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Assessment of Ras El Ma Karst Spring Features by Structural and Functional Approaches at the Region of Taza, Morocco
Jamal Naoura 1  
,   Imad El Kati 1  
,   Lahcen Benaabidate 2  
 
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1
Laboratory of Natural Resources and Environment, Polydidisciplinary Faculty, University of Sidi Mohammed Ben Abdellah, Taza 35000, Morocco
2
Laboratory of Functional Ecology and Environment Engineering, Faculty of Sciences and Techniques, University of Sidi Mohammed Ben Abdellah, Fes 30000, Morocco
CORRESPONDING AUTHOR
Jamal Naoura   

Polydidisciplinary Faculty, University of Sidi Mohammed Ben Abdellah, Taza 35000, Morocco
Publication date: 2021-10-01
 
J. Ecol. Eng. 2021; 22(9):32–47
 
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ABSTRACT
This work by considering two complementary approaches for investigating the Karst system of Ras El Ma source: (1) The structural approach based on field studies, (2) The functional approach requiring inputs data (precipitations) as well as output data at the exit of the karstic system. The choice of the Ras El Ma source is justified by the fact that it constitutes the main outlet of the Liassic aquifer at the Southwest of Taza town. The structural approach highlighted that the impact of South Rifan and North Middle Atlas faults, oriented mainly NE-SW to ENE-WSW and NW-SE, tectonically linked to the Hercynian and late-Hercynian phases; these faults compartmentalized the karst into panels. The functioning of this karst system is based on the coupling of inputs and outputs, the analysis of interannual hydrograph, flood hydrographs, the recession curves and the analysis of hydrogeochemical results. Respectively, the obtained results are presented as follows: A close relationship between flow rates and precipitation, interannual hydrographs marked by a contrasting variation in flow rates and a periodicity that occurs between low water and high-water years. Concerning flood hydrographs, there are two types, a unit modal hydrographs type which generally occurs following time concentrated rainfall and a second multi modal hydrographs type which follows the repetitive rainfall in the basin. The study of recession curves reveals a clear complexity of the systems supplying the source. However, due to the low drying-off coefficients (7.66.10-4), the aquifer seems to have a poorly developed drainage network in a flooded area. According to the Mangin method (1975), this karstic system is classified in the category of poor or complex karst systems taking into accounts two parameters (i) and (K), which characterize the functioning of the infiltration zone and the volume of flooded karst, respectively. The physicochemical parameters study highlighted the nature of drained rock by the sources. The correlation between conductivity and different chemical elements shows that bicarbonates and calcium are responsible for the mineralization of the waters of this source. It can be concluded that the low values of mineralization occur during the winter and spring floods. The spring regains its normal mineralization during the summer period.