Support method for interpretation of regional groundwater monitoring in urban areas

The correct management of groundwater depends on information regarding the evolutionary processes of groundwater and the characterization of spatial variability of recharge mechanisms. GIS-based index models have become a reliable alternative for mapping and interpreting recharge models due to their adaptability and reliability in estimating recharge. Furthermore, stable isotopes of hydrogen and oxygen in water (δ2H and δ18O) help determine the origin and monitoring of water in the hydrological cycle. This paper aims to contribute to the knowledge of groundwater recharge by developing a conceptual recharge model using stable isotopes and estimating the recharge amount using a spatially distributed water balance model based on GIS for the Zamora River Basin (ZRB) in Ecuadorian Amazon. Due to the basin's size and geography, it was necessary to divide it into six precipitation blocks. The high precipitation rates resulted in high (18.22%) and moderate (30.93%) recharge zones across the basin. The analysis of stable isotopes in water indicates that precipitation water comes from the east, from the Amazon plain. In the valleys, precipitation enriched in δ18O suggests that it has undergone a recycling process in the basin; groundwater recharge comes from these precipitations. This analysis provides a simplified representation of reality that can assist in predicting the impacts of human activities on the basin.

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Assessing the Napo Karst Formation vulnerability in the Western Amazon River Basin

Naranjo

Moulatlet

Hirata

et al. 2023

Preprint

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Karst environments are susceptible to contamination and directly affected by anthropogenic pressures. Remediation efforts are expensive, time-consuming, and often impractical. Hence, vulnerability maps can be valuable tools for protecting and preventing the aquifer’s degradation. This study aims to evaluate the vulnerability of the Napo Karst Formation (NKF), in the western Amazon basin in Ecuador, using three vulnerability models: EPIK, DRASTIC, and DRASTIC-LUC. The difference between the three models lies in the parameters used and how each one of them address the vulnerability. Because assigning values to each parameter depends on the author's expertise and the available data, these models can produce varying outcomes, which we analyze using spatial and sensitivity analysis. Our results showed that DRASTIC and EPIK classified 45.76% and 35.38% of the NKF area as highly vulnerable, respectively, while DRASTIC-LUC classified most of the NKF areas under moderate vulnerability (57.47%). The sensitivity analysis determined that the depth to water table (D) and the infiltration conditions (I) were the most critical parameters for the vulnerability assessment. The moderate-to-high vulnerability of the NKF raises a warning, as the impacts on surface and groundwater may affect local populations that directly depend on its water. This is the first study that evaluates the vulnerability to the contamination of karst formation in the Ecuadorian Amazon. The results of this research can be used as a baseline for future research and as technical information for decision-makers to reduce the activities that could aggravate surface and groundwater quality in Western Amazonia.

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Support method for interpretation of regional groundwater monitoring in urban areas

Cited by 3 publications

References 22 publications

Estimating groundwater recharge and precipitation sources of the Zamora River Basin, southeastern Ecuador, using GIS and stable isotopes

Estimating groundwater recharge and precipitation sources of the Zamora River Basin, southeastern Ecuador, using GIS and stable isotopes

Estimating Groundwater Recharge and Precipitation Sources of the Zamora River Basin, Southeastern Ecuador, by Using GIS and Stable Isotopes

Assessing the Napo Karst Formation vulnerability in the Western Amazon River Basin

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