Final answer:
The southwest monsoon brings much-needed rain for agriculture in South Asia but also causes severe flooding in certain areas. This seasonal weather pattern is key for sustaining the region's population but has negative consequences, especially in low-lying coastal regions and behind natural barriers like the Himalayas.
Step-by-step explanation:
The southwest monsoon is a critical climatic phenomenon that has significant impacts on South Asia. The advantages of the southwest monsoons include providing the essential water needed for agricultural production, replenishing rivers and streams, and supporting the biodiversity of the region. On the contrary, the disadvantages involve potential severe flooding, which can lead to destruction of property and infrastructure, disruptions in daily life and economic activities, and health hazards related to waterborne diseases.
During the monsoon season, the warm air from the heated landmass of the Thar Desert causes a low-pressure area that pulls moist air from the Indian Ocean and the Bay of Bengal over the land. This is why the monsoons typically arrive in late May or early June. It is the major source of support for South Asia's large population by watering the crops that are crucial for the livelihood of millions.
However, the monsoon can have disastrous effects on certain regions, like the coastal areas of Bangladesh and the Maldives, due to heavy flooding. The intense rains can overwhelm these low-lying areas. In contrast, the southwestern regions of Pakistan, the Thar Desert, and areas behind the Himalayan rain shadow receive little to no rain, stressing the importance of the monsoon for equitability in regional water distribution.