WATER QUALITY ASSESSMENT OF UNDERGROUND AND SURFACE WATER RESOURCES OF BAHIR DAR AND PERIURBAN AREAS, NORTH-WEST ETHIOPIA

摘要

Water quality assessment in the Ethiopian highlands is crucial owing to increasing competing need of water for domestic, agricultural and industrial uses. Twelve physico-chemical parameters were analyzed in water samples collected over a period of five months from three different sources; groundwater (hand dug wells and protected hand pumps) and surface water (streams and lake) in Bahir Dar and peri-urban areas. Differences in water quality parameters between the sources were compared to identify pollutant sources and level of compliance with certain water quality criteria. Based on cluster analysis, the sampling stations were classified into two major categories; inner city and outer city; with the surface waters recording far more pollution by fecal contamination. Chloride, TDS, conductivity, total hardness and all the species of nitrogen (nitrite, nitrate and ammonium) were higher in the inner city than the remaining water habitats except the outer ground water stations. Conductivity decreased along the presumptive pollution categories significantly, i.e. inner > middle > out skirt (P< 0.05) and showed medium to high correlation with chloride, total hardness, nitrate, nitrite, total dissolved solids in ground water (r = 0.58 - 0.85). Dissolved oxygen, pH and SAK254 were higher in the lake station than other water bodies. The results from this research would help in developing best management practices for the Bahir Dar municipal water scheme and for regional water scheme program in the future and provide information for formulating appropriate framework for an integrated water management strategy.