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Description
Flashcards by Hannah Goodenough, updated more than 1 year ago
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Created by Hannah Goodenough
about 11 years ago
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| Question | Answer |
| What is a drainage basin? | The area of land, bordered by a watershed, drained by a river and its tributaries. |
| What is a watershed? | The boundary of a drainage basin. |
| What type of system is the hydrological cycle? | A closed System. |
| What is precipitation? | Movement of water from the atmosphere to the earth surface in the form of rain snow or hail. |
| How does precipitation lead to flooding? | ->Prolonged or heavy rainfall. ->Snow acting as a store of water then melting. |
| What is overland flow? | This is a rapid form of water transfer over the surface of the ground. |
| When is overland flow most likely to occur? | ->During periods of heavy rainfall. ->When the soil has become completely saturated. |
| What is infiltration? | The movement of water from the ground surface into the soil. |
| What affects the rate of infiltration? | ->The moisture content of the soil. ->The soils porosity. (number of air spaces) |
| What is throughflow? | The downhill transfer of water through the soil layer to the river. |
| What is percolation? | The movement of water from soil into permeable rocks. |
| What is permeable rock? | A rock which can absorb water (porous) or allow water to pass through cracks and joints (pervious). |
| What is baseflow (groundwater flow)? | This is the very slow transfer of water through rocks. |
| When can groundwater/baseflow be faster? | In limestone areas where there are extensive underground channels. |
| What is the soil moisture of: ->Clay ->Sand | ->Poor. Clay soils can be very wet and boggy. ->Good. Sandy soils tend to be much drier so they absorb more precipitation. |
| What is depression storage? | When water is stored temporarily on the ground surface in the form of puddles. |
| What is interception? | Vegetation, particularly trees, stopping some precipitation on its way to the ground. |
| What does vegetation do to water transfer and why? | Vegetation slows it down. Some water is lost by evapotranspiration while some water is used for plant growth. |
| What is evapotranspiration? | When water loss from the ground surface to the atmosphere (evaporation) combines with water given off from plants (transpiration) to form a main output from the system. |
| What is the water balance equation? | P=O+E+/-S P=Precipitation O=Total run off(stream flow) E=Evapotranspiration S=Storage (in soil and rocks) |
| What causes a high runoff percentage? | ->Lack of trees ->Saturated soil ->Impermeable rock |
| What is impermeable rock? | A rock which cannot absorb water. |
| What causes a low percentage of runoff? | ->Lake (storage) ->Lots of trees. ->Dry soil ->Permeable rock |
| What is river discharge? | The volume of water passing a given point in a given period of time, usually expressed in 'cumecs' and calculated as: Cross sectional area x Velocity |
| Factors affecting the discharge of a river. | ->Distance downstream ->Climatic changes ->Land use ->Water abstraction ->Channel modifications |
| What is a storm hydrograph? |
A graph that shows the discharge of a river following a storm event.
Image:
images (image/jpg)
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| Compare the characteristics of a typical river during low-flow conditions and a typical river during high-flow conditions have? | A river during low-flow has clear water and a visible river bed while a river during high-flow has murky water and no riverbed visible. |
| The amount of energy available in a river to do 'work' depends on... | ->The height the water has to descend (gravity) ->The mass of water available. |
| When water starts to move downhill _______ energy is converted into ________ energy. | When a water starts to move downhill potential energy is converted into kinetic energy. |
| What is a load? | The sediment carried by a river. |
| What is solution? | The invisible transport of chemicals dissolved in the water. Eg. Calcium carbonate. |
| What is suspension? | Very fine-grained mud and silt which is carried in the main body of the water. (makes the river look dark and murky) |
| What is bedload? | Larger sediments being transported along the riverbed, which is too heavy to be picked up and carried as a suspended load. |
| What is traction? | Material rolling along the river bed. Eg Boulders. |
| What is saltation? | Material moving in a series of small bounces along the riverbed. Eg. pebbles |
| What is erosion? | The picking up and removal of material. |
| When does erosion occur? | When the river has surplus energy available. |
| What is abrasion? | Where particles of rock carried by the river scrape away at the riverbed and banks. This can dislodge rock particles to add to the load of a river (sandpaper affect) |
| What is hydraulic action? | Where the power of moving water is able to dislodge loose particles of rock from the riverbed or banks. |
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