Which of the following sources of water is least useful for irrigation purposes?
Answer Details
The source of water that is least useful for irrigation purposes is the sea. This is because seawater has high salinity levels which can damage crops and soil, making it unsuitable for irrigation. The high salt levels can cause the soil to become saline, making it difficult for crops to absorb water and nutrients, and eventually leading to crop failure. Therefore, while seawater can be used for other purposes such as desalination, it is not a suitable source of water for irrigation.