Indian Geography and Regional Features

Indian river systems and drainage patterns

A drainage pattern is the arrangement of streams and rivers in a region. It reflects the underlying rock structure, slope and relief, so geographers use it to infer the geology of an area.

• Dendritic — a tree-like, branching pattern in which tributaries join the main stream at acute angles. It is the most common pattern and develops on uniform rock with a gentle, regular slope. e.g. The branches of a tree resemble the drainage of a flat plateau of homogeneous granite.
• Centripetal — streams converge from all directions into a central lake or depression. It is the reverse of the radial pattern, in which streams flow outward from a central elevated point.
• Trellis — short right-angled tributaries join parallel main streams, typical of folded terrain. e.g. A folded ridge belt with parallel main channels.

Rivers are also classified by their relation to rock structure and original slope.

• Insequent — has no apparent relation to rock structure or the original slope; it takes an arbitrary course.
• Consequent — follows the original slope of the land.
• Subsequent — follows lines of weak rock structure.
• Resequent — flows in the same direction as a consequent stream but at a lower level.

In the Indus system, the Satluj is the key river for hydropower. The Bhakra Dam is built across the Satluj in Himachal Pradesh, and the Bhakra Nangal canal system draws its water from it. The Luhri hydro project, a run-of-the-river scheme, is also located on the Satluj in Himachal Pradesh. The Chenab carries the Salal and Baglihar dams, and Baglihar is the taller of the two. The Indus basin extends over Ladakh, Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana and Rajasthan.

The Krishna and Tungabhadra flow through the Deccan plateau of northern Karnataka, including the Gulbarga and Hampi region. Rivers on the route between Bengaluru and New Delhi include the Narmada and the Krishna, while the Yamuna lies along the eastern edge of Delhi and is not crossed on a route approaching from the south-west.

For the Ganga, cities listed from west to east follow increasing longitude. Kanpur (about 80°E) comes before Prayagraj (about 81.8°E), then Patna (about 85.1°E) and Bhagalpur (about 87°E).

The Barak system in the Surma–Meghna basin must be distinguished from the Brahmaputra. Subansiri, Dhansiri and Manas are Brahmaputra tributaries and cannot belong to the Barak system.

India's first underwater metro tunnel was built beneath the Hooghly river in Kolkata as part of the East-West Metro. National Waterways are numbered by route: NW-1 is the Ganga (Haldia–Prayagraj), NW-2 is the Brahmaputra (Sadiya–Dhubri), NW-3 is the West Coast Canal and NW-4 is the Godavari–Krishna route.

Indian states and union territories geography

Geographical identification questions combine location, extent and resources. Learn the key lines and boundaries first, then the features of each state.

The Tropic of Cancer passes through eight Indian states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. Only Gujarat and West Bengal have a coastline, so the line passes through two coastal states and six landlocked states.

Mizoram lies on the Tropic of Cancer and is elongated in the north-south direction. It shares international borders with Bangladesh and Myanmar. Tripura lies on the Tropic but does not border Myanmar.

Latitude and longitude locate a Union Territory. Ladakh lies roughly between 32° and 36° N and 75° and 80° E, so a point near 34° N and 77° E is in Ladakh. The Andaman and Nicobar Islands lie in the Bay of Bengal, Lakshadweep in the Arabian Sea and Puducherry on the south-east coast. Khardung La, the Nubra Valley and the Buddhist monasteries of Leh such as Hemis and Thiksey are all in Ladakh.

The share of forest in total geographical area is highest in small island Union Territories such as Lakshadweep, which has a very large forest-type cover relative to its land area.

Manikaran in the Parvati valley of Kullu district is known for its hot springs, which are the basis of geothermal energy.

Andhra Pradesh has diverse rock formations, including the Cuddapah and Kurnool basins, and it has the largest chrysotile asbestos deposits in India, mainly in the Cuddapah district. It also contains the Neelam Sanjiva Reddy Sagar (Upper Penner) hydel project.

Assam covers about 78,438 sq km, which is about 2.39 per cent of India's total area (78438 / 3287263 \approx 0.0239). Its territory spans the Himalayan hills, the Brahmaputra valley of the northern plains and the peninsular extension in the Karbi Anglong hills, so it includes three of the six physiographic divisions.

Telangana shares borders with Maharashtra, Karnataka, Chhattisgarh and Andhra Pradesh. It does not border Odisha or Madhya Pradesh.

The north-south extent of a state is the difference between its northernmost and southernmost latitudes. Chhattisgarh has the greatest north-south extent among Jharkhand, Telangana, Odisha and Chhattisgarh.

The distance of a capital from the Equator depends on its latitude, and the smaller the latitude the closer the city is to the Equator. Panaji lies at about 15.5° N, which is lower than Hyderabad (about 17.4° N), Mumbai (about 19.1° N) and Bhubaneswar (about 20.3° N). Panaji is therefore the closest to the Equator.

