Seasonal changes of groundwater production at Enji, Offa area, traced to climate change variability and aquifer vulnerability, Nigeria

Abstract

Enji area is located around Latitude N080 10. 77' 8.77'', Longitude E04° 42.55' 17.29'' and Latitude N08° 10' 10.50'', Longitude E04° 42' 8.51'' with elevation that varied between 415-429meters a.s.l. 12 wells were studied during the peak of dry seasons of December-March and peak of rainy season that represent August-November.The aim is to establish the seasonal variation of the groundwater production at the extreme weather conditions.Portable, durable and rugged MetPRO weather variability instrument was used to collect the data for the environmental study.Pumping test for aquifer vulnerability assessment included dipper, stopwatch, graduated plastic container, 1 h.p submersible pump, 5.5 KVA generator and field notebook were used to collect the field data.Suitable measuring datum of 0.5 m was taken from the ground level for all measurements.Results obtained included first fracture diagnosed at 25-27 meters depth of Enji area and at 33, 36 and 32 meters at Fatraaj, Gbomi and Keraaje respectively.Second aquiferous position was encountered at an average depth of 38, 32.8 and 39 meters.SWL varied from 7.5-9.5meters,DWL gave 18.1-29.6,TDD varied between 34.8-53.9,TRT was from 71734-89872 seconds and Yield varied from 0.49-0.81L/sec during dry season.Wet season measurement gave SWL to be 2.3-3.9,DWL was 18.1-36.8meters, yield varied from 0.81-1.04L/sec, TDD was from 39.62-58.42 and TRT varied from 22321-39896 seconds.Seasonal variation of the climatic condition has greatly impacted the aquifer properties with severely low groundwater production noticeable more during the peak of dry season in the area.