LESELAM: action against soil erosion and lagoon siltation in Mayotte

The LESELAM project funded by the European Union is a stepping stone in the Erosion Road Map developed for Mayotte. The aim is twofold: to understand the phenomena causing soil erosion, and to raise awareness of the problem among the population, elected officials and associations and thus encourage the adoption of techniques to limit soil losses, in both urban and agricultural areas.
30 March 2021

Combating soil erosion in Mayotte

The lagoon of Mayotte is one of the most remarkable lagoons on the planet. But this biodiversity is threatened by the silting up due to the arrival of land from natural, agricultural and urban areas of Mayotte. The LESELAM project is fully in line with the Erosion roadmap in Mayotte.


Context and challenges

Soil erosion in Mayotte is caused by the impacts of heavy tropical rainfall on unprotected soils:

  • in cities and building sites, along road embankments and bare earth roads and in parks and gardens with insufficient plant cover,
  • in agricultural areas, fields on medium to steeply sloping ground and fields managed as monocrops without plant cover or mulch,
  • in natural areas, forest plots, clear-cut or burned to make way for crops, and badlands (padzas), etc.

High human pressure tends to accelerate soil erosion, for example through poorly regulated urban sprawl, deforestation, the shift from extensive farming (typical multi-crop Mayotte-style gardens) to monocultures that leave soils unprotected. Erosion is exacerbated in the rainy season and poses 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 challenges in Mayotte.

The LESELAM project’s main objective is to produce the necessary knowledge to address the questions raised by those directly concerned on the ground: What are the main sources of erosion and to what extent do they worsen siltation in the lagoon? How efficient are the remedial measures proposed?

Achievements of the first two project phases

The LESELAM project included two initial work phases:

  • LESELAM 1 (2015–2017), with BRGM, CIRAD, IRSTEA, Les Naturalistes de Mayotte and CAPAM as partners.
  • LESELAM 2 (2018–2020), led by BRGM and Les Naturalistes de Mayotte, with subcontractor support from University of Tours, KERMAP, CAPAM, AGRIKAGNA and ADINM.

Achievements of these two phases included:

  • the establishment of an Erosion Observatory in three catchment areas, as a basis for assessing erosion throughout the island,
  • the development of Good Practice Guides,
  • raising awareness among communities and farmers,
  • a forward analysis up to 2035, which led to the implementation of an erosion control strategy.

LESELAM 3 (2021–2023)

A third project phase is under way, involving BRGM, Les Naturalistes de Mayotte, EPFAM and CEA as partners.

As well as the continuation of the LESELAM Observatory, LESELAM 3 will use the data and knowledge acquired to address water-use issues and resulting water conflict in the Dzoumogné basin, share practices in both urban (Doujani) and agricultural (Mro Mohou) areas, and fulfil communication needs at the general (media) or educational level (schools).