Flood Problems in Port Harcourt Metropolis, Nigeria

Transcription

1 Int. J. Environ. Eng. Nat. Resour. Volume 1, Number 2, 2014, pp Received: June 12, 2014; Published: August 30, 2014 International Journal of Environmental Engineering and Natural Resources Ephraim Ikechukwu Elenwo 1 and Sunday Ighovie Efe 2 1. Department of Geography and Environmental Management, University of Port Harcourt, Nigeria 2. Department of Geography and Regional Planning, Delta State University, Abraka, Nigeria Corresponding author: Sunday Ighovie Efe (ighovieefe@yahoo.com) Abstract: The study examines flood hazards in Port Harcourt. It adopted a field survey design of measuring the level of inundation in the various zones as well as administration of questionnaires. 320 questionnaires were administrated to solicited information on the perceived causes of flooding and the cost of properties destroyed by flood. The depth and flood area were measured during every rain event and averaged. Rainfall data were collected with the aid of rain gauges positioned at each delineated zone. The multiple regression analysis was used to determine the causes of flood in the area. The results revealed that Port Harcourt is heavily inundated with a mean area that ranges from 2.3 Km 2 at Afam street to Aba and Ikwerre roads with an area of 4.18 Km 2 and 4.1 Km 2 respectively. The people are highly vulnerable to flood hazards with an average of N1.3 billion worth of properties lost to flood during the period of study. The occurrence of flood in the area is significantly dependent on heavy rainfall, nature of terrain, houses on flood plains, block drains, poor heeding to protection law, types of soil, non compliance with regulations, land reclamation and absence of drainages with r value of 0.97, indicating 95% influence on flooding. This has serious urban and environmental planning implication, as such it is recommended that urban planning exercise should be vigorously pursuit, as well as provision of drainage facilities in all the roads and streets of Port Harcourt. Key words: Flood, causes, control, Port Harcourt, Nigeria. 1. Introduction Over the years, flooding has constituted serious hazards to the coastal inhabitants of the world and Nigeria in particular; as such it now formed news headlines in most electronic and print media. For instance, flood has accounted for large proportion of losses, especially in the case of death [1]. Also flood accounted for second only to typhoons and tidal waves as causes of mortality, and that about 173,000 deaths occurred from as a result of flood and the value has increased to over 10% in recent times [2]. Similarly, in Nigeria, Ogunpa flood of 1980 killed 100 people and displaced over 50,000 people [3], and in Kano 56 lives were lost to Kano 1988 flood events, and the Lagos floods of 1984, 2000, 2002, 2003, 2005, 2006 and 2007, destroyed most stalls at Lagos bar beach. These includes commercial shops: electronics stores, textile, and garri stalls etc. and houses in most area of the Victoria Island, Ajegunle, Ojota, Mile 2, Alaba market etc. were submerged under the flood [3-5]. In the recent times as a result of heavy rainfall, there have being floods hazards that causes harvests of woes, and huge economic lost to the inhabitants of Nigeria, for instance 2012 flood episode where Bayelsa state, Calabar, Port Harcourt and Warri in the Niger Delta region came under heavy inundation. And the inundation came washing away streets, collapsing bridges, submerging buildings, killing people, trapping some in their homes and separating thousands of others from theirs love ones and businesses, in fact nothing is spared by the marauding floods [6]. Similarly, according to a public affair analyst [7] the recurring flood disaster along the coastal

2 98 communities in Nigeria has left no fewer than 25 million Nigerians being displaced and devastated in recent times. Those living along the coastal communities of Rivers, Niger, Benue, Sokoto, Katsina, Lagos, Ondo, Bayelsa, Delta, Akwa Ibom, Anambra, and Cross River states are gravely affected by the incessant flood menace while most of the state governors have directed the flood victims to evacuate their communities and provide makeshift relief for them. It is sad that the federal government has abysmally failed to explore proactive measures in tackling perennial flood in some disaster prone northern states and blocked drains and water channels in the South East and some states