5.2 + 5.3

Question 1

describe orographic rainfall

Answer 1

• air is forced to rise over a barrier such as a mountain
• due to cooler temperatures (resulting from higher altitudes) the water vapour condenses into clouds
• heavy rain on the highlands, which empties the clouds and leaves a rain shadow down the slope

Question 2

describe cyclonic (frontal) rainfall

Answer 2

• warm and cold air move towards each other
• as warmer air is less dense it rises over the colder denser air
• as it rises it cools and condenses, the extra potential energy also means it looses the ability to store the vapour so it precipitates

Question 3

describe convectional rainfall

Answer 3

• warm air rises vertically up over cool air
• warm air cools due to increased altitude and condenses
• as more vapour builds up, it rains
• as the air cools down it begins to descend and is replaced by warmer air

Question 4

what conditions are needed for rainfall

Answer 4

• air cooled to saturation point with relative humidity near 100%
• condensation nuclei, such as dust particles to facilitate the growth of droplets in clouds
• temperature below the “dew point”, temperature at which dew forms, a measure of atmospheric moisture

Question 5

which water store has the longest residence time

Answer 5

crysphere- 15,000 years

Question 6

what is the largest store of water and what is its percentage. What is its residence time ?

Answer 6

Oceans, 96.9%

residence time: 3600 years

Question 7

what impacts the drainage basin hydroglogical system

Answer 7

1) the volime of percipitation direct impact on discharge, the higher the amoun the lower the variability
2) Type of percipitation (rain, snow or hail) snow can act as a temporary store and large fluxes of water can be released after a thaw, resulting in rapid melting
3) seasonality- some climates such as the mediteranean, a monsoon or continued have strong seasonal patters of percipiration which have major impact on the physical processes operating in the drainage basin system
4) percipiration intensity - If percipitation of e.g. rain is intense then it is less likely that it will infiltrate the soil as it will be laready saturated
5) variability:
- secular variability, long term for example as a resilt of climae change
- periodic variability, happens in an annual seasonal monthly diuralcontext
- stochaic variability, results from random factors, for example the localisation of a thunder storm within a basin
6) distribution of percipitation form basin (mainly for large basins e.g. nile) were bateries start in different climatic zones. At a local scale and shorter time scales,the location of a thunerstorm can have a large impact temporarily as inputs will vary

Question 8

list which land types intercept most, starting from most interception to least

Answer 8

• coniferous
• decidious, summer + spring
• decidious, autumn + winter
• arable farmland
• deforested

Question 9

what atmospheric factors contribute to high levels of intercpetion

Answer 9

• intermitent percipiration
• sunlight
• not windy conditions

Question 10

what increases infiltration rates

Answer 10

• many trees with many roots
• porous and sandy soil
• low water table
• porous/permeable rocks

Question 11

what increases surface run-off

Answer 11

• soil saturation
• imperbeable rocks
• clay rather than sany soil
• urbanisation
• steeper slopes

Question 12

wjat increases rates of soil throughflow

Answer 12

• sandy soil
• saturated soil
• premiale rock

Question 13

define evapotransipration

Answer 13

total amount of moisture removed from drainage basin by process of evaporation and transpiration

Question 14

what factors affect evapotranspiration and how do they affect it

Answer 14

• temperature: icreases rate of evaporation, evaporation and temperature increases with sunshine hours
  wind: will increase the rate of evaporation by reducing the relative humidity
• vegitation cover: transpiration increases proportionally with vegitaiton cover which depends on the season and type of vegitation. Low albedo vegitation, such as a dark forest will absorb more solar radiation which increase transpiration
• soil moisture content: determines the volume of water available for transpiration. It is dependandt on soil and rock permeability

Question 15

define Channel flow

Answer 15

water that has collected to flow in a rivulet, stream or river and is another output from the drainage basin system

Question 16

define discharcharge

Answer 16

• discharge of a river is the volume of water passing a specific gorging station per unit time and is measured in cubic metres per seceond, cumecs
• It is dependant on: percipitation flowing in the channel, contributions from drainage basin stores via surface run off, throughflow or groundwater flow

Question 17

what are the human disruptions in the drainage basin

Answer 17

cloud seeding
dam construction
urbanisation
ground water extraction
arable and pastoral farming

Question 18

what is cloud seeding

Answer 18

expulsion of particulates from power stations such as hydrosopic nuclei which provide space for water milecules to attatch onto to form clouds

Question 19

how does dam construction intefere with drainage basin

Answer 19

• increase surface storage

- exposed water increases evaporation

Question 20

how do aaquifiers interfere with drainage basin

Answer 20

• water is taken from ground
• goundwater stores decrease
• lowers the groundwater flow