Assessing and understanding the environmental changes in the Doubegue watershed (Burkina Faso) by combining temporal study of land use changes and stakeholders' knowledge

Abstract

Since the 1980s, the Bagre region (Burkina Faso) has witnessed significant environmental changes mainly due to anthropogenic causes (arrival of new population groups, demographic increase, reservoir creation, exacerbation of conflict linked to land ownership, and land and agrarian reform), and secondarily to climatic perturbations. For a comprehensive understanding of these environmental changes, and their causes and impacts in the Doubegue watershed, it is necessary to combine different analytical tools. An original methodology, which combines remote sensing and field survey, is proposed. A temporal study of land use change was conducted to identify areas at risk and ongoing processes. At the same time, a survey was carried out to study the local population's knowledge concerning changes to the resources of vegetation, water and soil. The analysis of a time series of satellite images reveals environmental changes mainly in the central area of the watershed, since the 1990s in particular, with an increase in cropped and bare soils. The survey also highlights reduction in vegetation cover, a decrease in soil quality and changes in the river system. In addition, stakeholders link the degradation of vegetation cover to changes in the river system. Finally, to reduce degradation of resources (vegetation, water and soil), actions are being developed and/or sought by the population and by organisations in the region. KEY WORDS: Burkina Faso, environmental changes, anthropogenic causes, temporal study of land use, stakeholder surveys, solutionsThe information, practices and views in this article are those of the author(s) and do not necessarily reflect the opinion of the Royal Geographical Society (with IBG).Notes 1 These soils have a high permeability and an unfavourable water regime. They are characterised by temporary waterlogging during the rainy season and a very rapid drying from the beginning of the dry season, providing conditions unfavourable for development of the vegetation cover (Nebie 2005). 2 The aerial photographs are from two IGB missions in January 1985 (seven images with a resolution of 1/50 000) and in October 1994 (37 images with a resolution of 1/20 000). 3 This method is used to group the pixels that belong to the same object class but with a different radiometry value. 4 The questionnaires used are presented in Robert (2011a). 5 The population is too dense and the fallow period too short for the soil to regenerate. Yields therefore decline and soils are depleted (Fontes and Guinko 1995).

Environmental determinants of E. coli, link with the diarrheal diseases, and indication of vulnerability criteria in tropical West Africa (Kapore, Burkina Faso)

“…Poor microbial water quality is often associated with high relative percentages of cultivated land in both tropical and temperate regions [ 99 , 100 ]. The watershed of the Bagre Reservoir has undergone profound changes since the 1980s with an increase in cultivated areas and bare soils to the detriment of natural vegetation [ 67 , 68 , 101 ], which may have resulted in increased erosion and particle transport towards the lake. This type of land use can also alter the size of the particles [ 102 ] leading to increases in the proportion below 5μm [ 103 ].…”

“…The Bagre Reservoir was built in 1992 for hydro-agricultural and hydroelectric purposes. The filling of the reservoir led to numerous modifications in terms of territorial recomposition and the surrounding region has undergone significant changes since the 1980s in terms of health, population growth (natural and migratory), and land use [ 66 – 68 ].…”

Environmental determinants ofE. coli, link with the diarrheal diseases, and indication of vulnerability criteria in tropical area (Kapore, Burkina Faso)

“…Poor microbial water quality is often associated with high relative percentages of cultivated land in both tropical and temperate regions [99][100]. The watershed of the Bagre Reservoir has undergone profound changes since the 1980s with an increase in cultivated areas and bare soils to the detriment of natural vegetation [67,68,101], which may have resulted in increased erosion and particle transport towards the lake. This type of land use can also alter the size of the particles [102] leading to increases in the proportion below 5µm [103].…”

“…The Bagre Reservoir was built in 1992 for hydroagricultural and hydroelectric purposes. The filling of the reservoir led to numerous modifications in terms of territorial recomposition and the surrounding region has undergone significant changes since the 1980s in terms of health, population growth (natural and migratory), and land use [66][67][68]. This site is suitable for satellite monitoring by Sentinel-2 (spatial resolution of 10 -20 meters) throughout the year.…”