In Same district, located in the Makanya Basin in Tanzania, farmers have been using a traditional irrigation technique known as Ndiva, a local word meaning micro-dam. This water harvesting technology has been in use since the 18th century, but agrarian communities in the district continue to improve it to capture water to irrigate their farms during dry spells and to adapt to current challenges.
Most farmers in the United Republic of Tanzania have traditionally relied on rain-fed agriculture, which can be a problem when rainfall is unreliable or provides insufficient water to farms. Water scarcity caused by frequent dry spells, mixed with increasing demand for water resources due to a rapidly growing population, is particularly challenging in the highland areas of the Kilimanjaro region. Climate change is increasing the unpredictability of precipitation patterns, thus causing further concerns for smallholder farmers. The Same district in the northern highlands, which consists of agrarian communities that grow several crops, including maize, beans and vegetables like brassica and Amaranthus, is one of the main affected areas.
This adaptation solution consists in the construction of Ndivas by excavating the soil to create a reservoir of the desired size. The micro dams vary in size depending on many factors including the area of the farms to irrigate, the number of farmers that will use the reservoir and the human capacities available. These human-made water reservoirs normally range from 200 cubic metres to 1,600 cubic metres. Ndivas are located adjacent to the farms on a raised area where they can collect water and allow it to flow to the gardens once the conveyance canals have been constructed. In some cases, concrete material is used to create reservoirs. On average, the canals can carry water to crops over a distance of 500 metres but can also reach 3,000 metres. The challenge is that water loss occurs through seepage when the water travels over longer distances. To address this issue, the farmers create stone pavements in the canal.
The Ndiva system can serve more than one farm and some community members establish their system as a group. As the system is easy to manage, working in groups is a viable opportunity as the workload can be shared. In a group-owned system, the members irrigate their gardens in turn.
