Relying on rain fed farming still remains a major constraint for crop production.
Collecting water from ground run-off and rooftops to be reused in farms during dry seasons, is one of the solutions to promote food security holistically. Here are some techniques to apply in water harvesting.
1. Sand Dams
By constructing a sand dam near a recurrent source of water, especially a river or where flow of water is not disrupted during wet seasons. This stops the run-off water, and traps it in the artificial reservoir allowing consistent water supply throughout the year. This technique is inexpensive and reaps full benefits as a long term solution.
2. Grey Water Recycling
Grey water makes up roughly 60% of household waste water. This waste water is from baths, sinks, washing machines and dish washers. As the cheapest and simplest technique, capturing of the grey water is done in a bucket or drain, and used for the farm or garden.
3. Contour Trenching
Also known as the ‘fanya juu’ technique, trench contouring entails digging of trenches along contour lines where water flows down the hill and soil thrown upslope to form an embankment which traps the run-off water and sediment, while still penetrating the soil below.
Through this technique, though tedious in implementation and maintenance, crops can be grown in low rainfall seasons from the subsoil water reserve gathered.
4. Fog Harvesting
Fog harvesting is best done at night and early mornings during the cold season in mountain faced regions or plains; e.g. Kajiado County and Coastal areas. Air is cooled to a point where it can no longer retain water vapour, hence forming ground level clouds.
These clouds (water droplets) are captured in a synthetic plastic mesh net, that is hoisted with two posts planted in the ground which drain the water in a gutter; then transferred in tanks. This technique is easy to replicate, cheap and the level of technology and maintenance is simple.
5. Groundwater Ponds
Using an artificial pond laid a few meters below the ground, increases the chances of a better harvest of rain water runoff. This water can be used for irrigation and livestock drinking water.
Compared to construction of a borehole, laying of a synthetic membrane on dug out grounds is cheaper, and traps the runoff water.
These ponds vary in size depending on the size of the farm. They are easy to manage and are cost effective.
6. Gutter Installation
This roof catchment system has been used for decades as a traditional means of water harvesting technique. The water can be harvested in small scale or large scale for the purpose of irrigation, livestock, drinking or all of the fore mentioned.
The size of the storage tank is dependant on the owners’ financial ability and water usage.
With gutter installation, water runs down the strip iron sheets which are bent at an angle and nailed onto the roof, suspended with galvanized wires. The water is drained into a storage reservoir placed on the ground.