Flooding Flashcards
what is evaporation?
when water drops turn into gas and move into the sky
what is condensation?
water drops turn from a gas into a liquid
what is precipitation?
waterfall from the sky e.g. snow, hail, rain
what is transpiration?
when water evaporates out of plants
what is percolation?
when rain moves into the land
what is ground water flow?
when rain moves through the land
what is surface run off?
water that flows over land
why do urban areas have increased flood risk?
•water will not infiltrate into the ground because of urbanisation and a lack of permeable surfaces
•this means there will be more over land flow meaning river discharge increases
what a human factors affecting flood risk?
•urban areas
•deforestation
•agriculture
how does deforestation affect flood risk?
•trees and water take in water which transpires back into the atmosphere
•less plants means less water is intercepted increasing the amount of surface run off
how does agriculture affect flood risk?
less crops to intercept water means more water infiltrates into the ground and more is left as surface run off
what are physical factors affecting risk of flooding?
•precipitation
•geology
•relief
how does relief affect flood risk?
*steep land means surface run off occurs before infiltration meaning the water runs into the river faster resulting in floods
how does geology affect flood risk?
-permeable rocks mean water can infiltrate into the ground becoming groundwater flow and going into the nearest river
-impermeable rock means water cannot Inflitrate into the ground increasing surface run off
how does prolonged/heavy rainfall cause flooding ?
•sudden bursts of heavy rainfall/prolonged rainfall result in the infiltration rate being too slow to cope
•the grand may become too saturated leaving more surface run off
what is a hydrograph?
a graph that shows the relationship between river discharge and precipitation
