Self-Purification and Rainfall Events in a Tropical Rural Catchment, Nigeria
This paper studies self-cleansing processes in an urbanized stream in a Nigerian city. The stream under study took its source from a refuse heap in the Central open-place-city market and empties its water into a University Dam 15 kilometres away.
Twenty-seven water samples were taken from nine sample points, which were selected with distances down- streams and according to land use changes in the period before and after the 1st and the 2nd rainfall events. The results showed that some parameters decrease progressively with rain events while some equally increase progressively. The result of the Pearson moment product correlation showed that in the period before rainfall onsets five water parameters (Ca+, P, total hardness, suspended particles, NO–3) significantly decreased in their concentration downstream; and after the first rainfall only NO–3 significantly decreased downstream from the source to the dam/ site (downstream) while in the period after the 2nd rainfall event all the water parameters decreased in concentration downstream with seven parameters significantly decreasing (i.e. Na+, Ca+, K+, Mg+, P, NO–3 and pH). The overall results indicated that the processes of self-cleansing become more active with increasing rainfall events.
Adejuwon, J. and L.K. Jeje (1977). University of Ife water supply scheme: Potential Environment Hazards. In: Adejuyigbe, F.M. (ed) Environmental and Spatial factor in Rural Development. University of Ife Press, Ife.
Ajibade, L.T. (2004). Assessment of water quality along river Asa, Ilorin, Nigeria. The Environmentalist, 24: 11-18.
Awani, B.C. (1989). Concentration of bulk precipitation to stream solute. Unpublished MSc Thesis. Department of Geography, OAU, Ile-Ife.
Dorfman Jacob, H.D. and Thomas (Jn) (1972). Models for managing regional water quality. Howard University Press. Massachusetts.
Kalinin, G.P. (1974). Global Hydrology. Jerusalem Israel Programme for Scientific Translation, Jerusalem.
Grava, S. (1964). Urban Planning Aspects of Water Pollution Control. New York. Columbia University.
Hynes, H.B.N. (1960). The Biology of Polluted Waters. Liverpool University Press, Liverpool, England.
Hynes, H.B.N. (1970). The Ecology of Running Water. Toronto University Press, Toronto.
Ifabiyi, I.P. (1997). Variation in water quality with rainfall incidences: A case study of Ogbe stream in Ile Ife. Ife Research Publication in Geography. 6(1&2): 139-144.
Lazoro, T.R. (1979). Urban Hydrology: A Multidisciplinary Perspective. Ann. Arbour Science. Collin work, Michigan USA.
Leclernc, L. (1964). Self-purification of fresh water streams as affected by temperature and by the oxygen, nitrogen and other substances. In: Advances in water pollution research. Southgate, B.A. (ed). Proceedings of the International Conference, London, Pergamon Press.
Ogunkoya, O.O. (1986). Quality of base flows as an index of signifier yield in the Basement complex of south western Nigeria. Journal of Environmental Management. 22: 291- 300.
Pereira, H.G. (1973). Land use and Water Resources in Temperate and Tropical Climate. Cambridge University Press, London.