Evaluating the effects of climate change and variability on water resources: a case study of the Cheliff basin in Algeria

In aim to well understand of the association between climate change, variability and their impact on water resources availability, an analysis was conducted of the trends in rainfall and stream flows across the Cheliff basin in Algeria. Sen’s non-parametric estimator of slope was employed to estimate the extent of tendencies, whose statistical significance was measured by the Mann-Kendall (MK) and the Modified Mann-Kendall (MMK) test. Results showed that the annual rainfall had a statistically significant downward trend in the whole basin. The largest downward trend of -4.58 mm y-1 was recorded in the south eastern region of the case study area. Significant decline trends in annual stream flows were detected at up to -1.18 m3 s-1 y-1. It was concluded that climate change appears to have an adverse effects on the hydrological cycle involving all water resources in the case study area. The reduced precipitation clearly resulted in a downward trend in water inflow as shown by recorded decrease from 1025 to 815 Mm3 between 1968-2001 and 2009. The costs of a water shortage can be an impaired the environmental balance which will affect the various human activities especially domestic water supplies and agricultural economy. The results of the current study will help to enhance the management of natural resources in the Cheliff basin.