(a) Explain the impact of tropical cyclones and western disturbances on the climate of India. 20 (b) Examine the critical issues…

India’s climate, water balance and physiography are linked by circulation systems that redistribute heat and moisture, by aquifers that store that moisture, and by the Deccan’s structure that channels runoff.

Tropical cyclones are warm-core systems generated over warm tropical seas, where latent heat release from evaporation lowers central pressure and deepens circulation. In India, most originate in the Bay of Bengal during pre-monsoon and post-monsoon months, while Arabian Sea cyclones are less frequent. On landfall, they dump intense coastal rainfall, produce storm surges and wind damage, especially in Odisha, Andhra Pradesh and Tamil Nadu. Their climatic role is not merely destructive: they release stored oceanic heat, redistribute moisture into the interior, alter short-term temperature and humidity, and can influence the timing of monsoon withdrawal by changing low-level moisture flow. Their timing also matters: pre-monsoon systems can add moisture before Kharif sowing, while post-monsoon systems can delay Rabi field operations. The Bay of Bengal’s shallow, warm waters make its cyclones particularly frequent and damaging.

Western disturbances are mid-latitude troughs in the westerlies, often of Mediterranean origin, which enter northwest India in December–February. Unlike the summer monsoon, which is a convective, ocean-to-land moisture transport, they carry moisture into a cold, dry winter atmosphere. Over Punjab, Haryana and Delhi they cause unseasonal rain and hailstorms. This affects Rabi crops: light rain may benefit wheat, but excessive rain, hail or cold damage can reduce yields. They also moderate winter temperatures and add to the non-monsoon rainfall budget of the north.

Groundwater issues are critical because India’s irrigation and domestic supply rely heavily on wells. Over-extraction in Punjab, Haryana and Rajasthan has created dark zones where water tables fall rapidly, pumping costs rise, and aquifers become vulnerable to salinisation. Contamination is widespread: arsenic is common in parts of the Gangetic plains, while fluoride is more typical of granitic and gneissic terrains, though it can occur locally in Deccan basalts. Access is inequitable: large farmers with borewells and power can extract more, while marginal farmers and rural households face scarcity and poor quality. Policy responses include Atal Bhujal Yojana, which promotes community-led demand management, and NAQUIM, the national aquifer mapping programme, which maps aquifers to guide management. State rainwater harvesting mandates exist, but implementation is uneven, recharge data are patchy, and overuse continues where water is cheap.

Deccan Plateau is a broad basaltic tableland formed mainly by the Deccan Traps, whose major eruptions occurred around 66 Ma in the late Cretaceous to early Paleocene. Repeated lava flows, cooled in thick sheets, were later dissected by rivers and weathered, producing step-like topography through differential erosion. The Western Ghats form a steep escarpment along the west, with horst-graben structural control, while the Eastern Ghats are more discontinuous and denudational. Internally, the plateau can be divided into the Maharashtra, Karnataka and Telangana plateaus. Drainage is dominated by the Godavari, Krishna and Kaveri, which cut through the basalt and carry sediment eastward. The black cotton soil, or regur, developed from weathered basalt, is thick and fertile, supporting cotton, pulses and oilseeds, but its swelling nature makes water management essential.

Together, cyclones and western disturbances show how external circulation systems shape India’s rainfall and crop risk; groundwater stress shows how uneven storage and access undermine that supply; and the Deccan’s structure shows how geology controls runoff, soil and agriculture. Sustainable development therefore requires monsoon-aware planning, aquifer conservation, and land-use suited to plateau geomorphology.