Examinando por Autor "Heredia, Javier"

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Flow and Transport Numerical Model of a Coastal Aquifer Based on the Hydraulic Importance of a Dyke and Its Impact on Water Quality. Manglaralto¿Ecuador
(MDPI, 2021-02-08) Carrión-Mero, Paul; Montalván Toala, Francisco Javier; Morante-Carballo, Fernando; Loor-Flores de Valgas, Carolina; Apolo-Masache, Boris; Heredia, Javier
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.
Hydrochemical and isotopes studies in a hypersaline wetland to define the hydrogeological conceptual model: Fuente de Piedra Lake (Malaga, Spain)
(Elsevier, 2017-01-15) Montalván Toala, Francisco Javier; Heredia, Javier; Ruíz, José María; Pardo-Uguzquiza, Eulogio; García de Domingo, Alfredo; Elorza, Francisco Javier
The Fuente de Piedra lake is a hypersaline wetland of great extension (13.5 km2 ) and rich in aquatic birds and other species. It became therefore the third Spanish wetland to be included in the Ramsar convention and has been a “nature reserve” since 1984. The lake has an endorheic basin (150 km2 ) with variable-density flows dominated by complex hydrogeological conditions. The traditional conceptualization of endorheic basins in semiarid climates considered that the brine in this hydric system was exclusively of evaporative origin and was placed only in the lake and its surrounding dis charge area in the basin. Previous geophysical and hydrochemical studies identified different types of waters and brines. In this work, natural tracers (Cl− , Br− , Na+ , Mg2+ ) and environmental isotopes ( 18O, 2H, 14C, 13C and 3H) were employed to a) discriminate different types of brines according to their degree of evaporation and genesis, and b) to estimate res idence times of brine waters and identify recharge areas of the different flow subsystems. A conceptual model of the hydrogeological system of the lake basin and its links to a regional karst system is proposed
Hydrochemical and Isotopic Characterization of the Waters of the Manglaralto River Basin (Ecuador) to Contribute to the Management of the Coastal Aquifer
(MDPI, 2021-02-19) Carrión-Mero, Paul; Montalván Toala, Francisco Javier; Morante-Carballo, Fernando; Heredia, Javier; Elorza, Francisco Javier; Solórzano, Joselyne; Aguilera, Héctor
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.