Recent trend analysis of hydro-climatic data in the upper and Niger Inland Delta of the Niger River basin (West Africa)

Abstract

The fresh water resources of the West Africa stressed due to the increasing population. The climate change has also affected the water resource availability due to the occurrence of recurrent and uneven extreme events such as drought and flood. In the context of Niger river basin, Niger Inland Delta (NID) water resource availability is a concern for water management over the basin. In this study, we evaluate the recent hydro-climatic trends in the upper basin and Niger inland delta of the Niger River basin in order to assess the potential climate change. Trend of Niger inland delta pan-evaporation were also analysed. An overall decrease of precipitation (1950-2010) and runoff (1950-2010) and an increase of temperature (1980-2010) and pan-evaporation (1970-2009) were observed (1950-2010); however, when a long study period is considered, all the trends are not statistically significant. In the same way, when IPCC standard period (1981-2010) is considered; all the climatic data show a significantly increasing trend in the NID except the evaporation whose trend is not significantly decreasing over the area. In this period, Significant decreasing trends are found for mean annual discharge at a 0.05 significance level. Therefore, it cannot be concluded that the climate has changed in the Niger basin with regards to trend analysis. But, it should be noted that the water resource availability will decrease in the NID if the current trend in the hydro-climatic data remains. Moreover, a spatial analysis shows that, the increase in precipitation is higher in the western part of the NID compared to eastern and inland part of the wetland. However, the results presented here shows a general idea about the water resource conditions in time and space, and should be taken as a basic skill for water resource management instead of models in order to reduce uncertainties.