Spatio-temporal trends in daily maximum rainfall in northwestern Algeria (Macta watershed case, Algeria)

Results of extreme precipitation trend analysis, at different spatial and temporal scales, have become alarming since the last century, due to the global climate change. This work describes the impact of climate change on the distribution and trend of maximum daily rainfall in the Macta watershed. Monthly maximum rainfall data that were collected over 41 years (1970 to 2010) on 41 stations were used to validate the present research. The extreme values of rainfall maxima (200 to 264 mm/d) are located in the northeastern part of the basin during the spring season. From 1992 onwards, shifts are observed from monthly, seasonal in addition to significant annual trends. Monthly, seasonal, and annual rainfall maxima trend analyses were identified using three methods, which are Mayer's adjustment method, Sen's innovative method (2012), and the Bravais-Pearson test. The study found out a downward trend during the first period (1970-1992). On the other hand, the second period (1992-2010) revealed significant upward trends. Climate change affects all regions except the center part of the study basin.