There is an Increasing awareness to the potential impacts of climate change on urban cities. Presently, roughly 50 percent of the world‘s population live in cities, but this figure is expected to reach 66% by 2050.
Most of the future growth of the urban population is anticipated in the developing world. Many low-income countries are already exposed to shortage of clean drinking water and poor sanitation, and often occupy high-risk areas such as floodplains and coastal zones.
As the concentration of urban population in is increasingly mixed up with growing risks of extreme events, millions of naira is lost and the cost is increasing by the day. The significant contribution made by the world‘s major cities to global climate change and the urgent need for energy, efficient infrastructure and changed patterns of resource consumption is notable.
With such a range of issues to tackle, it is not surprising that there have been calls for wider participation and more effective interaction between complementary disciplines. Climate change will increase the frequency and intensity of heavy rainfall events, thereby increasing the risk of urban flooding.
While addressing infrastructure issues is a necessary component of reducing urban flood risk, individual homeowners can have a significant role in reducing risk through protecting their own homes and reducing their contributions of storm water to municipal sanitary sewers and storm water management systems.
However, the barriers of low public awareness will have to be overcome to effectively engage homeowners in urban flood risk reduction. Some cities have been working to improve homeowner knowledge and risk-reducing behaviour through education and financial assistance programs in the advance world.
Urban flooding occurs in urban cities or areas where the impact of extreme rainfall are exacerbated by high concentrations of impervious surface, infrastructure, buildings, property and people. Urban flooding can have serious implications for both buildings and infrastructure, as extreme flows of water during heavy rainfall events can damage both overland and underground storm water management, infrastructure and road pavements.
Flooding has also become the greatest reasons for the numerous gully erosion problems because of concentration and discharge to many unsafe areas. This is mainly due to poor road designs, numerous public and private building springing up and exposing land surface in many built up areas.
In summary, there is no doubt that the population, infrastructure and ecology of urban cities are at risk from the impacts of climate change. However, tools are becoming available for addressing some of the worst effects. For example, appropriate building design and climate sensitive planning, avoidance of high-risk areas through more stringent development control, incorporation of climate change allowances in engineering standards applied to flood defenses, water supply systems and shoreline protection works.
Citizens also have a responsibility to mitigate their collective impact on the local and global environment through reduced resource consumption and changed behaviour. This review has described the most significant climate change impacts expected to shape the future character and functioning of urban systems in Nigeria.
Hence, several important knowledge gaps should be made topmost priority. Firstly, there is an ongoing need to improve preparedness and forecasting of climatic hazards, such as intense heat island or air pollution episodes, to safeguard human comfort and health in Nigeria.
Secondly, there is clearly a need for improved representation of intra-urban flooding, at local, city and catchment scales. New modelling techniques will also be needed to exploit fully emergent probabilistic climate change information. But there could be new cost implications arising from the use of such data, dependent on the level of risk and uncertainty that is acceptable in the resultant engineering design.