Question

How do humans affect the water cycle?

Answer 1

Hint: Water cycle depicts the evaporation of water, condensation of water vapours into rain and snow in clouds and finally their precipitation. Water cycle is now interrupted due to human interference like cutting trees, polluting water bodies etc.

Complete answer:
Humans interrupt water cycle in multiple ways:

1)Deforestation: The removal of trees has a major impact on the water cycle and the local or global climate. Trees release water vapours when they transpire, and it further creates a humid environment. This water vapour evaporates into the atmosphere where it accumulates before precipitating back to the Earth as rain, sleet or snow. If trees are cut down, there is less water to be evaporated into the atmosphere and subsequently less rain.

2)GreenHouse Effect: Human activity such as the burning of fossil fuels leads to the overall increase of the Earth’s temperature. Raising the Earth’s temperature results in an increase of evaporation, melting of ice or other processes of the water cycle that adversely affect the climate on Earth

3)Irrigation: With increasing human population our demands have increased. We need more food and to produce more food we need more water. Irrigation is the artificial watering of land and is used for watering land that does not get enough rain. Irrigation removes water from its natural sources and often causes leaching and run-off in the land where it is used. This removal of nutrients from the land results in more use of fertilizers by the farmers to keep their lands more productive. As a result waterways become more polluted.

4)Discharges: Before rainwater merges into the river it mostly picks up a whole range of pollutants. In rural areas the pollutants mostly include pesticides, herbicides, fertilizers, wastes from faulty septic systems and improperly handled manure. Such rain water flowing through contaminated streams, may affect plant and animal population in the water bodies. In urban areas the pollutants include gas, oil, pet waste, fertilizers, pesticides, salt and treated human waste from sewage treatment plants. Such waste when dumped into the water bodies contaminates the water bodies and in turn affects the water cycle.

Note: Deforestation, Irrigation, Burning of fossil fuels and Industrial discharges deteriorates water bodies, which leads to less evaporation of water and in turn less rainfall. This also leads to an increase of the environmental temperature which in turn leads to global warming.