Mega irrigation projects are the big elephants in the room. Located along many of the world’s large rivers in arid areas—the Indus, the Ganges, the Nile, the Amu Darya—they are spread over several hundred thousand to millions of hectares. For example, Pakistan’s Indus Basin Irrigation System is one of the largest integrated irrigation systems and extends up to 14 million hectares. But these systems are faced with challenges of an entirely different order than those facing other water systems.
First is their sheer size, spread over hundreds of kilometres. It is all but easy to distribute water equally, fairly or even reasonably. The chances that water is stolen or plainly diverted along the way are large. Damage may occur too. Canals may be breached and weirs may malfunction—all leading to a ripple effect in the lower part of the system. The downstream may also be flooded and waterlogged if there is too much water in the mega system. All these factors make mega irrigation systems difficult to handle.
Mega irrigation systems leave a heavy footprint on the entire landscape—not only the canals and drains, but also on the roads, bridges, urban settlements and residential property. They determine what happens in agriculture as well as other sectors. But the management of large irrigation systems is not usually spatial.
Thirdly, mega irrigation systems are such an important part of politics that there is no way that politicians and power brokers will ignore them. In fact, local power struggles are shaped by the mega systems themselves. The relations between upstream and downstream users, access to land and water, the breaching of structures during floods, reallocation of canal inlets—all these aspects are replete with political considerations. The power games play out in the form of influencing appointments, interfering with the water allocations or mobilising masses around water management issues.
The result of all these factors is that mega irrigation systems often underperform heavily. They leave areas with severe scarcity or severe abundance of water—both equally problematic. Too little water means low yields, insecurity, and salinisation. Too much water causes sogginess and saline land crusts, also depressing yields.
Many mega irrigation systems have, therefore, been subject to institutional reforms, bringing in business management, creating water users’ associations, removing and replacing staff and promoting direct payment for volumetric water use. Sadly, many of these well-mentioned efforts have left the systems worse off than before—with the old routines gone, but nothing effective to replace them. The Gezira system in Sudan is testimony to the unsuccessful attempts to put it in order.
The Gezira: a history of changes
Established in 1925 under the Sennar Dam, a global engineering marvel, the Gezira is the largest irrigation system in sub-Saharan Africa. Gezira is located in the rich soil zone of central Sudan and consumes one third of the country’s share of water from the Nile. The mega system experienced challenges in water management, both in supply and uses. Four big changes in polices, followed by a change in objectives of the scheme, resulted in cumulative effects. Daytime irrigation was changed to continuous irrigation (day and night). The cotton crop was diversified with other crops and these other crops were intensified, putting the system under pressure. The value of water rates and methods of collection influenced operation and maintenance. Also, all engineering staff was withdrawn, leaving the systems in the hands of agriculturalists instead. All attempts unfortunately resulted in low performance and low yield which discouraged farmers from attending to irrigation and contributing effectively in water management. As a mega irrigation scheme, Gezira needs to be turned into a mega multipurpose scheme.
Instead of putting institutional reform at the fore, it is better to also work on better water management in the mega systems. For instance, where land is sandy and there is no saline groundwater, the shallow groundwater can be used intensively, leading to precision farming and no need for drainage. This is the secret of “conjunctive management”—providing just enough water. Less water supply leads to scarcity and decline in groundwater tables; excess supply leads to water logging. But anything in the perfect middle will keep people pumping. As the groundwater (fed by seepage from canal water) is shallow, pumping it up is relatively cheap.
Mega irrigation systems should also be viewed for their functions other than that for agriculture: drinking water supply, fishery, forestry, navigation, climate proofing, public health, stockwater, roads and housing. This will help optimise the many functions of the mega systems. It will also generate revenue for their upkeep and create jobs. With better management, clear rights, rules and regulations, and utilisation of the available water irrigation intensities, mega irrigation schemes can fulfil their large purpose.
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