Sub-tropical
Explanation
The climatic character of a river basin is primarily determined by its latitudinal position. The Ganga-Brahmaputra basin is a distinct geographical region situated in the Northern Hemisphere, heavily influenced by the monsoon winds.
Detailed Analysis:
- Latitudinal Extent: The Ganga-Brahmaputra basin lies between 10°N and 30°N latitudes. This latitudinal belt is geographically classified as the sub-tropical region.
- Climatic Features: The area is dominated by a Monsoon climate. It is characterized by hot summers, heavy rainfall during the Southwest Monsoon season (mid-June to mid-September), and cool winters.
- Elimination of Other Options:
- Equatorial: This climate is found between 0° and 10° latitudes (e.g., the Amazon Basin). The Ganga-Brahmaputra basin is located north of this zone.
- Temperate: This climate typically prevails in latitudes between 30° and 60°. While the upper reaches of the Himalayas within the basin may experience temperate to alpine conditions due to high altitude, the vast plains and the basin as a whole are sub-tropical.
- Polar: This refers to the high-latitude frigid zones, which is incorrect for this region.
Key Takeaway:
The Ganga-Brahmaputra basin is situated in the sub-tropical region (10°N to 30°N) and is characterized by a distinct monsoon climate.