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This work describes the application of Hec-RASas Hydrologic Engineering Center derived River Analysis System model to the establishmentof floodplain maps for Martil river. Modeling with Hec-Ras enables calculation of, among other variables, water levels, depths and flow velocities for the different flow configurations and different cross-sectional zones along Martil River, i. e., from the confluence with the Lakhmiss and Mhajrat rivers to discharge into the Mediterranean Sea. This investigation, therefore, presents flood mapping and classification of risk areas using the Hec-GeoRas and Hec-Ras hydraulic modelling tools integrated into the Arcgis information system. The results indicate that the use of aerial photographsprovidesa good knowledge of the morphology and physical characteristics of the river, which will help decision makers to prevent floodingin the urban area of Tetuan.

Karstic aquifers play an important role for drinking and irrigation supply in Morocco. However, in some areas, a deeper understanding is needed in order to improve their sustainable management under global changes. Our study, based on chemical and isotopic investigation of 67 groundwater samples from the karst aquifer in the Rif Mountains, provides crucial information about the principal factors and processes influencing groundwater recharge and residence time. The δ18O and δ2H isotopic values indicate that the recharge is derived from meteoric water at high, intermediate, and low elevations for Lakraa Mountain, North of Lao River, and Haouz and Dersa Mountain aquifers, respectively. All samples show an isotopic signature from Atlantic Ocean except for those from the Lakraa Mountain aquifer, which shows Mediterranean Sea influence. Groundwater age determined by radiocarbon dating using the IAEA model indicates that the ages range from modern to 1460 years. This short residence time is consistent with the detectable tritium values (>2.7 TU) measured in groundwater. These values are similar to those of precipitation at the nearest GNIP stations of Gibraltar and Fez-Saiss, situated around 100 km north and 250 km south of the study area, respectively. This evidence indicates that groundwater in the Rif Mountains contains modern recharge (<60 years), testifying to significant renewability and the vulnerability of the hydrological system to climate variability and human activities. The results also indicate the efficiency of isotopic tracing in mountainous springs and would be helpful to decision makers for water in this karstic zone.

In Northern Morocco, seismic site effects in general and liquefaction hazard in particular can occur in the event of a major earthquake due to the thick sedimentary cover characterizing the peripheral Neogene basins of the Alboran Sea. An example is Martil Plain which was the subject of important economic development during the last two decades. In this regard, we present in this study as assessment of seismic site-effect hazard through the HVSR method and the Kg index. MASW and coredrilling data are also used to complete our analysis and interpret the spatial distribution of Kg maps. Our findings suggest more vulnerability to liquefaction in the Southern segment of the basin, which can be explained by the asymmetrical geometry of Quaternary sedimentation, due to tectonic uplift that influences also the surface and subsurface hydrology processes. As a result, some districts, especially those classified as economically disadvantaged, are found to be the most exposed to this hazard, which must be taken into consideration in future risk reduction and mitigation plans. We conclude the existence of significant seismic effects potential despite the moderate seismicity of the area. Therefore, our research needs to be completed by scenario based seismic hazard modelling to investigate the capacity of seismic events at the region to produce the above suggested amplifications.