Why does Nalgonda district suffer from severe water scarcity'though river Krishna flows through it ?

Why did people also suffer from various disease after consuming fishes living in local water reservoir?

Why does the wooden block float on water even though it is heavier than a marble ?

……………… alter the natural flow of rivers leading to water scarcity.

A swimmer wants to cross a 200 m wide river which is flowing at a speed of 2 m/s. the velocity of the swimmer with respect to the river is 1 m/s. how far from the point directly opposite to the starting point does the swimmer reach the opposite bank ?

How does the rain water reach from clouds to rivers or oceans?