Geography of Odisha


is one of the 28 states in the Republic of India. Odisha is located in the eastern part of the Indian peninsula and the Bay of Bengal lies to its East while Chhattisgarh shares its border in the west and north-west. The state also shares geographic boundaries with West Bengal in the north-east, Jharkhand in the north and Andhra Pradesh in the south. The state is spread over an area of 1,55,707 km2 and extends for 700 km from north to south and 500 kilometres from east to west. Its coastline is 450 km long. The state is divided into 30 districts which are further subdivided into 314 blocks called tahasil.
Physiographically, Odisha consists of coastal plains, central plateaus, central hilly regions, flood plains, and uplands. About a third of the state has a green cover.
Mahanadi is the largest river of the state and its catchment area covers 42% of the state. There are several other significant rivers that flow through the state such as the Subarnarekha, the Brahmani, the Baitarani, and the Vansadhara.
Chilika Lake, located on the east coast of the state is one of the world's largest brackish water lagoons. Besides that there are several other lakes in the state such as Anshupa, Tampara, and Kanjia.
Geologically the state is home to some of the oldest rocks of the world. Odisha also consists of two cratons, which are sedimentary formations from the Cretaceous period. They are found in many places and are home to coal deposits. The coasts are made up predominantly of deltaic sediments of Mahanadi, Brahmani, Baitarani, Subarnarekha rivers of Quaternary age.

Overview

Odisha topography consists of fertile coastal plains to the east bounded by Bay of Bengal. Mountainous highlands and plateau regions occupy the center of the state. Western and northwestern portions of the state consist of rolling uplands. The state also has some major floodplains encompassing the river systems.
The western and northern portions of the state are part of the Chota Nagpur plateau. The coasts composed of fertile alluvial plains and the valleys of the Mahanadi, Brahmani, and Baitarani rivers, which empty into the Bay of Bengal.
31.41% of Odisha has forest cover. There are many wildlife sanctuaries in Odisha. The Simlipal National Park is a national park and tiger reserve with a huge expanse of lush green forests with waterfalls and is inhabited by tigers, elephants, and other wildlife. The Bhitarkanika Wildlife Sanctuary, also a national park, has been protecting estuarine crocodiles since 1975.
Chilka Lake, a brackish water coastal lake on the Bay of Bengal, south of the mouth of the Mahanadi River, is the largest coastal lake in India. It is protected by the Chilka Lake Bird Sanctuary, which harbors over 150 migratory and resident species of birds.
The highest mountain peak in the state is Deomali, which is situated in Koraput district in southern Odisha. It is also one of the tallest peaks of the Eastern Ghats. Deomali is part of the Chandragiri-Pottangi mountain subsystem.

Location

The state of Odisha extends from 17.31N latitude to 22.31N latitude and from 81.31E longitude to 87.29E longitude.

Physical divisions

Physiography

Odisha can be divided into five major Physiographic regions based on continuity, homogeneity and other physiographical characteristics:
  1. Utkal Plains or the coastal plains of the east
  2. The central plateaus
  3. The central mountainous and highlands region
  4. The western rolling uplands, and
  5. The main flood plains

    Odisha Coastal Plains

The Odisha Coastal Plains or Utkal Plains are the sedimentary landforms of recent origin. Geologically they belong to the Paleogene and Neogene ages. Their western boundary is at around 250 feet eastern ghats and they have a nearly straight shoreline in east. This region stretches from the Subarnarekha basin in the north to the Rushikulya basin in the south.
A major part of this region is formed by deltas of the six major rivers i.e. the Mahanadi, the Brahmani, the Budhabalanga, the Subarnarekha, the Baitarani, and the Rushikulya. This has given rise to the names such as the "Gift of Six Rivers" or the "Hexadeltaic region". It spans along the coast of the Bay of Bengal with the maximum width near the Mahanadi Delta. It is narrower in the Northern Coastal Plain in Baleshwar District and narrowest in the Southern Coastal Plain in Ganjam District.
The North Coastal Plain is made up of the deltas of the Budhabalanga and the Subarnarekha, The widest and largest area is the Middle Coastal Plain which comprises the deltas of the Mahanadi, Brahmani, and Baitarani rivers. This region hosts a number of lakes and there is evidence of past 'back bays'. The South Coastal Plain consists of the lacustrine plain of Chilika Lake and the Rushikulya River delta.

Middle mountainous and highlands region

The middle mountainous and highlands region is the largest of the geographic regions and covers about three-fourths of the state. The region mostly comprises the hills and mountains of the Eastern Ghats which rise sharply in the east and slope gradually to the eroded plateaus in the west running from north-west to the south-west. Geologically the formation is quite old. It is a part of the Indian Peninsula which was a part of the ancient landmass of Gondwanaland. The rivers of Odisha and their tributaries have cut deep and narrow valleys in this region. The Odisha highlands are also known as the Garhjat Hills. This region is well marked by a number of watersheds. A number of river valleys of varying width and flood plains dissect the Eastern Ghats in this region. The average height of this region is about 900 meters above the mean sea level. The highest peak is Deomali.

