As I mentioned in a previous post, one of the most interesting aspects of the irrigation of the palm grove is the foggara system. This system is ancestral, as it originated in the 12th century, and is widespread in Algeria, some places in Morocco, and in Iran.
The basis of the system is that there is cliff in which there is a spring. At the bottom, you decide to plant palm trees. The spring is fed by a fossil aquifer that happens to surface at a given spot. As the water flows out of the spring, the level in the aquifer drops and the spring's flow rate ebbs.
To maintain the spring's flow, you can start digging a nearly horizontal gallery into the cliff, reaching back to the aquifer's front. The longer gallery you dig into the aquifer, the more flow your foggara generates. The beauty of the system is that the water flows by gravity (no pumping). Clearly, the aquifer's front will continue to recede away from the cliff as the foggara depletes the aquifer, and you'll be stuck digging further and further into the aquifer, always at a slight uphill.
Because this system is inherently low-tech, the galleries are unsupported and dangerous, which is why there are wells every 8-10 meters to ensure access all along the foggara. The longest foggara in Timimoun is 14km (9mi), and ends far into the desert. A foggara is therefore composed of two parts: one which is gaining water (in the aquifer itself), and one that is losing water (where the aquifer used to be).
From a socio-economic point of view, the foggaras are also very interesting, in that they are maintained in a cooperative manner. Clearly, the maintenance of 14km of tunnels is too much for a man and his sons. The water from that foggara is also more than is needed for the land a family can work.
The system works as follows: water flow is allocated on the basis of land ownership (lots of land=lots of water), and water and land rights are not separable. They can however be traded as a set. In proportion to his water rights, one is required to undertake repairs on the foggaras. Clearly, as parcels become more and more fragmented, it becomes increasingly difficult to coordinate the inputs of an ever-larger number of cooperative members, and the foggaras fall in disrepair. In addition, ever-smaller parcels become uneconomical and are abandoned by their owners, which leads to an increase in the marginal cost of repairs for each remaining individual land owner.
With all that said, we require a few illustrations... going along the flow.
Out in the desert, you can see the maintenance wells of the foggaras going on for miles.
Once you reach town, the well covers can be more or less decorated (yes, that big white tower is a well cover).
I was fortunate to go into one of these foggaras in two different parts. It was a bit like Indiana Jonesing through the Timimoun underworld...
Some parts are really narrow.
As you can see, the bottom is unimproved, which explains why water will get 'lost' as it flows through this part of the gallery (currently no water is going because of repairs).
In another, functioning, foggara, near the outlet.
Once the foggara reaches the hillside (cliff side), it emerges from it into what is called a 'comb' (un peigne). Water is then allocated by using the openings in the comb and channeled downhill to the parcels in question. The water can be further divided at downstream combs.
the same comb looking downhill. Notice the two combs. The first one serves to remove turbulence from the flow, thereby making the allocation by the second one fair.
Open air channels take the water to the parcels. These are made of carved sandstone.
Once the water reaches the individual properties, it's usually stored in a open air basin, such as this one.
Then the farmer will water individual 2x3 meter parcels separated by tiny dirt ridges, where he'll grow a variety of vegetables and legumes.
Some combs are broken (though this one might have been broken on purpose).
In the following two pictures, you can see the arrivals of various channels, and the complex allocation of water to various destinations. this results from the trading of land/water rights. It's actually quite intense if you care to zoom, with mini aqueducts. Wet clay indicates that these are maintained regularly.
Below is a sub-comb, if you will, where the flow is further subdivided. the channel to the right side of the picture is freshly made.
Unfortunately, the longer the foggara, the longer the losing part, and the less efficient the foggara becomes. The amount of water it produces is a function of its length, as is and maintenance cost. The amount of arable land (and income) is constrained by the water available. It follows that the system is inherently flawed from an economic perspective. At some point, the cost of maintaining the foggara exceeds the profits to be made from working the land it waters. It appears that we've reached this point in Timimoun.
The basis of the system is that there is cliff in which there is a spring. At the bottom, you decide to plant palm trees. The spring is fed by a fossil aquifer that happens to surface at a given spot. As the water flows out of the spring, the level in the aquifer drops and the spring's flow rate ebbs.
To maintain the spring's flow, you can start digging a nearly horizontal gallery into the cliff, reaching back to the aquifer's front. The longer gallery you dig into the aquifer, the more flow your foggara generates. The beauty of the system is that the water flows by gravity (no pumping). Clearly, the aquifer's front will continue to recede away from the cliff as the foggara depletes the aquifer, and you'll be stuck digging further and further into the aquifer, always at a slight uphill.
Because this system is inherently low-tech, the galleries are unsupported and dangerous, which is why there are wells every 8-10 meters to ensure access all along the foggara. The longest foggara in Timimoun is 14km (9mi), and ends far into the desert. A foggara is therefore composed of two parts: one which is gaining water (in the aquifer itself), and one that is losing water (where the aquifer used to be).
From a socio-economic point of view, the foggaras are also very interesting, in that they are maintained in a cooperative manner. Clearly, the maintenance of 14km of tunnels is too much for a man and his sons. The water from that foggara is also more than is needed for the land a family can work.
The system works as follows: water flow is allocated on the basis of land ownership (lots of land=lots of water), and water and land rights are not separable. They can however be traded as a set. In proportion to his water rights, one is required to undertake repairs on the foggaras. Clearly, as parcels become more and more fragmented, it becomes increasingly difficult to coordinate the inputs of an ever-larger number of cooperative members, and the foggaras fall in disrepair. In addition, ever-smaller parcels become uneconomical and are abandoned by their owners, which leads to an increase in the marginal cost of repairs for each remaining individual land owner.
With all that said, we require a few illustrations... going along the flow.
Out in the desert, you can see the maintenance wells of the foggaras going on for miles.
Once you reach town, the well covers can be more or less decorated (yes, that big white tower is a well cover).
I was fortunate to go into one of these foggaras in two different parts. It was a bit like Indiana Jonesing through the Timimoun underworld...
Some parts are really narrow.
As you can see, the bottom is unimproved, which explains why water will get 'lost' as it flows through this part of the gallery (currently no water is going because of repairs).
In another, functioning, foggara, near the outlet.
Once the foggara reaches the hillside (cliff side), it emerges from it into what is called a 'comb' (un peigne). Water is then allocated by using the openings in the comb and channeled downhill to the parcels in question. The water can be further divided at downstream combs.
the same comb looking downhill. Notice the two combs. The first one serves to remove turbulence from the flow, thereby making the allocation by the second one fair.
Open air channels take the water to the parcels. These are made of carved sandstone.
Once the water reaches the individual properties, it's usually stored in a open air basin, such as this one.
Then the farmer will water individual 2x3 meter parcels separated by tiny dirt ridges, where he'll grow a variety of vegetables and legumes.
Some combs are broken (though this one might have been broken on purpose).
In the following two pictures, you can see the arrivals of various channels, and the complex allocation of water to various destinations. this results from the trading of land/water rights. It's actually quite intense if you care to zoom, with mini aqueducts. Wet clay indicates that these are maintained regularly.
Below is a sub-comb, if you will, where the flow is further subdivided. the channel to the right side of the picture is freshly made.
Unfortunately, the longer the foggara, the longer the losing part, and the less efficient the foggara becomes. The amount of water it produces is a function of its length, as is and maintenance cost. The amount of arable land (and income) is constrained by the water available. It follows that the system is inherently flawed from an economic perspective. At some point, the cost of maintaining the foggara exceeds the profits to be made from working the land it waters. It appears that we've reached this point in Timimoun.
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