in the Niger Delta region which has equally rendered many Nigerians homeless and helpless. No matter how government will provide relief materials cannot savage the suffering dwellers of these affected communities. The worst is that property worth billions of naira has been destroyed by the flood. The continuous ravaging flood has put many Nigerians into untold hardship which those in the coastal communities are grossly affected while the relief materials provided by some of the affected state governors are not adequately enough to cater for the people. Since the upsurge of the flood challenge, economic activities have been totally grounded without immediate solutions to it. Even some of the highland communities are gradually taken by the flood while death casualties have increased to 95 percent. The prices of goods and services and transportation are at geometrical progression. Even 78,228 Nigerians have been displaced while torrential rains have wrecked seriously havoc in some states of the federation, most especially in the North and Niger-Delta region. Niger Delta people occupations are farming and fishing and nothing else. Only few people in that region involved in illegal oil businesses. From the above it shows that flood is a major environmental hazard ravaging the Nigerian landscape over the years. In Port Harcourt, flooding has constituted one of the environmental hazards. In metropolis and environs, the flood incidence of 2006, 2007, 2010 and 2012 are very fresh in the memories of most residents. During each of the years many houses came under heavy inundation soon after every rainfall that lasted for long duration. For instance from July-September 2012, most houses, workshops and commercial shops in Rivers state and Port Harcourt (Afam street, Choba, Aba road, Ikwere road amongst others) in particular were submerged under one meter inundation, and socio-economic activities during this period were brought to a halt, many people were render homeless and properties were destroyed. The residents are now very vulnerable to flood that they often get agitated as soon as they sight cumulonimbus cloud (rain forming cloud) in the area. To them rainfall is the major cause of the flood, added to blocked drains and low lying terrain. Based on this, the present Rivers state government has tried to expand most major roads with drainages,, but the problem still persist because there has not been a comprehensive study of the problem by the government. The drainages are not coordinated, thereby empty no where and the storm water move back into residential homes and flood the streets. Though residents have taken some measures to ameliorate the situation, but such actions merely reduce but does not eliminate flood loses in the area. 2. Materials and Methods 2.1 Study Area Port Harcourt lie within latitude and North of the Equator and between longitude and East of Greenwich meridian. At a height of about 12 m above sea level, it is approximately 60 km from the crest up stream of the Bonny River. Port Harcourt is expanding across the Obio/Akpor, and Ikwerre local governments in what is termed by the present government of Rt. Hon Rotimi Amaechi as the Greater Port Harcourt City. Port Harcourt has almost flat topography. The soil type consist s largely of

3 99 poorly drained silty clay mixed with sand. The city region is a rise and fall plain which slopes variously into two rivers and creeks, namely; the Bonny River, Diobu Creek, Amadi Creek and the Okpoka River. These were the four main sub basins identified on the topographical map of the city on the scale of 1:4800. The highest relief of the city being 18.3 m (160ft) and the lowest is 3.1 m (10ft), these features reduces infiltration capacity and precipitated overland flow that result in flooding [1]. Port Harcourt is situated in the sub equatorial region. It has a tropical climate with a mean yearly temperature of 28 C, a relatively humidity of 80%-100% and a mean yearly rainfall of about 2,300 mm. Months with more than 20 days of rainfall of 2.5 mm or more are June, July, August, September and October, but even the drier months of December, January and February also receive occasional heavy rainfall. However the tropical climate is moderated by the stabilizing influence of the Atlantic Ocean and a layer of humid air over the delta region. The prevailing winds are basically south-west in the rainy season and north-east winds during the dry season [8] and as such this