The Manglaralto aquifer is located at the north of the province of Santa Elena, Ecuador, its importance is based on the source of supply for the sector. The objective of this work is to characterize the waters of this hydrogeological system by means of hydrochemical techniques (Piper and Stiff diagrams) and their correlation with the geology of the area, as well as the determination of marine intrusion. The methodology used is based on the concentrations of the major ions, which have been obtained by the water-rock interaction, where the geological analysis helps to understand the conceptual hydrogeological model. The obtained results indicate that there are two groups of waters: in the part closest to the interior of the basin with facies mainly bicarbonate and calcium-sodium, while nearest the sea shows markedly calcified calcium facies, and the existence of marine intrusion in the well closest to the coastline.

Coastal aquifers are part of the natural resources contributing to local development and promote resilience in the most vulnerable communities near the sea. Manglaralto, an Ecuadorian coastal parish, is affected by water resource scarcity. The increase in salinity and deterioration of the water quality is generated by the local and floating population’s demand, causing an increase in the Total Dissolved Solids (TDS) concentrations and decreasing the aquifer’s piezometric levels. The aim is to establish a numerical model of flow and transport of the Manglaralto coastal aquifer by using hydrogeological data and Visual Transin software, relating the hydraulic importance of a dyke’s design (“tape”) and its impact on the quality of the water. The methodology is (i) hydrogeological database analysis, (ii) the system’s recharge concerning the soil water balance, (iii) the boundary conditions of the flow and transport model and, (iv) the results and validation of the numerical simulation. The results configure the importance of the coastal aquifer’s artificial recharge in the area where the tape is located, as reflected in the increase in piezometric levels and the decrease in salinity in wells near the sea. In conclusion, the numerical model of flow and transport allows expanding the knowledge of the variation of the piezometric levels and TDS concentrations over time, the importance of recharge in the hydrogeological system’s operation, and correct community management resilience and projection to sustainable development.

Modeling an aquifer provides significant advantages when evaluating and estimating the water resource for its sustainable use. This study focuses on the rural parish Manglaralto, a semi-arid area with a shortage of water, and without supply service by the public network. Still, it has a great demand for supply by the local and floating population (tourism). This has caused the coastal aquifer, which supplies the area’s water, to show signs of overexploitation, and its natural balance is compromised. The aim is to establish a geometric model of the aquifer through geological and geophysical analysis to set sustainable water-use guidelines. The methodology includes: (i) the processing of the current technical and hydrogeological information to know the aquifer’s data; (ii) geometric modeling of the aquifer through the correlation of technical information, using the GeoModeller software; (iii) proposals for the sustainable use of water in the framework of the United Nations’ Agenda 2030. The geometric model results reveal that the aquifer’s thickness varies from 4 m at the head of the river to 30 m at the sea’s mouth. The volume of water is estimated at 13.6 Hm3. The sustainable-use proposals ensure that more than half of the population receives the community company’s service. More than 40% of the territory is a protected area, and 64% of the population has sewerage service. This geometric model is a visual contribution that allows us to know the aquifer’s shape and establishes guidelines that help strengthen the water supply’s development and sustainability over time.

Coastal aquifers are strategic and fundamental in the development of touristic areas. The coastal aquifer within the Manglaralto River Basin in Ecuador is essential, as it is the only source of water supply for a large part of the northern part of the Santa Elena province. It is a semi-arid region where high volumes of water are pumped from the aquifer, causing a significant drawdown of groundwater levels, thus affecting the water quality. This work aims to characterize the characteristics of groundwater in the coastal aquifer using hydrochemistry and stable isotopes to propose a hydrogeological conceptual model. The methodology for determining the chemical and isotopic characteristics of groundwater follows the following scheme: (i) studies of ionic concentrations using the Piper diagram, (ii) assessment of the origin of salinity through the Cl/Br ratio, the presence of seawater intrusion through the Hydrochemical Facies Evolution Diagram HFE-D, (iii) characterization of precipitation events using stable isotopes (18O and 2H), and, (iv) development of a hydrogeological conceptual model of the study area. The results indicate that in the basin there are mixing processes of the existing water in the aquifer with recharge water, direct cation exchange processes in the freshening process during recharge, and evaporation in the unsaturated zone. A conceptual model of the flow system in the basin is built, based on the mentioned processes. The main conclusions are: seawater intrusion is present in the areas of the wells located closest to the coast, urban activity through septic tanks is affecting the quality of the aquifer, and rainfall is highly relevant in the different hydrochemical and isotopic processes that operate in the basin.

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The oil industry requires studies of the possible impacts and risks that exploration, exploitation, and industrialization can cause to the environment and communities. The main objective of this study was to assess the vulnerability caused by oil wells of the Salinas and La Libertad cantons in Ecuador by proposing a multi-criteria spatial analysis methodology that would aid in land-use planning and management. The proposed methodology relates the variables of distance, identification of gas emission from oil wells, permeability, and the state of oil wells (DIPS). The methodology consists of: (i) the diagnosis of oilfield wells; (ii) environmental considerations of productive wells, wells in temporary abandonment, and wells in permanent abandonment; (iii) the vulnerability assessment of both intrinsic and extrinsic aspects of the wells; and (iv) the development of a vulnerability map and recommendations for land management. The results showed 462 wells in the study area, of which 92% were shown to be located in urban areas. Of the total, 114 wells were considered to be productive wells, 89% of which are in urban areas. The vulnerability map identified the areas to be addressed, which coincided with coastal and urban areas associated with oil production. Our main recommendation is to elaborate land-use planning regulations and build safety infrastructure around the wells to guarantee their distance from houses, beaches, and tourism-development sites. The vulnerability map was shown to serve as an essential diagnostic for decision making in managing oil territories, especially in coastal areas.

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