CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Poor drainage systems form part of major threats to urban environments in Nigeria. Most of streets within the urban and rural settlement are faced with the challenges such as lack of drainages or properly designed drainages to evacuate storm water from the surface-course of our roads. Cities the world over are the dominating forces in the organization of human population. As the world most crowded places, cities continue to show increase in urban population. This increase leads to a growing urbanization trend. Duru and Nnaji (2008) defined urbanization as the increase in the population of cities in proportion to the region‟s rural population. Urbanization is the outcome of social, economic and political developments that lead to concentration and growth of large cities, changes in land use and transformation from rural to metropolitan pattern of organization and governance. Rapid growth of towns and cities has been common feature of the developing world (Aderamo, 2008). Although urbanization is the driving force for modernization, economic growth and development, there is increasing concern about the effects of expanding cities, principally on human health, livelihoods and the environment.
Drainage systems are constructed to ensure that waste water and sewage is transported neatly to disposal points, thereby keeping the environment well drained and free of waste. Examples of components that make up a good drainage system includes; closed ditches having pipe drains, drainage pipes, channels and conduits (Folorunsho, & Awosika, 2001). Sustainable Drainage Systems are approaches put in place to manage the water quantity (flooding), water quality (pollution) and amenity issues in the environment. Sustainable drainage is a concept that includes long term environmental and social factors in decisions about drainage. Sustainable Drainage Systems are intended to regulate surface water runoff close to where it falls and simulate natural drainage as closely as possible. They provide opportunities to reduce the causes and impacts of flooding, remove pollutants from urban runoff at source, and combine water management with recreation and wildlife. They also help to enhance water quality while protecting natural flow regimes in watercourses (Dipanjan & Mukherjee 2014).