climate characteristic often precipitate two types of floods (flash floods and long rain event floods) in the area. Flash floods are often the result of convectional storms; single event floods are associated with several days or even weeks of low intensity rainfall and are the most common cause of major flooding in these areas. Generally, four characteristics of floods are identified; flash floods, a few hours duration, single event floods; of longer duration, multiple event floods and seasonal floods which are often simply an extended form of multiple event flood. Flash flood occurs on streets during precipitation and other types; flood pond ages occur on surfaces depressions on urban areas [9]. At inception, the city of Port Harcourt which had land area of 30,000 acres, and as the government took over various parcels of land in order to lay out the city and discovery of oil in 1950 in Rivers State, the city of Port Harcourt expanded spatially beyond its original boundaries and presently the metropolis is about 470km 2 mainly towards the northern side as the eastern, western and southern sides are bounded by swamps, creeks, and rivers. Once established, people from all over the country flocked into the city and soon, Port Harcourt became a cosmopolitan society and not just being a port, it also became the provincial headquarter of and in 1967 became the capital of Rivers State [10]. Port Harcourt has increased steadily and rapidly since its origin. According to the population census of Nigeria, the population of Port Harcourt was 79, 634. In 1963, it rose to 179, 563, which represents an average annual growth rate of 8.7 percent. From 1963 t0 1972, the population of Port Harcourt was estimated to have risen from 179,563 to 213,343, an annual growth rate of almost three percent [10]. By 1973, Port Harcourt Population stood at 231, 632. The 1991 census figure put the population of Port Harcourt/Obio-Akpor city local government areas at 703,416, with Obio/Akpor accounting for 263,017 and Port Harcourt city local government area at 440,399 [11]. The growth and expansion of the city of Port Harcourt has been through the submerging of neighbouring independent villages into a rapidly growing conurbation. Today, the city has grown in spatial terms from the mere 40 square kilometer area by Hargrove agreement to about 313 square kilometer [12]. This growth has impacted on most waterways and flood drains in the metropolis, thereby precipitating flooding in the surrounding areas. 2.2 Methods of the Study The data utilized for the study were generated from a field survey of the inundated areas in 2012 in Port Harcourt. The metropolis was stratified into 4 zones (A Ikwerre road, Afam street, B Olu-Obasanjo road, Port Horcourt Aba Express road, C Old Aba road, Choba/Elekahia road, D east West road) see Fig. 1 based on inundated level; measurements of area and

4 100 Fig. 1 Map of Port Harcourt showing Settlement. depth of the flooded areas were then taken. The average measurements of the inundated area were calculated and used for the study based on best probable methods of floods measurement [1, 3]. Three hundred and twenty questionnaires were administered based on systematic sampling technique of interviewing the head of each household at every 5 th houses in the inundated area. Also inspection of existing drainage facilities (both around and within the sample point and their inter connections) within the city of Port Harcourt. The following variables were considered; flood intensity, urban index and drain data. Flood Intensity: this was derived from field measurements of flood indices for each sub basin, and the parameter are; (a) the number of streets with depression flood pond ages, (b) the number of streets that experiences flash floods of one hour or more duration rainstorm, (c) the number of streets with gully erosion, (d) the number of streets with accumulation of sediments or sediment yield. Each of this parameter was scored and summed up to obtain the aggregate score for each sub basin. Urban Index: Urbanization parameter consisted of the percentage built up area, percentage vacant plots, and lengths of roads which were obtained from field measurement from the map. The total built up area for each road was obtained by counting the total number of houses along the streets. This was done for the total number of streets sampled in each basin. The percentage built up area was for each sub basin was determined by dividing