coastal and river landscapes Flashcards
relief definition
physical features of land; steepness of slope, height above sea level, shape of landscape
name all stages of hydrological cycle
-interception
-precipitation
-infiltration
-percolation
-through flow
-surface run off
-water table
-groundwater flow
-water body
-evaporation
-evapotranspiration
-condensation
river gradient defintion
-steepness of river
long profile of river definition
line showing gradient of river from source to mouth
upper course of river features
-fastest flow
-narrow channel
-vertical erosion
-waterfall
-gorge
-V shaped valley
-interlocking spur
middle course of river features
-lateral erosion
-deposition
-meanders
-oxbow lake
-U shaped valley
lower course of river features
-widest channel
-slower flow
-high volume/discharge
-deposition
-estuaries
-flood plains
-levees
fluvial meaning
relating to rivers
4 means of transportation in river
-saltation
-suspension
-solution
-traction
thalweg definition
line of fastest flow in river; swings wide to side , causing erosion on outer bend and deposition on inner bend (causes meanders)
process of levee and floodplain
1) during rainfall and flood with high discharge river bursts banks
2)larger material deposited closer to river and small material carried further
3)after repeated flood events, layers of material build up alongside river to form floodplain (fertile and flat), and levees either side of river are increased in height.
flood definition
land not usually underwater becomes inundated. happens when a channel can no longer hold the volume of water flowing in it.
factors that increase risk of flood
-urbanisation infrastructure
-precipitation
-geology
-steep slope
-deforestation
-agriculture
-saturated ground
case study Boscastle, cornwall facts
-89mm fell in 1 hr
-90% Boscastle economy is tourism
human factors of Boscastle flood
-lots of concrete
-small + low bridges caused debris to become trapped
-material from building got trapped; acting like a dam
-several urban areas upstream
physical factors to Boscastle flood
-previous wet weather=saturated ground
-remainder of cat 2 Alex caused a storm
-heavy/prolonged rain in hrs before flood
-over years, river had become filled with sediment which reduced vol of water river could hold
-Boscastle lies at bottom of steep valley.
impacts of boscastle flood
-£50 mil total economic damage
-58 properties flooded
-sewage and debris leak led to water pollution
-90% boscastle economy is tourism
-1850 tonnes debris deposited in village
-75 cars swept into sea
-trees uprooted an swept through village by 40mph flood waters
-60 residents taken to hospital
floodplain definition
wide area of marshy low lying land either side of river. Formed mainly of alluvium (sediment/silt deposited by a river as it floods. over time height of floodplain increases
levee definition
raised riverbank found in lower course. ridge of sediment caused by repeat flooding. can be NATURAL or ARTIFICIAL
estuary definition
found where river meets sea, transitional zone between river and coastal environments. Tidal, and contain brackish water.
mudflat definition
form around estuaries, and over time develop into salt marshes
boscastle management strategies
-river Valency made 3m wider and 2m deeper
-raised car park on stilts
-permeable surface car park
-remove dead tree near river
-make bridges wider and higher
-environment agency installed 3 gauges along river (measure height of river)
-flood defence walls
results and effects of boscastle management strategies
-flood-defence scheme cost over £10 mil
-biodiversity increase as more trees have been planted on hillsides
-risk of flooding has been decreased, so risk of property damage decreases
-construction of these defence took up space and several years which disrupted locals
-bridge improves access to area
flood hydrograph definition
shows change in discharge caused by period of rainfall
