Editing Hydrogeology of Nigeria

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|-
 
|-
 
|Alluvium
 
|Alluvium
||High Productivity
+
||
 
||Alluvial aquifers occur along major river valleys, and are thickest (15 - 30 m thick) along the rivers Niger and Benue. Largely unconfined, with shallow water tables. Recharge is directly from rainfall and by infiltration from rivers.
 
||Alluvial aquifers occur along major river valleys, and are thickest (15 - 30 m thick) along the rivers Niger and Benue. Largely unconfined, with shallow water tables. Recharge is directly from rainfall and by infiltration from rivers.
 
||None
 
||None
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|-
 
|-
 
|Niger Delta Basin: Deltaic Formation, Benin Formation
 
|Niger Delta Basin: Deltaic Formation, Benin Formation
||High to Very High Productivity
+
||High Productivity
 
||The unconsolidated aquifers of the Niger Delta Basin are extensive and high yielding. The upper Deltaic Formation is unconsolidated and largely unconfined with shallow water table (0-10 m below ground level) (Offodile 2002).  
 
||The unconsolidated aquifers of the Niger Delta Basin are extensive and high yielding. The upper Deltaic Formation is unconsolidated and largely unconfined with shallow water table (0-10 m below ground level) (Offodile 2002).  
  
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|-
 
|-
 
|Chad, Kerri-Kerri and Gombe formations
 
|Chad, Kerri-Kerri and Gombe formations
||Moderate to High Productivity
+
||
 
||The Chad Formation can be unconfined or confined depending on local conditions. Deeper sandstone layers are often confined and can be artesian. Yields of between 2.5 and 30 l/s are quoted. The water table depth is often between 10 and 15 m (Offodile 2002).   
 
||The Chad Formation can be unconfined or confined depending on local conditions. Deeper sandstone layers are often confined and can be artesian. Yields of between 2.5 and 30 l/s are quoted. The water table depth is often between 10 and 15 m (Offodile 2002).   
  
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|-
 
|Sokoto Group (Gwandu and Kalambaina formations); Rima Group (Wurno, Dukamage and Taloka formations); Ilo/Gundimi Formation
 
|Sokoto Group (Gwandu and Kalambaina formations); Rima Group (Wurno, Dukamage and Taloka formations); Ilo/Gundimi Formation
||Moderate to High Productivity
+
||
 
||The lower sands of the Gwandu Formation are often confined; upper layers are unconfined. Water table can vary from 20 to 100 m depth. Storage is typically high. The Kalambaina Formation is locally permeable with perched aquifers in sandier layers (Offodile 2002).  
 
||The lower sands of the Gwandu Formation are often confined; upper layers are unconfined. Water table can vary from 20 to 100 m depth. Storage is typically high. The Kalambaina Formation is locally permeable with perched aquifers in sandier layers (Offodile 2002).  
  
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|-
 
|-
 
|Bima Sandstone, Yolde Sandstone  
 
|Bima Sandstone, Yolde Sandstone  
||Low to Moderate Productivity
+
||
 
||These formations have relatively low permeability and usually provide poor to moderate yields of about 1 to 5 l/s.  They vary substantially in thickness.  The water table depth is usually between 60 and 165 m.  Boreholes range in depth from 30 to 300 m. Recharge is usually directly from rainfall.
 
||These formations have relatively low permeability and usually provide poor to moderate yields of about 1 to 5 l/s.  They vary substantially in thickness.  The water table depth is usually between 60 and 165 m.  Boreholes range in depth from 30 to 300 m. Recharge is usually directly from rainfall.
 
||None
 
||None
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|-
 
|-
 
|Makurdi, Keana, Ezeaku, Awe and Asu River Group formations
 
|Makurdi, Keana, Ezeaku, Awe and Asu River Group formations
||Moderate Productivity (locally High)
+
||
 
||These formations tend to be indurated and dominated by fracture flow (although the Makurdi Sandstone is less so). Typical yields are around 2 to 8 l/s, but wide variations are seen, depending on the degree of fracturing and deep weathering. The aquifers therefore tend to be localised, and vary greatly in thickness. They are usually unconfined with the water table at about 10 - 40 m depth.  Boreholes are typically 40 - 150 m deep. Recharge is usually directly from rainfall.
 
||These formations tend to be indurated and dominated by fracture flow (although the Makurdi Sandstone is less so). Typical yields are around 2 to 8 l/s, but wide variations are seen, depending on the degree of fracturing and deep weathering. The aquifers therefore tend to be localised, and vary greatly in thickness. They are usually unconfined with the water table at about 10 - 40 m depth.  Boreholes are typically 40 - 150 m deep. Recharge is usually directly from rainfall.
 
||None
 
||None

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