Soil types of India

Indian soils are classified by their origin, texture and chemical composition. Each soil type has a characteristic set of nutrients and a characteristic distribution.

• Black soil — formed mainly from weathered basalt and rich in lime, iron, magnesia and alumina. It is clayey, deep and impermeable, and it swells when wet and shrinks when dry. It is found mainly in Maharashtra, Madhya Pradesh and Gujarat.
• Alluvial soil — deposited by rivers and varying from sandy loam to clay. Its nutrient content is typically rich in potash but poor in phosphorus. It is also rich in potash, phosphoric acid and lime, and it is classified by age as older alluvium (bhangar) and newer alluvium (khadar).
• Saline soil — contains high proportions of sodium, potassium and magnesium salts, which make it infertile. Its texture ranges from sandy to loamy, and it occurs widely in western Gujarat, the deltas of the eastern coast and the Sundarbans of West Bengal.

The USDA Soil Taxonomy divides soils into twelve orders, and Inceptisols, Entisols, Vertisols and Mollisols are all soil orders. Soil classification is therefore the category to which these names belong.

In the USDA system, the orders are distinguished by their profile development.

• Entisols — young soils with no diagnostic horizons, so they are weakly developed.
• Inceptisols — weakly or quickly developed soils with weakly developed horizons.
• Histosols — organic soils with a very high quantity of organic matter in the upper layers.
• Oxisols — very old, highly weathered soils of the tropics.

Agricultural crops and cultivation systems

Cultivation systems are named by how land is used and how crops are arranged in space and time. Local terms for the same system differ by region.

• Shifting cultivation — a plot is cleared, often by burning, cropped for a few years and then left fallow while the cultivator moves on. The names differ by region: Milpa is used in Mexico and Central America, and Ladang in Malaysia and Indonesia.
• Roca is the name for shifting cultivation in Brazil, Chena in Sri Lanka, Masole in Zaire (now the Democratic Republic of the Congo) and Tamarai in Thailand.
• Intercropping — two or more crops are grown simultaneously on the same field in a definite pattern, usually in fixed rows. It differs from mixed cropping, in which several crops are grown together without a fixed arrangement.
• Mixed farming — crop cultivation combined with livestock rearing, which is different from both intercropping and mixed cropping.

Rice is a kharif crop, and its three growing seasons in an agricultural year are Aus, Aman and Boro. It covers roughly one-fourth of India's total cropped area.

Dryland farming relies on drought-resistant crops that need little water. Jowar, ragi and groundnut are grown under these conditions. Sugarcane has a long growing period and a high water requirement, so it depends on irrigation and is not a dryland crop.

Plantation crops of India

Plantation agriculture is the large-scale cultivation of a single cash crop on estates, usually with heavy capital, scientific management and a processing unit attached to the estate. Typical plantation crops in India include tea, coffee, rubber, coconut, cashew and spices such as pepper and cardamom. The output is sold for industrial processing or export rather than consumed locally, which is what separates plantation crops from ordinary food crops.

The commercially important coffee species are Arabica, Robusta and Liberica, all belonging to the genus Coffea. Arabica is the most widely cultivated species, while Robusta is grown mainly for its higher yield and caffeine content.

Plantation crops need a humid climate, adequate rainfall and well-drained soil, so they are concentrated in hills and high-rainfall regions. Arid and semi-arid states, where agriculture rests on dry-farming crops such as millets, pulses and oilseeds, are not plantation states.

The features of plantation farming that examinations test are:

• Monoculture — growing one cash crop over a large estate.
• Capital intensity — heavy investment in land, machinery and processing units.
• Scientific management — improved planting, care and processing methods.
• Ownership and labour — historically, estates were often owned by foreign companies and worked by local labour.

A plantation is therefore not a system of mixed farming, and a statement that plantation farmers rear animals for sale describes a different system. Lakshadweep is noted in this context for coconut cultivation, where per-hectare productivity is recorded as the highest in India and the oil content of the nuts is recorded as the highest in the world.

Indian islands and straits

India's island territories are the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep islands in the Arabian Sea. The Andaman and Nicobar group is divided into two clusters by a sea passage, and the passages between island groups are called channels, while narrow sea passages between a country and an island or between two landmasses are called straits.

The Ten Degree Channel is the sea passage that separates the Andaman group from the Nicobar group. It lies between Little Andaman and Car Nicobar, and it does not separate the islands within the Andaman group or those within the Nicobar group.

The strait between India and Sri Lanka, the Palk Strait, and the Gulf of Mannar are often confused with the channels of the Andaman and Nicobar Islands, but they lie between India and Sri Lanka, not within the island territories.

