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This study aims to contribute to a better estimation of the density of fractures likely to favour the drainage of surface water in the High Ziz River (HZR) basin. The method adopted consists of the use of different airborne image processing techniques (filtering, enhancement and slope analysis) which allow a good discrimination of image discontinuities (lineaments) that can then be used for producing lineament maps. The influence of these lineaments on the underground flow is then studied. Indeed, it was possible to extract the lineament network, following the exploitation of remote sensing and an objectively completed analog analysis using the PCI Geomatica LINE module and its directional filters (Sobel directional filters by the ACP method), and to extract the hydrographic network of the HZR basin, using the ArcHydro tool. After superimposing these data, their thematic maps (of the lineament and hydrographic network) were developed. In addition, this comparison of the two hydrographic networks and lineament maps showed us very varied flow directions influenced by geological structures, particularly fracturing. The topography of the region also has a secondary impact on flows through the presence of slopes generally oriented towards the SE of the basin. The correlation of the results with the different directions of the orders of the hydrographic network allowed us to identify the potential effects of lineaments on the orientations of surface water circulation. In addition to these results, the realization of the Rose diagram indicated that the dominant trend in lineaments is N90–45N° (NE–SW).

One of the adverse impacts of climate change is drought, and the complex nature of droughts makes them one of the most important climate hazards. Drought indices are generally used as a tool for monitoring changes in meteorological, hydrological, agricultural and economic conditions. In this study, we focused on meteorological drought events in the High Ziz river Basin, central High Atlas, Morocco. The application of drought index analysis is useful for drought assessment and to consider methods of adaptation and mitigation to deal with climate change. In order to analyze drought in the study area, we used two different approaches for addressing the change in climate and particularly in precipitation, i) to assess the climate variability and change over the year, and ii) to assess the change within the year timescale (monthly, seasonally and annually) from 1971 to 2017. In first approach, precipitation data were used in a long time scale e.g. annual and more than one-year period. For this purpose, the Standardized Precipitation Index (SPI) was considered to quantify the rainfall deficit for multiple timescales. For the second approach, trend analysis (using the Mann-Kendall (M-K) test) was applied to precipitation in different time scales within the year. The results showed that the study area has no significant trend in annual rainfall, but in terms of seasonal rainfall, the magnitude of rainfall during summer revealed a positive significant trend in three stations. A significant negative and positive trend in monthly rainfall was observed only in April and August, respectively.