Distribution of Annual Rainfall in India

Annual Rainfall Distribution:

India witnesses an average annual rainfall of around 125 cm; however, the actual precipitation displays significant spatial variation due to factors like topography and proximity to the sea. This distribution is visually represented in the accompanying figure.

Region Categories:

1. High Rainfall Areas (>200cm): These regions encompass the western coastline, Western Ghats, sub-Himalayan areas in the northeast, hilly terrain of Meghalaya, Brahmaputra valley, and the adjacent hills.

2. Moderate Rainfall Areas (100-200cm): This category includes the southern parts of Gujarat, eastern Tamil Nadu, the northeastern Peninsula covering Odisha, Jharkhand, Bihar, eastern Madhya Pradesh, the northern Ganga plain along the sub-Himalayas, and the Cachar Valley along with Manipur.

3. Low Rainfall Areas (50-100cm): Encompassing Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat, and the Deccan Plateau.

4. Inadequate Rainfall Areas (<50cm): This group comprises parts of the Peninsula, especially in Andhra Pradesh, Karnataka, and Maharashtra, Ladakh, and the majority of western Rajasthan.

Rainfall Definition in India:

Due to the monsoonal nature, the annual rainfall exhibits considerable variability across different years. This variability is most pronounced in regions with low rainfall, such as portions of Rajasthan, Gujarat, and the sheltered side of the Western Ghats. Consequently, while areas with abundant rainfall are prone to flooding, those with scanty rainfall are vulnerable to drought.

Distribution of Rainfall Definition: Annually, the western coast and northeastern India receive more than 400 cm of rainfall. In contrast, regions like western Rajasthan, adjoining parts of Gujarat, Haryana, and Punjab receive less than 60 cm. Similarly, areas within the Deccan plateau's interior and east of the Sahyadri Mountains experience comparably low levels of rainfall.

Definition of Heavy Rainfall Region in India: At the beginning of the season, the windward side of the Western Ghats encounters notably intense rainfall, exceeding 250 cm. The most substantial rainfall during this period occurs in the northeastern part of the country. Mawsynram, situated in the southern extents of the Khasi Hills, receives the highest average annual rainfall globally.

Definition of Moderate Rainfall Region in India: Regions receiving 100 to 200 cm of rainfall encompass significant portions of Bihar, West Bengal, Odisha, Madhya Pradesh, Andhra Pradesh, and sections of other states. These areas are classified as part of the Moderate Rainfall Region.

Definition of Low Rainfall Regions in India: Regions with modest rainfall levels (50 to 100 cm) comprise sections of Maharashtra, Gujarat, Karnataka, Tamil Nadu, Andhra Pradesh, Madhya Pradesh, Punjab, Haryana, and western Uttar Pradesh.

Definition of Scanty Rainfall Regions in India: Scanty rainfall regions (approximately 50 cm) encompass the desert and semi-desert areas of Rajasthan, Gujarat, and adjacent regions.

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