Why western coast of India receives heavy rainfall but the Deccan Plateau receives very little ?

The disparity in rainfall between the western coast and the Deccan Plateau is primarily due to the orographic effect of the Western Ghats. During the southwest monsoon, moisture-laden winds from the Arabian Sea are obstructed by the Sahyadri mountains [2]. As these winds climb the windward slopes, they cool adiabatically, leading to heavy precipitation (250-400 cm) along the western coastal plains [4]. However, once the winds cross the crest and descend onto the Deccan Plateau, they undergo adiabatic warming, which reduces their relative humidity [2]. Consequently, the Deccan Plateau lies in the 'rain-shadow' area, receiving significantly less rainfall, often between 50-100 cm [3]. While the plateau lacks high mountains to force further uplift, the primary meteorological reason for the rain deficit is its leeward positioning relative to the Western Ghats.

Sources

1. [2] Exploring Society:India and Beyond ,Social Science-Class VII . NCERT(Revised ed 2025) > Chapter 3: Climates of India > The Monsoons > p. 55
2. [4] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 4: Climate > Distribution of Rainfall > p. 38
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Orographic Rainfall > p. 339