Impacts of human activities on the quality of river water: a case study of river Densu in Nsawam Adoagyiri of the Akwapim South District, Eastern Region of Ghana

Abstract

Activities in and around River Densu Basin poses a threat to the quality of the river. This study, therefore, assesses the impact of human activities on the water quality of River Densu from 2010 to 2015 using the Water Quality Index (WQI) and Nemerow’s Pollution Index. Twenty-five (25) physicochemical parameters were used in measuring the water quality to establish the extent of deterioration resulting from human activities. The data for the assessment was secondary data (2010-2015) obtained from the Ghana Water Company Regional laboratory in Weija Accra Ghana. The results of the study indicate that twelve out of the 25 parameters were above the guidelines set by WHO. Among the physicochemical parameters analyzed, turbidity, ammonia (NH3), iron (Fe), phosphorus (P), and aluminium (Al) exceeded the permissible limit in all the study years. The concentration of copper (Cu) exceeded the WHO standard for all the years except in 2011. Manganese concentration was above the WHO standard for all the years except 2010 and 2013. Nitrite exceeded the WHO standard in only 2015. Among the parameters which exceeded the WHO standard for all the years, turbidity recorded the highest increase and in the percentage range of 380% -6891.1%. According to the NPI results, five parameters namely turbidity, NH3, Fe, P, and Al were the principal pollutants from 2010 to 2015 whereas As, Mg, Zn, and Pb were found not to contribute to the pollution effect. The metal Cu did pollute the river in all the years except in 2011 whereas Mn didn’t pollute 2010 and 2013. The water quality index confirms that the water quality is fair between 2010 and 2011; marginal among 2012 to 2014 and poor in 2015. The water quality results indicate that the water quality is frequently threatened or impaired between 2010 to 2014 however, the quality of the river is almost always threatened or impaired in 2015. Generally, catchment activities such as illegal mining, farming along the banks of the river, and discharge of untreated waste are the main processes polluting the Densu river which is a serious threat to the health of inhabitants in villages which still use the water for cooking activities. The investigation recommends continuous monitoring of the above-mentioned activities which goes on in the catchment to arrest the deteriorating water quality