SPATIAL DISTRIBUTION AND TEMPORAL TRENDS IN DAILY AND MONTHLY RAINFALL CONCENTRATION INDICES IN KEBIR-RHUMEL WATERSHED

Abstract

In this study, the spatial and temporal patterns of rainfall concentration on daily and monthly scale were investigated in the Kebir-Rhumel watershed located in the northeast of Algeria. Based daily rainfall dataset between 1968 and 2013 of 20 weather stations, two indices were used in the study: the Precipitation Concentration Index (PCI) and the Concentration Index (CI), for measuring seasonality and daily heterogeneity of rainfall. In addition, the trends of annual rainfall, PCI and CI were tested by the Mann–Kendall method. The results show a disparity in rainfall amounts between norths sufficiently watered with a significant decrease in southbound. The values of the concentration (for daily and monthly scales) seem generally inversely proportional to the rainfall amounts. The concentration in the watershed is seasonal with a tendency towards the irregularity. The positive trends in annual precipitation, PCI and CI were found in most stations, although the trends were only very little statistically significant