Hydrogeological Characterization of a Coastal Area for the Groundwater Exploitation. Hondo River Micro-Watershed, Santa Elena-Ecuador

Abstract

The north-central sector of the Santa Elena province has coastal aquifers that their communities have exploited due to water scarcity. The study area comprises the lower part of the Hondo River micro-watershed in the 'La Aguadita' commune. The sector's inhabitants do not have access to drinking water or sewage; the supply is given by cistern tanks and artisanal water wells, with livestock farming as the main economic activity. This work aims to characterize the lower part of the Hondo River micro-watershed by hydrological, lithological, and geophysical analysis to identify areas of groundwater exploitation and proposal for sustainable development. The methodology included: i) analysis of hydrogeological parameters, ii) lithological-geophysical survey, iii) correlation of lithological and geophysical results, and iv) determination of groundwater exploitation zones. The saturated groundwater layer is between 3 and 30 m deep, consisting of gravel and sand. This study demonstrated that the community-academic interaction and the correlation of innovative theoretical methods allowed the establishment of the proposal of sustainable guidelines contributing to the decision-making authorities in integrated water management. Additionally, using walls (albarradas) as part of the ancestral techniques of Water Sowing and Harvesting (WS&H) contributes to the recovery of groundwater quality. The walls are keys to the supply and development of the community. The water quality in the rainy season meets the quality standards for irrigation, while in the dry season, it requires pre-treatment. In the regional context there is limited hydrogeological and geophysical information to a better understanding of the availability and sectorization of groundwater. Methodological trends for future studies are the environmental impact analysis and the correlation of Vertical Electrical Soundings (VES's) with electrical and electromagnetic tomography.