the total built up area for the streets by the total road length of the sampled streets. This was added and the mean computed to derive the total built up area for each sub basin, while the remaining percentage formed the total vacant plot for the sub basin [14]. Drain Data: The total number of streets with drain within the sampled area was determined in the field and their actual lengths measured on maps to determine their proportion to total lengths of roads. The drains were also examined to find out whether they are dug out, or concrete, or are covered or not. Descriptive statistics was used to summary the data and multiple regression analysis was adopted to ascertain the level of dependency of flooding on rainfall amount, nature of terrain, houses on flood plains, block drains, poor heeding to protection law, types of soil, non compliance with regulations, land reclamation and absence of drainages. The statistical package for social sciences (SPSS) version 17 was used to run the statistical analysis. Rain gauges were kept in the four zones and rainfall data were measured at every 10 am (900 Hours GMT) in Results and Discussion This section discussed the Flood characteristics in Port Harcourt Metropolis. Table 1 showed that the Niger Delta environment is highly inundated with a mean inundated area of 5.98 Km 2, with a depth of 8.09 m, and it takes an average of 15 days to drain off. In order of severity, Yenagoa and Warri and environs had Km 2 and 9.12 Km 2 being the highest flooded areas, and Ondo had the lowest level of inundation (2.97 Km 2 ) (Fig. 2 and Table 1). This flood features corroborated other studies in the Niger Delta region [1, 6]. However Port Harcourt metropolis had Km 2 flooded area, inundated depth of 8.1 m and the flooded water drain off within 18 days (Table 1) which is lower than those

5 101 of Yenagoa and Warri in the Niger Delta region. This indicated that Port Harcourt metropolis is the second lowest inundated area in the region. From Table 2, Aba and Ikwere roads had 4.18 Km 2 and 4.1 Km 2 respectively, being the highest flooded area in Port Harcourt metropolis, and Afam street recorded the lowest inundated area (2.3 Km 2 ), as this area has the lowest flooded street in Port Harcourt. However an average of 76% (2722 houses) in the metropolis comes under inundation soon after very rain event. However area whose houses were greatly affected are Afam (100%), Igwurutu road (92%), East West road (89%), and Choba/ Elekahia area (85%), which corroborated similar study and with little differences from others with qualitative assessment [5-6]. This observation in these areas is as a result of many un tarred streets that were characterized with potholes, undeveloped plots, as well as the heavy down pour of rain during this period. It was also observed that there is high percentage of vacant land as against built up areas. The field observation showed vacant spaces along the areas which are paved, resulting to high generation of run-off causing flash flood in the metropolis. Similarly, lag time for run-off generation is very short in these areas Benin Warri Yenagoa PH Calabar Uyo Aba Ondo Communit ies Fig. 2 Mean flooded area in the Niger Delta Region. Table 1 Mean characteristics flood events. Town Mean inundated Mean Length Width Highest height Mean Mean longest duration area (Km 2 ) (m) (m) (m) frequency lasted per month (days) Benin city Warri Yenagoa Port Harcourt Calabar Uyo Aba Ondo Mean Table 2 Urban index scores and flooded areas in Port Harcourt. Sub-basins Road/street Length (m) of Mean inundated Height of No. of houses on % of houses/streets road/street area (Km 2 ) flood (m) the road/street inundated 1 Ikwerre Road 6, Afam Street Olu-obasanjo 2, Road PH-Aba 5, Express Road 3 Old-Aba Road, 1, Choba/Elekahia 1, Road 4 East-West Road 1, Igwuruta Road 1, Mean 2, A Percentage built up area 7.33 B Percentage built up area vacant plot 92.67

