Author(s): Rachid Nedjai; Van-Tuan Nghiem; Thi-Phuong-Thao Do; Abdelhamid Azaroual
Linked Author(s):
Keywords: Land-use; Climate change; Remote sensing; LCM; WARMF
Abstract: The issue of land-use and climate changes on aquatic systems has been the topic of numerous scientific studies because many symptoms have been observed (evolution in flows, increasing organic carbon, nutrients and water temperature, generally accompanied by oxygen depletion, acidification and eutrophication). The goal of this work is to show the direct impact of the land-use change observed and climate change on the Loire watershed of French (117 500 km2), caused by a considerable reduction in farming activity over the past 30 years. The investigation of three dates of Landsat images (1985,2000 and 2013) allows the detection of the closure landscape and the substitution of grassland by trees, especially in the high areas. We use the LCM model of Idrisi-Taiga software to predict the land-use evolution, and potential climate change to 2030 downscaled to local watershed scale based on the IPCC model. Then the WAMRF (hydrogeochimical model) is applied to calculate the water flows under these new land-use and climate conditions. This first step is followed by a predictive phase prior to measuring the evolution of flows over the next 20 years. The results show a clear decrease of the flows during the simulation period (1985-2013) which is around 20%to the 2030. In fact, these observations can be related to the enclosure landscape caused by the rural exodus and forest development registered in France since 1970 and the warming by the climate change. The reduction in volume can be caused by evaporation, evapotranspiration and/or rises in infiltration which generate the underground circulation.
Year: 2014