2 - Hydrosphere Flashcards
HYDROSPHERE: WHAT IS HYDRAULIC ACTION?
when the force of water compresses air andpressure on the bank causes material to be dislodged.
HYDROSPHERE: WHAT IS ABRASION?
when the force of water throws the bedload against thebanks wearing them down.
HYDROSPHERE: WHAT IS SOLUTION?
when soluble rocks react with acids or salts in the water.
HYDROSPHERE: WHAT IS ATTRITION?
when rocks in suspension hit off each other erodingfurther.
V-SHAPED VALLEY: SETTING
- V-shaped valleys form in the upper course of rivers where the land is often steep and rivers have high energy.
- This causes vertical erosion to dominate through hydraulic action and abrasion.
V-SHAPED VALLEY: PROCESSES
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
V-SHAPED VALLEY: OVER TIME
- Weathering causes the rocks and soils to break down on the sides of the valley. This happens quicker in colder, wetter areas.
- The hillslopes become unstable causing a mass movement (landslide) and the material falls into the river channel.
- Here it is broken up by attrition and used as tool for further erosion.
- A narrow valley is left with the river filling the whole valley floor.
- The river continues to zig zag down its course through interlocking spurs.
WATERFALL: SETTING
- Waterfalls form in the upper course of rivers where there is a band of hard rock overlaying soft rock.
- This causes differential erosion as the rocks are eroded at different rates through hydraulic action and abrasion.
WATER FALL: PROCESSES
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
WATERFALL: OVER TIME
- Softer rock is eroded more easily creating an overhang of hard rock as it is undercut.
6. The hard rock becomes unsupported and collapses into the plunge pool due to gravity. - Here material is broken up by attrition and used as tools for further erosion.
- As this process repeats itself the waterfall retreats upstream creating a gorge.
MEANDER: SETTING
- Meanders form in the middle to lower course of rivers where water twists and turns arounds obstructions such as large boulders.
- The river starts to become more sinuous (curvy) as riffles and pools lead to changes in speed, depth and direction of the river channel.
- Pools are areas of deeper water whereas riffles are shallower with greater turbulence where lateral erosion can occur through HA and A.
MEANDER: PROCESSES
- Hydraulic action deepens the bed and is when the force of water compresses air and pressure on the bank causes material to be dislodged.
- Abrasion is when the force of water throws the bedload against the banks wearing them down.
MEANDER: OVER TIME
- The river flows fastest on the outside bend increasing erosive power.
- The river flows slowest on the inside bend leading to deposition.
- Helicoidal flow moves materials across the river channel. This leads to the development of river cliffs on the outside bend and beaches on the inside.
- As erosion and deposition continue the meander will migrate downstream.
OXBOW LAKE: FORMATION
- Over time, meanders become more pronounced.
- The neck of the meander will become narrower as it is eroded.
- During a time of high energy (for example a flood or during spring when snow is melting), the water may cut through the neck of the meander.
- Deposition on the river’s banks seals off the old meander, so water no longer flows around it. This is called an ox-bow lake.
- As it is no longer being supplied by water, it will dry up.
DRAINAGE BASIN INPUTS
Precipitation is all forms of moisture that reach the earth’s surface and is the only input into a drainage basin.
DRAINAGE BASIN TRANSFERS: STEMFLOW
when water moves down the stems or trunks of plants and trees.
DRAINAGE BASIN TRANSFERS: SURFACE RUN-OFF
when water moves across the earth’s surface due to gravity.
DRAINAGE BASIN TRANSFERS: INFILTRATION
when water moves down through the soil.
DRAINAGE BASIN TRANSFERS: PERCOLATION
When water moves through the rocks below the soil.
DRAINAGE BASIN STORES:INTERCEPTION
when precipitation is intercepted by vegetation slowing down the movement of water.
DRAINAGE BASIN STORES:SURFACE WATER
when water is stored in puddles, reservoirs, lochs or ponds.
DRAINAGE BASIN STORES: SOIL MOISTURE
when water is held in the upper layers of the soil profile.
DRAINAGE BASIN STORES: GROUNDWATER
when water is stored naturally underground in the spaces between rocks/soil forming the water table.
DRAINAGE BASIN OUTPUTS: DISCHARGE
when water enters the sea at the mouth of the river.
DRAINAGE BASIN OUTPUTS: EVAPORATION
water can be evaporated from stores due to heat from the sun.
DRAINAGE BASIN OUTPUTS: TRANSPIRATION
when water vapour is lost to the atmosphere from vegetation.
IMPACT OF DEFORESTATION ON HYDROLOGICAL CYCLE
- Results in fewer trees in the drainage basin which decreases the rate of interception meaning water reaches the main river channel much quicker and increasing river discharge.
- Fewer trees can also reduce the amount of transpiration resulting in less precipitation in some regions eg The Amazon Rainforest.
- Evaporation will increase as the ground is no longer shaded by vegetation.
IMPACT OF URBANISATION ON HYDROLOGICAL CYCLE
- Results in the removal of vegetation and addition of impermeable surfaces such as tarmac and concrete. This increases surface run-off and river discharge as more water enters the river channel much quicker.
- Reduced infiltration and percolation so amount of groundwater decreases.
- This can also lower the water table.
IMPACT OF IRRIGATION ON HYDROLOGICAL CYCLE
- Channel used to divert water from rivers to be used to water crops. This reduces river discharge and increases evaporation as water is stored in irrigation channels and dams.
- Water can also be extracted from the groundwater which can reduce the amount of groundwater storage.
- Use of poor-quality water can lead to soil salinization eg California.
IMPACT OF MINING ON HYDROLOGICAL CYCLE
- Removal of soil and rock to gain access to resources below. This exposes bare rock which can increase surface run-off or percolation into groundwater.
- Due to increased surface run-off dust and sediment from the mining process can be washed into river channels or surface storage leading to siltation.
IMPACT OF TRIBUTARIES ON A HYDROGRAPH
Many tributaries = steep rising limb, higher peak discharge, shorter lag time because water flowing in a channel is quick.
Fewer tributaries = gentle rising limb, lower discharge, longer lag time because water travel via surface run-off or groundwater is much slower.
IMPACT OF VEGETATION ON A HYDROGRAPH
Bare = steep rising limb, higher peak discharge, shorter lag time because no interception, little surface storage and surface run-off is quick.
Forest= gentle rising limb, lower discharge, longer lag time because water is intercepted and travels via surface run-off or groundwater is much slower.
IMPACT OF SIZE OF DRAINAGE BASIN ON HYDROGRAPH
Small = steep rising limb, shorter lag time because water does not have far to travel to reach the river.
Large = Higher discharge, longer lag time because it receives more precipitation and water has further to travel to reach the main channel.
IMPACT OF SLOPE GRADIENT ON HYDROGRAPH
Steep = steep rising limb, shorter lag time because water flows faster down a steep slope.
Gentle = longer lag time because water flows slower.
