A level geography cards #3

  • Created by: Tooth04
  • Created on: 12-05-22 15:24

5.5A Causes of flooding

The primary cause of flood is either meterological (short-term weather events e.g. depressions) or long-term climatic causes such as rainfall patterns. 

In the Uk flood is normally brought on by depressions, usually in autumn or early winter as part of a progressive cycle. Yet, the annual position in the jet stream means this can occur at other times in the year e.g summer flood of 07-08. 

The degree of flooding depends on the depression sequence, where a succession of intense storms from Oct to Dec 2015 has a cumulative effect on the drainage basin - antecedent rainfall raises the water table which means the water cannot percolate leading to surface water flooding and flash flooding. -> due to sinuous jet stream blocking high-air pressure systems with Data for Northern England from the Centre of Hydrology and Ecology reported many rivers flows up to 50x normal. 

Intense season monsoon rainfall in SE Asia can result in flooding, with 70% of annual rainfall falling in 100 days from July to Sept. Bangladesh vulnerable as cities are built near river courses and half the country is only 12.5m above sea level. 

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5.5A Causes of flooding 2

Pakistan suffered floods in July 2010 to August 2010 as 9000mm of water was recieved in a week, 10x annual average. Record monsoons rains fell casuing flash floods in the Punjab and Balochistan provinces, US$43b in damages with 2,2 million hectacres of farmland inundated and 1.2 million livestock dead

Southern Africa often experiences tropical cyclones, for example in Mozambique (2000) where Botswana (experienced 75% of annual rainfall in 3 days) and other Southern African countries ran into the Limpopo, Zambezi and other rivers which flow through Mozambique to the sea. These rivers eventually burst their banks, causing severe flooding in Mozambique.

Snow and ice melt happens late spring, where spring floods in York are intensified by snow melt in the upper valleys of the River Ouse catchment. 

In the Himilayas, glacial floods occur as ice dams melt, sometimes exacerbated by eathquake or landslide induced dam failure. Johulhaup in Iceland caused by volcanic activty.

Certain geologies, soil types and vegetation cover make basins more at risk from flooding. 

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5.5B Human actions on flooding

Economic growth and population movements has caused flood plains to be built upon and landscapes altered for agriculutural and industrial purposes. 

  • Urbanisation is a key factor:
  • creation of impearmeable surfaces  increases surface run-off and reduces percolation, interception and infiltration reducing lag time. 
  • Impeding channel flow so less resilent agaisnt water surpluses. 
  • Mismanagement e.g. river straightening means more water can be carried downstream reducing lag time but cause flooding downstream.
  • Changing land use associated with agriculture - deforestation, overgrazing, ploughing. 

Urbanisation is often concentrated on lower-lying land meaning that human and physical factores collide. In 2015, recurrent flooding in areas like Cockermouth Carlise with flood defences that were only built a decade ago led to safer from future flooding talks across the Uk and EU.

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5.5C Impacts of flooding

-900 million people live in flood prone areas, with up to 75 million exposed to flooding annually. This occurs most notably in Asia with 90% of deaths and 50% of economic damages occuring here. 

  • Socio-economic impacts;
  • 0.5m depth can wash away cars and 2m per second velocity can begin to collapse buildings.
  • In developing countries, people have not learned to swim and post-flood morbidity is likely to occur from water-borne diseases. 
  • Structural damage to property is a major flood loss, where flood insurance can be difficult to secure and reduction in property values due to flood risk. 
  • In areas of subsistence farming direct loss to food supplies can lead to insecurity and famine, or escalating prices. 
  • Infastructural losses; bridge in  Cockermouth made communication and transport difficult - in mega-cities like Mumbai they can be huge as growth outstrips flood defences. 
  • Areas of tourism can experinence downturns in visits. 
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5.5C Environmental impacts of flooding.

Floods can recharge groundwater systems, fill wetlands, increase connectivity between aquatic habitats and move sediment and nutrients into marine habitats. For many species, floods trigger breeding, migration and dispersal. Natural ecosystems are resilient towards flood. 

Yet, in environments degraded by human activity, flooding can become more sever. Intense flooding from overland flow can lead to eutrophication.

In developing countries, farmers have developed practices that require annual innundation to wotk with nature to bring a flow of nutrients and sediment. The building of the Aswan Dam on the Nile led to more controlled floods and sardine migration due to a lack of nutrients that affected sardine farmers. 

(Case study for env and social) Summer floods 2007 Eng and Wales - 387mm fell for 3 months - River Severn reached record levels in July 20th 2007 then storm -> flood -> 12 dead and £6m damages. Worcester on the mid-sever rose 4,5m above normal. 

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5.6A Climate changes effect on the hydrological cy

Precipitation input - widespread increase in intense rainfall events, precipitation increase in the tropics as temp decrease 10-30. Length, frequency and intensity of heatwaves increased widely, especially southern europe and southern Africa. 

Evapouration - some research suggests in Asia and NA evapouration is increasing, although increased cloud cover may work against this. 

Run-off and stream flow - alongside more climatic extremes, there will be an increase in hydrologic extremes with more droughts and floods. An accelerated cycle with more intense rainfall will increase run-off and decrease infiltration. Evident in the interiors of the Mediterrean and Africa. 

