Impact of development and urbanization on variation of water quality parameters of the Nima creek in Accra

Abstract

The spatial and temporal variations of the physico-chemical water quality parameters, microfauna and micro-flora composition of the Nima Creek in Accra vividly illustrate the environmental problems associated with water bodies in a community where development and urbanization are in progress. Monthly water and benthic bedload sampling were undertaken to determine the water quality and biological constituents of the creek from a point near the source to the confluence with the River Odaw. The study reveals two distinct zones of variable water quality parameters. The upstream section covering a low population density area which is not very much affected by anthropogenic activities, was marked by comparatively high Dissolved Oxygen (DO) level, low Bio-chemical Oxygen Demand (BOD) level, and high incidence of micro-organisms associated with oligosaprobic waters, such as Ulothrix, Phiodina rotifer, Gyrosigma and Navicula species. The upstream section of the creek could be described as comparatively unpolluted sections with good quality water. The middle and downstream sections covering the densely populated and low income areas of the catchment area had comparatively high BOD ranging from 120.0 to 609.0 mg/L, depleted DO ranging from 0.0 to 9.1 mg/L and pollution-tolerant orga-nisms like Vorticella, Synedra, Synura, Paramecium and Oscillatoria species. The values of physico-chemical and biological water quality parameters indicate unusual stress on the water quality in the middle and down-stream sections of the creek, which confirms the negative impact of high population density, slum and poor env-ironmental sanitation on water bodies. (Journal of Applied Science and Technology: 2001 6(1-2): 85-93)