Study of Salinization in Shallow Aquifers in the Ada East-West Districts of Ghana

Abstract

The paper examines the extent and levels of groundwater salinization in shallow aquifers in the Ada East-West districts of Ghana and possible causes. The samples comprise 11 surface water samples and 37 shallow wells, which served as sources of water for the local communities. TDS values in well samples varies from 87.5 to 5,160 mg/l with mean value of 1,912 mg/l, in lagoon samples from 6,350-27,100 mg/l, with a mean of 13,506.7 mg/l, in the Volta River from 42.4-165 mg/l with a mean of 93 mg/l, and in stream samples from 38.4-669 mg/l with a mean of 217.5 mg/l. Salinity values across the area is in the range from 33.8-43,574 psu/ppm with a mean value of 2,451 psu/ppm. Among the major ions Cl values range between 2 and 46,636.9 mg/l with a mean value of 1,858 mg/l while Ca range from 5.3 -1,089.3 mg/l with a mean of 107.2 mg/l. River Angor in Dendo and the sampled stream in Kodzi have exceptionally high conductivity values compared with the other sampled rivers and streams. Groundwater salinity overall increases from north to south and away from the Volta River in the direction east toward the Songhor lagoon in the study area. Less saline groundwater and streams are recharged from the Volta River. Between the high saline and low saline groundwater is suspected mixing zone of groundwater with average salinity value of 2,451 psu/ppm. Groundwaters are generally fresh to brackish in study area using TDS as classification. The salinity in the shallow aquifers is a result of evaporation, diffusion, and mixing of coastal water.