Hydrogeological basins: concepts and applications

Abstract

A hydrogeological basin represents a subsurface compartment, represented by an aquifer, a set of aquifers, or a part of a stratigraphic unit, which flow converges towards a single point or discharge area. Thus, an aquifer or aquifer system can either represent a single hydrogeological basin, or can be subdivided into different basins, depending on the divergent arrangement of the directions of the underground flow. Unlike a watershed that may have its exutory, represented by a point that represents the entire upstream area, the hydrogeological basins often have the discharge zone commonly represented by an area, a surface water body, or a surface watercourse segment. A set of hydrogeological basins can occur overlapped due to regional geological complexity, thickness of the strata, and surface relief. Determining the boundaries of the hydrogeological basins associated with an aquifer or set of aquifers is important to understanding the flow dynamics at subsurface and the relationship with the overlapping watersheds on the surface. Different techniques and methods can be applied to the determination and cartography of hydrogeological basin boundaries including, potentiometry, geophysics, hydrochemistry, hydrological techniques, tracer tests, isotopic hydrology, among others. However, despite its importance, this is not a recurring theme in the literature applied to groundwater resources, being a terminology still little used in scientific research. Most of the citations to this denomination only refer to aquifers, sets of aquifers, and hydrostratigraphic units, without considering the actual concept of hydrogeological basins. Considering these issues, the present paper proposes a review of the knowledge about hydrogeological basins to expand and update its concept and discuss its applications for different contexts, including water resources management, artificial recharge projects, estimation of water reserves, development of conceptual models and numerical simulations, among others.