Editing Hydrogeology of Liberia

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====Unconsolidated====
 
====Unconsolidated====
 
{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||Description
+
|Aquifer||Description
 
|-
 
|-
 
|Quaternary coastal and alluvial sediments
 
|Quaternary coastal and alluvial sediments
||Generally Moderate to High Productivity (variable)
 
 
||Where these sediments are dominated by coarse sand and gravel, and are suitably thick, they will form productive local aquifers. In other areas, if the sediments are dominated by fine grained sand and silt, or clay, they will have low permeability and storage and will form less productive aquifers. In the most productive areas, it is probable that sustainable borehole yields of between about 0.5 and 3 litres/second (l/s) would be possible, and possibly higher.
 
||Where these sediments are dominated by coarse sand and gravel, and are suitably thick, they will form productive local aquifers. In other areas, if the sediments are dominated by fine grained sand and silt, or clay, they will have low permeability and storage and will form less productive aquifers. In the most productive areas, it is probable that sustainable borehole yields of between about 0.5 and 3 litres/second (l/s) would be possible, and possibly higher.
 
|}
 
|}
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====Sedimentary - Mixed Intergranular and Fracture flow====
 
====Sedimentary - Mixed Intergranular and Fracture flow====
 
{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||Description
+
|Aquifer||Description
 
|-
 
|-
 
|Laterite
 
|Laterite
||Low Productivity
 
 
||The laterite generally has low permeability (UN 1988).
 
||The laterite generally has low permeability (UN 1988).
 
|-
 
|-
 
|Cretaceous (occasionally Devonian)
 
|Cretaceous (occasionally Devonian)
||Low to Moderate Productivity
+
||The coastal sandstones are likely to form low to moderate productivity aquifers, with relatively small stores of groundwater. In an investigation by the Liberia Water and Sewer Corporation (LWSC) for new urban water supplies, boreholes were drilled to 100 m in the sandstones, and many provided a sustainable yield of 5 m<sup>3</sup>/hour (1.4 litres/second or l/s) (UN 1988).  
||The coastal sandstones are likely to contain relatively small stores of groundwater. In an investigation by the Liberia Water and Sewer Corporation (LWSC) for new urban water supplies, boreholes were drilled to 100 m in the sandstones, and many provided a sustainable yield of 5 m<sup>3</sup>/hour (1.4 litres/second or l/s) (UN 1988).  
 
 
|}
 
|}
  
 
====Igneous====
 
====Igneous====
 
{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||Description
+
|Aquifer||Description
 
|-
 
|-
 
|Mesozoic Igneous Intrusive rocks - Unknown aquifer potential
 
|Mesozoic Igneous Intrusive rocks - Unknown aquifer potential
||Unknown
 
 
||Very little is known of the aquifer characteristics of these rocks. They are likely to be crystalline with very low intergranular porosity and permeability, so that groundwater potential will depend largely on the degree and type of  weathering and/or fracturing in the rocks. Groundwater is likely to be present mainly in the uppermost few tens of metres. Overall aquifer productivity is likely to be low.
 
||Very little is known of the aquifer characteristics of these rocks. They are likely to be crystalline with very low intergranular porosity and permeability, so that groundwater potential will depend largely on the degree and type of  weathering and/or fracturing in the rocks. Groundwater is likely to be present mainly in the uppermost few tens of metres. Overall aquifer productivity is likely to be low.
 
|}
 
|}
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====Basement====
 
====Basement====
 
{| class = "wikitable"
 
{| class = "wikitable"
|Aquifer||Aquifer Productivity||Description
+
|Aquifer||Description
 
|-
 
|-
|Precambrian
+
|Precambrian - Low to Moderate Productivity
||Low to Moderate Productivity
 
 
||Groundwater in basement aquifers is found only in shallow weathered zones, and below this in fractures in the rock. Aquifer productivity and groundwater potential depend on the extensiveness of weathering and fracturing. Some information from aquifer tests is given in UN (1988): six boreholes in Buchanan town, between 80 and 100 m deep, gave specific capacity values of 0.25 to 2.60 m<sup>3</sup>/hour/m; and two boreholes in Zwedru town gave specific capacity values of 7.60 m<sup>3</sup>/hour/m (63 m deep) and 24.5 m<sup>3</sup>/hour/m (44 m deep). The higher yields are likely to be in areas with better developed weathering and fracturing, and may also be related to high recharge from abundant rainfall (UN 1988).   
 
||Groundwater in basement aquifers is found only in shallow weathered zones, and below this in fractures in the rock. Aquifer productivity and groundwater potential depend on the extensiveness of weathering and fracturing. Some information from aquifer tests is given in UN (1988): six boreholes in Buchanan town, between 80 and 100 m deep, gave specific capacity values of 0.25 to 2.60 m<sup>3</sup>/hour/m; and two boreholes in Zwedru town gave specific capacity values of 7.60 m<sup>3</sup>/hour/m (63 m deep) and 24.5 m<sup>3</sup>/hour/m (44 m deep). The higher yields are likely to be in areas with better developed weathering and fracturing, and may also be related to high recharge from abundant rainfall (UN 1988).   
  

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