The northern edge of Brabant is, in several ways, a border area. Here lies the transition from sand to clay, from high to low, from dry to wet. This transition zone, 1 to 4 kilometers wide and 200 kilometers long from west to east, is called the Naad of Brabant. To the south of the Naad are the high, dry sandy soils, while to the north are the wet, impenetrable clay soils of the Dutch Delta. Rainwater and river water that infiltrates the high sandy soils flows underground over a sloping clay layer towards the clay soils. Here, the water can no longer flow underground; it moves to the surface, creating groundwater pressure. At the boundary between sand and clay, a very wet area forms, leading to the development of peat.

This wet and peat-rich area has long been important for peat extraction and agriculture. After the Eighty Years' War, the hydrological phenomenon was recognized as a military strategic principle, leading to the construction of the Southern Water Line. The polders in this strip could easily be flooded with water from the Aa, the Dommel, and the Raam, without the water subsequently sinking into the ground. By inundating the area, it was prevented that enemy troops could besiege the Brabant fortress cities. The extensive system of drainage canals, waterways, and sluices that had been built over the centuries for peat extraction and agriculture could now be used to evenly flood the land. Together, these inundated polders formed a broad waterline across the region.

Many inundation fields were re-established as agricultural land after the decommissioning of the Southern Water Line, but some areas proved to be too wet or saline. These regions have transformed into unique nature reserves, now home to plant and animal species that were once characteristic of the Dutch delta landscape. However, most of the land is still used for agriculture, and groundwater is drained as quickly as possible.

During heavy rainfall and high water levels in the streams and rivers, Brabant often suffers from flooding in the autumn. Additionally, the province faces water shortages and severe drought in the summer, primarily in the high dry sandy areas. The former inundation fields have already proven themselves in the past as water buffers, and they could potentially fulfill this role again in the future.

By focusing on water retention, a new utility function is created for the relatively wet agricultural lands, as well as a functional and economic foundation for nature and landscape development. The Southern Water Line can evolve into a robust area for nature and landscape development, where amphibious nature is given space at the dynamic boundary between land and water. It will not be a quaint, Arcadian landscape with manicured paths, but rather a rugged and partly impenetrable “border nature.” A delta landscape of mudflats and tidal flats, wet grasslands, wetland areas, floodplain forests, marshes, peat bogs, and buckwheat fields.

Additionally, the wetting of the Naad of Brabant can help reduce drought during the summer on the high sandy soils. The accumulation of water around the Naad makes it more difficult for water on the sandy soils to flow northward, resulting in a higher groundwater level. This allows water to be retained for a longer period.

In addition to the research from hydrological and geomorphological perspectives, a great deal of attention has also been paid to many other themes related to the Southern Water Line. These include (military) history, cultural heritage, monumental heritage, intangible heritage, nature development, tourism, mobility, leisure landscapes, and more. This research has been conducted at the provincial, regional, and local levels.