In hard rock terrain, fractured aquifers comprise the major source of groundwater availability where the phreatic aquifer is de-saturated. It is essential to understand the interconnectivity between phreatic aquifer and deep fractured aquifer, for better water management strategy. Identification of fracture zones in hard rock terrain and potential groundwater source delineation had been a perennial problem in hydrology in the recent past. In concurrence to this, understanding the groundwater flow through fracture system has also been a challenge to hydrologists and geophysicists. The purpose of this paper is to highlight the study executed over a small watershed area, in a granite terrain, wherein an attempt was made to delineate and map the fractured aquifer using numerical (factor) analysis of the conventional vertical electrical sounding (VES) data. Delineation of fracture zones at depths and mapping their geometry were obscure due to limitations in 1D interpretation of VES data through curve matching technique. Factor analysis for the same VES data was carried out and as a result, fractured granite aquifer was deciphered. Also, based on the factor analysis, a fault was deciphered in the study area bifurcating the fractured aquifer into two segments which was later confirmed based on satellite photo data and 2D resistivity imaging survey. This numerical approach of resistivity data interpretation in concatenation with resistivity imaging or other techniques would prove to be an effective tool in groundwater exploration.
Author(s) Details:
Rolland Andrade
Central Water & Power Research Station, Pune-24, India.
Recent global research developments in Numerical analysis of VES data for fractured aquifer simulation in a granite area: a case study
Assessing Sustainable Development of Deep Aquifers:
- Deep groundwater aquifers, protected by impermeable rock layers, serve as crucial resources during emergencies (e.g., floods contaminating shallow groundwater).
- Recent monitoring of Upper Jurassic wells in Bavaria and Austria revealed fluctuations connected to new exploitation activities, potentially indicating unsustainable development.
- Researchers propose a workflow using clustering algorithms to assess these fluctuations. They derive thresholds for two corridors: Natural Range Corridor (NC) and Action Corridor (AC).
- The AC hints at unsustainable development and should trigger detailed assessment. This method can serve as an early warning system for well operators1.
Influence of Artificial Recharge in Phreatic Aquifers:
- To ensure effective pumping-recharge systems, an analytical method predicts discharge rates under combined pumping and recharge conditions.
- This method relies on steady-state and Dupuit hypotheses2.
Fractured-Rock Aquifers:
- With increased water demand, fractured-rock aquifers (where water moves through rock fractures) gain importance.
- However, fractures may not always convey or store large quantities of water3.
Managed Aquifer Recharge (MAR):
- Over the last 60 years, intentional groundwater replenishment (MAR) has advanced due to unprecedented groundwater extraction, overdraft, and new water treatment technologies4.
Modern Groundwater Depths:
- Groundwater in heavily pumped aquifer systems often contains minimal modern water at certain depths5.
References
- Ogundana, A.K., Falae, P.O. Groundwater potential modelling and aquifer zonation of a typical basement complex terrain: a case study. Environ Dev Sustain (2024). https://doi.org/10.1007/s10668-024-04940-8
- Qian, J., Zhou, X., Zhan, H. et al. Numerical simulation and evaluation of groundwater resources in a fractured chalk aquifer: a case study in Zinder well field, Niger. Environ Earth Sci 72, 3053–3065 (2014). https://doi.org/10.1007/s12665-014-3211-z
- Ayinippully Nalarajan, N., Nambi, I.M. & Govindarajan, S.K. Numerical investigations on the reclaimable aquifer recharge from injection wells: a case study. Sustain. Water Resour. Manag. 8, 133 (2022). https://doi.org/10.1007/s40899-022-00730-0
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