Floods also destroy crops, cattle and agricultural land. On slopes, they wash away soil that finds its way into rivers and streams, clogging them up over a period of time and increasing the possibility of further flooding in the future. They make sewers overflow and have an adverse effect on telephone and electricity systems.
While almost all floods are bad, among the worst kinds are those that come unheralded at night, when people are asleep, thus catching them unawares and giving them little or no opportunity to escape.
The causes of floods are many, and include excessive rainfall, the overflowing of rivers, and the occurrence of high tides in coastal areas. Man has himself to blame as well, as he has added to his woes by indulging in unplanned and indiscriminate deforestation.
There are various ways of controlling floods. One is to build high banks called levees. Another is to use a ship called a dredger which increases the capacity of a river to hold water by removing mud and sand from its bed. A relief channel can be dug to divert floodwater from the main river. Deforestation on slopes can be countered by afforestation. In cities, storm water drains can be widened.
Advanced countries have sometimes come up with ingenious solutions. Between 1974 and 1982, for instance, British engineers constructed a moveable structure consisting of 51,000 tonnes of steel and 210,000 cubic metres of concrete called the Thames Flood Barrier. It is designed to protect London from flooding until at least the year 2030.
In conclusion, it may be pointed out that river floods are not without their uses, as they lead to the creation of fertile alluvial soil on the land it spreads itself out on before receding. Indeed, the rich ancient civilisation of Egypt, where little rain fell, would not have been possible without the Nile’s flood plain.