Identification and variations of the components of a regional groundwater flow system with intensive exploitation based on historical hydrogeochemical records in a coastal flow system.

The Costa de Hermosillo is a coastal flow system located in the northwest of Mexico. Since 1954, it has been subject to intensive exploitation of groundwater resources, resulting in a significant drop in the water table. It is important to note that the water table is now several meters below sea level. As a result, seawater intrusion has extended tens of kilometers inland. The impact of this problem on the region is significant in economic, social, and environmental terms. Extensive agricultural areas have been abandoned due to the salinity of the water extracted from wells affected by seawater intrusion.

The present study proposes a statistical methodology based on historical hydrogeochemical data from the Hermosillo coast to determine three fundamental aspects. 1) determining the number of flow components in the groundwater, 2) identifying the proportion of each component in the wells, and 3) analyzing the spatial and temporal distribution of these components.  The research involved three main aspects: To begin, historical data on hydrogeological and hydrogeochemical aspects, climatic variables, and static water level elevations in the area were compiled. This data was then subjected to rigorous quality control to select appropriate years for analysis. The analysis focused on wells that had records of major ions and some physical parameters for the years 1980, 1987, 1989, 1991, 1992, and 1993. Statistical techniques were used to identify four components present in the study area and to determine their proportions in the wells.

The identification and hydrogeochemical characterization of groundwater constituents are essential to enhance knowledge of the region. This approach is based on analyzing the concentrations of dominant ions in wells, which allows the establishment of relationships with the hydrogeological environment. The main objective is to overcome the current limitations of groundwater management in the coastal region of Hermosillo. The hydrogeochemical characterization proposed here is a crucial step toward addressing interrelated challenges and achieving integrated and sustainable water resource management in the region.