Int. J. Disaster Risk Sci. 2012, 3 (4): 207–217 doi:10.1007/s13753-012-0021-3 ARTICLE The August 2011 Flood in Ibadan, Nigeria: Anthropogenic Causes and Consequences Babatunde S. Agbola1, Owolabi Ajayi2, Olalekan J. Taiwo3,*, and Bolanle W. Wahab1 1Department of Urban and Regional Planning, University of Ibadan, Ibadan, OYO 200284, Nigeria 2Department of Geology, Obafemi Awolowo University, Ile-Ife, 220005, Nigeria 3Department of Geography, University of Ibadan, Ibadan, OYO 200284, Nigeria Abstract Determining when and where flood strikes can be Table 1 shows that more floods were recorded in the 1980s a daunting task. Apart from heavy and prolonged rainfalls and than in the 1960s and 1970s. Most of the recorded floods river overflows, there are anthropogenic causal factors of occurred in August, a period between the first rainfall peak flooding. These anthropogenic factors are significantly vari- and the rainfall break. The heaviest rain on record that caused able and exacerbate floods, but may be difficult to measure. flood in the city occurred in 1980 when the city recorded This study aims to unravel some of the anthropogenic factors, particularly with respect to their contributions to the flood in 274 mm of rainfall during a single flood episode. The second Ibadan City on 26 August 2011. Data were collected through heaviest recorded rainfall was 258 mm in 1963. The amount structured questionnaire and key informant interviews. The of rain that fell on 26 August 2011 was 187.5 mm, and August 2011 Ibadan flood was perhaps the worst in the his- was the third heaviest recorded. It started at 16:40 in the tory of this ancient city. Twelve anthropogenic factors are afternoon, continuing in intense torrents until 20:00 in the broadly identified as having contributed to the flood and the evening, with intermittent drizzling until 23:00 late at night, flood had five major consequences. Some policy implications accompanied by wind speeds as high as 65 km h−1 (Oyo State that can help prevent future flood occurrence are outlined. Government 2011). The rainfall was most intense in a 70- minute period between 18:10 and 19:20 when 75 percent Keywords floodplain management, Ibadan, Nigeria, urban or 140.63 mm of the rain fell. This translated to an average flooding, waste management rainfall intensity of 127.84 mm h−1 (National Water Resources Institute 2011). An accurate assessment of the havoc created 1 Introduction by floods in Ibadan over the years is difficult to obtain because of the paucity of official data. A number of official Natural disasters are on the increase globally and their estimates have been made. The losses from the flood disaster impacts affect the physical, economic, social, geographical, of August 1980 were estimated at over N300 million psychological, and cultural spheres of human endeavor. Flood (Nigerian naira, or USD 1.92 million), while over 500 lives is one of the most common natural disasters, irrespective of were lost (Akintola 1994). The estimated amount to fix the state of human development and natural conditions. the culverts and bridges damaged by the 2011 flood is Flooding has remained the second deadliest of all weather- N2.1 billio n (Oyo State Government 2011). related hazards in the United States, and has been detrimental Despite the fact that the rainfall of 26 August 2011 was not in many other societies in most parts of the world, because of the highest in the recorded history of the city, the monetary the large numbers of fatalities and the costly damages to prop- value of damages to property that resulted from the event erties and human lives (Ashley and Ashley 2008). Flooding were by far the highest. As Ward (1978) observed, floods are arises from structural failures, heavy rainfalls, and a host of unique events and similar flood-generating conditions may human-induced factors. Floods depend on rainfall amounts result in different flood outcomes. Understanding the per- and rates, topography, land use, soil type, and antecedent ceived causes and consequences of the 26 August 2011 flood moisture conditions (Funk 2006). motivated the present study. Pertinent questions addressed The city of Ibadan, Nigeria has a history of flood disas- include: (1) What were the perceived causes of the flood? ters—the most recent occurred on 26 August 2011. Floods are (2) What factors influenced the perceived causes? (3) What a common occurrence in the city and have been officially were the institutional challenges that contributed to the flood? recorded since 1951. But records on urban floods in Ibadan (4) What were the consequences of the flood? The perception are patchy and characterized by incomplete information. of the causes of urban flood informs local response and adjustment strategies. It will also reveal people’s knowledge of the causes of the flood, and what needs to be done to * Corresponding author. E-mail: Olalekantaiwo@gmail.com ameliorate flood hazards. © The Author(s) 2012. This article is published with open access at Springerlink.com www.ijdrs.org www.springer.com/13753 UNIVERSITY OF IBADAN LIBRARY 208 Int. J. Disaster Risk Sci. Vol. 3, No. 4, 2012 Table 1. Rainfall induced floods in the city of Ibadan, Nigeria, between 1951 and 2011 Date Rainfall (mm) Estimated Damage to Properties (naira) Estimated Loss of Lives 9–10 July 1951 161 Unknown Unknown 16–17 June 1955 173 Unknown Unknown 16–17 August 1960 178 Tens of thousands of naira Unknown 27–28 August 1963 258 Tens of thousands of naira At least 2 persons 14 May 1969 137 Tens of thousands of naira At least 2 persons 1973 (undated)* Unknown More than 100,000 3 20 April 1978 126 Over 2,000,000 At least 2 persons 31 August 1980 274 More than 300,000,000 More than 500 with over 50,000 displaced 1982 (undated)* Unknown Unknown Unknown 1984 (undated)* Unknown Unknown Unknown April 1986 (undated)* Unknown Unknown Unknown June/July 1987 (undated)* Unknown Unknown Unknown April 1997 (undated)* 151 Unknown Unknown 26 August 2011 187.5 Over 30 billion Over 100 Note: USD 1 = N156. Sources: Nigeria Environmental Study Action / Team (NEST 1991, 107), and National Water Resources Institute (2011, 10). *: Akintola and Ikwuyatum 2012, 199. 