Flashcards
Rivers
Cards in this deck (43)
- 1Hydrological cycle (water cycle)is the continuous movement of water on the Earth between the land, sea and air. It is powered by the Sun.
- 2Evaporationwhen water turns into water vapour and rises after heating
- 3Condensationwhen water vapour turns back into water droplets after cooling
- 4Transpirationwater vapour given off by plants
- 5Precipitationwater in any form that falls to earth
- 6Surface run offwater running over the surface of the earth
- 7Groundwater flowWater that travels underground through rock
- 8A drainage or river basinis an area of land that is drained by a main river and its tributaries (small rivers joining the main river).
- 9—River source
- 10—River mouth
- 11—Confluence (point where two rivers meet)
- 12The drainage basin cycle is an .... system as water can be added or taken away from it, into neighbouring river basins. Look at the diagram of the drainage basin cycle below and check you understand all the new terms on this diagram.open
- 13Aquifierrock that stores water
- 14Interceptionwhen water is stopped from reaching the ground often by plants
- 15Stem flowwhen water travels down the stem or trunk of a plant
- 16Infiltrationwhen water soaks into the soil surface
- 17PercolationWhen water moves downwards through underground rocks
- 18Through flowwater traveling sideways through soil
- 19When you look at the whole course of a river, we call this ariver's long profile
- 20—upper course (highest velo)
- 21—middle course (velo is less than upper)
- 22—lower course (velo is low)
- 23Hydraulic actionThis process involves the force of water pushing air into the cracks of the beds and banks which forces them apart
- 24AbrasionThis is the process by which the bed and banks are worn down by material in the river (load).
- 25AttritionMaterial (the load) carried by the river bump into each other and so are broken down and smoothed
- 26CorrosionThis is the chemical action of river water. The acids in the water slowly dissolve the bed and the banks.
- 27Rapids
- 28TractionBoulders and pebbles are rolled along the river bed at times of high discharge
- 29SaltationSand sized particles are bounced along the river bed by the flow of water
- 30SuspensionFine clay and sand particles are carried along within the water even at low discharges
- 31SolutionSome minerals dissolve in water such as calcium carbonate. This requires very little energy.
- 32oxbow lakesAn oxbow lake forms when a meandering river erodes the outer bank of a bend, creating a shortcut. Over time, sediment deposition cuts off the loop, leaving a U-shaped body of water separate from the main channel.
- 33how are deltas formedDeltas are formed at the end of a river, where the river meets the sea at its mouth.
As large rivers approach the sea they have the energy to carry large amounts of fine material in suspension.
When they reach the sea this slows their velocity and they lose their energy.
The fine material is then deposited into the mouth of the river and can block the channel.
The river has to divide into a series of smaller channels called distributaries tin order to each the sea.
Over time, the deposited material (sand and silt) builds upwards and can break through the river surface to form a delta.
Deltas will only form where large amounts of material are carried or the sea is calm. - 34Dischargethe amount of water in a river at any time
- 35human causes of flooding in bangladeshdeforesation in bangladesh
- 36human causes of flooding in bangladeshnew urban areas
- 37human causes of flooding in bangladeshglobal warming
- 38phsyical causes of flooding in bangladeshthe himalyans are north of bangladesh
- 39phsyical causes of flooding in bangladeshmonsoon climate (summer rain)
- 40phsyical causes of flooding in bangladeshfloodplain for nearby rivers (ganges)
- 41effects of flooding in bangaldesh-Part of the country ran out of electricity for several weeks
-Brings water for growing crops
-Railway, roads and bridges were destroyed. (Covered with water)
-People suffered from diseases, such as cholera.
-Little safe drinking water
-Delivery of overseas aid was almost impossible because the airport was under 2 metres of water (1998)
-Food shortages caused loss of life, destruction of crops and serious damage to property.
-7 million houses were damaged
-68% of the country was flooded
-Not enough hospital spaces due to diseases
-36 million people affected - 42causes of flooding-Most of the Bangladesh is a floodplain, no more than 6 metres above sea level
-Bangladesh has monsoon climate
-Heavy rain coincides with that of the highest temperature
-Global warming causing the sea level to ride
-Deforestation (cutting down trees) causing no interception
-Impermeable roads in Dhaka cause more surface run-off - 43floodplains and leveesFloodplains and levees are formed in the middle and lower course of a river
Floodplains and leveés are formed by deposition in times of river flood.
The river’s load is composed of different sized particles.
When a river floods it deposits the heaviest of these particles first. The larger particles, often pebble-sized, form the leveés.
Levees are raised banks right next to the river banks.
As the water continues to flood futher away from the river banks, the sands are deposited next, then the silts and finally the lightest clays.
This build up of sand, silt and clays leads to the formation of a flat piece of land (floodplain) either side of the river- just after the levees.
Every time the river floods deposition builds up the floodplain.