Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Hydrology & Fluvial Geomorphology > Content > Flashcards

Content Flashcards

1
Q

What is a drainage basin system?

A

Refers to the area drained by a river and its tributaries. It is a natural system with inputs, flows and stores of water and sediment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a hydrological cycle?

A

Refers to the cycle of water between atmosphere, lithosphere and biosphere (air, land and sea).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is precipitation?

A

The conversion and transfer of moisture in the atmosphere to the land.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is interception?

A

Interception is the precipitation that is collected and stored by vegetation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 main components of Interception?

A
  1. Interception loss — water that is retained by plant surfaces and which is later evaporated away or absorbed by the plant.
  2. Throughfall — water that either falls through gaps in the vegetation or which drops from leaves/ twigs/ stems.
  3. Stemflow — water that trickles along twigs/ branches & finally down the main trunk.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 4 main characteristics that affect local hydrology?

A
  1. Total amount/ Intensity of Precipitation.
  2. Type of Precipitation
  3. Geographical distribution
  4. Temporal variability (eg seasons)

Precipitation is the main input into the drainage basin system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is evaporation?

A

Refers to the transformation of liquid water from the Earth’s surface into a gas (water vapour).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is transpiration?

A

Refers to the water loss from vegetation to the atmosphere.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is evapotranspiration?

A

Refers to the combined loss of water to the atmosphere through transpiration and evaporation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is infiltration capacity?

A

The maximum rate at which rain can be absorbed by soil.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is Field Capacity?

A

Refers to the amount of water held in the soil after excess drains away.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is Wilting Points?

A

Refers to the range of moisture content in which permanent wilting of diff plants occurs.

They define the approx limits to to plant growth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is Throughflow?

A

Refers to water flowing through the soil in natural pipes and percolines (lines of concentrated water flow between soil horizons)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 types of Hydrographs?

A
  1. River Regime (Annual H)
  2. Flood Hydrograph (Storm H)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a River Regime?

A

A RR is the annual variation in the flow of a river.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 5 factors that affect the character of a River Regime?

A
  1. Amount & nature of precipitation
  2. Local rocks - esp porosity & permeability
  3. Shape/ morphology of the drainage basin (area & slope)
  4. Amount & type of vegetation cover
  5. Amount & type of soil cover
17
Q

What is a flood hydrograph?

A

A FH shows how the discharge of a river varies over a short time.

18
Q

What is a flood hydrograph?

A

A FH shows how the discharge of a river varies over a short time.

19
Q

Explain a Flood Hydrograph.

A

Before the storm starts, the main supply of water to the stream is through groundwater flow/ baseflow. During the storm, some water infiltrates into the soil while some flows over the surface as runoff. This reaches the river quickly as quickflow. This causes a rapid rise in the level of the river. The rising limb shows how quickly the floodwaters begin to rise, whereas the recessional limb is the speed with which the water level in the river declines after the peak. The peak flow is the maximum discharge of the river as a result of the storm and the lag time is the time between the height of the storm and the maximum flow in the river. (not the start or end)

20
Q

What are the 9 factors that influence the FH?

A
  1. Precipitation type & intensity
  2. Temperature & evapotranspiration
  3. Antecedent moisture - if it had been raining previously, ground is saturated/ near saturated = quick overland flow & a high peak flow & short time lag.
  4. Drainage basin size & shape
  5. Drainage density - basins w high drainage density (eg urban basins w network of sewers + drains) lower lag time
  6. Porosity & impermeability of rocks & soils - impermeable surfaces (commonly found in urban) cause more overland flow. Rocks eg chalk & gravel are more permeable & allow water to infiltrate and percolate.
  7. Slopes - steeper slopes create more overland flow/ runoff = shorter lag time & higher peak flow
  8. Vegetation type
  9. Land use
21
Q

What are the 4 methods of Sediment Transport in rivers?

A
  1. Suspended load – small particles eg clay/ silts
  2. Saltated load – large particles eg sand/ gravel/ tiny stones (transported in series of ‘hops’)
  3. Traction load/ Bed – pebbles are shunted along the bed
  4. Solution – calcareous rock dissolved
22
Q

What are the 3 things that cause deposition?