2 Study Area 3 Methodology Ibadan, one of the oldest cities in Africa, is the capital of Oyo The four localities in Ibadan (Apete, Moniya, Bodija, and State, Nigeria, and has eleven local government areas (LGAs). Odo-Ona) were selected for the study because the impact of By 1856, the population was estimated at 60,000, rising to the August 2011 flood was very severe in these areas (Oyo over 200,000 in 1890, to over 238,000 in 1921, and more than State Government 2011). A structured questionnaire that 386,000 in 1931 (Mabogunje 1962). The 1991 census in addressed the perceived causes and consequences of the flood Nigeria put the population of the city at 1.22 million with was designed and administered in the selected localities using a density of 475 persons km−2. Ibadan’s population was 2.55 million according to the 2006 estimate by the National a systematic random sampling method. The questionnaire Population Commission. The population was projected to was administered to household heads at each of the selected increase at 3.2 percent annually, to 2.89 million people by sites, a total of 600 questionnaires in the four localities, 150 2010 (Oyo State Government 2011). questionnaires in each. The questionnaire administration was The study sites include four localities in the Ibadan metro- undertaken over the course of a week by research assistants, politan area: Apete (Ido Local Government Area), Moniya postgraduate students of the University of Ibadan, each of (Akinyele Local Government Area), Bodija (Ibadan North whom was assigned to a locality. The use of the questionnaire Local Government Area), and Odo-Ona (Oluyole Local Gov- permitted the assessment of the divergent opinions of the ernment Area) (Figure 1). These localities are characterized people on factors that caused the flood as well as its conse- by a mixture of traditional, transitional, and modern housing quences. Information was also gathered from community and and culture, representative of the contemporary changes opinion leaders in the communities. Apart from the primary taking place in most cities in Africa. The population of Apete, data used in the analysis and discussions, secondary data Moniya, Bodija, and Odo-Ona in 1991 was 2464, 14,923, were obtained from the report of the Task Force on Flood 27,447, and 25,044, respectively. There has not been any Prevention and Management inaugurated in September 2011 update on the population of these communities because by the Oyo State government (Oyo State Government 2011). the National Population Commission is yet to release the breakdown of the 2006 census by localities. Topographical sheets covering the study area were obtained The study area is characterized by a typical West African from the Office of the Surveyor General, Oyo State, and monsoon climate with distinct rainy and dry seasons, and is spot heights to delineate the topography were obtained from drained mainly by the Ona and Ogunpa Rivers and their trib- Shuttle Radar Topographical Mapping (SRTM) data. The utaries. The floods in the city over the years were often the questionnaires were analyzed using frequency, cross tabula- result of prolonged rainfall that led to inundation of streams tion, percentage, and chi-square techniques. The study find- and river channels. The floods are sustained by dense ings are presented and discussed in two parts: the perceived networks of rivers and streams in the urban and peri-urban causes of the flood, and the consequences of the flood in neighborhoods. Ibadan City. UNIVERSITY OF IBADAN LIBRARY Agbola et al. The August 2011 Flood in Ibadan, Nigeria 209 3°40'0"E 4°0'0"E   Nigeria Ibadan Akinyele LGA Ido LGA Moniya  Lagelu LGA Legend  Ibadan Nigeria Apete Africa  Bodija 0 925 1850 2775 3700 Eleiyele Dam  km Ibadan Ibadan North R Egbeda LGANorth-West LGA LGA a Asejire Da m Ibadan p Ibadan North-East n South-West LGA gu LGA O Ibadan South-East LGA a Rp Odo-Ona gu n O Legend Ona Ara LGA  Dams  Studied Localities Oluyole LGA Stream/River Local Government Area Studied LGAs 0 9.5 19 28.5 38 km 3°40'0"E 4°0'0"E Figure 1. Map of the Ibadan metropolitan area, Nigeria, showing the studied localities Source: Administrative map provided by the Office of Surveyor General, Oyo State, Nigeria, 2011; drainage network extracted from Google image; and contours derived from Shuttle Radar Topographical Mapping (SRTM) data. 4 Perceived Causes of the Flood affect the free flow of water in drainage channels. Institu- tional factors are those that reveal the weakness of existing The perceived causes of the August 2011 flood are discussed government administrative structures in city planning and under four main themes: (1) hydrological factors; (2) waste development control with respect to physical developments management factors; (3) institutional factors; and (4) aware- (housing, schools, religious centers, and commercial enter- ness factors. Hydrological factors are those related to water prises) encroaching into setback of rivers/streams, deforesta- and they include prolonged heavy rainfall, dam breaking, tion of sanctuary forest, alteration of river channels, and blockage of culverts and drainage channels, and growth of increased impervious surfaces. The awareness factor relates vegetation in channels. Waste management factors are related to the role of the media in the dissemination of flood related to the way the waste management practices of the inhabitants information. UNIVERS 7°0I'0"TN 7°30'0"NY OF IB OA mi RDAN Ona R Ona RL Ona R IB Ona R Ogbere RRAOna R Omi R RY 7°0'0"N 7°30'0"N 210 Int. J. Disaster Risk Sci. Vol. 3, No. 4, 2012 Table 2. Perceived anthropogenic causes of the 26 August 2011 flood in Ibadan, Nigeria Factors Agree Disagree Don’t Know Count Percent Count Percent Count Percent Building close to riverbanks 533 89 46 8 21 4 Changing course of rivers by development 496 83 15 3 89 15 Inadequate housing development monitoring 183 31 344 57 73 12 Ignorance 418 70 66 11 116 19 Lack of early warning information 315 53 153 26 132 22 Riverbed sedimentation 141 24 27 5 432 72 River channels covered by weeds 312 52 218 36 70 12 Dam breaking 58 10 87 15 455 76 Heavy rainfall 567 95 33 6 0 0 Dumping refuse in drainage channels 444 74 80 13 76 13 Deforestation 234 39 56 9 310 52 Increased impervious surfaces 53 9 332 55 215 36 Source: 2011 fieldwork by the authors; questionnaires administered to 600 respondents in Apete, Moniya, Bodija, and Odo-Ona in the Ibadan metropolitan area. 4.1 Hydrological Factors for an hour or less (Gupta and Ahmad 1999). This results in high spatial variability in rainfall, which makes precise fore- Like many previous floods, the August 2011 flood came dur- casting difficult and poses problems for delivering reliable ing the August break period, a time when the city ordinarily flood warnings. should not experience rainfall of such magnitude. Ologu- The Eleiyele Dam located within the upper catchment of norisa and Adejumo (2005) noted that the most important the Ona River in Ibadan North government area was badly causes of floods were heavy, prolonged rainfalls and river affected by the flood. The stilling basin and the downstream overflows. Floods are natural phenomena, but damage and walls were damaged, while the waterworks, station trans- losses are the consequences of