09 Apr 2015
Tree Aid’s River Trees Restoration project at Bongo in Upper East Ghana is now in its fourth of five years, funded by RPS. Bongo District, on Ghana’s border with Burkina Faso, has one of the country’s highest rural population densities and is one of the poorest regions. Its average annual rainfall is 750-1050mm – mostly falling during July and August by which point the heavily-tilled soil is severely parched. The impacts in particular of the dry season not only on the efforts to nurture seedling plantations on the river banks but also on local people especially the most vulnerable community members has brought the issue of water management into sharp relief.
Working with villages who are reliant on the fluctuating water of the Nabakulga and Agansy rivers – tributaries of the White Volta River, the project has now increased to involve ten communities in actively restoring the degraded landscape and managing the available water.
In November 2013, RPS Land Surveyors Lars Suchy from the Leerdam office and Stuart Tosney from the Milton Keynes office travelled to Ghana and carried out a two-week topographical survey of 8 Tree Aid selected stretches of river corridor in Bongo District measuring 11.5 km in combined length. This topographical data informed a hydrology study produced by our Belfast office in order to identify the best sites for small-scale dams close to settlements and river trees planting. The Belfast office team comprised Civil Engineer Daniel Hogan, Senior Environmental Scientist Richard Bingham and led by Director of Water and Environment Grace Glasgow. The team’s Bongo River Trees Water Management report published in September 2014 has since been used by RPS dam engineers based in The Netherlands and by Tree Aid themselves in building their own partnerships with local agencies including the Water Resources Commission.
How do you preserve rainwater at the edges of the Sahel - an area with only five months’ precipitation a year? It is a tough challenge for people in Northern Ghana, where many are completely dependent on agriculture for their livelihoods.
In November 2014, André de Wit and Michel de Vré, two dam engineers from the RPS Leerdam office travelled to Upper East Ghana to conduct detailed site investigations with a view to designing up to four dams, hopefully two in the Eastern River catchment of the Agansy River and two in the Western River catchment of the Nabakulga – Akasa River complex.
Working from a shortlist of eight potential locations identified by the hydrology study, the team measured riverbeds and examined water capacity to identify potential locations for damming waterways to extend the period of time that water remains in the river to irrigate the river tree saplings as they establish themselves during the first four years and increase agronomical time. Three sites were found to be ideally suited for a dam, and an alternative fourth site was also successfully identified a few hundred meters upstream from another suggested site. RPS Dams Advisor Michel de Vré was one of the three-person RPS team investigating the dam sites – together with RPS Flood Defences Project Manager André de Wit and RPS Senior GIS Consultant Matthew Snape who also helped Tree Aid staff map all the tree planting sites while he was there. Andre says "We investigated how much rainwater runoff can be held and how quickly the water infiltrates into the bed. The depth of the river beds against the banks was then inventoried."
"There are many natural materials present in the form of rocks, sand, gravel and stone in order to make the dams. Only cement and steel has to be purchased" says André “Although building a dam increases the risk of flooding it is not always a disadvantage because the river deposits and moisture also provide nutrients in the adjoining, often depleted, agricultural fields."
Whilst RPS has drawn up detailed designs for the dams, tree planting remains a major component of the project: Ghanaian grown trees will be planted along the riverbanks. "The more green it is, the better you can hold the rainfall and prevent soil erosion” explains André “Including some fruit trees also means these can be used for food. "
RPS held information sessions with Tree Aid’s Ghanaian staff on the implementation process to discuss techniques and construction phases for the dams. "They see us as real experts and do not speed through the discussion as detailed effective discussion beforehand will achieve the best results" says Michel "They have paid a lot of attention in the meetings."
Local farmers and residents will be prominently involved in the construction of the Amanga West, the Ayopea, the Boko and the Bongo West dams which began on the 8th April 2015 and is expected to complete by the end of May. The dams will be community-built with waterways experts from RPS on hand to assist with works monitoring. As far as is reasonably practicable materials have been made by the community or locally sourced to reduce construction cost and time while supporting local trade. "Not only to save costs, but to allow the community to truly own the construction," says Michel, The implementation phase will thereby be the biggest challenge. We have to keep focus on the quality of materials and build to ensure we can assist with the best guidance for the teams building a significant creation to help in their effort to shape a new future."
Michel de Vré of RPS will supervise the completion of the Ayopea and Bongo West dams and the partial construction of the Amanga West and Boko dams. The remainder of the construction supervision will be provided by Daniel Collins, a Design Engineer from the RPS Galway office with an engineers' handover in the first week of May.
One Tree Aid volunteer's perspective on the project: Janet Ataba, Ayopea village
Janet is one of the villagers taking part in the project. She lives in Ayopea village with her three children:
‘My family farms millet, sourghum, groundnuts and beans, also chickens and livestock to protect us when crops fail. The old man of this house was a tree grower – one person’s effort can leave lasting benefits. At the beginning of the project I did not get involved – I thought it was men’s work. As I’ve learned more about what it is trying to achieve I’ve realized it is even more important for women to become involved. The learning exchange tour to Burkina Faso showed me how people had transformed their river banks. I will now personally challenge anyone who attempts to cut down a tree. So far I have received tree planting training and planted 10 mango trees at home. I help in the tree nursery and in tree planting on the river banks. My main hopes for the project are that it will benefit my children, because we depend so much on our land. I hope that we can succeed and my children will one day see this and give our village credit.’
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