Assessing Suitability of Hand Drilling Techniques for Abstracting Shallow Alluvial Aquifers along River Benue Floodplain, North Eastern Nigeria

Abstract:

The aim of the research is to assess the suitability of hand-drilling techniques for accessing groundwater for water supply and irrigation along the shallow alluvial floodplains of River Benue, North Eastern Nigeria. Hand drilling techniques are affordable means for the farmers to abstract water from these shallow aquifers. Assessing the sustainable use of these techniques will improve farming activities along the floodplain and to increase food security in the region and the country at large. The floodplain groundwater obtained from drilling logs ranges between 5 and 18 m. The depth of the groundwater levels across the floodplain are therefore within the depth for abstraction with the hand drilling techniques. Locations and elevations were determined using a ProMark3 dual frequency GPS instrument. Hydraulic conductivity were obtained from twelve pumping wells, the result shows that the floodplain formations are permeable to recharge the shallow alluvial aquifers. A Field Shear Vane Tester was applied at twelve different borehole location points to determine sediment shear strength on sediment. The shear strength result shows that the shear forces are higher on clayey silt and sandy silt, and lower on sand formations. It can be scientifically demonstrated that a low-cost hand drilling techniques such as augering and jetting remain possible for abstracting the shallow alluvial aquifers on the floodplain for irrigation farming in the study area.

Key Words: Hand drilling techniques, Alluvial Floodplain, River Benue, Boreholes, Field Shear Vane Tester