human action and inaction former, pump house, and control panels at the dam were all (Douglas et al. 2009). The results of the questionnaire survey completely submerged. The damage resulted from heavy (Table 2) revealed that 95 percent of the respondents attrib- stormwater and exacerbated the flood in the downstream uted the flood to the heavy rainfall, which lasted for several neighborhoods of the dam, as observed by 10 percent of the hours (Oyo State Government 2011), caused havoc in most respondents. However, 15 percent of the respondents dis- parts of the city, inhibited transportation, and damaged agreed that the damaged dam caused the flood, which they electricity infrastructure. This view was widely expressed by attributed to the rain and other environmental and behavioral all respondents from the four localities surveyed and hence attributes of the people (Table 2). The downstream neighbor- there was no significant local variation in the perception of hoods and areas along some of the rivers serving as natural the rain that fell on 26 August 2011 as the major cause of outlets for the Eleyele Dam water were most severely hit flood in the four residential localities (X2 = 24.522, P ≥ 0.05). compared to other areas where floodwater was only from It was widely agreed that the rain was very heavy and this led local rainfall. The sudden rush of water washed away dozens to the flood. Available data from the International Institute of people and properties along its path. The damage to the of Tropical Agriculture (IITA) (National Water Resources stilling basin and wing wall of the spillway channel of the Institute 2011, 10) shows that 187.5 mm of rain fell on the day Eleiyele Dam may be referred to as a secondary cause of of the event alone. This figure represented the highest daily the flood. The dam has an installed capacity of 27,000 m3 d−1 rainfall amount for the month as well as for the year. and it is one of the major sources of drinking water for the Thakur et al. (2011) identified climate change, rainfall city of Ibadan, together with the Asejire Dam located in the intensity, duration, and frequency, topography, degree of land Egbeda LGA (installed capacity of 82,000 m3 d−1) and cover, and nature of soils as some of the physical factors that Osegere Water Scheme (near Asejire Dam in the Egbeda LGA predisposed locations to flood disasters. Climate change may (13,500 m3 d−1). The Eleiyele Dam would have helped to alter storm occurrence and intensity and lead to local changes retain some of the floodwater from upstream areas if the in urban areas (due to alterations of the urban land surface and dam’s water retention capacity was not reduced due to silt- water pathways, compounded by such activities as construc- ation. The dam filled with water to capacity had its spillway tion, paving, soil compaction, and removal of vegetation). channel damaged under the water pressure. The water Blockage of drains and the diversion of natural flows com- released from the pressured burst worsened the flood in the bine to produce increased local runoff and higher flood fre- city. quency, magnitude, and duration in cities. Characteristically, Blockage of bridges, culverts, and drainage channels due rainstorms in the tropics are highly localized, intense, and of to high sediment yield from construction activities and short duration, covering less than 10 km2 and usually lasting several earth roads in the city is another factor that has been UNIVERSITY OF IBADAN LIBRARY Agbola et al. The August 2011 Flood in Ibadan, Nigeria 211 identified as responsible for flooding in Ibadan. Twenty-four to the adjoining lands bordering the rivers. The awareness of percent of the respondents agreed that river sedimentation the role of weeds, particularly those that grew along the river was a cause of the 2011 flooding, 5 percent disagreed, and channels, in precipitating flooding was high, as indicated by 72 percent did not know. Stream channels in urban areas get 52 percent of the respondents (Table 2). The highest percent- filled quickly after heavy rains and the floodwater often age of respondents that perceived vegetation growth on river passes through small culverts. These were initially adequate banks as a problem was in Moniya (36%), followed by to manage the water volume but no longer are, because of respondents from Bodija and Odo-Ona (both 22%), and increased urbanization and expanding areas of impervious Apete (20%). Significant variation in the data (X2 = 5.8371, surfaces that now produce runoff that exceeds the capacity of P ≤ 0.05) indicates that the perception of the contribution of the culverts. Many of the culverts have been in existence for vegetation growth to the severity of the flood varied among more than 20 years and have not been maintained by any of the four sampled localities. The possible reasons may be the the government agencies. Lack of regular maintenance of this level of experience of the respondents and the varying amount hydraulic conveyance infrastructure predisposes the culverts of vegetation growth in the water courses in the different to blockage from debris and urban wastes that effectively localities. Vegetation encroachments have been noticed in reduces their size, increasing the frequency of flooding in many segments of the Ogbere, Ona, and Ogunpa rivers. Apart urban areas (Douglas et al. 2009). The stream channels them- from the rivers and streams, the weeds encroach deeper into selves may contain so much municipal solid wastes and fecal the Eleiyele Dam and reservoir, where about 15 percent of waste in cellophane bags that their channels are smaller than the surface area was covered with weeds, including water they were two decades ago. A majority (74%) of the respon- hyacinth especially in the north-eastern and eastern segments dents agreed that dumping of solid wastes in drainage chan- of the dam site. nels and river beds was one of the causes of the August 2011 flood, while 13 percent disagreed and another 13 percent 4.2 Waste Management Factor indicated that they were not sure that dumping of solid wastes in drainage and stream/river channels could lead to flooding The percentage of the respondents who indicated that dump- (Table 2). The highest percentage of respondents that per- ing of refuse in rivers and drainage channels could have been ceived culvert blockage as a problem was in Apete (46%), responsible for the 2011 flooding was 74 percent (Table 2). followed by respondents from Bodija (36%), Moniya (21%), Dumping of refuse impeded the free flow of water. The and Odo-Ona (14%). Significant variation in the data (X2 = practice of dumping wastes in drainage and river channels 6.341, P ≤ 0.05) indicates that the perception of the