Hydrogeochemical assessment of groundwater quality in greenhouse intensive agricultural areas in coastal zone of Tunisia: Case of Teboulba region

The intensive greenhouse crop production in coastal zone of Tunisia as Monastir and especially Teboulba area has increased the demand on groundwater resources for irrigation. Groundwater, which represents one of the major water resources, is vulnerable to quality degradation due to over exploitation for agricultural activities and increase of anthropogenic activities. The study has been carried out to assess the evolution of hydrochemical properties of Monastir aquifers. Water samples, collected from forty-six origins between February 2016 and March 2017, were analyzed for physicochemical parameters. The results indicate high salinity and high concentration of nutrient and metals trace elements in Teboulba groundwater. Results also indicate that some elements as Cadmium and nitrate concentrations are above the Tunisian recommended irrigation water limits but remain below FAO limits. The results of the study suggest that greenhouse intensive agricultural activities, including excessive fertilization and irrigation are among processes regulating the nutrient chemistry in the groundwater of this region. Assessment of groundwater chemical composition showed a seasonal variability given that groundwater is undergoing an important mineralization process and is not suitable for irrigation under ordinary conditions. The seasonal evolution of geochemical facies is controlled by complex processes (natural and/or anthropogenic activities). Principal component analysis (PCA) indicates that physicochemical variations are regulated by the combination of different processes: natural geochemical; agricultural and industrial activities. Result from Hierarchical cluster analysis (HCA) indicates a spatial variability of hydrochemical characteristics of Teboulba groundwater.