Editor’s Note: This is an update on the Al Baydha project we introduced here.
In order to demonstrate our agricultural system, we need to keep goats, camels, and sheep off the site. Initially we were planning to build a standard chain-link fence, but decided we could do better. Instead, we are putting up a big earth berm — about 2.5 meters tall and between 4 and 5 meters wide, with a layer of large stones securing razor wire on top .
Cost-wise this will be about 60% less than a chain-link fence, but there are other advantages as well. The berm will not only keep out animals, but it will provide a good foundation for putting up a wind-break of trees. Wind is the second main cause of evaporation in our climate, and evaporation is the main cause of water loss. We’ll plant the outside of the berm with cacti and shorter, spikey desert plants to keep animals from climbing, and we’ll plant the inside with long-term nitrogen-fixing trees. Once those plants are established, we’ll have a good windbreak surrounding the entire agricultural area of the site, lowering evaporation and increasing water retention.
The berm will also function as our last area of water soakage before any water leaves our system. To prevent the berm from eroding in the cases of flood, we’ll build a permeable rock section at its lowest point; this will relieve pressure if there is a big flood, and allow for overflow. At the same time, planting the berm will stabilize it in rain or wind, and the plants roots will add strength against floods.
There are some risks involved: if a big flood occurs before our plants can get somewhat established, then there’s a possibility that some of the berm could get washed out. This makes the overflow gabion an imperative. Another risk is that goats climbing up the berm could get stuck and potentially die in the razor wire, but the plants on the outside of the berm should prevent that once it is planted.
All in all, it’s worth the risk; the berm costs less and supports more stackable functions than the chain link fence would have. Instead of just keeping animals out, we are also creating the structure for our wind break and increasing our area for water soakage.