The image on the top left shows the site location, and that on the bottom left shows a close up of the absorption bank (its leading edge -red line)
I was trawling through “Google Earth” trying to see some of the places I worked in over the last 50 years. One place I was interested to see was the Sudan where we were running the ‘Savannah Development Project’ centred in El Obeid and covering over 46K square miles. To cover the area we had our own plane, a Britten Norman Islander, to enable the plane to work in such a vast area, we had to make our own airstrips. When I lived there in the late 60’s, Sudan with a land area of one million square miles, the largest country in Africa, had only 814 miles of roads, including all the roads in Khartoum. So in order to get our D6 Caterpillar bulldozer to the areas where we needed the air strips constructed, it had to ‘walk’ the distance as there were no roads and no trucks to carry it, and if there had been, they would not have been able to cross the Wadis, on the way South.
Using the D6 was quite interesting. We equipped it with its own trailed tank of diesel and water and a trailer for the Driver’s needs, in all he covered over 1,000miles of desert, building us air strips. I would set him off and a month later would meet him in the nearest town to the ‘airstrip’. Needless to say he made a good living pulling bogged Suq Lorries out of the sand, or muddy wadi crossings, so we had no trouble keeping our driver on the job.
In those days I couldn’t find vetiver grass for the Sudan so concentrated on making contour furrows for planting sorghum. Using this system the furrows filled with runoff and I was able to produce the best sorghum crop the area had ever had. I knew these furrows wouldn’t last, so I took the D6 and using the ‘skills’ I learned with the Soil Conservation Service, I constructed a massive absorption bank across a dry Wadi in order to show the Sudanese, the importance of moisture conservation. I remember when I was building this bank thinking, you will be able to see this from the air.
39 years later, this absorption bank is quite conspicuous from Google Earth, just type in the coordinates 13 05’22.52”N 30 14’09.07”E and you will come right to it. The trees that have grown in the conserved moisture are most likely Acacia spp, previously there was absolutely nothing there, it was just a dry Gulch. But look at the run off the bank is holding. You could establish vetiver hedges with this technology, once established, in this 2 – 300mm rainfall area they would harvest their own water and nutrients to become sustainable and a ‘Linear’ farm could be developed behind them. A farm say four meters wide following the vetiver hedge across the slope for any length. The present farming system in these desert areas makes no sense at all – farms are laid out in squares or rectangles or silly circles, conserving no moisture at all! Just have a good look at this area shown with these coordinates, and you will see, just how hopeless the little farms surrounding the wadi, are.
Think about it for Ethiopia and other dry areas like northern Kenya, Kuwait, Morocco, and other areas with dry wadis??
Note: John took a similar approach in dry areas of Andhra Pradesh, India. He built contour V ditches with bull dozers, roppied the hard pans and planted trees behind in the conserved moisture. The results were impressive – tree survival rate increased from <5% to >95% and tree growth was incomparably good compared with “traditional” planting methods. Dick Grimshaw