The valley bottoms are tremendous spaces for studying environmental and social changes since theend of the Little Ice Age. The case of the Maurienne valley in the Northern Alps is paradigmatic. Humanpressure is very contrasting. There is an uneven concentration of settlement, an extension of large transportinfrastructures along the thalweg of the Lower Arc and the artificialization of watercourses. The alluvialfans stand out in this landscape heavily anthropized by the concentration of human issues. The historicalevolution of the settlement on cones raises questions about the factors of change at the origin of the profoundtransformation of landscapes in the Maurienne valley. The main historical milestones behind thesequestions are the torrential crisis of the end of the Little Ice Age and the post-1950 torrential extinction. Theobjective of this thesis work is to restore the socio-environmental trajectories of torrential landscapes by ageohistorical approach. This work focuses on four debris cones selected according to distinctive landscapefeatures (afforestation, urbanization, road infrastructure and business park, agriculture).The comparative study of environmental and landscape changes requires a double level of reading. Thefirst level enables to study historical evolutions of the environment on the scale of torrential watershedsand the valley by reading written sources. It targets human activities, settlement dynamics and torrentialactivity since the first third of the 18th century. This first level shows a reduction in damaging floods at thebeginning of the 20th century in connection with the torrential correction works of the Mountain LandsRestoration. The resurgence of strategic stakes impacted by the floods between 1940 and the late 1990shighlights the increase in human pressure near the torrential banks. The second level of reading concernsthe study of landscape trajectories by the diachronic comparison of iconographic sources. The explorationof the archives has made it possible to collect a corpus of cadastres and old maps. The most exploratory partof this research is the identification and interpretation of old photographs by implementing a participatorycollection approach. The objective of interpreting these geohistorical data in a Historical GIS is to quantifyland use and torrential influence. The result of the quantification is presented by landscape models (transects,transition diagrams, etc.). This second level of reading leads to the proposal of a summary diagram.This model illustrates the different trends that make up the landscape trajectories of debris cones. Thesemodels highlight five to six major historical periods. Our results show a landscape crisis at the end of thePAG (around 1800-1890). It ended in the second half of the 19th century with a major torrential crisis.This crisis is not characterized by a transformation of landscapes into a valley. This transformation is onlyidentified at the turning points of the years 1900-1930 and 1940-1980. The first turning point originatedin the decline of pastoralism, the modernization of agriculture and the industrialization of an essentiallyrural population. The first signs of declining agricultural activity on the cones are manifested by the abandonmentof plots of crops near the torrential banks. The second landscape turning point was caused bythe agricultural decline and the industrial crisis, with the 1960s as a transition point. The development ofmajor road and hydroelectric equipment following this second turning point requires strengthening of theprotection devices on the cones. This second turning point does not imply a lasting transformation of thelandscapes. On the contrary, the interventions of the inhabitants on the wasteland to revalue agriculturalland seem to draw a singular trend.