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

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. (C) 2015 The Author. Published by Elsevier B.V.