Evaluation of The Geology, Water Resources and Geotechnical Properties of Soils in Uga Area, Southeastern Nigeria

Abstract

Water is vital to life, ensures human survival and societal development.  Its overdraft and harnessing can affect the environment adversely. This study evaluates the water resources and geotechnical properties of soils in Uga area, south-eastern Nigeria. The study area lies in the rainforest zone where rainfall is extreme and thus boasts of high water resources potential. Comprehensive data are lacking for effective water planning purposes. This research work contributes to existing data on the water resources potentials of Uga and environs. Surface waters (Obiada River and Agwura Stream), springs (Nwagene, Obizi and Ogbei Springs) abound in the area. Nanka Sands which is a prolific water-bearing unit defines the underlying geology of the area. Flow rates of surface waters are high due to annual precipitation of 2500mm a year. Springs are clear. Nwangene Spring has a flow rate of 0.39 m/sec while Obizi spring has a flow rate of 0.04 m/sec. Borehole depth at Nanka and Oko is 380 meters and 314 meters respectively while static water level is 42 meters and 69 meters respectively. Huge sand deposits abound in the area. This research work highlighted the geotechnical properties of soils from the area. Cobble, pebble and gravel sized grains are absent. CBR values ranged from 30% to 35%. Highest MDD gave a value of 1-824gcm-3 with an OMC of 11%. The lowest MDD recorded a value of 1.622gcm-3 with an OMC of 8%. LI test conducted on one of the samples yielded a value of 16%. PL and PI tests gave zero values for all the samples. The geotechnical results implied that soils from the area are excellent to good reserves for sub-grade and sub-base materials respectively.