Regarding GW quality, the Campo de Cartagena groundwater mass was declared at risk of not reaching good quantitative or chemical status by the Segura Hydrographic Confederation in July 2020. The area experiences intense agricultural activity, it is an important supply point to European markets, especially for vegetables during winter. Water demand for irrigation is met by the Tajo-Segura Water Transfer (1/3 of demand) and groundwater (2/3 of the demand). This has led to an overexploitation of the lower layers of the multi-layer aquifer. While the lower layers of the aquifer do have a problem of overexploitation, the upper aquifer, formed in the Quaternary period, which discharges into the Mar Menor, does not have a problem of water quantity, rather the opposite. Seawater intrusion, the filtration of irrigation water, which has increased since the construction of the transfer, as well as periodic intense rains, have made the water table so high that water surfaces on to the ground at some points. These upper layers of the aquifer are highly polluted with nitrates, pesticides and nutrients and drains directly to the Mar Menor which often suffers severe eutrophication episodes resulting in reduction in water transparency and several episodes of anoxia (see Figure below).

Under the NINFA project, three solutions will be tested in this case study under WP2 and WP3:

• Robust, real time and affordable sensors will be developed in the lab will be tested at certain sites for GW monitoring and early-detection of pollutants.
• Assess the existing sources and pathways of GW pollution, their synergistic effects with stressors such as droughts and floods or prevention/mitigation measures, by testing and validating hydrogeological and reactive transport models for pollutants of interest.
• Develop a train of treatment technologies including nature-based solutions, to minimize nutrients, pesticides and other pollutants (metals and antibiotics from manure) leaching to GWs.