6 102 An average flood velocity was measured for all the sub basins in the metropolis to be 0.5 m/s. This shows that the velocity at peak is considerably high, with total flood hazards scores of 26, and a mean flood hazards scores of 6.5 (Table 3). Also an average of 2 streets is under inundation soon after every rain events with high accumulation of sediments along these streets. Table 4 showed the perceived types of flood experienced in the Metropolis. From the analysis, the preponderance types of flood in the area are flash flood and flood pond age, this is evidence from the 50% respondents who asserted that the prevalent flood types in the city are flash flood and flood pondages. There are no cases of river flood except in the coastal communities of the State. From Table 5, the frequency of flooding within the metropolis revealed that the flood incidence occurs all through the rainy period, as indicated by 38% respondents. Other respondents say it occurs ten times (10) with 23.0%, 7-9 times with 19% respectively. The information in Table 5 clearly shows that there is high impact of flood on the residents of the metropolis, which corroborated those with less magnitude [1, 3]. Table 6 revealed that the flood water lasts 2-7 days in a typical flood prone area, 27.2% of respondents attests to this. Other opinion are 26.0% attesting (12-24 h), 14% (it lasts for 8-14 day) amongst others. From field measurement, it was also observed that the flood water last 2-7 days in area with flash flood to over 5 months in area with flood pond ages when there is serious down pour. In fact these are features of most un tarred street in Port Harcourt metropolis. Table 7 showed the availability of drainage system in the metropolis (84%) and Table 8 showed the conditions of these drains in the area. The drainages are blocked with debris and waste dump (64%). Specifically, Blocked drainages accounted for 50% of respondents and they attributed this to the frequent occurrence of flooding experienced in the Metropolis. This is because the runoff increases as result of meandering nature of drainages, narrow and shallow drains which become incapacitated as soon as any rain event occurs, and thereby leading to flooding and erosion in the metropolis. 3.1 Causes of Flood Table 9 revealed the distribution of rainfall and inundated area and 10 showed the relationship between flooded area and rainfall amount in the metropolis. From Table 9 there is a corresponding linkage between rainfall amount and flooded area. Table 3 Flood intensity scores in the metropolis. Sub-basins Streets with Streets with Streets with Streets with accumulation Average flood flood pond ages flash flood gully erosion of sediments hazards scores Ikwerre road PH/Aba express road Choba/Elekahia East West road Total Table 4 Types of flood. Type of flood in the neighbourhood. Ikwerre road Aba road Choba/Elekahia East/West road Row total Flash flood Flood pond age Both types River flood Not applicable Total

7 103 Table 5 Frequency of flood occurrence in the metropolis. Frequency of Ikwerre road Aba road Choba/Elekahia East/West road Row total flood 1-3 times times times times plus All through the rainy season Total Table 6 Duration of flooding in the metropolis. Period of flooding Ikwerre road Aba road Choba/Elekahia East/West road Row total Less than 12 hours after rain hours days days days days Over one month Total Table 7 Availability of drainages in Port Harcourt metropolis. Availability of drainages Kwerre road Aba road Choba/Elekahia East/West road Row total Yes No Not applicable Total Table 8 Conditions of drainages in Port Harcourt metropolis. Conditions of drains Ikwerre road SB1 Aba road Choba/Elekahia East/West road Row total Drains available and flowing slowing and meandering Drains available but blocked Narrow drains available and incapacitated Not applicable Total Table 9 Precipitation amount and flooded area. Area/roads Rainfall(mm) Inundated area (m 2 ) Ikwerre road 2,390 4,100 Afam 2,265 2,304 PH Aba road 2,295 3,380 Olu Obasanjo road 2,396 4,180 Choba/Elekahia 2,297 3,650 Old Aba road 2,285 3,450 East/West road 2,284 3,560 Igwunta road 2,280 3,400 For instance areas with high rainfall amount also experienced high level of inundated area, these includes Olu Obasanjo road and Ikwerre road with 2,396 mm and 2,390 mm had flooded areas of 4,180 and 4,100 m 2 respectively. This was further confirmed on Table 10, where the correlated coefficient value of 0.985, indicating that rainfall contributed 97% to the frequent flooding of Port Harcourt metropolis over the years. This revealed a calculated t value of 18.34

