Integrated approach to assessing streamflow and precipitation alterations under environmental change: Application in the Niger River Basin

Abstract

Abstract Study region The Niger River Basin in West Africa. Study focus The paper reports an integrated approach capable to elucidate impacts of environmental degradation on streamflow and precipitation at the watershed scale. The approach combines trends and spatial analyses of long-term streamflow, precipitation, and leaf area index LAI. Specifically, I target the Niger River Basin, then I consider monthly precipitation series over the catchment. I also consider data from 8 streamgages selected along the river. New hydrological insights for the region Over the period 1961–2012, I conduct a change point analysis of the streamflow and report two sub-periods 1961–1982 and 1983–2012. A comparison of precipitation and streamflow during these two time-slices shows meaningful changes. I describe a Kernel density analysis of streamflow and yield a probabilistic estimate of discharge anomalies along the river. Later, I evaluate seasonal trends of precipitation and streamflow. The analyses bring out critical alterations in time and space. However, these alterations seem to foreshadow critical environmental degradations occurring across the watershed. I consider LAI series derived from MODIS images, then I examine and discuss trends in land-cover dynamics in relation with the patterns in precipitation and streamflow. This late analytical step yields a holistic picture of the ongoing alterations in the Niger River Basin. Finally, I emphasize suggestions, valuable for a comprehensive water resources and environment management.