CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF  STUDY
.A flood is an overflow of an expanse of water that submerges land  Floods are among the most devastating natural disasters in the world, claiming more lives and causing more property damage than any other natural phenomena. In Lagos metropolis, though not leading in terms of claiming lives, flood affects and displaces more people than any other disaster it also causes more damage to properties. At least 20 per cent of the population is at risk from one form of flooding or another (Etuonovbe, 2011).
Iwena (2005) described flooding to be the accumulation of an abnormal large volume of water in an area which has refused to percolate or flow away, it usually occurs when there is heavy rainfall in an area and all the water refuses to sink into the soil but flows on the earth`s surface as floods. When such floods occur in the cities it is referred to as Urban Flooding.
Etuonovbe (2011) stated that flooding may occur when water in the river overflows its banks, or sometimes results from a torrential rainfall due to climate change. It happens without warning but with a surprise package that always delivers to unprepared community like the ones in the Lagos metropolis i.e Makoko, Ikorodu, Victoria Island, Ajegunle, Bariga and so on. In Makoko, flood disaster has been perilous to people and communities. Recently and other parts of lagos state have been affected by flooding, chasing the inhabitants away and retarding commercial activities. It has shattered both the built-environment and underdeveloped areas. It has claimed  lives, and thousands of properties got lost or destroyed due to its occurrences. One prominent feature about it is that flooding does not discriminate, but marginalizes whosoever refuses to prepare for its occurrence (UNHabitat, 2008).There are factors of flooding depending on locality
McGranahan et al. (2007) noted that while economic activity and urban Development often increase the environmental pressures that lead to flooding, it is the low Income settlements and poor groups within all settlements that tend to be the most vulnerable. Coastal towns are by far the most developed of Africa’s urban areas and by implication, have a high concentration of residential, industrial, commercial, educational and military facilities which are vulnerable to this environmental hazard (UNHabitat, 2008).
Whereas flooding itself is a situation that results when land that is usually dry is covered with water of a river overflowing or heavy rain, flooding occurs naturally on the flood plains which are prone to disaster.
Generally, Flood is caused by two major factors which involves the human and man-made factors, these factors obviously are responsible for the generation and continuous occurrence of flooding in the environment, and at any point negatively effects the environment at large.
 The impact of flooding may be a worldwide phenomenon, but the effects are more devastating in African cities stated (Niasse, 2004). Also Makoko in Lagos state is not an exception given their prevailing socio-economic problems in the area of housing in the urban areas. Urban areas will be faced with increases in the frequency and intensity of heavy rainstorms, ocean surges and other extreme weather events. The urban centers that will be more at risk are those where these events are already widespread.
Floods of 2010 have created huge problems for the people of affected areas of the country. The World Bank estimated some 17.6 million have been affected by this disaster (Independent Evaluation Group, 2010). Damage of crops, roads, housings and other infrastructure is estimated more than $6.5 billion. Health problems including the spread of water-borne diseases have made the life challenge for the people of affected areas.
Floods and storms may have considerable adverse impacts depending on location, intensity and duration. In 2003, floods accounted for 3,723 fatalities around the world, exceeded only by heat waves (about 22,000 due to the very extreme summer heat wave in Southern Europe) and earthquakes (about 48,000, mostly due to the Bam Iran disaster) (Munich Re 2003). The International Federation of Red Cross and Red Crescent Societies reports that weather-related disasters from a global perspective have been on the rise since 1996 and increasing from an annual average of 200 (1993–97) to 331 (1998–2002) (International Federation 2001 and 2003). The number of disasters attributed to floods is on the rise, while on average the number of people killed due to floods remains steady (Munich Re 2003). The economic costs of flood disasters have been increasing globally. Pielke et al. (2002) found that flood losses were falling to a proportion of GDP although the gross loss is on the rise. The increase in flood disasters is possibly due to more heavy rainfall events, increased economic activity, and efficiency of the use of a catchment (Green 1999; Mirza et al. 2001).