Mountain peaks of the island territories are also tested by name and location:

• Saddle Peak — the highest point of the Andaman and Nicobar Islands, in North Andaman.
• Mount Harriet — the principal peak of South Andaman.
• Mount Thuillier — a peak of Great Nicobar in the Nicobar group.
• Mount Diavolo — a peak within the Andaman and Nicobar Islands.

A Himalayan peak such as Lhotse, which lies on the Nepal-China border, is outside these islands and must be excluded in questions about island peaks.

Biosphere reserves and national parks

A biosphere reserve is an area recognised under UNESCO's Man and the Biosphere Programme, which combines the conservation of biodiversity with sustainable use of resources by local people. A biosphere reserve is not the same as a national park or a tiger reserve, although the same area may be several of these at once. In India, a national park is a legally protected area for wildlife and ecosystems, and a tiger reserve is a protected area set up under the tiger conservation framework.

A tiger reserve may also be included in the UNESCO world network. Panna Tiger Reserve in Madhya Pradesh was declared a UNESCO Biosphere Reserve in 2020, so the year of designation is an essential detail when a question concerns the network.

Some biosphere reserves cover more than one State. The Nilgiri Biosphere Reserve spans parts of Tamil Nadu, Kerala and Karnataka, which makes it the reserve spread over three States. Other reserves such as Agasthyamalai and Achanakmar-Amarkantak cover only two States, and Seshachalam lies within a single State.

Species reintroduction is another frequently tested topic. Cheetahs brought from Namibia were released in Kuno National Park in Madhya Pradesh in 2022. Each well-known national park has a signature species that questions link with it:

• Kaziranga — one-horned rhinoceros, Assam.
• Keoladeo Ghana — water birds, Rajasthan.
• Keibul Lamjao — the sangai deer, in a floating park in Manipur.

In matching questions about sanctuaries, each pair must be checked against the State in which the sanctuary is actually located. A single wrong State in a set of pairs makes that pair the answer to a 'not correctly matched' question.

Lakes and water bodies of India

India has natural lakes formed by glaciers, tectonic movement, river action or coastal processes, as well as man-made reservoirs and lagoons. Examination questions usually ask students to link a lake with its State, or to identify a lake by a nearby landmark or by the type of water body it is.

Lakes are commonly grouped by origin:

• Glacial lakes — found at high altitude in the Himalaya, such as those in Sikkim and Himachal Pradesh.
• Lagoons and backwaters — shallow coastal water bodies, such as Kaliveli in Tamil Nadu and Vembanad in Kerala.
• Freshwater lakes of the northeast — such as Loktak in Manipur, Barapani (Umiam) in Meghalaya, and Pulicat, which lies on the boundary of Andhra Pradesh and Tamil Nadu.

A glacial lake in East Sikkim near Gangtok, known as Lake Tsomgo or Changu Lake, is a typical high-altitude example, and it should not be confused with the lakes of Ladakh or Himachal Pradesh.

Some lakes are known through landmarks near them. Panchmuli Lake is associated with the Kevadia area of Gujarat, which is also the site of the Statue of Unity.

In matching questions, a lake is matched to its State by its location, so students should memorise the State of each major lake rather than relying on the regional name alone.

Census 2011 population statistics

The Census of India is conducted every ten years, and the 2011 Census provides the reference data for population size, age structure, sex ratio, literacy, density and urbanisation. Each of these terms has a precise definition, which is often tested through statements that look similar but differ in one key condition.

Adolescents are persons in the age group of 10 to 19 years. This group makes up roughly one-fifth of the total population, not half, and it is regarded as a youthful segment with high potential for education, skill development and the workforce. In this age group males outnumber females.

Literacy in the Census is defined by the ability to read and write with understanding in any language. The condition is applied to persons aged seven years and above, and a person who can only read, without being able to write, is not counted as literate.

Population density is the population divided by the geographical area of the State. It is the correct measure for comparing States, not the total population. Among the north-eastern States, Assam had the highest density, while Arunachal Pradesh had the lowest.

Urban classes are based on population size. Class I towns have 100,000 persons and above, and Class VI towns have fewer than 5,000. The share of the urban population held by a class is different from the number of towns in that class, and in the 2011 Census the Class III band of 20,000 to 49,999 persons held the largest share among the options listed.

Indian sea ports

India has major ports on both coasts, and each port is associated with particular cargo, hinterland and industries. In examinations, a port is usually linked to its cargo, its State, or the physical features of its site.

• Mormugao — a major port in Goa, used for the export of iron ore, with Japan among its principal buyers.
• Kandla (Deendayal) — a major port in Gujarat, known for general cargo and petroleum handling.
• Ennore — a port in Tamil Nadu linked to coal, power and general cargo.
• Kochi — a port in Kerala known for container traffic and shipbuilding.