contribu- is common in the city areas (Onibokun and Kumuyi 1999; tion of blocked culverts to the severity of the flood varied Olaseha and Sridhar 2004) where there are no provisions for among the four sampled localities. This variation could waste bins by the government and people have been unable to be due to the local perception of flood predisposing factor organize private refuse collectors, either because of lack of in each locality coupled with the collapse and subsequent communal cohesion or because such services are not afford- washing away of some bridges and culverts in these able. Typical waste streams in river channels are largely made localities. up of degradable (leaves, tree cuttings, leftover food) and The absence of river/stream management policies, with non-degradable (rags, plastics, nylons and iron, furniture, particular regard to the maintenance of the river/stream utensils, bottles, and so on) materials. This refuse is often channels and the waste disposal behavior of the city residents, deposited in anticipation of rains believing that they will wash may be largely responsible for the blockage and constriction them from gutters into streams and rivers. It is common to see of drainage channels and stream/river beds. The only river in wastes in drains and gutters (both open and covered), where Ibadan that has been channelized is the Ogunpa River. The they can accumulate and impede the flow of water, which channelization has involved dredging and the construction of then flows onto the adjoining road. The practice of disposing concrete embankments to ensure that the channel can carry waste into water channels is more common in the rainy more floodwater. The project started in 1982 and completed seasons than in the dry seasons. In dry seasons, wastes the lower and middle sections of the river. Construction are allowed to dry before they are burnt in an open space. work stopped in 2005 and left the upper section of the river The seasonal variation in waste management adopted at the untouched. household level has serious implications for the severity of Vegetation growth on the banks of some of the rivers and flooding. Thirteen percent of the respondents indicated that streams was another factor identified as contributing to the dumping of refuse did not affect flooding and 13 percent recent flooding in the city. Some of the river channels were claimed ignorance of the role of waste management practices covered with weeds nourished by the composted household on flooding. No significant variation exists in the perception organic wastes dumped into the water, inhibiting the free flow of indiscriminate disposal of wastes as one of the contributing of floodwaters. This condition becomes aggravated when the factors to floods in the studied residential localities (X2 = river loads include different types of household wastes that 21.646, P ≥ 0.05). The practice of waste disposal in water act as drags on the riverbed. The vegetation reduced the depth channels needs to be discouraged to reduce the incidence and width of rivers and stormwater was forced to backflow on of flooding. These waste materials acted as catalysts for the UNIVERSITY OF IBADAN LIBRARY 212 Int. J. Disaster Risk Sci. Vol. 3, No. 4, 2012 August 2011 flooding: they blocked the drainage channels of strongly believed that the planning officers, including those at most rivers and led to the swelling floodwaters overflowing the Ministry of Physical Planning and Urban Development the banks. City residents’ priority was to remove wastes from (MPPUD), should have informed them before granting plan their immediate household environments by dumping them approvals. The planning officials argued that many develop- into water channels, as if doing this is the ideal and healthy ers willfully violated government planning and building regu- way of managing waste. The residents only end up creating lations, especially the statutory setbacks, and many others more problems because even if the waste dumped is washed either altered approved plans or built without approval. The downstream, when the degradable part is decomposed, it will city planners further claimed that inadequate tools and facilitate the growth of vegetation in water course which will personnel who would ensure real-time monitoring were the combine with the non-degradable part to further constrict the major hindrance to their effective monitoring of physical flow of water and contaminate the rivers/streams. development activities in their areas of jurisdiction. Wahab (2011) observed that the planning authorities and the MPPUD 4.3 Institutional Factors were grossly understaffed to be effective in their development control activities. He stated that while in 2011 the eleven The weakness of existing institutional frameworks for the LPAs had a total of 203 personnel (65 professional town plan- monitoring and management of the urban environment may ners, 97 technical, and 41 administrative staff) the MPPUD also have contributed to the flooding. Manifestations of the had 49 personnel (17 professional, 12 technical, and 20 weak institutional frameworks are reflected in many detri- administrative staff) monitoring development in the Govern- mental activities taking place in the city. Building construc- ment Reservation Areas and Estates throughout the 33 LGAs tion on river floodplains, indiscriminate waste disposal, and of Oyo State. The August 2011 flood exposed the weaknesses illegal parking of vehicles at unauthorized locations are com- of the existing flood prevention system as well as the weak- mon in the city. In some instances, building approvals were nesses of the various local planning agencies entrusted with granted without a clear understanding of the nature of the the responsibilities of managing disaster risks. Ignorance of environment and the impacts of the construction on the over- the physical and environmental conditions of the different all environmental quality of the locality. Such constructions residential neighborhoods, particularly concerning flood risk both obstruct the free flow of water and are at risk of being flooded. There were 26,553 buildings within the approved potential, was identified as one flood risk factor in the city statutory setbacks of rivers/streams in the eleven LGAs of the of Ibadan. The percentage of respondents who indicated that metropolitan area of Ibadan in 2011 (Oyo State Government ignorance was a contributing factor was 70 percent (Table 2). 