-Earth embankments provide habitat for plants and animals. CHANNELISATION River channel may -Effectively protects -Altering the river be widened or immediate area because channel may lead to a deepened to carry is moved away greater risk of flooding, more water. quicker. as water is carried there May be straightened -Long lasting. faster. to carry water -Unnatural and visually faster. intrusive. FLOOD RELIEF Channel course of -People close to channel -Needs large area of CHANNELS river can also be safer as flood water land, altered, diverting diverted to relief channel. Difficult to buy if floodwaters away. -Used for water sports. farmland. -Very expensive. DAMS Built along course of -Water usually stored in a -Very expensive. river to control reservoir behind dam. -Sediment trapped amount of Then used to generate behind wall of dam discharge. hydroelectric power or leading to erosion Water held back by recreation. further downstream. dam and released in -Settlement and controlled way. agricultural land may be lost when the valley is flooded to form a reservoir. FLOOD WALLS Vertical barrier -Can be used in areas They have to be usually made from where space is limited. constructed very well so prefabricated -Easily and quickly erected no leaks through. concrete. in pre-constructed sections. STORAGE AREAS Large depression -Natural looking. -Need a large area of close to the river -Does not damage the land that is not being that will fill with environment. used. water if the river -Only come into use overflows and when the river is therefore protecting flooded. surrounding land. SOFT ENGINEERING DESCRIPTION ADVANTAGES DISADVANTAGES TECHNIQUE FLOODPLAIN authorities and -Very cheap way to reduce -Resistance to ZONING national risk restrictions in areas of government of damage to property. shortage of housing. introduce policies to -Sustainable as reduces -Enforcing planning control urban impact of flooding and controls difficult in LIC’s. development close building damage. or on floodplains. -Surface runoff less likely to cause flooding as floodplain not built on.
-Earth embankments provide habitat for plants and animals. CHANNELISATION River channel may be widened or deepened to carry more water. May be straightened to carry water faster. -Effectively protects immediate area because is moved away quicker. -Long lasting. -Altering the river channel may lead to a greater risk of flooding, as water is carried there faster. -Unnatural and visually intrusive. FLOOD RELIEF CHANNELS Channel course of river can also be altered, diverting floodwaters away. -People close to channel safer as flood water diverted to relief channel. -Used for water sports. -Needs large area of land, Difficult to buy if farmland. -Very expensive. DAMS Built along course of river to control amount of discharge. Water held back by dam and released in controlled way. -Water usually stored in a reservoir behind dam. Then used to generate hydroelectric power or recreation. -Very expensive. -Sediment trapped behind wall of dam leading to erosion further downstream. -Settlement and agricultural land may be lost when the valley is flooded to form a reservoir. FLOOD WALLS Vertical barrier usually made from prefabricated concrete. -Can be used in areas where space is limited. -Easily and quickly erected in pre-constructed sections. They have to be constructed very well so no leaks through. STORAGE AREAS Large depression close to the river that will fill with water if the river overflows and therefore protecting surrounding land. -Natural looking. -Does not damage the environment. -Need a large area of land that is not being used. -Only come into use when the river is flooded. SOFT ENGINEERING TECHNIQUE DESCRIPTION ADVANTAGES DISADVANTAGES FLOODPLAIN ZONING authorities and national government introduce policies to control urban development close or on floodplains. -Very cheap way to reduce risk of damage to property. -Sustainable as reduces impact of flooding and building damage. -Surface runoff less likely to cause flooding as floodplain not built on. -Resistance to restrictions in areas of shortage of housing. -Enforcing planning controls difficult in LIC’s.
year-4-revision-notes-for-final-exams.docx