Mapping of Burnt surfaces in the Context of Protected Areas in the Sudanian Savannahs of Northern Cameroon: Contribution of Time Series of Sentinel-2 Images

Abstract

In Africa, bushfires are common practices in savannah regions. Their impact, is the subject of many scientific debates. The protected areas, of North Cameroon are subjected to ambivalent effects of these fires. Using high-resolution remote sensing data, this work aims at assessing burned areas at the interannual and intraannual scale in order to explain the complex environmental dynamics of landscapes, to contribute to fire management in a context of protected areas. To achieve this, time series of sentinel-2 images from the Multi Spectral Instrument from the year 2015-2020 have been used. By the unitemporal and multitemporal methods, the development of spectral indices has made it possible to locate the burned surfaces and to determine the periods of the fires. Observations and field surveys aimed to understand the factors of fires using, their typology as well as the roles of the actors. The findings show that each spectral index has its own ability to detect burnt surfaces: The NDVI can detect fires only at the start of the dry season, the SAVI is suitable for identifying intermediate and late fires, while the NBR is best suited for separating burnt and unburnt surfaces throughout the season, regardless of the method employed. Depending on their periods of occurrence, the fires spread more in parks with a fairly extensive grass cover compared to overexploited ordinary areas. They then depend on socio-environmental factors, namely the state of land used, the continuity of the herbaceous cover and the social practices in place. The mapping and monitoring of burned surfaces by remote sensing therefore constitute a tool and a method for diagnosing the state of the herbaceous plant cover and for managing natural resources.