2011). Yet, most of the property owners claimed they had A factor identified by the respondents for the low level of approved building plans. Judging by the quality of most of the awareness on flooding was the absence of data and informa- properties that violated setback regulation, it is clear that tion from government and other agencies on the flooding affluent residents were the culprits in peri-urban neighbor- potential of some of the rivers as well as the flood vulnerabil- hoods and low-income residents were the culprits in the ity of the different residential and commercial zones in the inner city. Monetary inducements, poverty, greed, inadequate city. A flood vulnerability map of the city was not available to awareness, and undue political influence were some of the guide urban development and assist people in their prepared- reasons for the violations. Table 2 shows that 31 percent of the ness for flood. By 2011, Ibadan still had no development respondents believed that flooding in the city is linked to this (master) plan to guide and direct its growth (Wahab 2011), problem. A greater percentage (57%) however could not link which explains the sprawling nature of the city. Although flooding with poor urban management and 12 percent stated a high illiteracy rate was thought a contributing factor to that they did not know whether it contributed to the flooding. vulnerability to flood, lack of up-to-date information rather The largest number of respondents who indicated institution- than literacy might largely be responsible for the severe flood al weakness as a factor in flooding came from Bodija (34%), problems in Ibadan, because the 2011 flood affected both the followed by Apete (29%), Odo-Ona (19%), and Moniya literate and illiterate population. The available statistics from (18%). There was a significant difference in the identification the Nigeria Demographic and Health Survey (NDHS) show of this factor across the different communities (X2 = 7.191, that 84.5 percent of people in the flooded areas of Ibadan had P ≤ 0.05). The variations could have been influenced by the formal education and 15.5 percent did not (National Popula- socioeconomic characteristics of the residents. Strong poli- tion Commission 2009). Apart from inadequate data and cies are needed that restrict physical developments within the information from the government, other reasons for flood ecologically sensitive areas. Such policies would curtail the vulnerability include low personal assessment of flood dan- number of injuries and fatalities from flood disasters. ger, faith in technological solutions, and the reliance on gov- Allocation of blame between the affected property owners ernment for flood management. It is of paramount importance and the officials of the Local Planning Authorities (LPAs) in to educate people on the risks of living in the floodplains, and the eleven LGAs exacerbated the poor environmental man- on the wide range of non-technological alternatives that could agement. While the property owners claimed ignorance of the offer some measure of protection (McPherson and Saarinen effects of constructing buildings close to river setbacks, they 1977). UNIVERSITY OF IBADAN LIBRARY Agbola et al. The August 2011 Flood in Ibadan, Nigeria 213 Table 3. Approved setbacks for major rivers in the Ibadan development. Other notable areas with large number of build- metropolitan area, Nigeria ings within the approved statutory setbacks include Akinyele No. River Name Setback (m) and Egbeda, emerging industrial areas. Perception of flood hazard is an important component in 1 Odo-Ona Elewe 15 flood response. The perception of flood hazard influences 2 Adamo 15 3 Alalubosa 15 people’s choices of location, developmental activities, and 4 Sango 15 responses. This perception may be influenced by level of 5 Others 15 environmental awareness, education, social class, and 6 Oluyole 15.5 income. Because they do not envisage that flood could reach 7 Kudeti 30.5 their locations, people often construct buildings within flood- 8 Orogun 30.5 9 Onire 30.5 plains and engage in indiscriminate dumping of wastes. Their 10 Gbaremu 30.5 assumption is usually that rivers and streams have limitless 11 Alaro 30.5 capacity to accommodate and transport wastes. Adelekan 12 Ogbere 30.5 (2010) noted that floodplain dwellers did not anticipate flood 13 Gege 30.5 14 Ogunpa 45 events despite the fact that they were located within flood- 15 Odo-Ona 45 plains and were not prepared for floods. Ashley and Ashley 16 Ona-Ara 45.7 (2008) affirmed that human behavior contributed to fatal flood occurrences where prevailing poverty was reinforced Source: Oyo State of Nigeria 2005. by poor economic policies. Besides building constructions within the gazetted set- Rapid urbanization, population growth, internal migration, backs and within the floodplains, another construction-related and poverty have led to increasing development of sensitive factor identified was the hydrological modification of streams ecosystems especially in developing countries (Douglas et al. and rivers within the city of Ibadan through diversion and 2009). Today, there are noticeable building developments within the setback limits of most rivers and streams that land reclamation activities by filling river courses with sand traverse the city of Ibadan. The Oyo State government’s 2005 to gain additional land space to build. The natural courses of gazetted setbacks, which range from 15 m to 30 m and 45 m rivers and streams have been diverted using various manmade for sixteen streams and rivers in the metropolitan area of structures. Areas that were initially floodplains have been Ibadan, are shown in Table 3. Despite the existence of this sand-filled and transformed to accommodate residential, document, there are still various ongoing construction activi- commercial, and religious land use. The raising of some ties within these zones. These gazetted setbacks were issued floodplains has drastically reduced the capacity of the remain- in response to the flood that ravaged the city in 1980. Since ing floodplains to contain stormwater discharge during heavy then, the setbacks have not been reviewed, particularly in line rainfalls and increases the risk of flooding. The diversion of with the changing climatic regimes locally as well as the river courses for construction purposes has not been limited dynamics or changing status of the water bodies and increas- to affluent low-density residential areas, but also has been ing urbanization. Residents in properties located within these common in high- and medium-density residential areas. The setbacks are particularly vulnerable to flooding because of the diversion obstructed the normal flow of water and created closeness of their properties to rivers and streams. The per- unnecessary artificial meandering of these rivers. In some centage of residents that agreed that building within river instances, where the rivers’ courses had not been diverted, and