A bird’s eye view on Africa’s rice irrigation system

As the drone reappeared in the sky and lowered its altitude in an attempt to land, the research team’s driver Richard, who had been volunteering to help out with the mission, ran towards the unpiloted plane in jubilation. ‘You’re welcome!’ he said enthusiastically in both English and Hausa, the language that is spoken in northern Nigeria.

The growmoreX team of the London based company GMX Consultancy, which runs a drone-based farming application service, was in Nigeria to do a preliminary assessment for the development of a 3,000 hectares irrigated rice farm. The farm will be built on land that was acquired in a long term lease from the local government’s irrigation authority. The aim of the project was to survey and map a total of 7,500 hectares in preparation of planning and building the irrigation infrastructure for the rice fields.

Although a manned aircraft could have done the job, it also would have cost a fortune. The alternative is unmanned aerial vehicle (UAV) technology. The project site was in a sparsely populated area, located approximately 75 kilometres from the town New Bussa, some 500 kilometres away from the capital Abuja with limited access to roads, electricity, clean water, and other amenities. Local livelihoods here are mainly based on small-scale agriculture. Crops are grown annually during the rainy season, and include sorghum, rice and beans. Tomatoes are grown during the dry season using pump-fed irrigation.

First flight

A fixed-wing UAV, which was imported directly from the US with assistance from a local project partner, was used for the first flight. It took a day to assemble it. That gave the team time to sort out technical hiccups and figure out how to use its automatic mission planning function. The activity attracted attention from local villagers, who had already been informed about the forthcoming agribusiness development.

When all the checks were completed, the team set the UAV’s navigation system to ‘automatic’. Then the UAV’s propeller was turning and it was launched into the air, witnessed by a crowd of people who had gathered to watch the first flight. The mission had begun.

Although the UAV had made it into the air, it suddenly began to fly away instead of starting its pre-programmed mission – likely due to the direction of the wind. The team lost telemetry communication with the drone, and it was thought that the UAV had crashed.

Suddenly, the radio established a connection with the UAV again, and it finally began its automatic mapping mission. It took the UAV only a few minutes to reach the optimal surveying altitude of 150 metres above ground level. Once at this altitude, it began to fly in a specific pattern, shooting images automatically as it went.

Advance planning

After the UAV landed safely the camera was checked immediately. The photos looked sharp and beautiful. There were a lot of them: during the 55-minute flight, the drone took overlapping photos of nearly 300 hectares of land.

The UAV was able to fly for roughly four hours a day when the sun cast the fewest shadows. This meant that the team was able to map about 1,000 hectares in a single day. That is fast, especially if the harsh terrain and working conditions with high temperatures are considered. Estimations assume that it would have taken a professional surveyor working on foot about twenty days to cover the same area.

To operate an UAV requires advance planning. The researchers made sure no specific regulations barred the team from using the UAV. The local Emir, the village chief and a military airport located about 100 kilometres from the project site were informed of the plans to make use of an UAV. Fortunately, the local authorities welcomed the new technology. There was only one condition: the Emir insisted that we do a flyover of his village, so that his people could see both the drone and the pictures it would take.

The village flyover had an unexpected result. For the first time the team could establish exactly how many houses and dwellings there are in the village, thus enabling researchers to make a much better estimation of its population. This information will be very useful, because the research team is planning to hire local labour to build the rice farm and to run it.

The hypothesis was proved wrong

Wonderful as the village flyover was, the main objective was to begin planning the rice farm’s irrigation infrastructure. For the preliminary investigation, the researchers needed to create a map at a scale of 1:2,000 (1 centimetre on the map represents 20 metres). With such a map the research team could make informed decisions on the best layout of the paddy fields, the irrigation and drainage systems.

Based on the limited information from previous visits to the site, it was hypothesised that it would have been able to lay out the rice fields as large, rectangular basins. Large earth moving and farming machinery would have been needed to build and cultivate those basins. Paddy fields for rice cultivation need careful water management as water levels impact weed and nutrient distribution. This meant that for every 100 metres, half a metre of soil at the top of the field had to be removed to raise its lower end during the levelling process.

However, the drone survey proved the hypothesis wrong. Although it was certainly true that parts of the project site were flat, most of the terrain was an undulating landscape.

The sloping terrain combined with a thin top soil layer led the team of researchers to radically change their designed hypothesis, away from large rectangular basins and towards long, narrow fields that would follow the terrain. But this change also meant that a very different irrigation system design was necessary.

Avoiding unnecessary costs

By using data required from UAV technology, agricultural planners can now easier avoid incorrect infrastructural planning. This information also makes it easier to organise the right procurement of machinery, avoiding unnecessary large upfront investments that can break a project if they are improperly planned.

Water is the deciding factor in Africa’s rice self-sufficiency. Most rice cultivation is rain-fed in Africa. The lack of irrigation infrastructure is a major obstacle to increase rice production on the continent. Most of the existing systems are poorly designed, built, and maintained.

The good news is that UAV technology can potentially accelerate the planning, design and construction of Africa's irrigation infrastructure. As this project has shown, UAV technology could provide agriculturists with a cost-effective method of irrigation infrastructure planning.

And that is not all. After the farm planning stage, UAVs could be useful for farmers to estimate more accurately how much fertilizer and planting materials they will need during the growing season. Once crops have been planted, UAVs equipped with special sensors can monitor their growth.

With the help of agricultural UAVs, Africa can leapfrog into the quickly-advancing area of precision agriculture – just as African mobile phone companies bypassed traditional fixed line infrastructure to create an innovative mobile finance system.