Identification, classification and mapping of water bodies and springs at the Ramsar (1981) site, Baño de San Ignacio, Linares municipality, Nuevo León State, México

Abstract

Wetlands are closely connected to groundwater, which is the primary source for land ecosystems that rely on natural discharges on the surface. This study was conducted to analyze the topographic conditions and differentiate natural groundwater discharges in the Baño de San Ignacio wetland, a RAMSAR site (No. 1981) designated as a Protected Natural Area in 2000. The research took place during the dry season of 2024. Field measurements of hydrogeochemical parameters were taken in various water bodies, and flights with an Unmanned Aerial Vehicle were conducted to identify water bodies with varying characteristics such as temperature, pH, electrical conductivity, dissolved oxygen, and redox potential. Additionally, previously unrecorded topographic depressions and stream beds were identified. Particular geological conditions led to the presence of 1,644 topographic depressions, with those having lower circularity (1.02-1.52) and elongation (1.0-2.1) indices predominating (0.3-0.9), as well as higher shape and elongation indices (0.7-1.1). With the use of the Horton-Strahler number, two main streams (with order 7) were identified as draining the wetland, along with a total of 21 lagoon bodies, 6 thermal springs, and 2 cold springs. The average values of the hydrogeochemical characteristics of the hot springs (temperature 34.4º C, pH 6.8, -226 mV ORP, DO less than 0.5 mg/l and EC of 7,800 μS/cm) and lagoon bodies (temperature 23.5º C, pH 7.0, 32 mV ORP, DO 1.8 mg/l and EC of 1,800 μS/cm), indicate that the wetland is discharged by groundwater flow systems with different trajectories, which are classified as regional and intermediate. The study confirms the wetland's dependence on natural groundwater discharges. The large number of topographic depressions indicates that the number of lagoon bodies will significantly increase during the rainy season compared to those identified during the dry season.