Impact of Climate Change on Water Resources in Lower Niger Basin in Nigeria

The objective of this paper is to investigate the temporal trends of streamflow in the Lower Niger River Basin in Nigeria using Mann – Kendall (MK), Spearman’ rho (SP) and Thiel – Sen (TSA) non parametric tests at 5% of significant level. The effect of auto – correlation in the time series was eliminated using a Trend Free Pre – whitening (TFPW) approach .The results obtained show negative trends in annual maximum series and both deceasing and increasing trends in annual minimum series. The estimated slopes range -354.94£b£ -52.62m3/s/year and -0.92£b≤ 30m3/s/year for annual maximum and minimum series respectively. Both MK and SP tests showed consistent performance and ability in detection of trends at 5% significant level. The negative trends in streamflow combined with simultaneous decrease in rainfall and increase in air temperature are plausible evidence of climate change. Also, positive correlation between freshwater discharge and salinity intrusion into River Niger was observed. The combined effect of streamflow reduction and salinity intrusion will impact adversely on the agricultural potentials, water quality status and vegetation of the Lower Niger River Basin. Finally, this study recommends against construction of new reservoirs as this will exacerbate the observed negative trends, leading to unsustainable development. Keywords: Trend analysis, Climate change, Nigeria, Salinity intrusion, Mann – Kendall and Thiel – Sen Estimator. DOI: 10.7176/CER/11-4-02 Publication date:May 31st 201