At least 31 people have died in a series of flood and landslide events in Afghanistan so far this monsoon season, according to the State Ministry for Natural Disaster Management. A further 74 people have been injured, and 41 more are missing, and about 250 head of livestock have been lost. Twelve people were killed and forty more are missing following a flash flood in the Jalrez District of Maidan Wardak Province, to the west of Kabul, which is reported to have damaged or destroyed more than 100 houses. Other events have occurred elsewhere in the province, as well as parts of Kabul.
A building damaged by flooding in Maidan Wardak Province, Afghanistan. AP.
Flash floods and landslides are a frequent problem in Afghanistan, where a mostly dry climate is broken by occasional bouts of heavy rainfall. The dry nature of the climate means that little of the landscape is covered by extensive vegetation (which can stabilise hillsides with root-growth), making the area vulnerable to flash floods. This situation is made worse by the widespread use of dried mud bricks as a building material, resulting in buildings that offer little protection against flooding and are easily swept away.
Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea.
Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.
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