Deccan Plateau: location, rivers, black soil and rain shadow
The Deccan Plateau is the great triangular tableland of peninsular India, bounded by the Western and Eastern Ghats. Learn its extent, rivers, Deccan Trap rocks and why its interior is dry.
The Deccan Plateau is a large, roughly triangular tableland in peninsular India, lying south of the Narmada river between the Western Ghats and the Eastern Ghats, sloping gently eastward so that its great rivers — the Godavari, Krishna and Kaveri — flow into the Bay of Bengal.
Where the plateau lies
The Deccan Plateau, also called the Peninsular Plateau, is the broad tableland that forms most of southern India. It is shaped like an inverted triangle, with its broad end at the Narmada river basin near the Satpura and Vindhya ranges in the north and its tip towards the northern fringes of Tamil Nadu in the south.
It covers most of Maharashtra, Karnataka, Telangana and Andhra Pradesh, excluding their coastal strips, along with smaller parts of Kerala and Tamil Nadu. Its area is given as 422,000 sq km on the narrower definition, while broader definitions that count more of the peninsula reach about 5 lakh sq km, so the figure you meet depends on where the boundary is drawn. The plateau is usually divided into the Maharashtra, Karnataka and Telangana plateaus.
Rocks and soil: the Deccan Traps
The north-western plateau is built from the Deccan Traps, layer upon layer of basalt laid down by lava flows after a massive volcanic eruption at the end of the Cretaceous period, about 66 million years ago. In places these lava layers are more than 2 km thick, and beneath them lie much older granite and sedimentary rocks formed during the Precambrian era and the assembly of Gondwana.
Weathering of the basalt produces black soil, or regur, which is high in clay, retains moisture and resists erosion, but develops deep cracks in the dry season. It is one of the plateau's great agricultural assets. In the drier eastern parts, where the rock is different, red soils are more common and less fertile.
Rivers and the rain shadow
The plateau is one of India's great watersheds. The Godavari, Krishna and Kaveri all rise in the Western Ghats and flow eastwards to the Bay of Bengal, and their valleys hold the plateau's best-watered farmland. Dams across these rivers store water for irrigation and hydroelectric power.
Climate follows the same eastward logic. Moist air from the Arabian Sea is forced up the Western Ghats, cools and drops its rain on the coast, then descends onto the plateau dry. The interior is therefore semi-arid in the north and tropical elsewhere, with hot, dry summers in April and May and most rainfall arriving with the monsoon from July to September.
Life and livelihood on the plateau
The plateau is rich in minerals, including iron ore, coal and mica, and its black-soil tracts support cotton, millets, pulses, oilseeds and sugarcane, with rice where irrigation reaches. Agriculture remains the main occupation in much of the region, while cities such as Hyderabad anchor industry and information technology.
The name itself is a geography clue: Deccan comes from the Sanskrit word dakṣiṇa, meaning south, marking this as the land south of the great northern plains. Its dry woodlands, home to teak, axlewood and acacia, also shelter tigers, elephants, gaur and blackbuck.
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Frequently asked questions
Where is the Deccan Plateau located?
The Deccan Plateau covers much of peninsular India south of the Narmada river, bounded by the Western Ghats in the west, the Eastern Ghats in the east, and the Satpura and Vindhya ranges in the north, tapering towards the Nilgiri Hills in the south.
Which rivers flow through the Deccan Plateau?
The Godavari, Krishna and Kaveri are the principal rivers. They rise in the Western Ghats and flow eastwards across the plateau into the Bay of Bengal, because the plateau slopes gently from west to east.
Why is the Deccan Plateau dry?
The Western Ghats intercept the moisture-bearing southwest monsoon winds, so the air reaching the plateau interior is already dry. This rain-shadow effect gives the interior a semi-arid climate, with most of its rain falling between July and September.
What is black soil of the Deccan?
Black soil, also called regur, forms from the weathering of basalt rock. It is rich in clay, holds moisture well and cracks when dry, and it is famously suited to growing cotton, especially in Maharashtra.
What is the average elevation of the Deccan Plateau?
The plateau's average elevation is about 600 metres. It is higher in the west, near the Western Ghats, and lower towards the east, which is why its rivers flow east.