8 104 which is significant ate P > 0.05 (Table 10), indicating that the level of inundation in the area is significantly depended on the amount of rainfall experienced in the area. While the remaining 13% is accounted for by houses on drains, block drainages, absences of drainages amongst others (Table 11). This differs from those whose works did not capture the influence of rainfall amount in their studies [1, 4, 6]. Table 11 showed that the major causes of flood in the Port Harcourt Metropolis are the heavy rainfall, nature of terrain and buildings on flood plains (96%, 92% and 89% of respondents respectively). This implies that heavy and torrential down pour of rainfall in the area results in runoff where houses that are built on flood plains comes under heavy inundation soon after every rain event in the area. This corroborated the field measurement in Tables 9 and 10, which showed that rainfall amount is a function of flood occurrence in Port Harcourt (r = 0.985). The low lying terrain which accounted for 92% is also a major precipitant of flood in the metropolis. For instance the highest relief of the city is 18.3 m (160ft) and the lowest is 3.1 m (10ft), and most of the areas under study fell within 3.1 m to 10 m above sea level, these features reduces infiltration capacity and precipitated overland flow that result in flooding [1]. In the same vein, the slope of the sub-basins is a contributory factor. The slope of the land starts from a little above 50ft (15.24 m) and slopes gently down the east-ward direction to a point where it reaches the lowest point (10ft or 3.05 m) at the middle. The Aba Port Harcourt express road, one of the two distribution roads, passes on this lowest point where the Diobu Creek naturally takes its course thus interfering with the latter s catchment area. Afam street is made to encroach on the lowest point where the creek (Diobu Creek) takes its incursion. Old Aba road follows the same characteristics like the two roads above. The road runs through the lowest areas where Okpoka River is situated (Fig. 1). The road therefore serves as a receptacle for flood water flowing into the river. Finally the East/ West road which connects Port Harcourt and the entire state to the Western part of Nigeria also exhibits these same characteristics mentioned above. This road passes on the Okpoka River, where it narrows out as creek. In addition to the construction of major roads at the lowest point in the sub-basins, buildings are aligned at a tangent to the slope, facing in the North to the South direction rather than East to West. Thus, buildings also obstruct the normal channels for storm water, therefore forcing the water into streets surfaces and Table 10 Relationship between precipitation amount and flooded area. Unstandardized coefficients Standardized coefficients T Sig. Model B Std. error Beta B Std. Error (Constant) Rainfall a Dependent Variable: Flooded area Table 11 Perceive causes of flood in the metropolis. Causes Ikwerre road Aba road Choba/Elekahia East/West road Total % Block drains Houses on flood plains Heavy rainfall Absence of drainages Poor heeding to predictions Land Reclamation Non compliance with regulations Nature of terrain Type of soil

9 105 Table 12 R values of the causes the causes flood. S/N Causes of flood No. of Coefficient of determination (% Percentage Rank r-values respondents contribution) of these factors 1. Block drains Houses on flood plains Heavy rainfall Absence of drainages Poor heeding to predictions Land reclamation Non compliance with regulations Nature of terrain Type of soil R * 95 * Joint contribution of predictors (R 2 = 0.95) significant at P > Table 13 Model summary of the regression analysis. Model R R square Adjusted R square Std. error of the estimate Sign. F change Durbin-Watson a , homes around the metropolis. Others are blocked drains by waste and houses, poor heeding to weather predictions, type of soil, Non Compliance with regulations, land reclamation and lack of drainages in most streets and roads in the metropolis to evacuate runoff into near by creek (Table 11), as such this facilitates overland flow that resulted into flooding in the area. It was observed in the field that there exist large gutters (drainages) in some major roads, but they are sub-standard, inadequate and are not linked up with others, thereby are easily blocked by debris carried by storm water when it rains. Tables 12 and 13 further confirmed that heavy rainfall, nature of terrain, houses on flood plains, block drains, poor heeding to protection law, types of soil, non compliance with regulations, land reclamation and absence of drainages are the dominant factors that leads to high level inundation of the areas. For instance the coefficient of determination showed that all these factors accounted for 95% (r = 0.972) contribution to flooding, and heavy rainfall, nature of terrain, houses on flood drains and absence of drainages accounted for 85%, 80%, 76% and 34% respectively to the level of inundation in the area. Predictors: (heavy rainfall, nature of terrain, houses on flood plains, block drains, poor heeding to protection law, types of soil, non compliance with regulations, land reclamation and absence of drainages). 