Mangroves of India

 

Mangrove are the dense shrubs or forests found along tidal estuaries and deltas, salt marshes, and on muddy coasts in the tropical and sub-tropical regions. These are mostly found in Asia, Africa and South America. The largest area of mangroves are found in Indonesia, followed by Brazil, Australia, Nigeria, and Mexico. 

The areas where mangroves are found poses many challenges for the plant community like high salinity, tidal inundation twice a day, low oxygen etc. However, mangroves are equipped with varied morphological and physiological adaptations to survive these conditions. They have complex root system that extend above and below the water line with amazing filtration system to sieve out or exclude salt. This allows them to survive in saline sea water as well as in fresh water. Mangrove have additional benefits for environment like they prevent coastline erosion, protect inner areas from tsunamis, storms and high waves and also provide habitat, breeding, and feeding grounds for aquatic and other organisms. They are important carbon sinks also known as blue carbon.

As per the Indian State of Forest Report of 2019, mangrove cover in the country is 4,975 square km, which is 0.15% of the country’s total geographical area. The largest area under mangroves is in West Bengal. Indian mangroves consist of 46 species representing about 57% of the world's mangrove species (Ragavan et al, 2016)

In India, the mangroves are mostly located in the river estuaries and deltas; backwaters and islands. Therefore, the mangroves of India are broadly classified into three regions, as (Mandal and Naskar, 2008) -

1. Deltaic or Eastern Coast Mangroves,

2. Estuarine & Backwater or Western Coast Mangroves and

3. Insular mangroves or Andaman & Nicobar Islands. 

 

Deltaic or Eastern Coast Mangroves	West Bengal - Sunderbans (Ganga-Brahmaputra)
	Odisha - Bhitarkanika (combined delta of the Mahanadi, Brahmini and Baitarani)
	Andhra Pradesh - Coringa wetland (the Gautami-Godavari river), Krishna (three islands located between Gollamattapaya and Nadimeru distributaries, and the Krishna river).
	Tamil Nadu - Pichavaram and Muthupet mangrove (Cauvery)
	Puducherry mangroves
Estuarine & Backwater or Western Coast Mangroves	Gujarat - Gulf of Kachchh; Saurashtra coast or Kathiawar; Gulf of Khambhat (estuaries like the Sabarmati, the Mahi, the Narmada, and the Tapti); South Gujarat coast (small tidal creeks and few minor estuaries.
	Maharashtra – Mumbai, Thane creek and small patches in Raigarh, Ratnagiri and Sindhudurg district.
	Goa coast - Zuari and Mandovi estuary
	Kerala - Mangroves in Kannur and Kasaragod, Kozhikode (Kadalundi), Ernakulam (Pithuvypin, Mangalvanam Bird Sanctuary and Kundannur area.), Allepey.
	Daman and Diu mangroves
Insular mangroves or Andaman & Nicobar Islands.	The mangrove forests of these islands are situated along the tidal creeks, inland channels and in shores (bays).

References -

India State of Forest Report, 2019. Forest Survey of India, Ministry of Environment, Forest & Climate Change, Government of India

Mandal, R.N. and K.R. Naskar. (2008). Diversity and classification of Indian mangroves: a review. Tropical Ecology 49, 131–146.

Ragavan, P., Saxena, A., Jayaraj, R.S.C., Mohani, P.M., Ravichandran, K., Saravanan, S., and A. Vijayaraghavan (2016). A review of the mangrove floristics of India. Taiwania, 61 (3), 224‒242.

Selvam, V. (2003). Environmental classification of mangrove wetlands of India. Current Science. 84.

 

Meteorological Sub-divisions of India 2020

India has been divided into 36 subdivisions by Indian Meteorological Department on the basis of meteorological data and also considering practical applicability.

For reasons of practical convenience, compilation of statistics, issue of weather warnings to government functionaries and informing the general public, the sub-divisional boundaries were always made to conform at least to the jurisdiction of basic revenue districts.

R. R. Kelkar and O. P. Sreejith (2020), IMD Pune

This process was undertaken as -

• Large states with varying climate were divided into smaller divisions on meteorological grounds.
• Small states and Union Territories with similar meteorological climate were combined together.
• Finally, IMD gave names to those sub-divisions that did not follow existing political subdivisions.

To simplify for understanding, the 36 meteorological subdivisions of India can be classified as-

Criteria of sub-divisions	Number of subdivisions	States
Named after the state	9 subdivisions	o  Arunachal Pradesh, o  Odisha, o  Jharkhand, o  Bihar, o  Uttarakhand, o  Punjab, o  Himachal Pradesh, o  Chattisgarh, o  Telangana.
Group of smaller states or UTs - States and UTs with small area and similar climate	6 sub-divisions	o  Assam and Meghalaya, o  Nagaland, Manipur, Mizoram and Tripura, o  Haryana, Chandigarh and Delhi, o  Jammu and Kashmir and Ladakh, o  Tamil Nadu, Puducherry and Karaikal, o  Kerala and Mahe.
Larger states divided into two	12 sub-divisions	o  East Rajasthan, o  West Rajasthan, o  East Uttar Pradesh, o  West Uttar Pradesh, o  East Madhya Pradesh o  West Madhya Pradesh. o  Gujarat Region o  Saurashtra and Kutch. o  Sub-Himalayan West Bengal and Sikkim o  Gangetic West Bengal. o  Rayalaseema, o  Coastal Andhra Pradesh and Yanam.
Larger states divided into three  and more than 3 - Larger states which have a greater variation in climate	7 sub-divisions	o Karnataka, o North Interior Karnataka   o South Interior Karnataka o Konkan and Goa, o Madhya Maharashtra, o Marathwada, o Vidarbha.
Islands	2 sub-divisions	o Andaman and Nicobar Islands in the Bay of Bengal o Lakshadweep islands in the Arabian Sea.

To further understand the history of Meteorological sub-divisions of India, refer to this research article by R. R. Kelkar and O. P. Sreejith (2020),

Reference –

IMD website, India Meteorological Department, Ministry of earth Sciences, Government of India. Accessed on 24/12/2020. https://mausam.imd.gov.in/

Map Data Source – Meteorological Subdivisions map, IMD website, India Meteorological Department, Ministry of earth Sciences, Government of India. Accessed on 24/12/2020. https://mausam.imd.gov.in/imd_latest/contents/index_rainfall_subdiv.php

R. R. Kelkar and O. P. Sreejith, (2020). Meteorological sub-divisions of India and their geopolitical evolution from 1875 to 2020. Mausam, 71, 4 (October 2020), 571-584. https://metnet.imd.gov.in/imdmausam/