causes of flooding and management of flooding Flashcards
how does prelonged rainfall cause flooding
after lots of rain the soil becomes saturated, further rainwater cannot infiltrate and therefore increases run off into rivers which will eventually overflow
is prelonged flooding a physical or human cause?
a physical factor
what is river discharge?
river discharge is the amount of water flowing in a river
how does heavy rainfall cause flooding?
heavy rainfall means there is a lot of run off which quickly increases discharge
how does snowmelt cause flooding?
when a lot of snow melts it causes a lot of water to go into the river in a short space of time which increases discharge quickly
How does the geology of the area increase the risk of flooding?
If the rock is impermeable, water doesnt percolate into the rock so therefore flows on the surface, creating a bigger runoff
how does deforestation cause flooding?
if there are no trees then water cannot be intercepted, so by removing trees more water gets to the ground and therefore into the rivers; quickly increasing the discharge of the river
how does urbanisation cause flooding?
urban areas have a lot of buildings and roads which are made from impermeable materials, this means that there is a lot of run off and the drains take the water straight to the rivers; which also increases the discharge of the river
how do dams and reservoirs work?
dams are huge walls built in the upper course of a river and a reservoir is a large artificial lake that is built behind it
name some benefits of dams and reservoirs?
reservoirs store water and release it slowly in order to prevent flooding, the water can be used as drinking water and to generate hydroelectric power. reservoirs are attractive and can be used for recreation.
what is channel straightening?
the rivers course is straightened, this is done by artificially cutting off meanders
name some disadvantages of dams and reservoirs?
dams are very expensive to build, and creating a reservoir can flood existing settlements. Also material is deposited in the reservoirs and not in the rivers which can make farmers land less fertile
name the advantages of channel straightening?
water doesn’t travel as far so moves out of the area quicker, reducing the risk of flooing
what are man made levees?
man made embankments along both sides of the river
what are the benefits of man made levees?
they are cheap and also increase the volume of water that a river can hold