stream setback zones could predispose residents of such their widths had been reduced by sand-filling for construction properties to flood was 89 percent, 8 percent disagreed, and of buildings and commercial outlets, such as petrol stations 4 percent were not sure (Table 2). The largest number of and shops. During the 2011 flooding, some of these stream respondents who indicated that building within a floodplain channels were unable to accommodate the volume of storm- could precipitate flooding was in Bodija, followed by Odo- water due to high and continuous rainfall, and floodwater Ona, Moniya, and Apete. There was no significant variation spilled over onto adjacent land where it overran properties (X2 = 28.849, P ≥ 0.05) in the perception of this factor in the nearby. In all, 83 percent of the respondents agreed that four localities studied. Most of the respondents believed that human alteration of river channels could precipitate flooding this factor is important in exposure to flood risk. Some of the and increase injury and death, 3 percent disagreed, and 15 reasons for the development of floodplains and riverbanks percent were not sure (Table 2). Twenty-nine percent of include ignorance, poverty, inheritance, and scarcity of land respondents from Apete, 26 percent from Bodija, 23 percent for development. Greater encroachments were noticeable from Odo-Ona, and 22 percent from Moniya agreed that within the traditional core areas of the city—Ibadan North, hydrological modification of river channels was a major Ibadan North East, Ibadan North West, Ibadan South-West, contributing factor to the flooding. No significant spatial vari- and Ibadan South East (Oyo State Government 2011). The ation was noticed (X2 = 13.393, P ≥ 0.05). The recognition of floodplains of the Ogunpa and Ona Rivers within Apete, the role of this variable was almost uniform in all the sampled Bodija, Odo-Ona, and Moniya have been encroached by localities. The continuous encroachment on areas that could UNIVERSITY OF IBADAN LIBRARY 214 Int. J. Disaster Risk Sci. Vol. 3, No. 4, 2012 ordinarily have been preserved was a result of perceived eco- increased by 175.9 percent, the modern low-density areas nomic returns from investment on such land. The perceived recorded a 302.3 percent increase, in the modern high-density status of the neighborhood and the scarcity of alternative areas it increased by 169.6 percent, while in the utilities and lands were two critical factors indicated by the respondents as government reservation areas it increased by 386.1 percent in driving the hydrological modifications of land. In urban areas these 30 years, at an annual rate of 5.8, 10.1, 5.6, and 12.8 floods were not often caused by absolute surplus of water percent respectively. Although only 9 percent of the respon- alone, but may also result from irrational land use patterns dents believed that impervious surfaces contributed to the that turn useful precipitation into flood (Zheng and Qi 2011 flood in Ibadan (Table 2), it is one of the most important 2011). factors cited in flood studies (Akintola 1994). There was a Deforestation was also identified as an important contrib- significant spatial variation (X2 = 9.111, P ≤ 0.05) in the uting factor to the incidence of flooding in Ibadan. The perception of the role of impervious surfaces as one of the increasing urbanization of the city has resulted in the conver- contributing factors to the flood. The low level of awareness sion of areas hitherto used for small- and medium-scale of the contribution of impervious surfaces could be due to the agriculture or forestry into building sites. The situation was assumption that rivers and streams have unlimited capacities compounded by the increasing deforestation of the wetlands to contain any amount of water. Despite government regula- and riparian forest areas including the Eleyele watershed, tions on what percentage of a plot should be built up in which served as storage areas for floodwater. Most of these low density (35%), medium density (40%) and high density wetlands and riparian forest areas had been cleared and laid (50%), many people were either not aware or simply ignored out for residential development as in Apete community. the regulations. Impervious surfaces were prevalent in resi- Another concern is the clearing and development of the Igbo dential areas because most people claimed that they did not Agala sanctuary forest in a hilly part of the city. The clearing have time to weed grasses, while some claimed that they and development of the sanctuary forest exposed the area to could not tolerate reptiles and scorpions that were likely to direct rainfall on the soil surface and heavy runoff was the hide in the grasses. They preferred concrete around the build- immediate consequence. Today, most of the sanctuary has ings to shrubs and grasses. Female respondents particularly been built up and this is increasing the stormwater that flows pointed out that concrete made cleaning easier compared to downstream to some of the neighborhoods and localities having to weed grasses although many would prefer a land- in the city that now experience flood regularly. Thirty-nine scape with flowers and grasses. The cost of landscaping also percent of the respondents believed that deforestation was a made people opt for concrete surfaces in their compounds contributing factor in the August 2011 flood, 9 percent dis- because the maintenance of a natural landscape would have agreed, and 52 percent were not sure (Table 2). The highest required annual budgeting for landscaping. percentage of respondents who identified deforestation as exacerbating the flood was in Bodija (39%), while the least 4.4 Awareness Factor was in Moniya (18%). A significant spatial variation (X2 = 9.619, P ≤ 0.05) was reflected in the opinion of respondents The lack of precise and specific early warnings from mass concerning the relationship between deforestation and flood- media was another contributing factor to the high number of ing. This could be attributed to the variation in their level of fatalities recorded from the August 2011 flood. Some respon- education. While Bodija is a high-income elite community dents indicated that there was generalized information on the (government reservation area adjoining the state government radio pointing to the possibility of heavy rainfall in the city. secretariat), Moniya is a low-income residential community. Good as this information was, it was not specific as to when One of the outward manifestations of urbanization in to expect the flood, what people should do when the rain Ibadan is the increased percentage of impervious surfaces started, and what might be readily available adjustment