Water Harvesting Structures in Africa

Thumbnail link to image of unmortared stone walls on Phiri farm, ~18K	"You start catchment upstream and heal the young before the old/deep gullies downstream," says Mr. Phiri. Beginning at the top of the watershed, he built unmortared stone walls at random intervals on contour (that is, along lines of equal elevation). These walls slow the flow of storm runoff as the water moves through the spaces between the stones. This makes the water running off the granite dome more manageable as it is directed to unlined reservoirs, which like everything else, were built with nothing more than hand tools and the sweat of Mr. Phiri and his two wives. The larger of the two reservoirs Mr. Phiri calls his immigration center. "It is here that I welcome the water to my farm and then direct it to where it will live in the soil," he laughs. "The soil," he explains, "is like a tin. The tin should hold all water. Gullies and erosion are like holes in the tin that allow water and organic matter to escape. These must be plugged." Mr. Phiri's "immigration center" is also a water gauge, for he knows that if it fills three times in a season, enough rain will have infiltrated into the groundwater to last for two years. The smaller reservoir directs water via a culvert to an above-ground ferro-cement cistern that feeds his courtyard in dry spells. He has another cistern, shaded by a lush granadilla creeper, collecting water from his roof. Aside from these two cisterns, all water harvesting structures on the farm aim to infiltrate the water into the soil as soon as possible. Near the home is an outdoor wash basin from which all greywater is drained to a covered, unmortared, stone-lined, underground cistern where the water quickly infiltrates. Water harvesting structures (Back to top) From the top of the watershed to the bottom, there are numerous water-harvesting structures such as check dam walls, gabions, terraces, swales and fruition pits. The government had put in large swales many years ago throughout the region, but they had put them just off contour so that they'd stop sheet flow erosion and carry the storm runoff to a central drainage. The erosion problem was solved, but all the lands were being robbed of their water. So Mr. Phiri dug large "fruition pits" about 10' x 6' x 4' in the basins of all his swales. When it rains, the pits fill with water and the overflow runs into the next pit, and so on up to his property line. Long after the rain, water remains in the fruition pits percolating into the soil. Around the pits, thatch grasses are grown for erosion control, building and sale. Mr. Phiri has also planted many thriving fruit trees along the swales to provide food, shade and windbreaks. They're watered strictly by rain and the rising groundwater in the soil. As Mr. Phiri explains, "I am digging fruition pits and swales to plant the water so that it can germinate elsewhere." "I have then taught the trees my system," continues Mr. Phiri. "They understand it and my language. I put them here and tell them, 'Look, the water is there. Now, go and get it.'" Neither basin nor berm for holding water is put around them; rather, roots are encouraged to stretch out and find water. A diverse mix of open-pollinated crops such as squash, corn, peppers, eggplant, reeds for baskets, tomatoes, lettuce, spinach, peas, garlic, onion, beans, granadilla, mango, guava and paw paws, along with such indigenous crops and trees as matobve, muchakata, munyii and mutamba are planted between the swales. This diversity gives him food security, for if some crops fail due to drought, disease or pests, others will survive. The use of open pollinated varieties enables Mr. Phiri to collect, select and use his own seed from one year to the next. Nitrogen-fixing plants abound. The pigeon pea is one example, and is also used for fodder and mulch. Mr. Phiri has found that fertilized soils don't take and/or hold water well. As he says, "You apply fertilizer one year, but not the next and the plants die. Apply manure and nitrogen-fixing plants once, and the plants continue to do well year after year. Fertilized soil is bitter." The food and fruit Mr. Phiri produces is