THE EFFECT OF FLOOD ON ROADS DURABILITY IN NIGERIA

CHAPTER TWO

LITERATURE REVIEW

Conceptual Framework

This study was guided by the conceptual framework that is underpinned by the vulnerability framework of Marshall et al (2010). The framework indicates the various conditions that will influence the level of vulnerability of a community.

There is a fast growing literature on vulnerability which uses terminologies such as risk, hazard, exposure, sensitivity, adaptation, adaptive capacity, resilience and coping strategies (IPCC, 2001; Tapsell et al, 2002; Adger et al., 2002; Burton et al., 2002; Brooks, 2003; Westerhoff and Smit, 2009).

According to the UN/ISDR (2004), vulnerability can be defined as the conditions determined by social, economic and environmental factors or processes which increase the susceptibility of a community to the impact of hazards. Vulnerability, thus, is the degree to which a system is or can be susceptible to or unable to cope with adverse impacts of hazards (IPCC, 2001). Vulnerability defines the extent to which systems open up to harm or are unable to shield itself from hazards. Generally speaking, being vulnerable is that, the more a system is exposed to a hazard, the more it is susceptible to forces and impacts of the hazards (Messner and Meyer, 2005).

In this study, vulnerability connotes the inability or the lack of capacity of a system to adapt or respond to foreseeable or present impacts of flooding incidents and hazards. The study adapts the vulnerability framework which will support the analysis on the impact of flooding and the adaptation strategies being employed to reduce the degree of vulnerability.

An individual or household is vulnerable to climate change and flooding if the risk will result in a loss of wellbeing where the individual or household is unable to cope(Heltberg and Bonch-Osmolovskiy, 2011). Vulnerability as noted, is the product of the exposure of people or systems to the impact of climate change which is influenced by the constraints they face in being able to reduce the exposure and their sensitivity and resilience. Flood vulnerability is viewed by many to be a function of exposure, sensitivity and adaptive capacity to deal with flooding incidents (Ford et al, 2005; Fay et al, 2010). That is to say, vulnerability is dependent on level of exposure to hazard, degree of sensitivity to hazard and resilience or adaptive capacity of a system.

When systems are unable to stand strong through their actions to reduce the impacts of flooding, it tends to increase their level of vulnerability. Vulnerability is experienced when the interactions and actions of the members of the system, such as the central or local government, community members, etc are not directed to coping or reducing the potential impacts of the flooding incidents.

Exposure according to IPCC is the degree of climate stress upon a particular system analysis which may be presented as either long-term changes in climate conditions or by changes in climate variability including the magnitude and frequency in extreme events (IPCC, 2001). Exposure is known to be determined by the magnitude, timing and speed of climate event and the variation to which a system is exposed (Fay et al, 2010). In essence, exposure is dependent on the characteristics of the system and the attributes of the climate (Smith et al, 2003). In the community system, the level of exposure can be a condition that makes households and communities susceptible to the adverse impacts of floods hence, increasing their vulnerability. In communities, some people are more exposed to the risks of floods than others due to their location, type of buildings, occupancy and available resources.

The impact of flooding on a system basically depends on how sensitive the system is to the changes that have occurred. That is to say, sensitivity depends on how stressful the system has become due to the incident that has occurred.

According to Fay et al (2010), sensitivity is the degree to which a system is affected in its current form by a climate trend, climate variability or climate shock. From the conceptual framework, it can be realized that the potential impact of flooding that can make systems vulnerable is the combination of the degree of exposure, and the sensitivity of the system to flooding and it’s the strength of the system to withstand.

In other words, the actual damage caused by a flood incident on a community

depends on the degree of exposure and sensitivity of the organized system. In addition, it connotes that, access to information, household income, formal and informal supports, public interventions and provision of infrastructure greatly influence the degree of socio-economic vulnerability.

As the community is exposed and sensitive to the hazards, it is imperative that some adaptation responses occur to minimize the adverse impacts. Thus, systems must be able to demonstrate the ability and facility to respond accordingly.

Adaptive capacity in this regard, refers to the potential or capability of a system to adjust to climate variability and extremes, so as to moderate potential damages, to take advantage of opportunities, or to cope with consequences (IPCC, 2001; Smith and Pilifosova,2001).

