Zonation of coastal geo-electrostratigraphic units via stratigraphic modified Lorenz plots and rock typing

Abstract

The characterization of aquifers presents hydrogeophysical challenges due to complexities inherent in their lithology and groundwater flow regimes. This work advances subsurface characterization by integrating geoelectrostratigraphic information with a hydraulic flow unit (HFU) and flow zone indicator framework. Comprehensive geoelectrical surveys were conducted within a heterogeneous coastal milieu, the goal being to delineate the spatial architecture of the aquifer system. The surveys yielded resistivity distributions indicating stratified geological formations comprising fine-to-coarse grained sands intercalated with low-permeability clay horizons. The introduction of the stratigraphic modified Lorenz plots (SMLP) refined the permeability-porosity relationship by revealing spatial variations in flow efficiency, thereby differentiating between conductive and superconductive hydraulic zones. Hydraulic conductivity ranged from 5.29 × 10^–6 to 8.79 × 10^–5 m/s, permeability ranged from 751.24 to 12467.23 mD, hydraulic capillary radius ranged from 1.21 × 10^–6 to 3.25 × 10^–6 m, and Aquifer Quality Index ranged from 1.65 to 4.83. Via the application of petrophysical correlations, four distinct hydraulic flow units (HFU1–HFU4) were identified based on values of permeability, effective porosity, and Flow Zone Indicator (FZI). The steeper slope of HFU3 suggested enhanced groundwater transmissivity, whereas the moderate slopes of HFU1, HFU2, and HFU4 indicated restricted hydraulic connectivity. A major novelty of this study lies in integrating petrophysical, electro-hydraulic, and geospatial data to generate high-resolution 2D parametric maps. This approach has enabled the visualization of spatial permeability distributions and groundwater storage variations, offering a diagnostic tool for aquifer productivity assessment. The results obtained have implications for optimizing groundwater extraction strategies and improving regional water resource management policies.