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.
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.
In many parts of Nigeria today, there is a great need for properly managed sustainable drainage systems in order to help manage surface water runoff. Neighborhoods keep springing up without proper planning, which also involves planning for drainage and sewage or waste disposal. Residents regularly dump their waste in gutters, and this clogs the gutters and prevents the flow of water, causing the gutters to overflow.
It is common to see flooded streets with litter floating everywhere after a short period of rainfall. Such situations create very unsanitary conditions for residents of the neighborhoods and contribute to the degradation of the environment.
In the year 2012, 363 people were feared dead while 2.1 million citizens were displaced across Nigeria as a result of floods. According to the National Emergency Management Agency (NEMA), 30 states out of 36 in Nigeria were affected by that flood experience and it was concluded as the worst that has ever happened in the past 40 years, causing damages of an estimated value of N2.6 trillion Naira. These floods also gave rise to environmental pollution problems which affected the health of Nigerians across the various affected areas.
Nigeria is currently experiencing its annual rainy season, and in order to avoid lethal floods it is important to have very effective drainage systems and strive towards ensuring free flow of water during and after heavy downpours.
Poorly maintained drainage systems and poor waste management habits can adversely affect our environment in the following ways;
- Flooding: The immediate effects of flooding include loss of human life, damage to property, destruction of crops and other plants, loss of livestock
- Erosion: The absence of good drainage systems can cause erosion problems. This has been experienced in many areas of Nigeria, where roads have been washed away and gullies created as a result of flooding.
- Diseases: Deterioration of health is another effect of flooding, due to the increase in waterborne diseases and unsanitary conditions. Stagnation of water occurs when water passages are blocked. This makes the people around such environments susceptible to infections from mosquitoes and other insects. We are exposed to numerous air and water borne diseases if we have our environments polluted with stagnant water.