PILOT SITES
Low Volturno river
The Low Volturno River plain is situated in the Caserta province of Campania, Southern Italy. It is geographically bordered by the Tyrrhenian Sea to the west, the Roccamonfina Volcano to the north, the Matese Massif to the east, and the Campi Flegrei caldera to the south. The region has a Mediterranean climate with hot, dry summers and wet winters. The dominant geological formations in the plain are alluvial and volcanic in origin. The alluvial deposits, made up of sand, silt, and clay, are derived from the Volturno River, while the volcanic deposits include tuffs and other materials from explosive events in the Campi Flegrei caldera and smaller eruptions from Somma-Vesuvius. Groundwater flows from east to west, primarily recharged by precipitation, with lateral recharge from the surrounding karst and volcanic aquifers. The region is heavily influenced by human activity, with urban and agricultural areas that are closely linked. Previous studies have shown the presence of both seawater intrusion (SP) and anthropogenic groundwater leakage (AGL), resulting from ongoing and past seawater intrusion, as well as intense agricultural and suburban development.
Po Delta Plain
The Po Plain site, located along the Adriatic coast in Northern Italy, stretches between the southern Venice lagoon and Ravenna Province. It is part of the largest hydraulic reclamation project on the Mediterranean coasts, much of which lies below sea level. The hydrological system is artificially controlled through a network of canals, pumping stations, and gates managed by local reclamation consortia. Agriculture dominates the land use, with irrigation water sourced from the Po River, while excess water is drained and discharged into the sea. This results in excessive nutrient loads in coastal lagoons. The main hydrogeological challenges in this area include land subsidence, groundwater salinization, saltwater intrusion along rivers, and pollution from agricultural practices. The decreasing piezometric levels, driven by lack of recharge (due to climate change) and increased pumping, will likely cause the saltwater-freshwater interface to move inland, aided by the extensive network of buried sandy paleochannels and old coastal ridges. Additionally, the upconing of paleo-seawater, rich in ammonium, from peaty lenses formed during maximum transgressive flooding, is expected due to heavy drainage from reclamation canals.
Puck Bay
The Puck Bay catchment area, located in northern Poland along the southern coast of the Baltic Sea, is primarily used for agriculture (51%), with forests covering 28%, permanent meadows and grasslands 12%, and low-density urban areas 9%. The groundwater system is complex, consisting of several aquifer units. Shallow groundwater exists in small, perched aquifers and sand lenses within moraine deposits, mainly used locally by farms and summer houses. Two deeper Quaternary aquifers, located in glaciofluvial sand and gravel deposits, are separated by a moraine till layer. The entire hydrological system is drained by the Baltic Sea (Bay of Puck), either directly through submarine groundwater discharge (SGD) or indirectly via streams and rivers. These Quaternary aquifers are the primary source of water supply in the region. Pollution in the groundwater is localized, with notable vertical geochemical inversion. High concentrations of nitrogen compounds, phosphates, and potassium are found in shallow waters, reflecting the local impacts of agriculture and municipal waste from households and farms, including poor sanitation, animal husbandry, and the storage and distribution of organic fertilizers.
Vistula Spit
The Vistula Spit is a long, narrow sandy peninsula on the southern Baltic Sea coast, extending 73 km in length in Poland. It runs in a northeastern direction, separating the Vistula Lagoon (with brackish water and a salinity of 0.2-7‰, averaging 3‰) from the Gulf of Gdańsk (with a salinity of 7-8‰). The region is primarily forested, with Krynica Morska, the largest town, housing 1,284 residents. The formation of the Vistula Spit is linked to Holocene processes, which created a system of dune ridges. Geologically, the area is homogenous, consisting of marine and aeolian sands, along with peat formed in local interdune peatbogs. The main water source is a shallow, unconfined freshwater lens located above low-permeability sediments about 40 meters above sea level. The aquifer is made up of Pleistocene-Holocene sands, with a thickness of about 40 meters. This hydrosystem is recharged by precipitation and drained by the Baltic Sea (Gulf of Gdańsk) and Vistula Lagoon. Groundwater depth varies, being shallow on the beaches and deeper (over 20 meters) under the central dunes. Increased ammonia concentrations (greater than 1 mg/l), of natural origin, have been found in some groundwater samples. Groundwater exploitation results in significant variations in chloride concentrations over time.
Cape Flats
The Cape Flats cover approximately 450 km², extending from False Bay in the south to Tygerberg and Milnerton in the north. The climate is Mediterranean, with wet winters and dry summers. The Cape Flats Aquifer is composed of fluvial, marine, and aeolian Quaternary sedimentary deposits from the Sandveld Group, with a maximum thickness of about 55 meters, underlain by impermeable weathered Malmesbury and granite basement rocks. The Witzand formation (unconfined) and Springfontyn formation (semi-confined) are the dominant aquifers, with localized deposits of calcrete and peaty clay lenses. Groundwater flows from northeast to southwest, with a shallow water table (<2 meters), which often causes flooding during winter. Land use is dominated by agriculture, particularly the Philippi Horticultural Area (PHA), and urban areas including residential, industrial, and business zones, alongside grassland-covered sand dunes and sand mining. Groundwater serves as the primary irrigation source for PHA, especially during dry periods, and is the largest water user in the Cape Flats Aquifer. Climate change (CC) and variability could increase pressure on the aquifer by reducing rainfall and recharge, which are crucial for diluting salinity. The proximity to the ocean heightens the risk of seawater intrusion, particularly if groundwater levels drop due to increased abstraction and reduced recharge. This could lead to a deterioration in water quality, affecting both farmers and residents, and increasing remediation costs if the aquifer is to be used for water supply augmentation by Cape Town.
