Vertical Velocity of Pollutants through Porous Rocks of Anambra State: Implications for Water Resources Planning and Management

Abstract

Indiscriminate siting of human activities has become a common practice in Anambra State, resulting to generation of mobile pollutants. To this effect, an infiltrometer was used to investigate the velocities of pollutants (four fluids) through five sedimentary formations of varying lithological characteristics, with a view to proffering efficient strategy for management of groundwater resources in the area. A purposive/judgmental sampling technique was used to select the formations used. The study tested the following hypotheses:(i) the velocity of pollutants through rocks is not related to the lithological characteristics of the underlying rocks and (ii) pollution level (densities of pollutants) is not related to the vertical infiltration (velocity) of pollutants. The following findings were recorded: (i) the velocity of pollutants through rocks is closely related to the lithological characteristics of rocks, including porosity and hydraulic conductivity, (ii) pollution level (densities of pollutants) is weakly related to vertical infiltration of pollutants. Consequently, the study recommended that the lithological characteristics of underlying formations should be known before selecting such sites for human activities that generate pollutants so as  to safeguard the groundwater resources of the area. This is to say that shale terrains or any other formations that have, at most, porosity and hydraulic conductivity values of 18% and 2.3 x 10^-8 cm/sec. respectively, should be used for human activities that generate mobile pollutants. It also recommended that site selection for various wide scales human activities that generate mobile pollutants should be based on the knowledge of underlying geology of the place in question, and not merely on the availability of such space and close proximity to users. Further research areas were also recommended.

Keyword: Pollutants, porous rocks, groundwater, lithological characteristics and management