restricting where floodwaters can go. Impervious surfaces options they should take advantage of to save themselves. include hard concrete surfaces such as pavements and roads Only one radio station out of the six in the city aired the warn- that do not allow water to seep into the soil, obstruct natural ing about the anticipated flood on that day. Ninety-two per- channels movement and ensure that water moves to rivers cent of the respondents in the city indicated that they listened more rapidly than it does under natural conditions (Douglas to radio at least once a week. Radio is one of the most effec- et al. 2009). The higher the percentage of impervious surface tive means of disseminating information on flood in local area, the higher the runoff contribution will be to stormwater; communities (National Population Commission 2009). The all the water collected from rooftops and other impervious percentage of people that believed that provision of adequate surfaces within a given area flow directly into the drainage early warning and response information would have reduced channels, thereby increasing the amount of stormwater in the fatalities from the 2011 flood was 53 percent (Table 2). There drainage channels. Information on current impervious surface was no significant variation in the opinion expressed by coverage in Ibadan is unavailable. However, Akintola (1994) respondents in the four localities about the role of early warn- observes that the percentage of impervious surfaces in the ing in reducing the devastating effect of the flood (X2 = 18.333, city increased, particularly between 1965 and 1994. In the P ≥ 0.05). The respondents who indicated that early warning traditional core area of the city, the impervious surface information would not have made any impact argued that UNIVERSITY OF IBADAN LIBRARY Agbola et al. The August 2011 Flood in Ibadan, Nigeria 215 floods did not occur frequently in the city. Compliance with This reduced their daily business profits. Traders noted that early warning instructions might not have been effective, they did not make as many sales in the evening anymore. knowing that compliance to a given instruction could be Most people preferred to shop from early morning to late significantly influenced by previous experience. afternoon. The reduction in sales and earnings for traders and The factors contributing to flood severity identified by business people might have direct impacts on their standard respondents in this study correspond to ones identified by of living. Oguntala and Oguntoyinbo (1982); Olaniran (1983); Akintola The flood affected critical infrastructures such as electric- (1994); Oriola (1994); Adewale, Sangodoyin, and Adamowski ity poles. In many neighborhoods, electricity supply was dis- (2010); and Adelekan (2010). Numerous factors combined rupted for days because the flood toppled many poles. The to precipitate the 2011 flood. Although largely caused by the absence of electricity affected some artisans and business high and prolonged rainfall, it was exacerbated by improper people who depend on electricity for their daily activities. waste management, building construction within flood zones, Some people opted for generators, which increased their costs institutional weakness, lack of awareness of flood vulnerabil- of production and increased air pollution. Because of the ity, hydrological modification of rivers and streams, dam damages to the stilling basin and the downstream walls of the breaking, and expansion of impervious surfaces. The Eleiyele Dam, water supply in many parts of the city was also respondents indicated river channelization, early warning, interrupted. By September 2012, thirteen months after the proper environmental sanitation and management, and dam flood disaster, the dam had not restarted pumping water to the construction as some of the most viable ways of reducing city and many people cannot access water from public taps flooding, and that the use of insurance should be encouraged until the government fixes the dam. Oyekan and Roger (1982) to reduce post-flood stress on people. They felt that the noted that after the 1980 flood, the city of Ibadan was left responsibility of flood management should be shared by the without safe drinking water for more than three weeks due to community and the government, but that they would expect the damage of Eleiyele Dam. The 2011 flood also affected the government to provide the framework for this partnership. many roads. In Apete, Moniya, Bodija, and Odo-Ona many Identifying the factors that caused the flood is not enough; roads were rendered impassable by the floodwater. The there is also the need to determine its consequences. By culverts and bridges gave way under the heavy pressure of the addressing the consequences of the Ibadan flood, the integra- floodwater and many communities and neighborhoods were tion of the anthropogenic causes into flood study will contrib- isolated. Among the communities affected were Awotan and ute to a holistic understanding of factors that should be Apete, which were isolated for days, and cost of transporta- considered in flood modeling and in the design of an effective tion increased fourfold. Children whose schools were outside early warning system. Identifying the consequences will also the community could not go to school for days. A number of help in strengthening the existing institutional framework for these roads would require major structural redesigning, par- disaster response. ticularly the bridges and culverts that suffered from structural damages because of the flood. Infrastructural damages at the University of Ibadan were 5 Consequences of the 2011 Urban Flood considerable. The University lost properties estimated at in Ibadan City N10 billion to the disaster. These included many gigantic buildings, laboratories, and expensive equipments destroyed The various consequences of the 2011 urban flood in Ibadan in the flood. A portion of the university’s perimeter wall was can be broadly categorized into economic, infrastructural, also pulled down, together with 13 electric poles. This devel- hydrological, physical displacement, and psychological opment compounded the already poor electricity supply to the impacts. These impacts are in addition to the fact that the institution. Similarly, many people spent large sums of money flood caused death and injury to over a hundred people. The to repair their broken perimeter walls, household items, psychological impact manifested itself in the form of fear of and vehicles damaged by the floodwater. This affected the rains and flood with implications for the health and income financial status of most victims. of people. After the flooding, any sign