Analysis of temporal and spatial rainfall variability over the Wadi Sly basin, Algeria

Climate variability can be considered the main reason for drought and water scarcity. In this paper, the spatiotemporal variability of rainfall at different timescales (monthly, seasonal and annual) has been evaluated using data from 7 rain gauges well distributed in the Wadi Sly basin, in the northwestern side of Africa (Algeria), in the period 1968-2018. In particular, two non-parametric tests for trend detection have been used to detect the possible trends in rainfall series. Moreover, to identify further trends in the different rainfall values of the series, the innovative trend analysis technique has been applied. Results of the test application on rainfall data showed a marked negative trend in spring and a less clear negative trend at annual scale and in winter. This negative trend mainly involved the south-eastern side of the basin. Conversely, a slight positive trend has been identified in summer and autumn. The seasonal trend behaviour has been confirmed at monthly scale.