Helen O. Anie
Floods may be defined in a variety of ways according to type, origin and magnitude. The two types of phenomena so called are firstly, inundations of normally dry lands and secondly, exceptionally high rates of discharge in water course. The origin of inundations may be the breaching or overtopping of coast or drainage defenses by the flowing water or alternatively, discharges by drainage beyond their bankful capacity. According to NEST (1991), a flood is a body of water which rises to overflow land which is not normally submerged. This may result in major disasters involving structural and erosional damages, disruption of socio-economic activities, transport and communication, loss of life and property, contamination of water and the environment in general.
Kirkby (2006) sees flood as existing when the discharge of a river or water course cannot be accommodated within the margins of its normal channel, so then water spreads over adjoining grounds on which crops or forest are able to flourish but simply put, a flood is any water in an area that is not normally submerged.
According to Oriola (2000) whenever the stream channel in an average section is overtaxed, causing overflow on an adjacent land definitely outside the usual channel boundaries, the stream is said to have reached flood stage. He recognises six types of flood- flash floods, single event floods, multiple event floods, seasonal floods, coastal floods and estuarine floods. Flash floods are common in the city centres. A single event flood is caused by rainfall with one peak flood period and last longer than flash flood. The multiple event floods occur after long period of rainfall that comes in succession. Seasonal floods are very common in most riverine areas that are river flood plains. This is the case of the Niger Delta region, of which Ozoro is a part.
Imoroa (2003) identified flood as one type of natural hazards, as those elements in the physical environment that are harmful to men and are caused by forces extraneous to them. He linked the causes of flood to three atmospheric factors, namely rainfall excesses, snow and ice, and coastal factors. Brown and Cutchen (2000) have observed that the real cause of a flood is man. They said because of his desire to make money quickly or through his lack of understanding of the way nature works, he tries to change the normal course that water follows across the land. Man builds dams, his home and factory in areas that are known to be in danger of flooding.
In examining the effects of flooding, Akinmade (2005) opined that natural flooding is not a
problem until people choose to build their homes and other structures on flood plains. He further explained that these structures are subjected to damage and loss when inundated by floodwaters. He further stated that people have chosen to build on so many floodplains that is why flooding is the most universal natural hazards in the world.
Whitlow (1996) described floods as the commonest of the natural hazards and in recent decades have accounted for no less than 64 percent of all death tolls resulting from natural hazards. He also explained that this is the price that mankind has to pay when attempting to compete with rivers for the use of their floodplains or when building on vulnerable coastlines.
Botkin and Keller (1998) in their study of floods in United States supported the above argument when they observed that about 100 persons lose lives in floods every year and accompanying damages exceed $3billion. They noted that the 1993 flood of the Mississippi River took about 50 lives and caused over $10 billion in damages. This loss of life, although terrible is relatively low compared to areas of the world that lack sophisticated monitoring and warning systems, like the underdeveloped countries.
Despite the negative effects of flood on man and the environment enumerated above, flooding
indeed has been noted to have some benefits to man and also to the environment. For example in India and Bangladesh, the patterns of agricultural production are dependent upon water brought by major rivers and renewal of fertility through siltation. The existence of Egypt today is also dependent on the same reason.
Obatola (2005), describing the effects of floods on the people of the Niger Delta, said floods have a tremendous influence on the pattern of human life and economic activities in the Delta region. He observed that at present, crops like yams, cassava and maize are restricted to drier parts of this area and that yams and cassava are the main food crops grown by the natives; farming activities began around mid – December when the floods are receding. All these point to the positive effects of flood on man and the environment as well as the effects of flood on socio-economic activities. Therefore, since the effect of flood is variously perceived, the perception may not objectively depend on the severity of flood damage in its totality.
A total of eighty (80) questionnaires were proposed to be administered in the five selected survey areas. The breakdown is shown below:
The number of questionnaires earmarked for the above selected survey areas is based on the size and population of the settlement as well as the severity of the flooding in that area.
Data analysis and discussion of results
Table 1: Rate of response
Source: Fieldwork, 2008.
