The monsoons start retreating from India in the second week of September and by 15th of October, the monsoons arc more or less over. The entry of monsoons is more spectacular than its exit.
Characteristics of India's Rainfall:
(a) It has seasonal concentration. 75-80% rain falls between July to September and is caused by SW Monsoons. The retreating monsoons contribute nearly 12% whereas winter and pre-monsoon showers cause 2-10%.
(b) Most of the rain of India is orographic.
(e) Monsoon rains are seasonal, erratic, unbelievable and unreliable.
(d) Its regional distribution is uneven, 10% of Indian's area rcvcivcs nearly 200 cm of rainfall, 20% area, 125-200 cm, 40% area, 40-125 cm, 24% area, 40-80 cm and 6% area less than 40 cm.
Importance of monsoon rainfall in India's economic landscape
India is primarily an agrarian country. Agriculture is thus the backbone of its economy which is popularly known as a 'gamble in monsoon'.
In fact Monsoons are the life and soul of India's economic landscape particularly that of agriculture in determining cropping pattern. Over 200 cm rainfalls is ideal for the cultivation of rice, tea, jute.
100-200 cm: rice, wheat, sugarcane 50-100 cm: wheat, corn, pulses, etc.
Uncertainty in the arrival of monsoons proves disastrous for the health of the crops. It compels the farmer to look for means of irrigation, which may be convenient to him in that area.
Concentration of rainfall from July-September (3 months only) necessitates developing means of irrigation in order to grow rabi crops.
Excessive rainfall due to uncertain character of the monsoons may cause floods and result in havoc to life, land, crop and property.
The following are the main flood prone areas of the country:
(1) Basins of the rivers, which originate from the Himalayas.
Punjab, Haryana, Delhi, U.P, Bihar, Assam and West Bengal
(2) River basins of Peninsular India, Orissa, Tamil Nadu and Andhra.