WINDHOEK – Is it profitable to rehabilitate rainwater on farms in semi-arid Namibia?
That is one of the frequently asked questions amongst local farmers at the start of every rainy season for whom runoff and floodwater farming is a traditionally practiced water harvesting system which helps overcome problems of soil moisture and crop failure in a hot, dry area with erratic rainfall and shallow, highly erodible soils.
New Era caught up with Australian farmer and rainwater rehabilitation expert, Robyn Cadzow last week while on a visit to Namibia to attend the 18th Namibian Rangeland Forum near Witvlei in the Omaheke Region.
Cadzow says in the case of Namibia where 70 percent of its inhabitants are directly or indirectly dependent on agriculture as a main source of income, it is vitally important to acknowledge that to be productive, cattle should have a variety of nutritious and palatable pasture. To have that variety of plants, pasture has to be recipient to the moisture and nutrients to convert CO2 into the energy required to grow and produce enough seed and leaf matter, she noted.
Bare soil is vulnerable to bombardment by raindrops (when it rains) and the soil is pulverised into smaller particles which in turn seal the soil surface, causing more water to run off down the creek instead of soaking into the soil profile.
“Hard-set soils affect seedling emergence and if we can ensure there are plants or plant residues like butts of the perennial pasture species, then we are helping to slow the evaporation rate from the soil and increase the seedling’s chance of establishment. There are always arguments for and against rehabilitating soil that has started to shift with the wind or water or scalded country – this is one for getting out and getting on with it,” Cadzow explained during the interview.
Some of the benefits of rehabilitation include better water infiltration into soil profile, more vegetative species grow, more palatable forage for cattle, and consistently higher prices as livestock are in better condition and health.
The collection of rainwater is either from natural or man-made surfaces.
Rainwater harvesting is being used for productive purposes such as drinking water for people and livestock, irrigation, recharge of aquifers, household activities, construction etc.
In arid environments rainwater harvesting is usually applied to supplement other existing water sources, while in humid regions harvesting it may provide enough water for all demands.
In some cases, rainwater may be the only available or economical water source.
Two main approaches to harvesting water for agricultural purposes are distinguished:
• Micro-Catchment Water Harvesting (MCWH) which largely deals with gathering surface runoff and transferring it in the water unsaturated (vadoze) root zone of soils; and
• Runoff Farming Water Harvesting (RFWH) where water is routed by diversion systems to a storage system for subsequent application in irrigation or for livestock consumption.
A number of NGOs are involved in rainwater harvesting for rural communities.
UNICEF supported the construction of water tanks in schools in the four “O” regions on the northern border with Angola, RISE Namibia has implemented a pilot domestic rainwater harvesting project in the Erongo region in the northwest, and IBIS is supporting rainwater harvesting initiatives in the north as part of an ecological housing project.
Various initiatives have been planned and commenced for rainwater collection to augment irrigation of community gardens. One such example is the Epako Rainwater Harvesting Project near Gobabis, in the Omaheke Region.
The project is funded by the local NGO Early Intervention Programme and aims to ensure that healty food is available for the youth, promote their skill development and responsibility, and foster self-esteem.
A further example is the UNDP and Omalundu Iimuna Kommitiye Elungameno Project funded by GEF (Global Environmental Fund) that provides the Onkani community (Omusati) with practical tools for adaptation and increasing community awareness about climate change risks.
Among other measures the project supports the implementation of small-scale rainwater harvesting and storage methods to improve water conservation and usage while adapting to more erratic and heavy rains predicted.
The project is implemented by the Onkani community with support from Ministry of Agriculture, Water and Forestry, the Desert Research Foundation of Namibia, and the Namibia National Famers’ Union (NNFU).