Thus, adaptive capacity portrays the ability for a social system for instance, to be responsive to anticipated and actual hazards that impact on the system. It relates to the social, economic, political and cultural conditions a system that consciously or unconsciously prepares for, avoids or moderates and recovers from exposure effects (Smith et al, 2003; Westerhoff and Smit, 2009) to flooding risks.

Developing countries are known to have low adaptive capacity (Adger, 1999; Smith et al, 2003) because they lack wealth, access to technology, stability a institutions, equitable distribution of power as well as well functioning social systems (IPCC 2001). Adaptive capacity of social systems is developed through experiences, learning, resources, technology, external supports and networks among others.

Theoretical Framework of the Study.

The effects of flood on the environment go beyond the health hazards and environmental degradation. The displacement of people following the occurrence of disaster in an environment tends to cause considerable changes in socio-economic lives of the people. Ultimately, such implications adversely affect nation productivity and development especially when the nation primarily depends on land and other environmental resources for survival and their economy is environmentally dependent, Ofomata (1980).

There are some theories which best highlights what flood does to its victims, but only two would be explained in this research work.

i.Psychological theory of flood disaster.

Psychological research has shown that the occurrence of flood can cause serious mental health consequences for victims. These consequences take form of post trauma stress disorders and symptoms which have been less investigated.

ii.Disease model of flood disaster.

Displacement which is the primary concern has a risk for communicable disease transmission after the disaster and it is associated primarily with the size and characteristics of the population displaced, specially the proximity of safe water and functioning latrines, the nutritional status of the displaced population, the level of the immunity to the vaccine-preventable diseases such as measles, and the access to healthcare services.

Causes of Flood Disaster.

Flood is caused either naturally or by man’s activities (man-made).

Natural causes of floods:

i.High rainfall; heavy rainfall raises the water level, when water level is higher than the river bank or the dams, the water over flows from the river this leads to flooding.

ii.Snowmelt

iii.Relief; flooding often occurs in lowlands. This is because rivers flow more slowly in low-lying areas. If the water volume increases suddenly, floods occur.

iv.Coastal flooding; flooding always occurs in coastal areas. High tides or storms cause the water level to rise. When water level is higher than the level of the coastal lowland it leads to flooding.

Human causes of floods:

i.Deforestation; large areas of forest near the rivers have been cleared and these lands are used to make settlement, roads and farmland. Less vegetation protects the soil; the soil is quickly lost to rivers and the sea. This raises the river bed which causes the river to overflow its banks easily.

ii.Poor farming; some farming practices can damage the vegetation cover, so the soil will be washed into the river easily. Practices such as overgrazing and over cultivation.

iii.Poor water management; when the dams are poorly constructed or maintained they can easily collapse and this results in flooding

iv.Population pressure.

v.Poor drainage system maintenance.

Flooding could also occur when the ground is saturated that it cannot absorb any more liquid.

Implication of Flooding and its Socio-economic Implication.

i.Implication of Flooding on Lives and Properties;

Flood incidents come with great cost to the community and other surrounding communities, ranging from loss of property to human lives. Household items like Television sets, radios, beds, mattresses, fans, wardrobes, fridges, sofa chairs, woolen carpets, gas cookers, sewing machines, cell phones and valuable documents were identified as the common things that get damaged as a result of the flooding. Victims of this disaster had acquired the items over the years which have just been destroyed by a day’s floods. One serious impact of flooding is the panic and fear among people associated with deaths of loved ones. Over the years, there have been many occasions that flooding has caused the death of people especially, children and the aged.

ii.Implication of Flood on Economic Activities.

Besides loss of property and lives, business activities of respondents are also affected by flooding. The study showed that residents of the community usually go to work late or do not go to work when the area is flooded. This leads to low business returns (in the case of the self-employed) and formal queries to employees. Women find it difficult to go to the market and also to take their children to hospitals and schools because the roads are covered by floods

iii.Implication of Flood on Sanitation.

With regards to sanitation issues during floods, flood water sometimes carries the rubbish away and leaves them at undesired places making it unsightly. Faecal matter, dirt and rubbish are often suspended in water and carried away into the homes of residents. It also becomes difficult to access sanitation facilities, as most residents rely on public toilets which are not close to residences. Flooding has inhibited the construction of household latrines.

