Articles | Volume 20, issue 4
Hydrol. Earth Syst. Sci., 20, 1355–1372, 2016
https://doi.org/10.5194/hess-20-1355-2016
Hydrol. Earth Syst. Sci., 20, 1355–1372, 2016
https://doi.org/10.5194/hess-20-1355-2016

Research article 06 Apr 2016

Research article | 06 Apr 2016

Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)

Mohammed Achite1 and Sylvain Ouillon2,3 Mohammed Achite and Sylvain Ouillon
  • 1Laboratoire Eau-Environnement, Université Hassiba Ben Bouali, BP 151, Hay Es-Salem, Chlef, Algeria
  • 2LEGOS, Université de Toulouse, IRD, CNRS, CNES, UPS, 14 avenue E. Belin, 31400 Toulouse, France
  • 3University of Science and Technology of Hanoi, Dept. Water-Environment-Oceanography, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam

Abstract. Here we investigate the changes of temperature, precipitation, river runoff and sediment transport in the Wadi Abd in northwest Algeria over a time series of 40 hydrological years (1970–2010). Temperature increased and precipitation decreased with the reduction in rainfall being relatively higher during the rainy season. A shift towards an earlier onset of first rains during summer was also found with cascading effects on hydrology (hydrological regimes, vegetation, etc.) and thus on erosion and sediment yield. During the 1980s, the flow regime shifted from perennial to intermittent with an amplification of the variations of discharge and a modification of the sediment regime with higher and more irregular suspended particulate flux. Sediment flux was shown to almost double every decade from the 1970s to the 2000s. The sediment regime shifted from two equivalent seasons of sediment yield (spring and fall) to a single major season regime. In the 2000s, autumn produced over 4 times more sediment than spring. The enhanced scatter of the CQ pairs denotes an increase of hysteresis phenomena in the Wadi Abd that is probably related to the change in the hydrologic regime. At the end of the period, due to irregularity of the discharge, the ability of a rating curve to derive suspended sediment concentration from river discharge was poor.

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Short summary
Changes of T, P, Q and sediment fluxes in a semi-arid basin little affected by human activities are analyzed from 40 years of measurements. T increased, P decreased, an earlier onset of first summer rains occurred. The flow regime shifted from perennial to intermittent. Sediment flux almost doubled every decade. The sediment regime shifted from two equivalent seasons of sediment delivery to a single major season regime. The CQ rating curve ability declined due to enhanced hysteresis effects.