A
  1. Reduction in gradient – decreases velocity & energy
  2. Decrease in the volume of water in the channel
  3. Increase in friction between water and channel
23
Q

What are the 4 Erosion processes in rivers?

A
  1. Hydraulic action – the force of water & air on the sides of rivers and in cracks
  2. Abrasion – the wearing away of the bed & bank by the load carried by the river.
  3. Attrition – the wearing away of the bed & bank by the load carried by the river = creates smaller & rounder particles
  4. Solution – a form of chemical erosion which affects calcareous (lime-rich) rock.
24
Q

What are the 3 Patterns of Flow in rivers?

A
  1. Laminar flow – smooth, straight channel / low velocity / parallel to channel bed
  2. Turbulent flow – high velocity / increase in bed roughness / associated w hydraulic action
  3. Helicoidal flow – horizontal turbulence / ‘corkscrew’ motion / associated w presence of alternating pools & riffles in channel bed = erosion & deposition by HF creates meanders.
25
Q

Channel landforms

A
26
Q

Channel landforms

A
27
Q

Channel landforms

A
28
Q

Explain a few general Urbanising Influences on Hydrology.

A

Removal of trees & vegetation = decreased evapotranspiration & interception, increased stream sedimentation

Construction of storm drains & channel improvements = local relief from flooding but concentration of floodwaters aggravates flood problems downstream.

Initial construction of infrastructure eg houses/ streets = decreased infiltration & lowered groundwater table → increases storm flows and decreases base flows during dry periods.

29
Q

How do Dams impact evaporation and transpiration?

A

There has been an overall increase in evaporation due to the construction of dams.

For example, Lake Nasser behind the Aswan Dam loses up to ⅓ of its water due to evaporation.

Water loss can be reduced by using chemical sprays on the surface or by building sand-filled dams/ covering damns with plastic.

30
Q

Define drought.

A

Drought is an extended period of dry weather leading to conditions of extreme dryness.

31
Q

What are the 2 types of droughts?

A
  1. Absolute drought – period of at least 15 consecutive days with less than 0.2mm of rainfall.
  2. Partial drought – period of at least 29 consecutive days during which the average daily rainfall doesn’t exceed 0.2mm.
32
Q

What are the 5 factors that cause such dry conditions?

A
  1. Global atmospheric circulation – dry, descending air associated with the subtropical high-pressure belt → main cause of aridity around 20-30° N and S.
  2. Distance from sea/ continentality – limits the amount of water carried across by winds.
  3. Cold offshore currents – limits the amount of condensation in the overlying air.
  4. Rain-shadow effects
  5. Human activities such as desertification.
33
Q

What are some human factors that intensify floods?

A
  • Urbanisation & urban growth – increase in impermeable surfaces
  • Floodplain developments – increase risk of damage
  • Bridges, dams & obstructions – leads to ponding & possible flooding
  • Changes in vegetation cover – eg agriculture
  • River engineering works – eg leeves
  • Human-induced climate change – carbon footprint?
34
Q

What is a Recurrence Interval?

A

Refers to the regularity of a flood of a given size.

35
Q

Forecasting & Warning methods

A
  • Collection of meteorological information and mapping of channels → better gauging of rivers
  • Better & current info about human populations, infrastructure, elevation & stream channels to improve flood risk assessment models.
  • Better and More complete & timely sharing of info between forecast, national agencies, relief organisations, media & general public.
36
Q

Prevention & Amelioration (improvement) of floods

A

Socioeconomic control

  • Disaster aid
  • Insurance

Physical control

  • Event modification – eg environmental control & hazard-resistant design.
  • Flood abatement – decreasing amount of runoff → using: reforestation, slope treatment to reduce runoff coefficient (eg contour ploughing & terracing), preservation of natural water storage zones eg lakes
  • Flood diversion – construction of levees, reservoirs & modification of river channels.

Hydrology & Fluvial Geomorphology (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions