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This study aims at investigating annual and seasonal precipitation trend over Macta basin (northwest of Algeria) using the Mann–Kendall (MK) test, the modified Mann–Kendall (MMK) test, and the Innovative Trend Analysis (ITA). To achieve this aim, the monthly precipitation amounts from 48 meteorological stations for the period between 1974–1975 and 2011–2012 have been used. At the annual scale, the MK and MMK tests revealed that 19 stations (40%) show significant trends, while for the ITA method, the number of stations that shows a significant trend is greater (37 stations). Findings also unveiled that there is the sub-region of decreasing trends in the northern part close to the Mediterranean Sea coastal area, particularly in the western part, whereas in the south the trends are rather positive. At seasonal scale, the MK and MMK tests show few significant trends. In autumn, precipitation increases (42 stations up and 6 down). In winter, spring, and summer, the number of positive and negative trends is almost equal. The ITA method, whose significant trends are once again greater, shows that in autumn, 60% of the series are positive while 40% are negative. For the other seasons, the number of stations with decreasing trends is slightly greater than those increasing. Thus, seasonal precipitation tends to increase during the dry season mainly in autumn. Conversely, during the rainy season, precipitation undergoes a negative trend. Findings also unveiled that the ITA approach produces more significant results than the MK and MMK tests. Similarly, study of spatiotemporal trends showed a complex behavior. [ABSTRACT FROM AUTHOR]

In Algeria, the weather of the last three decades has a negative impact on water resources. The aim of this paper is to determine their impact on the rivers of the Macta basin (North-West of Algeria). The study of annual rainfall (September to August) over the period 1930-2002 shows a sharp decrease of rainfall from the first half of 1970. The flow of Trois Rivières station (wadi El Hammam), Sidi Ali Ben Youb station and Sidi Bel Abbes station (wadi Mekerra) were affected. Over the period 1976-2002, the annual average depth of runoff of runoff is 28 to 36% lower than for the period 1949-1976. On average, rainfall may be lower for all seasons, but the flows are not reduced in the autumn.