The global reheating observed in these last years is followed with a change of rainfalls bunches at the global and regional area.The floods frequency increasing,dangerously impacts the socio-economic activities of sev...The global reheating observed in these last years is followed with a change of rainfalls bunches at the global and regional area.The floods frequency increasing,dangerously impacts the socio-economic activities of several countries throughout the world.Indeed,for Niger as a country located in West Africa where the majority of the population existence depends on the agricultural and pastoral activities,this change of rainfalls bunches may have unwanted consequences.The aim of this work is to analyze the evolution and trend of rainfall in Niger during the period 2008-2024 compared to the period 1971-2000 characterized by episodes of drought.To achieve the objective of this work,annual data of rainfalls and the number of rainy days from four meteorological stations representative of the four major climatic zones of Niger are used.These are the station of Agadez(in Sahelian zone),the station of Tahoua(in mid Sahelian and Saharan zone),the station of Niamey(in Sahelian zone)and the station of Gaya(in mid Sahelian and Sudden zone).Thus,the standardized index of Lamb(1982)and the least squares method are respectively used to analyze the variability of the interannual rainfalls and their tendency.The results obtained show a significant improvement in rainfall in the four climatic zones compared to the period from 1971 to 2000,and especially in the Nigerien Sahara where 88.2%of the years were wet.The latitudinal gradient South-North of the rainfalls has known an upgrading going from 1 mm/km during the period of 1971-2000 to 1.26 mm/km during the period of 2008-2024.Our results also show that this improvement in rainfall is linked to heavy rainfall events which are the cause of floods observed mainly during wet years(2010,2012,2013,2017,2019 and 2024).Finally,the results show that,excepting the Sahel-Niger,the other climatic zones are experiencing an increasing trend in rainfall.Therefore,in the face of current climate change,West African countries must mobilize to put in place a strategy to mitigate the consequences of heavy rainfall.展开更多
文摘The global reheating observed in these last years is followed with a change of rainfalls bunches at the global and regional area.The floods frequency increasing,dangerously impacts the socio-economic activities of several countries throughout the world.Indeed,for Niger as a country located in West Africa where the majority of the population existence depends on the agricultural and pastoral activities,this change of rainfalls bunches may have unwanted consequences.The aim of this work is to analyze the evolution and trend of rainfall in Niger during the period 2008-2024 compared to the period 1971-2000 characterized by episodes of drought.To achieve the objective of this work,annual data of rainfalls and the number of rainy days from four meteorological stations representative of the four major climatic zones of Niger are used.These are the station of Agadez(in Sahelian zone),the station of Tahoua(in mid Sahelian and Saharan zone),the station of Niamey(in Sahelian zone)and the station of Gaya(in mid Sahelian and Sudden zone).Thus,the standardized index of Lamb(1982)and the least squares method are respectively used to analyze the variability of the interannual rainfalls and their tendency.The results obtained show a significant improvement in rainfall in the four climatic zones compared to the period from 1971 to 2000,and especially in the Nigerien Sahara where 88.2%of the years were wet.The latitudinal gradient South-North of the rainfalls has known an upgrading going from 1 mm/km during the period of 1971-2000 to 1.26 mm/km during the period of 2008-2024.Our results also show that this improvement in rainfall is linked to heavy rainfall events which are the cause of floods observed mainly during wet years(2010,2012,2013,2017,2019 and 2024).Finally,the results show that,excepting the Sahel-Niger,the other climatic zones are experiencing an increasing trend in rainfall.Therefore,in the face of current climate change,West African countries must mobilize to put in place a strategy to mitigate the consequences of heavy rainfall.
