Horizontal and vertical compartmentalization in the fissure and karstic aquifers of the Lagoa Santa Karst Environmental Protection Area and surroundings, Minas Gerais, Brazil

Dantas, Júlia Cotta Maciel; Velásquez, Leila Nunes Menegasse; Paula, Rodrigo Sérgio de

doi:10.1016/j.jsames.2023.104219

Cited by 2 publications

(1 citation statement)

References 5 publications

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“…This system is sometimes covered by the shale aquitard and the coverings, which can act as recharge zones for the main carbonate aquifer system, with a low thickness, not exceeding 50 m in the study area (De Paula, 2019). It is important to note that the weathering mantle of the soil can reach depths of up to 60 m, with an average of 30 m, while the water inlets are typically located around 30 m below this weathering alteration mantle (Dantas et al, 2023). Most of the water levels observed in monitoring wells are found way above the depth of the inlets.…”

Section: Geological and Hydrogeological Contextmentioning

confidence: 99%

Estimating transmissivity and storativity in a karst aquifer by direct and indirect methods

Pena,

de Paula,

Velasquez

et al. 2024

Hydrological Processes

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The karst aquifer located in the Environmental Protection Area of Lagoa Santa, Minas Gerais, Brazil, exhibits the characteristic morphological features of an evolved karst environment, including large caves, sinkholes, and copious springs. Understanding the hydrogeological characteristics of karst aquifers is crucial for effective management of public resources and prevention of contamination, as these aquifers are highly vulnerable, making it essential to identify and mitigate potential risks. Given the ongoing economic and population growth in this region, the assessment of the hydrogeological parameters that control the dynamics of local flow becomes relevant for the proper evaluation of hydrogeological models and the management of water resources. Four classical pumping test analysis methods were compared to quantify the flow and storativity of the aquifer: Theis (1935), Neuman (1972), Moench (1984), and Agarwal (1980). In addition, indirect estimation methods based on the identification of capture zones and the analysis of recession curves of water courses were employed, since these approaches are cheaper and easier to apply in areas with low information. The statistical analysis of the results suggests that classical solutions can be applied to the karst aquifer to estimate hydrogeological parameters, apart from the Storage Coefficient obtained using the Neuman method. In general, the indirect estimation methods tend to produce values that are consistent with those obtained through direct methods, albeit with some reservations. The transmissivity values obtained from the pumping tests were approximately 3.0 × 10−4 m2/s, while the storage coefficient is estimated to be around 3.7 × 10−3. The indirect estimation methods yield transmissivity values of about 1.8 × 10−4 m2/s using the capture zone method, and storage coefficient values of 4.0 × 10−3 and 3.9 × 10−2 using recession curve analysis.

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Section: Geological and Hydrogeological Contextmentioning

confidence: 99%

Estimating transmissivity and storativity in a karst aquifer by direct and indirect methods

Pena,

de Paula,

Velasquez

et al. 2024

Hydrological Processes

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Karst Hydrological Connections of Lakes and Neoproterozoic Hydrogeological System between the Years 1985–2020, Lagoa Santa—Minas Gerais, Brazil

Pacheco Neto,

de Paula,

Galvão

2024

Water

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This study focuses on a complex Brazilian Neoproterozoic karst (hydro)geological and geomorphological area, consisting of metapelitic–carbonate sedimentary rocks of ~740–590 Ma, forming the largest carbonate sequence in the country. At the center of the area lies the Lagoa Santa Karst Environmental Protection Area (LSKEPA), located near the Minas Gerais’ state capital, Belo Horizonte, and presents a series of lakes associated with the large fluvial system of the Velhas river under the influence, locally, of carbonate rocks. The hydrodynamics of carbonate lakes remain enigmatic, and various factors can influence the behavior of these water bodies. This work analyzed the hydrological behavior of 129 lakes within the LSKEPA to understand potential connections with the main karst aquifer, karst-fissure aquifer, and porous aquifer, as well as their evolution patterns in the physical environment. Pluviometric surveys and satellite image analysis were conducted from 1984 to 2020 to observe how the lakes’ shorelines behaved in response to meteorological variations. The temporal assessment for understanding landscape evolution proves to be an effective tool and provides important information about the interaction between groundwater and surface water. The 129 lakes were grouped into eight classes representing the hydrological connection patterns with the aquifers in the region, with classes defined for perennial lakes: (1) constantly connected, (2) seasonally disconnected, and (3) disconnected; for intermittent lakes: (4) disconnected during the analyzed time interval, (5) seasonally connected, (6) disconnected, (7) extremely disconnected, and (8) intermittent lakes that connected and stopped drying up. The patterns observed in the variation of lakes’ shorelines under the influence of different pluviometric moments showed a positive correlation, especially in dry periods, where these water bodies may be functioning as recharge or discharge zones of the karst aquifer. These inputs and outputs are conditioned to the well-developed karst tertiary porosity, where water flow in the epikarst moves according to the direction of enlarged karstified fractures, rock foliation planes, and lithological contacts. Other factors may condition the hydrological behavior of the lakes, such as rates of evapotranspiration, intensity of rainfall during rainy periods, and excessive exploitation of water.

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Horizontal and vertical compartmentalization in the fissure and karstic aquifers of the Lagoa Santa Karst Environmental Protection Area and surroundings, Minas Gerais, Brazil

Cited by 2 publications

References 5 publications

Estimating transmissivity and storativity in a karst aquifer by direct and indirect methods

Estimating transmissivity and storativity in a karst aquifer by direct and indirect methods

Karst Hydrological Connections of Lakes and Neoproterozoic Hydrogeological System between the Years 1985–2020, Lagoa Santa—Minas Gerais, Brazil

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