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In southern Tunisia, agricultural land has been subject to significant anthropogenic pressures since the early 20th century, which have contributed to significant changes in land use. The region's strong demographic growth has led to socio-spatial changes (sedentarisation, the descent of mountain populations down to the foothills and the Djeffara plain, the development of agriculture in the jessour (water and soil conservation works that block the gullies dug in the loess) at the expense of the rangelands. The current landscapes of southern Tunisia, from the Matmata region to the surroundings of Tataouine, now display signs of a rural exodus that is reflected in the abandonment of the jessour. This exodus has significant landscape and environmental impacts that can be measured through the use of diachronic vertical imagery (aerial photographs, satellite images). It can be observed that from the 1950s onwards, jessour developed strongly in the ravines, in line with demographics. The rural exodus that appeared in the 1970s led to the concentration of populations in the new towns, which did not prevent water and soil conservation works from continuing to be used and maintained. While some areas, particularly in the southern part of the study area, are still seeing the appearance of new jessour, most of them are abandoned and subjected to regressive erosion due to the suffocation that rapidly destroys them.

Urbanism and mobility strongly constrain present and future environmental conditions in large urban centers. The disorganized expansion of Algerian cities now creates multiple risks related to the transport sector. Air pollution is one of those risks.The objective of this study is to develop a methodology for assessing air pollutant emissions from road traffic. The methodology is based on a coupling between GIS and deterministic modeling to better represent the spatio-temporal distribution of emissions.It is applied to the city of Oran in Algeria, which shows that the growth of the urban fabric, and in particular its peripheral spreading over the period 1966-2015, has led to a transfer of population from the city center to the peripheral poles of Bir El Djir, Es Sénia and Sidi Chahmi. This spread is confirmed by the study of a chronological series of satellite images. This evolution of the urban form generates a greater need for mobility and aggravates the circulation and congestion problems of fossil-fueled vehicles that are sources of significant polluting emissions whose negative impact on health and environment is no longer to prove.The implementation of a pollutant emissions cadastre is an essential step in order to evaluate the air quality in the Oran region. These emissions are here quantified in time and space thanks to the application of the EMISENS model, based on vehicle counts. Given the evolution of the urban fabric and transport, these emissions should continue to increase because of the mobility needs induced by the uninterrupted spread of the city and by the high attractiveness of the city center to the Oran agglomeration citizens.