Evaluación de la vulnerabilidad a la contaminación de las aguas subterráneas en la cuenca del río Santa Rosa, Ecuador

Abstract

CONDITION FOR PUBLICATION OF PROJECT. the integrity of our ecosystems. Its importance is undeniable in the Santa Rosa River basin (El Oro), where groundwater supports critical uses in the face of variable surface water quality. This study aimed to assess the risk of contamination under the hypothesis of greater susceptibility in floodplains with shallow water tables and high permeability, in order to prioritize environmental management. Cartography and secondary data were integrated with fieldwork; intrinsic vulnerability was estimated using GOD and DRASTIC, and hazard was estimated using POSH, verifying water tables and physicochemical parameters in situ. The GOD method classified the basin as very low vulnerability (371.18 km²; 49.31%), low vulnerability (263.39 km²; 34.99%), and moderate vulnerability (118.13 km²; 15.70%). DRASTIC showed a predominance of low vulnerability (58.18%) and areas of high vulnerability (21.75%) in the east-northeast of the Santa Rosa River basin, associated with permeable alluvial soils and gentle slopes. The main sources of pollution were agrochemicals, urban waste, livestock excreta, artisanal mining, and solid waste. The vulnerability-hazard integration indicated 22.1% high risk and 33.9% moderate risk, concentrated in coastal areas. These findings underscore the need to implement strategies that reduce pollution pressures on groundwater, thereby protecting its quality and ensuring a safe supply in the critical areas identified in this study. Keywords: Water management; groundwater vulnerability; GIS analysis; pollution; hydrogeological modeling.