Empirical Study.

Mogbo (1976) carried out a study on environmental disaster and he said that man has degraded his environment as hostile witnesses. The witnesses exercise deleterious effect on man’s health, wellbeing and development. These deleterious effects often come as an unforeseen and sudden event (disaster) that causes great damages, destruction and human suffering after its occurrence.

Adejoku (1992) on his own part said the state of disequilibrium can reasonably induce ocean flood, this was gotten from the study he carried out on the causes of flood in Accra, Ghana. The guardian 20th June 1996 reported that ocean rise is caused by low pressure system far out in the Atlantic ocean. This low pressure system generated land swells are associated with waves, tide and tidal current as well as large shore current in the form of surges.

There have been series of reports on flood disaster in recent time (nation- wide).Each time it occurs, the affected communities look towards government for assistance.

Onuoha 2002, with increasing world attention to the issue of environmental degradation and increasing manifestation of these problems in various parts of Nigeria, the Nigerian government made the first attempt to intervene through policy making on environmental protection

There has been a notable increase on the number of studies investigating the causes and effects flooding. This research seeks to review and assess available evidence on the ex-post micro-economic effects of flooding on the accumulation of human capital, focusing on consumption, nutrition, education and health including mental health.

Three major findings come forward in this work. First, disaster (flooding) appears to bring substantial damages to human capital including death and destruction and it produces deleterious consequences on nutrition, education, health and many income generating processes. Some of these detrimental effects are both large and long lasting.

Secondly, there is a large degree of heterogeneity in the size but not much in the direction of the impacts on different socio-economic groups. Yet regularity across natural hazards is that the poorest carry the heaviest burden of the effect of this disaster across different determinants and outcomes of human capital.

Finally, although the occurrence of natural cause of flooding is out of control for authorities, there still is a significant room for policy action to minimize their impacts on accumulation of human capital.

2.2. CHARACTREISTICS OF FLOODS

Gabler et al (1990) shows that there are several factor used to describe the extent and nature of floods. For instance, Its duration, area of coverage, velocity of flow, and volume of water discharged per unit time.

However, these factor are generally affected by amount of precipitation, seasonality (season of the year), Nature of the soil, Nature of slope as well as the geomorphic characteristics of the area. This notion was supported by Akin (2007). The most important characteristics are;

FLOOD DURATION: flood duration refers to the length of time which an area is under peak water discharge or runoff. Some floods are known to rise and recede within an hour, (A case in point is Umuahia-Urban in South Eastern Nigeria). While other flood areas remain at thigh stage for several days, especially in the rainy season at the coastal areas. A flood hydrograph shows the continuous trace of discharge against time during a flood event.

FLOOD FREQUENCY: flood frequency as a statistical measure of probable occurrence of flood of a given magnitude. Magnitude of every flood is defined by its frequency. Large flood occurrences are relatively infrequent and they have long reoccurrence intervals of perhaps about ten years. On the other hand, small floods occur more frequently at least about four times yearly having a small return period or reoccurrence period.

Flood seasonality: this is measure of any seasonal nature of flood of any magnitude. Floods are most common in rainy or wet seasons especially in the tropical regions of the world. This is so because large rivers are known tom attain their peak flow during the rainy season while conventional rainfalls can also cause streams to flood.

Flood velocity: flood velocity is the speed at which flood water moves. It is usually ascertained by measuring the distance of the flood water flow

2.3 CAUSES OF FLOODING

(A) region averaging about 2000mm annually. This intense rainfall is most prevalent in the rainy or wet season of the year from March to September.

Heavy rainfall makes it difficult for most soils in the tropics to infiltrate rain water at the rate of rainfall intensity. The situation is further worsened by the amount of paved surfaces that characterize our urban environment which also frustrates infiltration of rain water.

(B)SOIL NATURE: the nature of the soil through which rain water flows or percolates, determines to a great extent the rate of infiltration and the volume of water that will be generated as run-off. Most soils have high infiltration capacity others have low infiltration capacity.

