• AHMED EL-RAYES

      Articles written in Journal of Earth System Science

    • Estimation of hydraulic conductivity in fractured crystalline aquifers using remote sensing and field data analyses: An example from Wadi Nasab area, South Sinai, Egypt

      AHMED EL-RAYES ADEL OMRAN GERIESH MOHAMED VOLKER HOCHSCHILD

      More Details Abstract Fulltext PDF

      Fractured crystalline aquifer is considered as the main source of water supply in most of the arid and semi-arid regions. Fractures play an essential role as pathways through which groundwater flows from high catchments to supply the productive wells in lowlands. The hydraulic conductivity measurements for highly fractured crystalline aquifers are a must for optimal management of groundwater extraction from these aquifers. The current work aims at estimating the hydraulic conductivity of the crystalline aquifer by using an unconventional approach based entirely on the processing of remotely-sensed lineament data and field observations. Extracted lineaments at four sites near the productive wells along Wadi Nasab area (WNA) were traced from Landsat (ETM+7) and other ancillary geological data by using image processing and GIS tools. Hence, four discrete fracture networks (DFN) were designed and practiced for the selected test sites to model the groundwater flow through the fracture system in order to estimate the hydraulic conductivity of the investigated crystalline aquifer. The achieved results indicated that the hydraulic conductivity of fractured basement aquifer of WNA varied between 2.3 $\times$ 10$^{-7}$ and 6.1 $\times$ 10$^{-7}$ m/s. The estimated hydraulic conductivity values are close to the values of previous field infiltration tests in the nearby area at Sinai. The previously estimated infiltration rates (expressing the vertical hydraulic conductivity) on the fractured crystalline outcrops ranged between 2.6 $\times$ 10$^{-6}$ and 6.5 $\times$ 10$^{-7}$ m/s, which are concordant with achieved results. Moreover, the achieved values match the previously published values of hydraulic conductivity for similar crystalline aquifers around the world, reflecting the high validity of the used unconventional, low-cost approach to estimate the hydraulic conductivity of fractured crystalline aquifers. The designed approach can be potentially practiced on similar basins in Sinai peninsula and other comparable basins having similar geological and climatic environments around the world.

      $\bf{Highlights}$

      $\bullet$ Estimating the hydraulic conductivity of fractured crystalline aquifer by using remotely sensed lineament data and field observations.

      $\bullet$ Discrete fracture networks (DFN) models the groundwater flow to estimate the hydraulic conductivity of the crystalline aquifer.

      $\bullet$ The estimated hydraulic conductivity values are varied between 2.3 $\times$ 10$^{-7}$ m/s and 6.1$\times$10$^{-7}$ m/s, which come in agreement with the previously estimated values using the conventional infiltration tests.

      $\bullet$ The results reflect the validity of using this unconventional and low-cost approach to estimate the hydraulic conductivity of fractured crystalline aquifers.

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