Why the availabilit of water resources varies over space and time?

Availability of water resources varies over space and time mainly because of the variations in seasonal and annual precipitation.

• If we talk about India, it is a vast country. While it rains heavily in one part of the country, the other part experiences drought. For example, northeastern parts of the country experiences floods almost every year but the north western parts of the country like Rajasthan and north Gujarat suffer from recurrent droughts.
  
• Similarly, while most of the states in the country do not receive rainfall during winters, Coromandel Coast receives rainfall during winters. Northern parts of the country also receive some showers during the winter season.
• However, it has to be noticed that today water scarcity is caused mainly due to increase in population, expansion of agriculture, establishment of large scale industries etc.