Abstract
Located in the UNESCO Geopark of Haute Provence, the Duyes watershed is representative of the hydrodynamic processes of the Mediterranean peri-alpine mid-mountains with deformed sedimentary bedrock. The local archives record a major hydroclimatic event associated with ten days of heavy rainfalls affecting this valley in April 1774 with a large-scale landslide with several damages: sinking of arable land, catastrophic flooding, destruction of buildings and roads. The archives describe the events in the terms of the time: "continuous rainfall", "abundance of water from the torrents", "revolution of the earth", "openings and crevasses", etc. The documents also point out that these "strange inconceivable revolutions" were concomitantly associated with two earthquake tremors without stating if this was a cause or a consequence of the detachment of several millions tons of rock and mud masses. This event took place at the end of the Little Ice Age (LIA, 1350-1850) in the context of a densely populated rural world practicing traditional peasant polyculture in the form of mid-mountain extensive agropastoralism.The first part presents and comments the 1774 archives as an example of a geohistorian's work. The second part details the climatic and hydrogeomorphological contexts of the valley at the time based on field observations and current data, including morphometric mapping using the LIDAR digital terrain model (DTM) and torrential flood simulations. Extensive fieldworks and the expertise of the local population also form the backbone of this study. Current flood and landslide risks are briefly recalled, based on the climatology of the years 2022 to 2024, in particular in May 2023 when heavy rainfall caused gullying of dirt roads and landings at the foot of steep fields and pastures in many valley locations.This research aims to contribute to the geohistory of the environmental and human societies co-evolution, and more specifically on the interactions between hydrogeomorphological processes and the dynamics of anthropized agrofestry landscapes in Mediterranean mountain regions. It also stresses the value of practical training in “landscape reading”, following the pedagogical principle of 讀景 put forward by Professor Jiun-Chuan Lin in his magnum opus on applied geomorphology (地形學,2022).