All of the 80 sampled population representing 100% of them returned their questionnaire answered.
Table 2: Impact on transportation and housing
Source: Fieldwork, 2007.
In Oramudu, 13 out of 15 respondents agreed that indeed the flood has affected the road transport system only two (2) respondents said No and this is only 13.3% of the total number of respondents. In Etevie, 21 out of the 25 respondents which amount to 84% of the total population sampled said yes, that the flood has affected the road transport system. Four (4) out of the 25 respondents interviewed said No, that flooding have no effect on the road transport system. In Erovie, a total number of 10 questionnaires were given out, it was discovered that all the 10 respondents unanimously agreed that the flood has suffered the transportation system. On a general note, table 2 above reveals that people’s perception of the impact of flooding on transportation is high.
Table 3: Perceived Impacts of Flooding on Housing
Source: Fieldwork, 2008.
Urude, 20% of the sampled population, which accounted for five (5) out of the 20 respondents, said that flood water overflows houses. 30% said it weakens foundation. This accounts for 6 out of 20 people interviewed. Two (2) respondents which represent 10% said it brings deposits, while the remaining 35% said all of the above. In
Etevie community, 40% of the sampled population said that the flood attacks people’s houses, this 40% accounts for 10 out of the total number of 25 respondents. Six (6) respondents which represent 24% of the total population sampled said that flood water weakens foundations. 32% which accounts for 8 respondents said all of the above while one respondent which represents 4% had no idea.
None said it brings deposit. Generally, out of the eight respondents 22 which represent 27.5% of the sampled population said that flood water over flood houses. 21, which represent 21%, said it weakens foundation. 7, which represent 8.75%, said it brings deposits. 20 respondents said all the above listed factors and these 20 respondents account for 25% of the sampled population. 10 respondents which represent 13% of the total population sampled had no idea.
Table 4: Negative impact of flood and crops and farmlands
Source: Fieldwork, 2008.
In table 4 above, out of the eighty (80) respondents, 13 respondents which represent 16.25% of the total population sampled did not respond as to what harmful effect the floods have on their crops and farmlands. 14 respondents which represent 17.5% of the total population sampled said it kills their crops. 36.25% of the sampled population said that the flood makes the tubers of their root crops to get rotten, this 36.25% accounts for 29 respondents. Five (5) respondents said it wash away soil nutrients. These five (5) respondents represent 6.25% of the total population sampled. The remaining 23.75%, which accounts for 19 respondents said flood inflicts all the above harm on their crops and farmlands.
Table 5: Economic impacts of residents
From table 5 above, it could be observed that 25% of the sampled population said market prices of food items increase during flood period while 16% of sampled respondents said food items become scarce and expensive in the dry season. The remaining 41% said that combination of A and C above i.e. market prices of food items increase during flood and food items become scarce and expensive in the dry season.
From the analysis, it could be decided that the floods have a tremendous effect on the economy and socio-economic activities of Ozoro residents. Food becomes very expensive and scarce during the dry season.
Conclusion and recommendation
Bolten, O.B. and Keller E.A. (1998): Environmental science: earth as a living planet. New York; John Wiley & Sons Inc.
Imoroa, N.O. (2003): Delta state in Udo R.K. and Mamman A.B. (eds) Nigeria: giant of the tropics. Volume 2, State Surveys. Yaba, Lagos; Gabumo Publishing Co Ltd.
Kirkby M.J. (2006): Infiltration, through flow and overland flow, InChorley R.J.(eds) Water, earth and man: a synthesis of hydrology, geomorpholgy and socio-economic geography. London; Methuen and Co Ltd.
Obatola, G.A. (2005): “The Niger delta and its environmental hazards”. Benin City; Ethiope Publishing House.
Oriola, E.O. (2000): Flooding and flood management, Ilorin, Nigeria; Haytee Press and Publishing Co. Ltd.
Whittow, J. (1996): “Environmental hazards” in Douglas, (eds) Companion encyclopedia of geography: the environment and human kind, London; Routledge.