Evaluation of the impact of flood on groundwater quality in hand-dug wells in Monrovia, Liberia

Abstract

Globally, acceleration in population growth and changes in land-use patterns have increased human vulnerability to floods. In Monrovia, the capital city of Liberia, flooding remains unabated due to the heavy downpour of rain, poor drainages and the construction of buildings in waterways. In 2018, a major flood event occurred causing several residents of Monrovia to lose their personal belongings and even rendering some homeless. Besides damages to private properties and infrastructure, there are fears that the flood may have affected water resources in the area. This study, therefore, sought to assess the impact of flooding on water quality within a total of twelve (12) hand-dug wells in four communities in the Cape Mesurado peninsula of Liberia. Using the United States Environmental Protection Agency (USEPA) Standard Methods, a suite of physico-chemical (turbidity, pH, lead, nitrate, nitrite, phosphate, cadmium, copper and zinc) and microbial (E. coli and Fecal coliform) parameters were evaluated during both dry and wet seasons. To adequately assess the impacts of flooding on groundwater quality, water samples were collected from three flood-prone communities (Clara Town, Vai Town, West point) and one control community (Chocolate city) with results compared against WHO standards. A two-tailed Student T test was employed to point out significant differences between the results of dry and wet seasons. An increasing trend was observed in pollution levels from dry to wet season and all of the water samples analyzed fell short of the appropriate World Health Organization (WHO) standards for safe drinking water; suggesting that water samples from these sources are unfit for human consumption. Significant differences were observed between dry and wet seasons concerning turbidity, nitrate, nitrite, copper, lead, cadmium, E. coli and Facal coliform with no significant variation in pH, Phosphate and Zinc. Based on the findings of the research, it can be concluded that flood adversely affected water quality in the study communities with an even more pronounced consequence in the flood-prone communities of Clara Town, Vai Town, and West Point. It is recommended that the public be warned against consuming water from all of the test sources and proactive measures are adopted in the flood-prone communities to avoid contamination from municipal solid wastes and other refuse before flooding. The authors recommend that more studies of this nature be periodically expanded to other flood-prone communities across Monrovia to regularly monitor water quality and flood impacts on the socio-economic livelihood of the population.