3.2 Dependent: Flooded Area The nature of terrain and buildings blocking drains are confirmed by the slope of the land in the metropolis. The land sloped from 50ft (15.24 m) and slopes gently down the east-ward direction to a point where it reaches the lowest point (10ft or 3.05 m) at the middle. The Aba Port Harcourt express road, one of the two distribution roads, passes on the lowest point where the Diobu Creek naturally takes its course thus interfering with the latter s catchments area. The situation is same as one goes towards Afam Street. The street is made to encroach on the lowest point where the creek (Diobu Creek) takes its incursion. The construction of old Aba road follows the same characteristics like the two roads above. The road runs through the lowest areas where Okpoka River is situated (Fig. 1). The road therefore serves as a receptacle for flood water flowing into the river. The East/West road that connects city with the western part of Nigeria also exhibits these same characteristics. This road passes on the Okpoka River, where it narrows out as creek. In addition to the construction of

10 106 major roads at the lowest point in the sub-basins, buildings are aligned at a tangent to the slope, facing in the North to the South direction rather than East to West. As such, buildings obstruct the normal channels of storm water, thereby forcing the overland flow into streets to inundate homes around the metropolis. This confirmed earlier studies on flood issues [1, 4, 13]. Another very important problem contributing to flooding in the metropolis is building on drains/ inadequate site plan. For example it was observed that in most cases there is non existence of site analysis plan on land before building commences. During this survey most respondents claim ignorance of what site analysis is all about, so they carelessly develop without recourse to site analysis when developing their plots. One very good example is the Eagle Power house at (Olu-Obasanjo Road) located on the bank of Diobu creek, Prior to the construction, a lot of sand was pumped into the land but was not allowed to settle before construction commenced, and as such during wet season in the metropolis, a pumping machine was kept on stand by to pump water flowing from the ground. This is the case with most buildings in Port Harcourt built on flood plains. This corroborated other works but with more in depth explanation on the causal factors of flood in the area [4, 5, 13]. Table 14 showed that flooding has impacted negatively on the inhabitants of Port Harcourt. A total 1.3 billion naira is lost to flooding in these areas. This arose from 115 houses, 38 shops, 71 workshops, 3 primary schools, and 12 churches that were inundated during this period. On the average it is estimated that N1,337, 100, 000 are lost to flood hazard after every heavy down pour in Port Harcourt metropolis. This result is in line with those of other studies but with lower losses in Port Harcourt metropolis [1, 5]. The study in Table 15 revealed that 40.6% of respondents built high wall at all house entrances to prevent flooding. Others engage on cleaning of their drainages to allow for easy flow of storm water during rainfall, about 17.2% agreed they take this measure, while about 5% of respondent take no action, but leave with the agony of flooded homes and loss of properties. Table 14 Effects of flood on the inhabitants. S/N Area/roads Properties affected Estimated cost (N) 1 Ikwerre road 15 houses; 12 shops, 11 workshops, 1 primary school million 2 Afam 10 houses, 3 shops, 4 workshops miion 3 PH Aba road 18 houses, 5 workshops, 1 church,2 primary school million 4 Olu Obasanjo road 16 houses, 8 workshops, 1 church million 5 Choba/ Elekahia 15 houses, 7 shops & 18 workshop, 8 churches, 1primary school million 6 Old Aba road 16 houses, 5 shops, 8 workshops, 3 church million 7 East/West road areas 17 houses, 8 shops, 13 workshops, 4 church, 15 shops million 8 Igwunta road 8 houses, 4 workshops, 3 shops million Total 115 houses, 38 shops, 71 workshops, 3 primary schools, and 12 churches 1,337, billion Table 15 Measures taken to combat flooding in Port Harcourt city. Measures to combat flooding SB1 SB2 SB3 SB4 Row total Built high pavements at entrance Bailing out of water Construction of internal drainages Cleaning of outside drainages Seeking alternative accommodation No action Not applicable Total

