenches will be covered in green. This is important because this green layer prevents the remaining water from evaporating. It will be kept in the ground. This gives the seeds and young trees a real good chance to root and survive.

The water from the next big rains will not be wasted anymore. It will be caught in the trenches and consumed by the trees and plants. The roots of the vegetation also have another function. That is filtering the water while it soaks into the ground. This will result in healthy drinking water.


Grazing by animals

Once the area is green, it needs to be managed. We can do this by using animals. That is also what nature itself does when no people are involved. Animals prevent the area from turning into a complete jungle. But they also fertilize the area by their droppings and spread seeds this way. It is an important part of the ecosystem. With animal management we improve the diversity of plants



A green ‘trench’ Foto: VOMM

An irreversible cycle

Finally, when we have contour trenched the area, we started an irreversible movement of nature. Every time when the rain falls down, the water will be soaked up by the land and vegetation. It will reduces floods immediately and improve the amount and quality of groundwater. The new forest has a very good chance of succeeding if managed properly. Wildlife will come back and the diversity of plants and animals will increase.

Contour trenching is a simple ‘water harvesting’ technique that could change the world forever.


Peter Westerveld

‘Contour trenching’, as Peter Westerveld calls this technique, is method to harvest water and re-green degraded lands. Peter Westerveld is a Dutch artist who was active in Kenya & Tanzania. He did years of experiments with this technique and his results were stunning. He proved that this technique is a very simple and cheap way to transform dry lands. Peter Westerveld died in 2014, his work and contribution to the world may never be forgotten. He offered us the knowledge, now it’s up to us to do something with it. His knowledge could change the world forever.


Learn more about Peter Westerveld and contour trenching