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

The aim of the research is to assess the suitability of hand-drilling using augering and jetting techniques for accessing groundwater for water supply from the shallow alluvial aquifers along the 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 suitability of these techniques will improve farming activities along the floodplain and will increase food production in the country. The depth to the alluvial aquifers ranges between 6 and 18 m for the twelve hand-drilled wells. The depths of the aquifers across the floodplain are therefore within the depth for abstraction with the hand drilling techniques. The hydraulic conductivity of the shallow alluvial aquifers was obtained from twelve pumping wells, and the results range from 1,849 to 34,646.4 m/day with a mean value of 10,195.2 m/day. Thus, indicating hydraulic conductivity of gravel to clean sand, suggesting that the floodplain formations is highly permeable to recharge the shallow alluvial aquifers. A Field Shear Vane Tester was used at twelve different borehole location points to determine sediment shear strength. The shear strength result shows that the shear forces are higher on clayey silt and sandy silt, and lower on sandy 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.