11 Recommendation The study showed that heavy rainfall, houses on flood drains, nature of terrain and blocked drains are some of the major causes of flood in the metropolis, and therefore this study recommends an urgent need to carry out a comprehensive study of the flood pattern, to be able to develop a drainage network plan for the city of Port Harcourt. This plan should be made to follow the natural water ways to enable gravitational force aid the easy flow of the water to adjoining rivers. The state housing and urban development should mandate it enforcement division to make it mandatory for every building plan to accompany with it a site analysis report. This will do two things; minimize the hindrance development pose on the natural drainage in the city; and ensure that land is optimally utilized for the purposes they were meant to serve. There is also the need for the establishment of flood insurance policy that will absorb the monumental losses arising from flood hazards in the region The government should set up a body of planners, surveyors, engineers, climatologists, etc, to be drawn from the relevant ministries and agencies to which a site analysis report must be sent for approval before buildings commences, and this body should be backed up by legislation as it applies to the relevant sections in the Urban and Regional Planning Decree No.88 of In order to check the execution of developments that does not have approved site analysis report, the relevant department and ministries that carry out plan approval should be directed not to approve plans that do not have site analysis approval from the body that is suggested to be responsible for that purpose. 5. Conclusions The study revealed that Port Harcourt metropolis is Heavily inundated soon after every rain event, and the inundated area span from Afam street (2.3 Km 2 ) to Aba and Ikwere roads with 4.18 Km 2 and 4.1Km 2 respectively. This has impacted negatively on the socioeconomic activities of the residents. An average of N1.3 billion is lost to flood hazard after every heavy down pour in Port Harcourt metropolis. It is therefore recommended that the government of Rivers state should engage an integrated drainage network of the city, which can be implemented in phases. And they should also incorporate climatological data/ information into their urban and environmental planning in the metropolis. References [1] S.I. Efe, Climate change and flood hazards in the Niger Delta Region of Nigeria, Niger Delta Research Digest 5 (2011) [2] United Nation Disasters Relief Coordinate (UNDRC), Guideline for Flood Prevention and Management in Developing Countries, United Nation Department, New York, 1976, pp [3] S.I. Efe, Urban flooding in Abraka Delta State, Nigeria, Journal of Environmental Conservation and Research 1 (2) (2007) [4] E.O. Oriola, Flooding and Flood Management, in: H.I. Jimoh, I.P. Ifabiyi (Eds.), Contemporary Issues in Environmental Studies Ilorin, Haytee Press and Pub. Co. Ltd, 2000, pp [5] S.I. Efe, J.O.A. Mogborukor, Flood hazards in warri a third word City, Nigeria, Journal of Social and Management Sciences 5 (2) (2010) [6] K.A. Aderogba, Qualitative studies of recent floods and sustainable growth and development of cities and towns in Nigeria, International Journal of Academic Research in Economics and Management Sciences 1 (3) (2012) [7] G. Odidi, Flood disaster: Many pains, few solutions Friday, 12 October 2012, Last Updated Thursday, 11 October, [8] Port Harcourt Mater Plan Specialist Konsult, Stockholm, 1975, pp [9] R.C. Ward, Floods: A Geographical Perspective, Macmillan, London, [10] W. Ogionwo, Social survey of Port Harcourt, Heinemann Educational Publishing Ltd. Ibadan, Nigeria, 1979, p [11] Census News, A House Magazine of the National Population Commission 3 (1) (1992) 22. [12] Rivers State Ministry of Lands and Housing, Maps, [13] F.G.I. Omiunu, Flooding and Traffic Management in Benin-City Region, in: P.O. Sada, F.O. Odemerho (Eds.), Environmental Issues and Management in Nigeria Development, Ibadan Evans Brother Nig. Ltd., 1998, pp [14] R.I. Obateru, Land Subdivision Guide Evan Publishing Ltd., Ibadan, Nigeria, 1986.