EQ2- 5.5+6 surpluses + climate change

Question 1

areas susceptible to flooding

small river basins

Answer 1

-saturated soils so less infiltration
-steep slopes increase fast run off
-lots of tributaries so more water available to flood
-over topping/bankful stage = flooding stage

Question 2

areas susceptible to flooding

urbanised areas

Answer 2

-impermable concrete so cannot infiltrate/perculate
-increase surface run off
-fewer trees to intercept
-drainage systems can overfill- pluvial flooding= no river system but sheer excess of water so drains cannot cope w quanitiy of water

Question 3

areas susceptible to flooding

river estuaries

Answer 3

-river meets sea risk of coastal flooding
-storm surges
-EG- river thames

Question 4

areas susceptible to flooding

low lying parts of flood plains

Answer 4

-get them in middle/lower- tributariy water connects to main channels here
-increased discharge in lowerpart of river

Question 5

meteorological causes of flooding

flash flooding

Answer 5

-floods occur following intense torrential storm
-in uk w/extreme rainfall events in summer months
-intensity of rain exceeds capacity of river to cope w/amount of water
-sept 2016: one caused travel chaos in england as thunderstorms deposited almost half a months worth of rain in some places within hours

Question 6

meteorological causes of flooding

monsoon rainfall

Answer 6

-a seasonal change in direction of prevailing winds of a world region
-south + south east asia between may+ sept (warm moist air from sw indian ocean blows to india, sri lanka,bangladesh)
-july 2016: heacy MR in phillipines led to flooding landlsides + evacuations in villages just NW of the capital Manila
-in this case a larger than normal low pressure system brought heavier rain than usual

Question 7

meteorological causes of flooding

mid latitude depressions -low pressure

Answer 7

-this happens when polar front jet stream is meandering steadily in mid latitudes
-each depression brings 2 bands of rain :
1. showers + rain w/ warm front
2. heavier rain w/ cold front
-the ground may be able to absorb some of rainfall but when groundwater + through flow cannot transfer the water quickly it becomes saturated
-so rain turns to runoff + this ups rivers discharge = floods

Question 8

meteorological causes of flooding

melt water + glacial outbursts

Answer 8

-flooding can occur when snow melts + water cant infiltarte into soil/ground surface
-winter 2013: norfolk police reported flood caused by snowmelt + ice after very mild, wet + windy weather caused rapid thawing
-combination of heavy rain + thaw brought flooding in some places
-red river in dakota usa 2009: record flood leevls due to rise in temp causing SM

Question 9

jokulhaup

Answer 9

-a type of glacier outburst flood that occurs when dam containing a glacial lake fails

Question 10

surface water flooding

Answer 10

-floodijng occurs when intense rainfall has insuffecient time to infiltarte teh soil, so flows overland

Question 11

groundwater flooding

Answer 11

-flooding that occurs after the ground has become saturated from prolonged heavy rainfall

Question 12

flash flooding defintion

Answer 12

-flood w/ an exceptionally short lag time: often mins or hours

Question 13

human causes of flood

deforestation

Answer 13

reduce interception+evapotranspiration
-^surface run off-ensures rain reaches river channels faster=more flashy hydrographs
-^rates of erosion (soil)-more sediment in river so less capacity to hold water
-eg nepal+tibet known to be ^ frequency + magnitude of floods in bangladesh from ganges

Question 14

human causes of flood

urbanisation

Answer 14

-more impermable surface so ^ rate of surface run off into river via urban drainage system
-river lag times shortened by urban drainage systems-aim to transfer water effeciently into water corses so that streets dont flood or have standing wtaer]
-bridges+culkets

Question 15

human causes of flood

floodplain mismanagment

Answer 15

-alterations at 1 point in drainage basin can cause negative imapcts further downstream
-hard engineering is designed to reduce frequency of floods
-HE- embankments to ^ channel capacity but may simply operate by transferring discharge to unprotected areas or choke points downstream

Question 16

human causes of flood

flood plain drainage

Answer 16

-common in dveeloped countries to provide land for agriculture+ expend urban areas
-drainage processes reduce natural storage capacity of floodplain, especially where natural wetland r lost
-land may shrink as dries out, get lower+ more susceptible to flooding

Question 17

climate change

precipitation input

Answer 17

-higher frequency og intense rain events mainly over land areas
-warmer temps more rain is falling as rain rather then snow
-sahel is an exception

Question 18

climate change

evaporation + evapotranspiration

Answer 18

-lower atmosphere becomes warmer
-ET rates rise resulting in increase in amount of mositure circulating throughout troposphere

Question 19

climate change

soil moisture

Answer 19

-warmer temps have led to increase drying of land surface in some area w/the effect of an increased incidence + severity of drought
-sahel region has been experincing harsher drought conditions

Question 20

climate change

run off + stream flow

Answer 20

-a 1degree c rise in temp could increase global run off by 40%
-seasons w highest water demand (summer + fall) are impacted by reduced availability of fresh water
-

Question 21

climate change

groundwater flow

Answer 21

-surface water levels dry to much it can drop
-so more pressure to extract from aquifers + groundwater flows

Question 22

climate change

reservoir, lake + wetland storage

Answer 22

-increase evaporation leads to reduced water in these stores
-eg pantel brazil

Question 23

climate change

permafrost

Answer 23

-stores methane: 21 more times warmer than co2
-changes in phsyical climate at high latitudes, primarily rise in air + ocean temperature are leading to permafrost degrationin northern areas
-impacts groundwater supply

Question 24

climate change

snow

Answer 24

-the length of snow cover season has decreased; especially in northern hemisphere in last 50-100 years
-snowmelt is easier

Question 25

climate change

ice

Answer 25

-ice stores in retreat
-glaciers have retreated globally since end of ‘little ice age’
-thinning of glacier due to melting ice has accelerated since 1970s
-this is due to rapid temp rise + changes in precipitation type

Question 26

climate change

ocean

Answer 26

-in areas of ocean warming an increased evaporation will occur
-there is limited evidence however more cyclones are being generated
-eustatic + isostatic adjustement

Question 27

Anthropogenic Global Warming

Answer 27

-due to ^ ​greenhouse gases​ in atmosphere . could lead to many diff impacts affecting the hydrological cycle:
-if temps rise=period between ENSO cycles (now every 2-3 years) could ​decrease​=affect south usa+australia
-global temo ^=^evaporation=​droughts​ + ​increasing water scarcity​.
-BUT, for some=^ convectional rainnfall + enhanced tropical cyclone/depression intensity=more intense+periodic flooding

Question 28

CC= ​reduce inputs, reduce stores but may increase outputs​ w/in the hydrological cycle:

Answer 28

-Less precipitation
- Less water available in stores
-Reduced size of snow and glacier mass
-Water Table drops (height/ capacity of groundwater store) and Aquifer stores deplete
-High rates of evaporation
-More frequent cyclones and monsoons

Question 29

storm desmond
uk
2015

Answer 29

• it made an atmospheric river, bringing in moist air from the Caribbean to the British Isles.
• so, rainfall from Desmond was unusually heavy.
• heavy rain n strong winds were caused by an area of low pressure which arrived on Friday from the Atlantic.
• £500m damage

Question 30

causes of storm desmond

Answer 30

• urbanisation
• thing soils n veg=low interception n heavy grazing
• non porous n igneous rocks= more surface runoff
• number of tributaries
• heavy prolonged rainfall=saturate soils,
• steep sided mountain valleys=faster runoff

Question 31

impacts storm desmund

Answer 31

• £500mn damage
• 100 bridges damaged
• ## 5000 homes flooded