Flood generating mechanisms at Ilorin, Nigeria

Olaniran, O. J.

doi:10.1007/bf00209065

Cited by 20 publications

(22 citation statements)

References 4 publications

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“…For instance, increasing incidence of exceptional daily amounts in the context of climatic change may mean, other things being equal, a rise in the incidence of flooding and erosion while in case of the converse there may be widespread droughts. Some incidents of urban flooding have been attributed to increased frequency of large daily rainfalls >25.4 mm in Nigeria such as the Ibadan flood of 1969 (Akintola, 1978) and the Ilorin floods of , 1976of and 1979of (Olaniran, 1983. Oyegun (1982) has also shown that daily rainfall totals >12.7 mm are erosive in character and generate sediment yield from sub-urban surfaces in Nigeria.…”

Section: Introductionmentioning

confidence: 99%

Evidence of climatic change in Nigeria based on annual series of rainfall of different daily amounts, 1919?1985

Olaniran

1991

Climatic Change

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Annual series of light rainfall, moderate rainfall and heavy rainfall are computed for 4 zones arranged from south to north in Nigeria: Coastal, GuineaSavanna, Midland and Sahelian zones. Daily rainfall data for the period 1919-85 are utilized. Each series is examined for evidence of change in structure in terms of pattern of decrease and increase in dry and wet years, the overall trend, and the occurrence of runs of dry and wet years. The northern Nigeria (Midland and Sahel) heavy rainfall series and the Sahel moderate rainfall series are found to depict evidence of climatic change as defined by Landsberg (1975) that climatic conditions must change to a new equilibrium position with the values of climatic elements changed significantly. On the other hand Landsberg's definition of climatic fluctuations as involving temporary deflection which can revert to earlier conditions is found to fit the 4 regional light rainfall series and the Midland area moderate rainfall series. The southern Nigeria moderate and heavy rainfall series are found to depict only evidence of high frequency oscillations about a stable long-term mean. The recent drought in Nigeria north of about 9 ~ N is shown to be associated with a large decline in moderate and heavy rainfalls over this part of the country.

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Section: Introductionmentioning

confidence: 99%

Evidence of climatic change in Nigeria based on annual series of rainfall of different daily amounts, 1919?1985

Olaniran

1991

Climatic Change

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“…Such studies includes Gobo (1988), McEwen (1989), Oriola (1994) Babatolu (1996); FEPA (1998), Fowler and Kilsby (2003) Odekunle (2001), and Ologunorisa (2001Ologunorisa ( , 2004. Other studies have identified the characteristics of extreme rainfall that are associated with flood frequency to include duration, intensity, frequency, seasonality, variability, trend and fluctuation (Olaniran, 1983;Ologunorisa, 2001;Ologunorisa and Diagi, 2005).…”

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The changing rainfall pattern and its implication for flood frequency in Makurdi, Northern Nigeria

Ologunorisa¹,

Tersoo²

2006

Journal of Applied Sciences and Environmental Management

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The study deals with analysis of recent changes in the characteristics of extreme rainfall and their implication for flood frequency in Makurdi. Data on extreme daily rainfall, evapotranspiration and flood occurrences were collected for analysis. The annual rainfall was analysed for trends using spearman rank correlation coefficient, annual rainfall variability analysed using standardized rainfall anomaly index while recurrence intervals were analysed using Gumbell Extreme probability theory. The results of the analysis show among other things that there was a remarkable continuous downward trend in annual rainfall amounts; that the period between 1996 and 2001 witnessed the highest frequencies of extreme rainfall events and flood frequencies; that major floods were associated with high recurrence intervals, and that the seasonality of flooding in Makurdi occurs between May and October. @JASEM Increasing flood risk is now being recognized as the most important sectoral threat from climate change in most parts of the world. This has prompted public debate on the apparent increased frequency of extreme, and in particular, on perceived increases in rainfall intensities (Dyson, 2000). Several studies have adduced extreme rainfall to be the major cause of flood worldwide. Such studies includes Gobo

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“…Urbanization process is fast replacing the Guinea savannah vegetation in the city with artificial (paved) surfaces with consequent effect on runoff generation, hence, frequent occurrence of flooding (Enendu, 1982;Olaniran, 1983;Iroye, 2008), sediments yield (Jimoh, 1997) and erosion (Jimoh, 2000). The city is drained mainly by River Asa; whose tributary channels drain the four drainage basins being investigated in this study (Fig 1).…”

Section: Study Areamentioning

confidence: 99%

“…Problems associated with high runoff discharge have been a common occurrence in most parts of Ilorin for sometimes (Enendu, 1981;Olaniran, 1983;Jimoh, 2000). This extreme hydrometeorological event exemplifies the problem currently operating in most urban centres not only in Nigeria but in most developing countries of the world (Frimpong, 2014;Aderogba et al 2012;Satterthwaite et al, 2007;Action Aid, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…As population density and land values rise in urban centres, floods become a great problem both economically and as a threat to safety. Olaniran (1983) reported three floods event in Ilorin in just one decade, causing untold hardships and damages in the town. Flood problems persist till date in the study area, it has not abated, hence, the need for more attention in studies relating to pattern or runoff discharge in the city.…”

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confidence: 99%

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Correlating pattern of river discharge with degree of urbanization in sub-catchments of River Asa in Ilorin, Nigeria

Iroye¹

2017

Ethiop. J. Env Stud & Manag

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Flood generating mechanisms at Ilorin, Nigeria

Cited by 20 publications

References 4 publications

Evidence of climatic change in Nigeria based on annual series of rainfall of different daily amounts, 1919?1985

Evidence of climatic change in Nigeria based on annual series of rainfall of different daily amounts, 1919?1985

The changing rainfall pattern and its implication for flood frequency in Makurdi, Northern Nigeria

Correlating pattern of river discharge with degree of urbanization in sub-catchments of River Asa in Ilorin, Nigeria

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