LESELAM: combating soil erosion in Mayotte

The LESELAM project aims to understand soil erosion in Mayotte and to raise awareness of the issue among the local population in order to reduce soil losses, in both urban and agricultural areas.
24 March 2021

Soil erosion in Mayotte is caused by the impact of heavy tropical rainfall on unprotected or poorly protected soil.

The strong pressure of human activities tends to accelerate soil erosion: more or less unregulated urban expansion, deforestation, shift from extensive farming (typical multi-crop Mayotte-style gardens) to intensive single-crop farming that leaves soils unprotected, etc.

The erosion becomes very active in the rainy season and is a serious threat to Mayotte's lagoon, one of the most beautiful in the world.

The LESELAM project was designed to better understand, prevent and remedy these soil erosion problems in Mayotte.

LESELAM: building your house in Mayotte while protecting the soil

In Mayotte, a large number of individual houses are built on sloping plots of land, sometimes outside of building zones. Earthworks and construction work often cause severe soil erosion.

However, solutions exist to control erosion on building sites. They are introduced to us by Baptiste Vignerot (BRGM), as part of the LESELAM project, which aims to understand soil erosion in Mayotte and to raise awareness among the population in order to limit soil loss, both in urban and agricultural areas.

© BRGM

Coming soon.

LESELAM: what will agriculture look like in Mayotte in 2035?

In Mayotte, the face of agriculture is changing very rapidly, often resulting in the deterioration of natural resources and, in particular, a risk of soil erosion.

To try and predict how the phenomenon of erosion will evolve, the LESELAM project team carried out a forward-looking agricultural study to establish several contrasting scenarios concerning changes in the use of land in agricultural areas. The scenarios, which were established using information gathered through interviews with local stakeholders, were then discussed in several working groups, involving farmers, union representatives, agricultural advisers and local institutions.

© BRGM

BRGM: Geoscience for a Sustainable Earth

Fight against Soil Erosion and Siltation of the Lagoon

Agricultural Outlook for Mayotte in 2035

An Exercise in Participative Forecasting

Among other things, our project is looking at how soil erosion will change in the future.

The answer depends on how we humans use land in the future, how we manage urbanization issues and the type of agriculture we practise there.

To anticipate future changes in agriculture, we decided to implement participative forecasting.

Our goal was to consider the future with local people and to envision how agriculture might change in the long term. We chose 2035 as our horizon. 15 years isn't much, but it is for Mayotte as things change quickly here.

To conduct our exploration of the future, we called upon several groups of people, who worked in tandem. We worked with the state, the regional council, the agriculture department, the land management bureau, and a group of small farmers consisting of a dozen people from our research basin in Mtsamboro in the north.

To help our participants imagine the future, we created three scenarios for 3 possible agricultural transformations. The first imagines current problems continue, which would prevent the emergence of professional, entrepreneurial agriculture. The goal is to make participants think about the result of inaction or what will happen if voluntary policies are not implemented. The other scenarios involve voluntary policies. This lays out actions to enable the development of small family-run agriculture that would add value. The aim is to involve as many locals as possible. The third scenario imagines investor involvement. So more productive companies in limited numbers, which involve fewer farmers, thus leaving more people out in the cold.

The scenarios were presented as fictitious articles describing the imagined changes.

The workshops lasted about three to four hours, with 45 minutes dedicated to each scenario. To foster productive debates, participation was limited to ten people, so all could speak. The workshop ended with a short questionnaire. After discussing each scenario, they answered questions, allowing us to quantify their final positions.

To work with small farmers, our approach had to be adapted as our method was based upon articles written in French. This was not ideal for the farmers, some of whom were illiterate. So the scenarios were summarized orally. The farmers fully understood the scenarios and the related hypotheses. Then we asked them to tell us how the scenarios could be adapted to their farms and for their farmers' group. For this, we used simplified representations of farms. We presented the example of a collective farm, as proposed in one of the scenarios, and we asked them how they would organize collectively for a project of this type. The discussion was rich and lively. Some people in the group espoused a traditional approach while others took a more innovative approach. The workshops brought these ideas to the fore. Interesting conclusions were drawn. This way of bringing farmers together to reflect was new for them. And the fact is, there's a long way to go before a project emerges from within the group.

To conclude, we organized a follow-up session with all of the participants.

This session allowed the groups to share their conclusions. We saw that there was little disagreement among them and that they had moved towards a shared vision of the agriculture they wished to develop by 2035. The workshops provoked reflection on the future, but there's much to do. Other people will take over now, to define an agricultural development strategy as well as envision and plan concrete actions to achieve the scenarios that we discussed.

Combating soil erosion in Mayotte

The LESELAM project aims to combat soil erosion in Mayotte in order to achieve a sustainable balance between the development of agriculture and rural communities while protecting the quality of the lagoon environment.

© Naturalistes de Mayotte

Most soil erosion in Mayotte is caused by heavy tropical rainfall on unprotected ground. The high pressure that man exerts on various environments - agricultural and urban - accelerates this erosion. Soil erosion is a major problem in Mayotte. It threatens the survival of both the lagoon and farmland. It was to better understand, prevent and remedy the problems of soil erosion that LESELAM was created. The project has three objectives: to quantify the problems of erosion in several pilot catchment basins; to deploy demonstrators for remedial practices; and to educate and make aware those faced with these problems.

Climatological and hydrological measuring stations are installed on 3 catchment basins in Mayotte. Two agroforestry basins: this one, Mro Oua Bandrani, and Salim Bé, south of Dembeni. And one heavily urbanized basin: Mtsamboro, in the north of Mayotte. The results from the rainy seasons in 2015-2016 and 2016-2017 showed elevated erosion in the urbanized basin of Mtsamboro, where 6 to 10 tonnes of soil per hectare end up in the lagoon, compared to only 0.25 tonnes per hectare in the two agroforestry catchment basins.

To fight soil erosion, there are several techniques. On farmland, and in urban and suburban parks and gardens, we implement conservation planting, and soil restoration and protection, notably mulch. In purely urban areas, notably those with embankments, and in areas with construction sites, we protect the soil with vegetation and make sure development and construction rules are adhered to.

To facilitate the adoption of these solutions, we have implemented a number of awareness schemes, with information meetings, conferences, surveys and awareness workshops. We also created sign-boards and a website to contain all of the information.

We want to extend the project with LESELAM 2, so as to put in place concrete measures to fight erosion and to increase from several catchment areas to the whole country, so as to reduce the negative impacts of soil erosion in Mayotte.