Central plateaus

The plateaus are part of the western slopes of the Eastern Ghats. They are mostly eroded plateaus with elevation varying from 305 to 610 meters. There are two broad plateaus: the Panposh-Keonjhar Pallahara plateau comprises the Upper Baitarani catchment basin in the northern part of the state, and the Nabrangpur-Jeypore plateau comprises the Sabari basin in the southern part of the state.

Western rolling uplands

The western rolling uplands have heights varying from 153 metres to 305 metres. These are lower in elevation than the plateaus.
It consists of the following geographically distinct uplands.
  1. The Rairangpur rolling upland - This region encompasses the northern part of the Mayurbhanj district. The uplands are a part of the Subarnarekha basin, and slopes towards the north.
  2. The Keonjhar rolling upland - This region is part of Kendujhar district and lies at the edge of Keonjhar Plateau. It is part of the Baitarani River basin.
  3. The Rourkela rolling upland - This is part of Sundergarh district and lies on the Upper Brahmani basin.
  4. The Bolangir-Bargarh-Rairkhol rolling upland - This is part of multiple districts and lies on the Upper Mahanadi and its tributaries basin.
  5. The Aska rolling upland - This is situated in Ganjam District on the Upper Rushikulya basin.
  6. The Rayagada rolling upland - This uplands is part of the Rayagada district and lies on the Nagavali and the Vansadhara river basins.
  7. The Malkangiri rolling upland - Located on the southern tip of Odisha, this upland is situated on the Sabari-Machhkund basins of the Dandakaranya Region.

    Major Flood Plains

These flood plains are formed due to major rivers in the highlands, uplands, and plateaus. The height varies from 75 to 153m. The nine major flood plains of Odisha are:
  1. Baripada flood plain
  2. Anandapur flood plain
  3. Talcher flood plain
  4. Bhuban flood plain
  5. Sonepur flood plain
  6. Athagarh flood plain
  7. Aska flood plain
  8. Rayagada flood plain
  9. Malkangiri flood plain

    Geology

The geology of Odisha is complex and varied. The state is home to some of the oldest rock formations on the planet. The second oldest rocks on the planet were found in Champua, Kendujhar which are 4.2 billion years old. Odisha is part of two cratonic blocks called North Orissa Craton and the West Orissa Craton. There is a third block called the Eastern Ghats Granulite Belt. It has been considered as a ‘mobile belt’ during the middle Proterozoic Era. These formations are separated from each other by deep-seated regional fault boundaries. The fault boundaries are called the north Orissa boundary fault and the west Orissa boundary fault.
The North Orissa Craton comprises extensive banded iron formations, granite intrusives, and undeformed volcano-sedimentary assemblages belonging to the Archaean to-early Proterozoic times. They are followed by folded limestone-bearing rock formations of the Proterozoic age.
The West Orissa Craton is underlain by occurrences of granites of the Archaean age and undeformed limestone-bearing platform sediments of the Proterozoic age. Small occurrences of Archaean banded iron formations and greenstones can also be found.
The Eastern Ghats Granulite Belt is mainly composed of Khondalite formations and moderately extensive charnockites, granites, migmatites, and local pegmatites formations covering approximately 52000 km2. Occurrences of anorthosites, alkaline rocks and chromite-bearing ultramafic rocks are found close to the boundaries of the block. The name Khondalite is derived from the Khond tribe who inhabit Odisha.
The similarity of lithology, tectono thermal events, and major rift features, e.g. the Mahanadi rift, place Odisha close to Eastern Antarctica.
Later geological formations such as Gondwana basins are also found in Odisha. The Mahanadi Master Basin holds a major part of the Gondwana basins of Odisha. Gondwana sediments are exposed in sedimentary basins found in Ib River valley, Talcher, Katringia, Gaisilat, Athmallik, Chhatrapur, and Athgarh. These deposits are estimated to be ranging from early Permian to Early Cretaceous in age. Most of the coal deposits of Odisha are found in this region.
The East Coast Odisha is made up predominantly of deltaic sediments of Mahanadi, Brahmani, Baitarani, Subarnarekha rivers, besides aeolian and marine patches. The eastern coastline Odisha originated in the post-Cretaceous era and was modified appreciably during the Quaternary due to the growth of river deltas and the effects of glaciation and deglaciation. The Quaternary sediments of the east coast of Odisha are composed of laterites and unconsolidated clays, silts, sands, and gravels.