anything but bitter. He's been generous in his abundance, giving away trees to anyone who wants them. Unfortunately, as Mr. Phiri points out, the majority of the trees he gives away die when people do not implement rainwater-harvesting techniques before planting. He propagates his trees in old rice and grain bags near one of three open wells near the bottom of his property. Mr. Phiri describes the open wells with another analogy. "Water is like blood-it is always attracted to the wound. Gullies are wounds. Blood goes to the wound to coagulate and heal it. It does this with gabions and swales where the gully is filled with fertile soil." With this knowledge, Mr. Phiri anticipated that the water harvested throughout his land would seep into the soil and make its way to the wounds below; he dug his three wells at the bottom of his land. Wells of abundance (Back to top) The soil is his catchment tank. In times of drought, his neighbors' wells go dry (even those that are deeper than Mr. Phiri's), yet Mr. Phiri's wells always have water "into which I can dip my fingers," for he is putting far more water into the soil than he takes out. Except for one well, which is lined with a hand pump for household water use, all are open and lined with unmortared stone. "These wells," explains Phiri, "are those of an unselfish man. The water comes and goes as it pleases, for you see, in my land it is everywhere."
Thumbnail link to image of Mr. Phiri and his banana plants, ~26K	In times of severe drought, Mr. Phiri will draw from these wells to water annuals in nearby fields. He uses a donkey pump, also known as an Egyptian Shaduf, which is simply a hand pump that uses an old tractor tire to pump the water. A crank opens and closes a bladder (the tire) like an accordion, creating the needed suction. A lush, natural wetland lies below the wells at the lowest point of Mr. Phiri's property. Here, Mr. Phiri practices aquaculture in a series of three reservoirs. As the smaller two dry up, the fish are harvested or relocated to the largest. It is also here that Mr. Phiri densely grows bananas! Dry lands all around him, yet here on Mr. Phiri's farm is a thick forest of bananas! Sugarcane, reeds, and grasses such as elephant grass are also grown on and leading up to the banks to hold the soil. His livestock benefits from the dense grasses, grown to sift the water as it enters the reservoirs. This prime fodder is reserved for his cows when in calf. When Mr. Phiri began, he was forced to appear in court three times for violating laws that prohibited cultivation in wetlands. These were laws that had been around since colonial times. Finally, on his third court appearance he was able to convince the magistrate to come see his farm. Upon seeing Mr. Phiri's work, the magistrate dropped all charges on the spot. Within the soil of the farm lie the Tigris and Euphrates rivers; the reservoirs are where they surface. The cycle of Mr. Phiri's Garden of Eden, starting to be noticed after 30 years of obscurity and sometimes scorn, continues to grow. Of the last three decades Mr. Phiri says, "Sure, it's a slow process, but that's life. Slowly implement these projects, and as you begin to rhyme with nature, soon other lives will start to rhyme with yours." He and the non-governmental organization he created, the Zvishavane Water Resources Project, are spreading his techniques. He has influenced CARE International in his region to the point that, rather than giving away food, they now implement Mr. Phiri's methods so that people can grow their own food. He has also gone to schools where the teachers were striking due to lack of water and the harsh conditions in dusty, windscraped classrooms. He taught the teachers and students how to harvest the rainfall, and together they've turned the schools into lush gardens and now have no reason to strike. "Remember, children are our flowers," says Mr. Phiri, "give them water and they will grow and bloom." Mr. Phiri's project is very much at the grassroots level (a big reason why it works), yet the Zvishavane Water Resources Project is always in need of funds. If you'd like to help, write to Mr. Zephania Phiri Maseko, ZWRP, P.O. Box 118, Zvishavane, Zimbabwe.

