Silt trap (gabion) at the Nyanyadzi Irrigation Scheme

The recent Cyclone Idai, caused unprecedented destruction in the eastern and southern parts of Zimbabwe, with Chimanimani being one of the hardest hit areas in the country. Investment in the climate proofing of agricultural systems such as the Nyanyadzi Irrigation Scheme is essential in effective disaster risk reduction.

The 412-hectare Nyanyadzi Irrigation scheme was established in the 1930’s and is one of the oldest irrigation schemes in Zimbabwe. It is located  in the dry area of Chimanimani, Natural Region V and has been the communities’ main source of agricultural water for several  decades. The increasing frequency of unpredictable weather particularly drought and heavy rainfall events worsens the  environmental degradation caused by streambank cultivation, deforestation and overgrazing. This has accelerated soil erosion in the area and the transportation of silt into the schemes water canals.  Nyanyadzi Irrigation scheme became dysfunctional after Cyclone Eline in 2000, where heavy rains caused structural damage to the scheme and filled the canals with silt, blocking the flow of water to the community and the farming plots

“The first Cyclone in 2000, destroyed our canals and we were unable to farm for five years. The canals were blocked with sand and the sand was also washed onto our farms”.

- Mrs  Mabika , Farmer

The farmers have over the years tried to build silt traps on their own, however due to a lack of expertise and funds, the traps constructed were not strong enough. The irrigation scheme remained  in a perpetual cycle where it would fill up with sand after each rainy season:

‘’ After the rainy season , all the canals would be blocked with  silt, rock, leaves and branches. Farming would come to a standstill without access to water.  We would come together as the farmers and try to clean the canals by ourselves  for the water to flow again to our farms, but it would take us a long time. Sometimes it would take 2-3 months to clear the canals and in that time crops like maize would dry out, and the entire yield would be lost.’’

– Samuel, Farmer

Weathering the storm

UNDP, Oxfam and its partners worked with the community of Nyanyadzi to rehabilitate the scheme to better withstand the effects of heavy rainfall and siltation. In 2019 , the scheme was hit by Cyclone Idai, however unlike in 2000 when Cyclone Eline hit, the scheme suffered minimal damage due to the silt traps.

With the cyclone came significant flooding at the scheme, but it was confined to the Mashaireni weir area. The weir  allowed water to safely pool  behind it and flow into the scheme’s canals acting as a  flood control measure helping to stabilise the effects of heavy rainfall and increased levels of siltation.  However, the elevated levels of water in the catchment area came with increased levels of silt which filled a 600m portion of one of the canals. The silt traps  constructed at strategic points throughout the scheme,  helped capture and reduce the amount of silt which would have been washed into the canals.  Mr Gororo, secretary of the Nyanyadzi Irrigation Management Scheme attributed the limited impact of the Cyclone on the scheme to the gabions (silt traps) which had been constructed. 

Silt trap (gabion) at the Nyanyadzi Irrigation Scheme

 

After Cyclone Idai, the famers of Nyanyadzi quickly came together to  clear the blocked section of canal.  Each farmer contributed $5 per acre of land they were farming, to assist with the hiring of  38 men to clear the canal of silt and rocks.  The work took less than a month to complete and the farming season was only briefly interrupted.  

The cleared irrigation canal at the scheme.

 

This farming season,  176 hectares of land have been cultivated with sugar beans, tomatoes, okra, onions and vegetables

“Because of the silt traps that were built, right now we have our tomatoes and beans in the field.  We have a lot of water and have been able to move forward, the only thing left for us to do, is sell what we will harvest” – Mrs Mabika

Mrs Mabika, farmer in Nyanyadzi holding her recently harvested tomatoes.

 

The need for continued Climate Change Adaptation 

There are still some long-term issues to address in Nyanyadzi which are contributing to the continued soil erosion and washing away of silt into the canals. Gulley’s have continued to develop causing gulley erosion which can destroy farmable land, buildings and limit road access.  Poor agricultural practices such as streambank cultivation are still taking place, removing the vegetation needed to stop the run off water and soil erosion.

“In order to adapt to the changing climate with droughts and extreme rainfall events becoming more frequent in the future, the community needs to both flood proof their irrigation scheme and protect the larger catchment area from environmental degradation and soil erosion. Replanting the forests, regenerating the grasslands and taking up sustainable agriculture practices will help to enhance water infiltration into the soil and reduce erosion and siltation.” – Sidsel, UNDP

A gully in Nyanyadzi which is encroaching one of the community houses.

 

The Oxfam-UNDP/GEF Scaling up Adaptation in Zimbabwe with a focus on rural livelihoods was implemented in 15 wards of Chimanimani District in partnership with SAFIRE and several government Departments in the Ministries of Environment, Water and Climate and Lands.

Images: UNDP / Oxfam 

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