Assessment of the impact of land-cover change on water quality: case study of the Chiba watershed, Nabeul, Tunisia

Water scarcity and water quality degradation are important problems that can affect human well-being. Population growth, unplanned urbanization, land-cover change, and the intensification of agricultural and industrial activities are the main reasons for water resource issues. The main aim of this work was to evaluate the effect of land-cover change on groundwater quality in the Chiba watershed, Nabeul, Tunisia. A remote-sensing technique was used to identify the principal transitions in land cover between 1998 and 2018. Additionally, four water quality indicators (electrical conductivity, chloride concentration, nitrate concentration, and sodium absorption ratio) were utilized to investigate variations in water quality in the study area. It was found that most of the watershed was covered with agricultural land in 1998 (87.5%) and 2018 (88.6%). Based on a comparison of these two periods, various types of land-cover transitions were observed. Moreover, the water quality indicators revealed that the salinity hazard and nitrate contamination in the watershed were high. The spatial relationship between water contamination level and land-cover transition category indicated that barren land to built-up land transitions had the strongest negative effect on water quality among all of the main land-cover transitions. Demonstrating the impact of land-cover change on water quality should encourage local decision makers and water managers to implement strategies for sustainable urban planning and periurban agriculture.