Author information

(Back to top)
Brad Lancaster is a permaculture teacher and designer in Tucson, Arizona. You can reach him for comment by email at bradlank@aol.com. This article will be incorporated into an upcoming book that Mr. Lancaster is writing about water harvesting techniques.

Water for farming

Running dry

The world has a water shortage, not a food shortage

Sep 18th 2008 | from the print edition

MOST people may drink only two litres of water a day, but they consume about 3,000 if the water that goes into their food is taken into account. The rich gulp down far more, since they tend to eat more meat, which takes far more water to produce than grains. So as the world’s population grows and incomes rise, farmers will—if they use today’s methods—need a great deal more water to keep everyone fed: 2,000 more cubic kilometres a year by 2030, according to the International Water Management Institute (IWMI), a research centre, or over a quarter more than they use today. Yet in many farming regions, water is scarce and likely to get scarcer as global warming worsens. The world is facing not so much a food crisis as a water crisis, argues Colin Chartres, IWMI’s director-general.

The solution, Mr Chartres and others contend, is more efficient use of water or, as the sloganeers put it, “more crop per drop”. Some 1.2 billion people, about a fifth of the world’s population, live in places that are short of water (see map). Farming accounts for roughly 70% of human water consumption. So when water starts to run out, as is happening in northern China, southern Spain and the western United States, among other places, farming tends to offer the best potential for thrift. But governments, whether to win votes or to protect the poor, rarely charge farmers a market price for water. So they are usually more wasteful than other consumers—even though the value they create from the water is often less than households or industry would be willing to pay for it.

The pressing need is to make water go further. Antoine Frérot, the head of the water division of Veolia Environnement, a French firm, promotes recycling, whereby city wastewater is treated until it can be used in industry or agriculture. This costs about a third less than desalination, and cuts pollution. He expects his recycling business to quadruple in the next decade.

Yet as Mr Frérot himself concedes, there are many even cheaper ways to save water.
As much as 70% of water used by farmers never gets to crops, perhaps lost through leaky irrigation channels or by draining into rivers or groundwater. Investment in drip irrigation, or simply repairing the worst leaks, could bring huge savings.

Farmers in poor countries can usually afford such things only if they are growing cash crops, says David Molden of IWMI. Even basic kit such as small rainwater tanks can be lacking. Ethiopia, for example, has only 38 cubic metres of storage capacity per inhabitant, compared to almost 5,000 in Australia. Yet modest water storage can hugely improve yields in rain-fed agriculture, by smoothing over short dry spells. Likewise, pumping water into natural aquifers for seasonal storage tends to be much cheaper than building a big dam, and prevents the great waste of water through evaporation.

Even when water is scarce, it is often squandered. Mr Molden cites the example of cotton-farmers in Uzbekistan, who used to receive a fixed allocation of water for irrigation whether they needed it or not, in a holdover from the days of Soviet central planning. Simply putting farmers in control of the irrigation network, and allowing them to decide how much water they needed, cut consumption by 30%.

Cotton paying a high price for water Science Photo Library

Similarly, rice farmers can sharply cut water consumption by flooding paddy fields only some of the time. Wheat growers in hot places such as India and Australia can conserve water by minimising tilling, leaving a layer of mulch on the fields’ surface to absorb rainwater and limit evaporation. In arid regions like the Middle East, Mark Zeitoun of the London School of Economics suggests substituting thirsty crops such as oranges with more abstemious olives and dates. Ideally, countries that are short of water would concentrate on growing the most valuable cash crops, and use the proceeds to import staples.

Agronomists are beginning to devise tools to help monitor the efficiency of water use. Some have designed algorithms that use satellite data on surface temperatures to calculate the rate at which plants are absorbing and transpiring water. That allows governments and development agencies to concentrate their efforts on the most prodigal areas.

But efficient use of water, cautions Pasquale Steduto of the United Nations’ Food and Agriculture Organisation, is just one step to better agricultural yields. Even if farmers use the right amount of water they also need decent seeds and enough fertiliser. In Africa in particular, these and other factors such as pest control, storage and distribution are a bigger drag on yields than a shortage of water.

Raising yields does not always involve greater water consumption, especially when farms are inefficient. It would take little extra water to double cereal output in many parts of Africa, Mr Molden argues. IWMI reckons that some three-quarters of the extra food the world needs could be provided simply by bringing yields in poor countries closer to those of rich ones. That is more palatable than the puritanical alternative: giving up meat and other thirsty products altogether.

Bottled-water