Snow - snow cover has decreased and spring melt occurs earlier. 

Ice - rapid temperature change and changes in precipitation type = more rain, less snow. Tropical glaciers like the Andes have shown the most rapid changes, with low flow sjowing limited cryopshere supply.

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6.4A Energy security

  • Energy security - referes to the uninterrupted availiability of energy sources at an affordable price.
  • LT - timely investments to supply energy in line with economic developments and enviornmental needs. 
  • ST - ability of an energy system to react promptly to sudden changes. 

Energy security has 4 aspects; reliable and uniterrupted supply, affordable and competitively priced supply, accessible and availiable supply, energy mix dependent on domestic rather than imported sources. 

Consumption is measured per capita using - kilograms of oil equivalent per year (kgoe/yr), gigajoules (10x9 joules or GJ/yr) or exajoules (10x18 joules or EJ/year), megawatt hours per year (MWh/yr). 

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6.4A Energy mix

Energy intensity -  a measure of how efficently a country is using its energy. A high energy intensity indicates a high price or cost of converting energy into GDP. Energy intensity decreases with economic development as energy is used more efficently so the cost per unit of GDP becomes less. 

Energy mix - combination of different availiable sources to meet energy demand. 

These sources include; non-renewables, recycleable fules such as nuclear and renewables. 

Globally, fossil fuels account for over 80% of the energy mix . 

Some countries can be too reliant on imported sources, where a high dependence can lead to threats such as; artificial and abrupt hikes in prices, supplies cut off by military campaigns or civil unrest - importing countries can become victims of blackmail. 

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6.4B Consumption of energy.

Physical availiability - do they have to be imported -> transport cost raises price for the consumer. Are availiable resources going to be expensive and difficult to extract?

Technology - modern technology can help tap energy resources that aren't so readily accessible, yet this often requires great control and expensive equipment. 

Economic development - costs are relative and a percieved expensive energy cost may be viable in another country. The higher the level of development and the standard of living the lower the sensivity to energy costs. 

Climate - very high levels of consumption in NA, ME and Australia reflect the extra energy spent trying to make the extremes of climate more comfortable. Yet, low energy consumption in Africa reflect its low levels of economic development. 

Environmental priorities- 'green' policies could have a depressing impact on consumption. Renewables such as solar and wind are environmentally friendly.

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6.4C Energy players

Meeting the demands means energy has to go through an energy pathway - a route taken from a source to its point of consumption. At both ends influential players have particular involvements in the energy business. 

TNCs - Nearly half of all oil and gas TNCs are state-owned and very much under government control; they operate in exploring, extracting, transporting, refining andn producing.

OPEC (Organisation of the Petroleum Exporting Countries) - twelve member countries that own 2/3 of global oil reserves. Therefore, they are in a position to control prices and the volume on the market. Been accused of holding back production to drive prices up.

Energy companies - convert primary energy into electricity and the deliver it. Considerable influence when setting consumer prices and tarrifs. 

Government - guardians of national energy security and can influencing sourcing for geopolitical reasons. 

Consumer - largely passive in price setting.

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6.4B USA vs France

The USA rank second in global energy consumption and France rank twelth. Yet France only use 1/10 of the USAs energ.

USA pop. 331.4m vs France 67.3m, higher US consumption due to greater demand and greater climatic range which requires energy to make for comfortable living.

  • 2014 consumption - USA vs France 
  • 83% fossil fuels vs 50% fossil fuels
  • 10% renewables vs 10% renewables 
  • 8% nuclear vs 41% nuclear 

France imports 46% of its energy due to natural gases and uranium needed for thier over 50 reactors. USA only imports 15% of its primary energy making it a more secure mix. 

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6.6A Renewable and recyclable energy

The physical geographies mean not all countries can utilise renewable sources. For example not all countries have permanent flwoing rivers for hydro or warm climates with longshine hours for solar. Only hydro and tidal can provide reliable base-load energy. 

-Very few countries where renewables will completely replace current fossil fuels. - As oil prices tumnled in 2015, higher cost renewables became less attractive. -Increase in renewables would have environmental impacts such as more valleys drowned for HEP plants. -People become less interested in the idea of renewables when they are required to personally intergrate them.

Countries will look more towards nuclear energy with its ability to produce waste that can be reused. Yet, there are downsides ; Saftey (Chernobyl), secuirity in an era of international terrorism, dfficulty disposing highly radioactive waste, technology gatekeeps and cost of building gate keeps. 

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6.6A UK energy mix

Since 1970, there has been a shift away from coal, yet reliance on oil and natural gas has settled. This provides 80% of the Uk's primary energy. 

A significant amount of electricity is generated by coal-fired power stations, with the contribution of renewables remaining relativley small. 

The Uk consumes less energy now than it did in 1970, despite a 6.5m population increase, with the Uk being more efficent at producing and using energy. 

The rise of the less-energy intense service sector in the wake of mass deindustrialisation. Households use 12% less energy whilst industry use 60% less. Yet these savings have been offset by transport as there are more vehicles and more flights. By 2030, the UK will be using the same amount of energy as today. 

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