Spatio-temporal analysis of trends in annual maximum rainfall in the North-West of Algeria: Comparative analysis of recent and old non-parametric methods

This article examines the spatial variability of extreme precipitation trends in northwestern Algeria (Macta) and compares the results obtained from the four recent and old non-parametric methods. A dataset of annual maximum precipitation consisting of 41 observation years (1970-2010) and 41 rain gauges was used. The results of the four old and new methods used to detect trends, Mann-Kendall (MK), Bravais-Pearson (BP), Spearman (SR) and innovative trend analysis (ITA), show good agreement. They revealed that a decrease in the trend of annual maximum precipitation was detected during the first period (1970-1992) with -44% (MK), -61% (BP), -68% (SR) and -76% (ITA). On the other hand, in the second period (1993-2010), a total shift occurred in which a significant increase in annual maximum precipitation trends was observed with +63% (BP), +34% (MK and SR) and +93% (ITA). These results show the ability of ITA to detect partial trends that the other three tests do not allow. Our results allow decision-makers to properly design adaptation strategies in the face of the intensification of these extreme events.