Evolution of Bioclimatic Stages under climate change in the Ouergha Catchment (Northern Morocco)

Abstract

Climate change is one of the greatest environmental challenges facing humanity in the 21st century. This change is having a negative impact on the world, and in particular on the Southern part of the Mediterranean. Climate projections predict a reduction in precipitation, with mountainous regions being the hardest hit. The intensity of the effects of climate variability will particularly affect humid and sub-humid areas, such as the Ouergha watershed in Northern Morocco. The aim of this study is to analyse the evolution of annual precipitation between 1960 and 2020, and to assess its impact on the spatio-temporal evolution of bioclimatic stages and to make future projections of bioclimatic stages according to two scenarios (RCP4.5 and RCP8.5). The results of the study indicate a significant drop in water supply, estimated at around 30% over the studied period. A sharp drop in precipitation marked the months of the wet seasons. The effects of this decline on local ecosystems are manifold. The semi-arid and sub-humid bioclimatic stages have replaced the humid and hyper-humid stages, whereas the RCP scenarios show that the rate of change reaches 34.4%. This led to an amplification of the water crisis during the dry seasons.