2.4 - Pakistan Floods Flashcards
ITCZ - Interntational Convergence Zone
A low pressure band around the Earth which generally lies near to the equator. The trade winds in the northern and Southern Hemispheres join to develop frequent thunderstorms.
Causes Of Flooding
Monsoon
Glacial Meltwater
Seasonality
Hydrological Flooding
ENSO - La Niña
Monsoon
The Indian subcontinental heats rapidly which causes hot air from the sea breeze to rise creating a low pressure filled with cool air from the Indian Ocean is drawn in
Glacial Meltwater
Melted water from glaciers can cause high elevation lakes which can overflow due to excessive glacial meltwater
Seasonality
Seasonal rainfall
Hydrological Flooding
Excessive infiltration leads to a saturated ground which results in overland flow leading to flash floods as the water has nowhere else to go.
La Niña
La Niña causes warmer than average sea surface temperatures in the eastern ocean, providing additional moisture for monsoon depressions.
Pakistan Floods
1/3 of country submerged
1000+ deaths
Agriculture finished and they’re highly dependant on this
$10bn damage
Extreme Monsoon Rainfall
Hot summers make the monsoon less predictable as the atmosphere can bear more moisture.
Heavy & Prolonged Rainfall
The jet stream meanders more due to an increased temperature gradient, meaning rain events take longer to move on, and the ground becomes saturated quicker and river banks first as they reach capacity.
Intense Storms & Flash Flooding
Steep slopes increase water flow, ENSO enhances rain, Floods wash away embankment allowing water to spread more widely.
Snowmelt
Temperatures rise, Black pollution absorb more heat, causing the river to have increased discharge and the glacial lake to have outbursts.
