Thursday 18 April 2013

Trap rainwater now for use in the dry seasons


The rain season has begun in most parts of Uganda. When it rains, it is normal for us to seek shelter from building or any other structure from where we watch runoff water in the compound making its way to the valley.
These are cubic metres upon cubic metres of water that can be trapped and stored in barrels, tanks, and reservoirs for use during periods of shortage. There is a looming shortage of water globally especially with the onset of climate change and farmers must invest in water-saving technologies. UN Water, which comprises several institutions and organisations including the Food and Agriculture Organisation, states that the need for water has been growing at more than twice the rate of population growth in the last century.
Water scarcity
In Uganda, some farmers in rural areas no longer store rainwater for just agriculture; they use it in their houses which have flush toilets and shower bathrooms. In a previous Farmers’ Diary article (March 27, 2013), it was pointed out that Uganda has a lot of natural water sources but suffers from what World Watch Institute describes as economic water scarcity. We have the water sources but we lack the financial means to use those sources. We cannot pump water from Lake Victoria or the River Nile to deliver it to water-stressed areas where most of our farmers entirely depend on rain.
Most see the rainwater running off roofs and all over their compounds but they lack the financial means, the infrastructure, the investment, and proper management to trap that water and store it for use during the dry season.
While it is impossible to completely rule out the need for money to have a water catchment or a fairly large water container, relatively low-cost technologies have been introduced to enable poor households harvest valuable amounts of rainwater. One good catchment area is the house roof. There should be enough money of course to fix gutters at the edge of the roof to lead rainwater into a tank.
Options
There are not only longer lasting but more expensive plastic gutters but also cheaper metallic ones that may need replacement at a certain stage. Some people purchase large plastic water tanks—as large as 10,000-litre storage capacity or more. But these are expensive and a less endowed household may opt for the metallic types, which are not as durable and cost less.
The amount of water stored in this way often depends on the size and the number of water tanks a household has. Some people build underground or over-ground water tanks using concrete.
Store large quantities
Such tanks should be built by experienced builders as they may develop cracks and let out all the water. There is a recently introduced technology of building water tanks with unfired blocks made with soil-compacting machines.
It is cheaper for people to dig a pit and turn it into a water tank. The advantage with this kind of tank is that it can be as wide as the amount of water required. Such water reservoirs are lined with polyethylene, or butyl rubber, or even tarpaulin to prevent water from soaking into the ground. This type seems the easiest way to store large amounts of water for livestock farmers and vegetable growers who want to practice simple irrigation.
It is possible, for instance, for earth reservoirs to store up to 50,000 litres of rainwater or even more. The compound of a homestead is another good catchment area for rainwater. The runoff water can be directed by a carefully dug gully into an earth reservoir. Some wire mesh or sticks stuck closely together across the gully will help to prevent rubbish from going into the reservoir.
To keep the water clean and to minimise contamination, the top of the reservoir may be covered with iron sheets or logs. If iron sheets are used, the cover edge may be lined with gutters to trap more rain water into the reservoir.
The water stored in such ways may be used for irrigation of vegetables, maize, beans or any other such crops during the dry season. It may also be used for livestock. It is not enough, however, for farmers to acquire rainwater harvesting skills. It is recommended they use that water more efficiently by taking a number of steps including growing a diverse array of crops suited to local conditions and adopting irrigation systems which deliver water directly to plant roots.
An earth reservoir  with a capacity of 30,000 litres.

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