Research shows that an average soil in West Africa reaches saturation at soil moisture storage of 200mm. this saturation is achieved mostly in September in Nigeria. This assertion implies that most parts of the Nigeria landscape especially the low relief areas are liable to flooding in September which is the peak of the rainy season.

(C)DEFORESTATION: large scale deforestation in the forest and vegetations of the world has helped to increase the flood occurrence. This is statement is mad in light of the fact that forest and vegetations hold back direct rain water and release it gradually to the soil such that rainfall intensity can match the rate of infiltration. This enables proper infiltration to be achieved, discouraging flooding.

High infiltration is usually maintained in the forest areas, hence removing trees and vegetations without replanting or even exploiting them in manner which out-matches its replacement or replenishment would create more floods in the world.

(D)CLIMATE CHANGE: change in our climates has also exercabated the occurrence of floods in the world. Climate is a vital environmental factor that shapes and reshapes various human activities (Etuonovbe 2011). The united National Framework Convention on Climate Change (UNFCCC) define climate change as change in the climate which is attributed directly or in directly to human activities that alter the composition of the global atmosphere and which increases climate variability observed over a comparable time period(Sani-sidi 2012).

The National Emergency Management Agency (NEMA), attributed climate change to the worst flood disaster witnessed in the country in 2012. Climate change acts indirectly to aggravate urban flooding by altering pattern of flooding in flood prone areas, thereby frustrating efforts of flood prediction (Adjugo 2009).

(E)POOR WASTE DISPOSAL: poor waste disposal especially in our urban centers cause blockage of drainage channels. These channels which are supposed to allow free flow of water are blocked with debris and most times refuse and sewages. These substances increase the bed load of the drainage channels and rivers causing them to rise. The result is rivers overflowing its bounds into adjourning flood plains. Bridges and dams are also constructed across rivers and this obstructs river flow and cause occasional flash floods.

(F)POOR LAND USE POLICY PLANNING AND MANAGEMENT:Poor land use policy planning and management constitute a major problem to urban flooding in the world especially in the developing countries of the world. Land use policies and adequate planning which should ensure proper sitting of buildings, structures, road construction, drainage construction and land use ordering, is seriously lacking in the developing nations (Adelye and Rustum 2011). It is unavailability of these control tools that have permitted the uncontrolled development as witnessed in the developing nations of the world. It is unfortunate to note the inability of most developing countries like Nigeria to properly plan and order use of land which has at least promoted the occurrence of flooding or failed to control it. (Adegboye, 2011).

2.4 FLOOD PREDICTION

The prediction and forecast of floods depends greatly on the consistency of available meteorological database. The development of the hydrological operational multipurpose sub-programme (HOMs) has been one of the greatest achievements in this regard. However improvements should be made in the method of forecasting and promoting public awareness because of the enormous benefits. The network of instruments, satellite, and other meteorological flood prediction devices can be employed, coupled with the appropriate model to forecast in real time the onset and other features of the phenomena in question (Blanford 2006).

Development of some of these hydrological forecast systems in a number of countries has resulted in substantial saving of lives and some reduction in damages. Installation of similar systems would also reduce vulnerability of some areas and promote early evacuation of vulnerable areas.

However, problems have been identified in relation to evacuation of people due to the resistance of population that has been subjected to flood. (Plister 2002), observed that this was a significant factor in the lack of response to an evacuation order in New South Wales, Australia and noted that the effect of crying wolf as a factor that might make future evacuation more difficult if not impossible.

Olowu (2010) emphasized that in the many developing countries, especially in Africa, the weakness of state infrastructure, absence of appropriate legal and policy framework and sometimes inadequate resources particularly render them more vulnerable to the consequences of flooding and other natural disasters.

2.5 FLOOD OCCURRENCES

It is difficult to determine the extent of flood damages and to compare in satisfactory manner one flood with another due to the relative tendency to overestimate flood damages particularly at the time of the flood (Smith 2006).

In 1913, the damages from flood along the Mississippi and Ohio River were computed to be the excess of $ 162,000,000. The same magnitude of flood also occurred in Mississippi and Ohio in 2003. In 1955, Northern and Central California was subject to severe flood which resulted from continued heavy rains in the Mountainous areas.

