I was once deeply saddened to see maize crops weltering by the shores of Lake Malombe. Drought had taken its toll that year, but these crops were not like other crops in the country. They were so close to a huge water body. It only required some innovation to bring the water to the crops and make them survive the drought.
The Government of Malawi has not spared its effort to establish irrigation schemes across the length and breadth of Malawi. We used to hear of schemes such as Limphasa during the Banda era, and since then more schemes have been introduced. We have now coined the phrase “greenbelt” to describe an initiative meant to exploit our surface and ground water for purposes of irrigation.
All this is necessary in view of the erratic patterns of our rains. We cannot rely on rain-fed agriculture alone any more. Moreover, when we migrate to irrigation, we will be able to harvest two or three times per year on the same parcel of land. Granted, irrigation is the way to go if we are serious about ensuring food security in this country.
People have been told so much about the benefits of irrigation. But that is only half the story. People are not being told about the negative impacts of irrigation. Everybody, as a result, regards irrigation as the panacea of all our ills, insofar as food security is concerned.
The truth of the matter is that irrigation is not without its problems. Among the negative impacts of irrigation are altered hydrology of areas, soil salinization, and intoxication of surface or ground water. By salinization is meant the building of salts in the soil. Water typically contains salts and when it is directed to fields to water crops, the crops take up the solvent (which is the water in its near pure form) and leave behind the dissolved salts. Over time these salts can, and often do, accumulate to toxic levels.
Intoxication comes about because the water that has been diverted to fields picks up fertilizers and/or pesticides and when part of that water returns to the water body, it pollutes that water body with these toxins. Therefore, the communities downstream who would ordinarily rely on the water body for their water supply are inconvenienced as a result of the altered quality of the water.
Altered hydrology results in some of the most dramatic impacts of irrigation. When water is diverted from a river or a canal, the flow downstream is reduced. The reduced water flow can have serious consequences. In some cases, rivers, lakes or reservoirs dry up.
Lake Chad of West Africa is a case in point. Because of the heavy irrigation on the rivers that empty into this lake, it has been observed that over the past 30 or so years the lake has shrunk considerably. Satellite imagery reveals that the current size of Lake Chad is one twentieth of its original size. If irrigation upstream continues at the same level as currently, the lake will disappear before the end of this century.
There are many communities that depend on Lake Chad for their livelihood, some for agriculture, others for fisheries, and yet others for transport. The disappearance of the lake will spell doom for these people, who will have to undergo drastic changes in their lifestyles in order to cope. It is, obviously, a worst case scenario. Meanwhile the United Nations is trying to do what it can to halt the shrinkage or even reverse it.
I am certainly no prophet of doom. I do not want to give the impression that we will lose our lake or the Shire River to irrigation if we embark on heavy irrigation. But to be warned is to be forearmed as is normally claimed, so I feel duty bound to sound the warning. When people are adequately briefed about the possible negative impacts of irrigation, they will hopefully tread with caution and where possible mitigation measures will be taken to minimize the impacts. If we proceed blindly we will one day wake up to a seriously altered Malawi that will not be good for anything, and our efforts to maximize crop yields from our land will instead result in achieving the exact opposite effect.
As we search within our vocabulary and use buzzwords like “greenbelt”, let us do so with abated breath, being mindful that carelessly undertaken irrigation will not be the blessing it is meant to be, but rather a national curse.