Urbanization impact on the water resources with major Third World cities: A case study for Nairobi and its environs

The expansion of low income urban dwellings (slums and shanty towns) and th e high level of unplanned and poorly planned industrial developments have k ept the rivers and drainage systems within the city of Nairobi and its envi rons under high levels of pollution. Recent investigations of the surface waters around Nairobi indicate that ri vers Ngong, Mathare, Nairobi and Rui Rwaka become heavily contaminated by h eavy metals after flowing through both the industrial area and the low inco me urban centers. It is observed that both Nairobi and Mathare rivers becom e especially polluted after they flow through Majengo and Mathare slums res pectively. The Ngong river on the other hand receives oily and toxic heavy metal discharges as it flows through the industrial area, while Rui Rwaka r eceives alcohol, heavy metals and offensive effluents fi-om the breweries f actory as it flows through the area of concern. Chemical results of water samples collected from the Ngong River at the ind ustrial area show high electrical conductivity and total dissolved solids ( TDS) with high pH and temperature compared with the upper reaches of the ri ver at Ngong Road. Mathare and Nairobi rivers have higher electrical conduc tivity, and dissolved solids (TDS) due to discharges into them as they pass through the Majengo and Mathare slums respectively. Rui Rwaka contains hig h total suspended solids (TSS) after receiving the offensive effluent disch arges from the Breweries Factory. Water from these rivers is used for drink ing and for other domestic purposes in those parts of the city and hence th e exposure to wafer borne diseases.