Re-using cyclone debris to build back better agricultural infrastructure in Manicaland

The village of Nyanyadzi has a sensitive relationship with water. Situated at the confluence of three rivers: the Odzi, the Save, and the Nyanyadzi,  “there is plenty of water here,” confirms Edmore Mutsavi, a UNOPS agricultural engineer. Yet with a climate characterized by high temperatures and low rainfall, Nyanyadzi faces both vulnerability to flooding and reliance on irrigation throughout the year.  “The issue is keeping the water moving to the right places so that agriculture can thrive.” 

Historically, the village has relied on one of the oldest water distribution systems in Zimbabwe, the Nyanyadzi Irrigation Scheme, established in 1934. When operating effectively, the scheme is a fine example of cooperative resource sharing. Communal lands allocated to 704 local residents for farming usage are supplied with water through a subscription-based scheme that draws water from the rivers and three boreholes. In good summers, the Nyanyadzi scheme is abundant with maize, groundnuts, watermelon and sugar beans, and tomato, butternut and onion crops in the winter.

Over the years, parts of the scheme have been upgraded by government bodies and international agencies. But the impact of Cyclone Idai in 2019 here was severe. “When the pipeline was washed away by floods, it completely took out the water source for farming. Whole sections of the old canal were destroyed and damaged. Since then, there has been depressed production and general failure at the farms in the area,” reports Mutsavi.

Supported by World Bank funding, the UNOPS-contracted team arrived in Nyanyadzi in July 2022 to rubble and rocks piled high in the places where canals used to be, and crumbling river banks threatening the water supply. Farmers had been coping with the damage by using temporary earth canals, from which huge amounts of water seep out, and by drastically reducing the size of the plots supplied with water. Others had simply hoped for rain. But this is a risky strategy: Nyanyadzi is situated in Natural Region V, the region with the highest temperatures and lowest rainfall in Zimbabwe. The task at hand, to build back better infrastructure, was pressing. 

Due to the increasing impact of climate change, the rehabilitation programme was designed with “worst case scenarios” in mind using weather data from the cyclone. A key moment in this design process was the decision to build in gabion walls, an architectural feature named after the Italian word gabionne meaning ‘basket’. Constructed from woven cube-shaped baskets filled with loose rock, these building blocks are highly resilient against extreme weather because of the way they allow water to flow through while retaining structure. 

Flexible, strong, and relatively inexpensive, the triumph of the gabion walls on this project is their re-use of debris created by the cyclone. “When complete,the gabion structures will contain 5,625 cubic meters of loose rock carted and mobilized from the debris left by Cyclone Idai and the flooding of this area” reports Mutsavi. Rather than a problem, the abundance of cyclone debris in Nyanyadzi immediately became a solution. The displaced rock is tidily put back where it came from and incorporated into an upgraded form with lasting benefits for the agroecology of the site. They represent an approach grounded in sustainability, in local materials and local labour, and fulfilling multiple community needs at once.