of rain made people The flood resulted in the forced physical displacement of anxious. Some indicated that they were worried that another 4 percent of the respondents from their homes for different flood would occur. Popular anxiety was further heightened lengths of time. This displacement was most prominent in when people noticed that the flood happened in August, when Apete and Odo-Ona areas, especially among the flood vic- the city was supposed to be experiencing the August rainfall tims that lived close to the rivers. Although not all the people break. Radio communications reminding people to expect affected relocated from the flood hazard zone, some did more floods in the year made them even more frightened. relocate to new places because of the fear of another flood. In terms of the effects of their fear on economic activities, There were also those that relocated because their residential 19 percent of the respondents indicated that they now returned buildings were badly damaged by the floodwater. Most build- home early from their offices/shops because they observed ings that suffered less from the heavy flooding had structural that the rains fell mostly in the evenings. They did not want to damages that might become a problem over time. Others get caught up in the rain but be home before the rain started. indicated that they had to relocate their shops from perceived UNIVERSITY OF IBADAN LIBRARY 216 Int. J. Disaster Risk Sci. Vol. 3, No. 4, 2012 flood-prone sites to secure sites. Some respondents (79%) form of jingles and drama can be used to create awareness on indicated that they might come back when they thought that floods and emphasize the importance of proper waste dispos- the situation had normalized. Ologunorisa and Adejumo al methods required for a good and safe standard of living. (2005) noted that many times flood victims did not relocate Because of the greater need for public awareness and sensiti- from their affected properties and residences largely because zation on floods and on what needs to be done to reduce of the relatively affordable accommodation cost in the loca- fatalities, all these media opportunities have to be exploited. tions. To relocate to new locations might imply increased cost Ologunorisa and Adejumo (2005) observed that flood control of accommodation, especially given persistent inflation in the needed the cooperative agreement between government and country and the prevailing poverty. The high cost of rent cou- local communities, and an enlightenment program through pled with unemployment, underemployment, and uncertainty environmental education and mass media that can be largely in the economy compelled a large number of people to remain accomplished using radio. in their present locations, in spite of the destructive flood they In order to reduce mortality from flood events, there should had witnessed there. be proper land use planning in the city. The state government, The flood particularly affected certain economic activities. in collaboration with the eleven local governments and the Twelve percent of the respondents claimed that the floodwa- public, should invest in the preparation of a strategic develop- ter entered their shops and spoiled their wares worth millions ment plan to guide the use of land and the character of devel- of naira. A number of companies could not continue produc- opment in the city. At the same time, regulations concerning tion until they had fully ascertained the integrity of their machines and electric wiring system. Two percent of the the use of open space for development in the city must be respondents who were farmers claimed that the floodwater enforced. One of the most efficient means to mitigate damage washed away fish from their fishponds, estimated at millions to lives and properties is discouraging inappropriate land use of naira. Poultry farmers also indicated that the floodwater in or near floodplains, as inappropriate land use is often damaged their poultry farms; many livestock were washed associated with impenetrable surfaces that exacerbate flood- away, particularly on farms close to riverbanks. The Agricul- ing. Most countries attempt controlling nature rather than ture and Allied Matters Trade Group (AAMTG) of the Ibadan working with it, and this may explain the preference for engi- Chamber of Commerce and Industries (ICCI) estimated neering solutions to flooding, which typically require little or that fishponds and poultry of members, worth hundreds of no change in individual or collective human behavior (Nash millions of naira, were washed away by the flood (Momoh 1982). People’s ability to manipulate nature to protect lives 2011). and properties from flooding may be limited. There is a need Finally, the August 2011 Ibadan flood had hydrological for the government and other stakeholders to review existing implications in the form of sediments and waste yields from regulations concerning setbacks to rivers and streams with a the flood. The floodwater left behind sediments and wastes view to accommodate the effects and impacts of climate both in the river channels and in the adjoining land areas to change and increasing floodwater on the new setbacks. the channels. Mainly, the wastes were household items. The The experience of the August 2011 flood not only showed sediments and waste materials inhibited the free flow of water the need to increase the existing setbacks at the rivers and in the channels, reduced channel sizes, and urgently needed to streams, but indicated the need for a better strategy to keep be cleared up. the larger parts of the floodplains in the city fairly clean. There is no drainage master plan in existence in the city and this explains why the drainage and river/stream management 6 Conclusion: Policy Implications has been haphazard over the years. In order to facilitate a coordinated effort aimed at managing stormwater and flood To effectively deal with the challenge of urban flood in the in the city, the existing master plan of the city needs to be city of Ibadan, it is imperative that the Oyo State government updated for massive urban renewal, and a contemporary invest in regular and up-to-date climatic and weather-related drainage master plan needs to be developed as a tool for urban data collection so that it can make adequate and precise fore- managers. The government also needs to conduct a spatial casts about the weather patterns in the city. The provision of analysis to delineate the city into different flood hazard zones. this weather forecast service will require considerable invest- This delineation will help to identify the most prevalent ment and staff capacity building. 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