In March to May of 1965, the upper Mississippi and the Missouri river basin and the Red River of the North were flooded as a result of the melting of a heavy snow cover, whereas in this country, Nigeria, snow has never been experienced due to our tropical location and perpendicular position to the sun. In 2007, Pakistan, in the middle East experienced an unusual flood which destroyed over 70 acres of land with properties worth over $2 million.

In Nigeria, the effect of flooding is mainly due to excess rainfall, urbanization and poor waste disposal. Flooding in Nigeria occur in three main forms; River flooding, Urban flooding and Coastal flooding (Gwary 2008, adeoti 2010). Flooding of Ogunpa stream in Ibadan killed several people and completely grounded socio-economic activities. It also submerged 500 houses in different parts of the city. The flood occurred as a result of heavy rainfall and about 32 people died and 1000 injured from the incident (Nigerian tribune, 8th September 1980)

In illorin, kwara State, flood disasters has been recorded in 1973, 1976 and 1979. Recently, in August 2008, the residents of makurdi were thrown out their houses and farm lands, left impoverished after two days of heavy down pour of rainfall which was described as disastrous (Taiwo, 2008).

Akani and Bilesanmi (2011) reports how a Lagos flood forced lagosians to relocate as a result of heavy rainfall of 7th and 8th July 2011,not knowing that there was going to be a more devastating torrential rain that will result in more disastrous flood in Lagos metropolis in the following week. Flooding in Nigeria have at various time affected Nigeria cities, especially in the densely populated cities like Kano, Lagos, Portharcourt, Aba, Ibadan, etc, destroying life and properties (Mordi 2011, Amaize 2011).

In early October of 2012, the River Benue, one of the two major rivers in Nigeria, which rises from North West Cameroun, was flooded due to excess

2.6 FLOOD CONTROL AND MANAGEMENT

It is important to note that a significant and crucial factor in saving lives is in trying to control these flood occurrences or at least minimize vulnerability of some areas. It is clearly known that control and management may not provide the ultimate panacea for flood hazards in the world, but it will however provide a perspective to ameliorate its impacts on human activities, lives and property. Since man cannot fully control the climate that produce the rains flooding our landscape, then there is need for urgent and systematic preparations which would help mitigate the impact of flood (Afiesimama 2008)

Olowu (2010) emphasized that in many developing countries especially in Africa, the weakness of state infrastructure and absence of appropriate legal and policy framework. However, sometimes the inadequate nature of resources particularly renders them more vulnerable to the great consequences of flooding and other large scale disasters.

Understanding the spatial dimension of flood hazards and initiating disaster preparedness measure would promote control and management of flood. In recent times researchers have pointed out the fact that one of the ways to study and understand flood behaviours is by generating the flood extent of flood risk map because such maps can be used for spatial planning and management of land (ogbonna 2011).

In addition, there are also research concerning GIS- based integrated assessment of population vulnerability and agricultural vulnerability to flood (Pradham 2010). Comprehension Geographic information is very critical for making important decision because of the spatial coverage of most disasters and the fact that disaster management work usually involves a large number of agencies working in areas. It allows sharing of information in real time, thus saving resources and time.

G.I.S provides a mechanism to centralize and visually display critical information during an emergency by showing an interactive flood Risk map. Flood Risk mapping determines the area at risk and should be the basis for all flood damage reduction program and subsequent action. The purpose of the risk map is to;

•Increase public awareness of the areas at risk of flooding

•Provide information of areas at risk by defining flood risk zone to give input to spatial planning.

•Perform spatial planning and land management which provide various tool to prevent natural hazards.

Spatial planning according to Samarajiwa Et Al (2007) is to support hazard early warning system, Risk assessment and mapping. Burton Et Al (1968) categorized the alternative measures of reducing flood losses into two types;

•Corrective measures and

•Preventive measures

The corrective measures are divided into two; flood Control and other methods. The preventive measures include two component parts; flood regulation and other preventive methods.

Flood control measures involve the construction of reservoirs, levees and walls, channeling of streams and construction of drainage systems. This means that flood control measures and structural and technological adjustments to flood hazards (zevenbergen 2008) preventive measures includes flood regulation, evacuation of flood prone areas, land use planning, by fore carters etc. also the provision of flood insurance will help in so many ways to compensate affected occupants.