Select either urban flooding or water pollution and discuss its (a) causes (b) effects (c) control measures

Topic chosen: Water pollution.

Water pollution is the addition of harmful substances to bodies of water (rivers, lakes, seas, ground water) so that the water becomes unsafe or unfit for human use and for aquatic life.

(a) Causes of water pollution:

• Industrial waste: factories discharge chemicals, dyes, heavy metals and hot water into rivers and streams.
• Sewage and domestic waste: untreated human waste, refuse and detergents are emptied into water bodies.
• Agricultural chemicals: fertilizers, pesticides and herbicides are washed by rain from farmland into rivers.
• Oil spillage: leaks from pipelines, tankers and oil-drilling pollute rivers and coastal waters, as in the Niger Delta.
• Mining waste and refuse dumping: silt, chemicals and rubbish enter water courses.

(b) Effects of water pollution:

• Spread of water-borne diseases such as cholera, typhoid, dysentery and guinea worm.
• Death of aquatic life: fish and other organisms are killed by toxic chemicals and oil, reducing fish catches.
• Shortage of clean water: the water becomes unfit for drinking, cooking and domestic use, and costly to treat.
• Damage to farmland and eutrophication: polluted water damages crops when used for irrigation, and nutrient enrichment causes excessive weed growth that chokes the water.

(c) Control measures:

• Treatment of waste: industrial effluent and sewage should be treated before being discharged.
• Enforcement of laws: government should make and enforce anti-pollution laws and penalise offenders.
• Proper waste disposal: provide proper dumps and sewage systems so that refuse and waste are not thrown into water.
• Control of oil spills and farm chemicals: maintain pipelines, clean up spills promptly, and use fertilizers and pesticides carefully; public enlightenment on keeping water bodies clean.