Increasing Irrigated Agriculture Area and Its Related Water Consumption Set Djorf Aquifer at Risk of Water Quantity Depletion

Assessing the impact of irrigated agriculture on Djorf groundwater is a fundamental key to the sustainable management of coastal freshwater resources. This study integrates Geographic Information Systems (GIS), remote sensing, and machine learning techniques to investigate the relationship between irrigated cropland in the coastal area and the water-level dynamics of the Djorf aquifer, located in the semi-arid region of southeastern Tunisia. A supervised classification using a Random Forest Model (RFM) and ground-truth GPS data was applied to detect irrigated areas in the coastal zone of Djorf. The model showed good performance, with an overall accuracy of 0.99. Moreover, the kappa values varied from 0.72 to 0.94 from 2005 to 2025. The Djorf aquifer experienced an expansion of irrigated agriculture, with an increase in area from approximately 400 ha in 2005 to 500 ha in 2015 and 1600 ha in 2025. This expansion of irrigated agriculture led to a reduction in groundwater level by 1.5 m from 2005 to 2015 and by 5 m from 2015 to 2025, as indicated by the Tajerjemet piezometric well in the southern part of the Djorf area. In the northern part, the groundwater level remained unchanged from 2005 to 2015 but decreased by 3 m from 2015 to 2025, as indicated by the Garaat Tyour piezometric well. In the center of the zone, the groundwater level decreased by 1.5 m from 2005 to 2015 and by about 9 m from 2015 to 2025, as recorded by the Henchir Arrassa piezometric well. The significant drop in groundwater levels over the last decade, from 2015 to 2025, is attributed to the substantial expansion of irrigated agriculture. The irrigated agricultural area continues to expand despite the Tunisian law classifying the Djorf zone as a restricted area for water well drilling, aimed at minimizing the degradation of groundwater in the Djorf aquifer. Alarmingly, the aquifer has resumed a rapid decrease since 2015, and urgent action is needed to prevent further degradation.