#Thread on India's #CarbonateAquifers:
Aquifers may be divided as unconsolidated (alluvial) or consolidated (hard-rock).
Among the consolidated - carbonate aquifers (made of Limestone/Dolomite) are special, as they are often very productive. Map - Shah et al (2018).
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Aquifers may be divided as unconsolidated (alluvial) or consolidated (hard-rock).
Among the consolidated - carbonate aquifers (made of Limestone/Dolomite) are special, as they are often very productive. Map - Shah et al (2018).
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Limestone often dissolves in the groundwater (a process called karstification), creating much more space & hydraulic conductivity. Space for water is denoted by Specific yield = % of vol of water/rock.
@CGWB_CHQ here gives values for Specific Yield for as carbonates 2-15%:
@CGWB_CHQ here gives values for Specific Yield for as carbonates 2-15%:
Some widely used carbonate aquifers are in Chhattisgarh, Cuddapah & Vidhyan sedimentary basins; and in Kashmir.
Kashmir is famous for prolific springs ('nags') some of which discharge at over 3000 lps! These are basically underground rivers curring through limestone like butter.
Kashmir is famous for prolific springs ('nags') some of which discharge at over 3000 lps! These are basically underground rivers curring through limestone like butter.
Caves are the classic karst landforms formed by the dissolution of limestone & dolomite by GW.
Whether it is the more known Amarnath Cave, or the increasingly well-known Mawsmai cave of Meghalaya or Kotumsar cave of Chhattisgarh - all limestone. (Dar et al, 2014)
Whether it is the more known Amarnath Cave, or the increasingly well-known Mawsmai cave of Meghalaya or Kotumsar cave of Chhattisgarh - all limestone. (Dar et al, 2014)
Chattisgarh basin (in box) denotes well how Limestone (Ls) is often deposited among other sedimentary rocks. The "outer" sandstone (green) is deepest/oldest, shale in "centre" in newest/top. Raipur is on productive Ls aquifer, has deeper Ls aquifer separated by impermeable shale
On closer look hydrogeology complicates, & Raipur can be seen to have a thin veneer other rocks, over 600 meters of prolific limestone/carbonate aquifer (~10 L/s). Here's a 3D map (CGWB) of Raipur's aquifers (the waters of which I have drunk most of my life):
