Geography - Water Cycle EQ2 Flashcards
What are teleconnections
Climatic anomalies which relate to each other at large distance. Teleconnections mean that the development of the ENSO within the pacific ocean has a impact on climates around the world.
What is a Humboldt
A cold northbound ocean current, flowing up the west coast of South America.
What is phytoplankton
Microalgae similar to terrestrial plants, contain chlorophyll and require sunlight. Base of aquatic food webs.
What is thermocline
Sharp boundaries between cold deep water and warmer upper layer.
What is the definition for drought
An extended period (season, year or several years) of deficient rainfall relative to statistical multi year average for a region.
What is a meteorological drought
Occurs when long term precipitation is much lower than normal. It is region specific due to atmospheric conditions.
What is agricultural drought
A deficit of rainfall over cropped areas during critical periods of the growth cycle can result in crop failure. Occurs when there is insufficient soil moisture.
What is hydrological drought
Occurs when there are deficiencies in surface and subsurface water supplies. Originates with a deficiency of precipitation but is usually out of phase.
What is socio-economic drought
Occurs when long term precipitation is much lower than normal. It’s occurrence depends on variations of supply and demand.
What is El Nino-Southern Oscillation cycle (ENSO)
A naturally occurring large mass of very warm seawater in the Equatorial Pacific Ocean. The warm water is pushed by ocean currents, trade winds and the Walker circulation cell. However, roughly, every 7 years, the forces weaken, warm water moves east. Evaporation is higher and precipitation is greater, whereas colder currents (Humboldt) brings dry weather.
What is El Nino
Trade winds in western pacific weaken and die, may even be a reverse direction and flow. The piled up water moves back east (from west), leads to rising sea levels. The region of rising air moves east along with the associated convectional uplift. Eastern Pacific Ocean becomes 6-8 degrees warmer, El Nino effect overrides Humboldt.
What is La Nina
Extremely strong trade winds. Trade winds push warm water westwards, increasing sea levels. Low pressure develops with strong convectional uplift as very strong water heats atmosphere. Increase in Equatorial undercurrent and strong upwelling of cold water results in strong high pressure and extreme drought.
What happens in a normal year
Pacific winds circulate around Walker cell. Winds travel westwards along surface of pacific, taking warm waters with them. Cold Humboldt current is drawn into the circulation and flows westwards, water is heated by the sun.
What is upwelling
Colder water pulled up from deep down in oceans.
What is an ITCZ
An inter tropical convergence zone
Why has the Sahel region of Africa experienced drought
Physical causes - 2015/26 El Nino, increased water stress
Human causes - Air pollution, due to EU and NA, caused atmospheric warming
Growing population, demand for food accelerates, land is overcultivated, desertification
What are the impacts of drought in Sahel region
Impacts 11 countries. Land becomes desertified. Increases human vulnerability. Demand for food and water rises - as population rises.
Why has the Australia experienced drought
Physical causes - Climate is dominated by subtropics pressure belt.
El Nino events e.g. East coast drought in Queensland 2002/03.
Human causes - Population growth leading to an affluent water consuming lifestyle.
What are the impacts of drought in Australia
Food shortages, farmers rely on water for irrigation. The ‘big dry’ led to trend of warmer, drier climate South-East Australia
Drought risk from human activities - University of Birmingham
Concluded ‘society’ is not a passive victim of drought due to human responses. People have directly affected by development of droughts by abstracting water and reducing downstream supply. Indirectly affected development of droughts through changing land uses e.g. deforestation - higher albedo, higher surface temp and lower evapotranspiration, overall less precipitation rates.
What are the impacts of drought on wetlands
Can catch fire. Loss of habitat. Damage to crops. Lose ability to recycle, purify and decontaminate water.
What are the impacts of drought in forests
Vulnerable to pests and diseases. Forest fires. Loss of habitat. Damage soil. Damage to ecosystem. Reduced interception.
What is a wetland and why are they important
Land area saturated with water, permanently or seasonally. act as temporary stores within the hydrological cycle.
What is a forest and why is it important
Area full of trees and vegetation. Act as a habitat, timber production, water storage and regulation of hydrological processes.
What is drainage density
A measurement of the physical characteristics of a drainage basin.
A high figure - short lag time, increased risk of flooding. Large number of streams and small drainage basin.
A low figure - longer lag time, reduced risk of flooding. Smaller number of streams and larger drainage basin.
How is changing land use - urbanisation a human cause of flooding
Increases flood risks as impermeable surfaces increase, therefore water cannot infiltrate into the ground. shorter river lag times due to urban drainage systems.
How is changing land use - floodplain a human cause of flooding
Reduces natural storage capacity of floodplain. Land may shrink due to it drying, may also become lower, more prone to flooding.
How is changing land use - deforestation a human cause of flooding
Deforestation reduces interception and evapotranspiration - this results in increased surface runoff and causes precipitation to reach river channel faster - flashy hydrographs.
How is flooding mismanagement a human cause of flooding
Altercations at one point in the drainage basin affects downstream. Hard engineering can reduce flooding frequency - Keswick built 5m wall, however river rose above (5.9m).
How do you calculate flood frequency
T = recurrence interval
N = number of years of observation
M = rank order
T = (n+1)/M
What is positive feedback
In some situations, if there’s heavy rainfall, processes may not be able to work properly. Instead there is a ‘knock on or snowballing effect’, this can cause permanent or long term changes to the system.
What is negative feedback
A period of heavy rainfall may result in increased overland flow and channel flow above the surface and greater throughflow and groundwater flow below surface. These processes remove extra water, returning it to it’s normal state.
What’s the impact of climate change on the hydrological cycle
Climate change will result in intensification, acceleration or enhancement of the global hydrological system. Impacts will vary around the world due to differential amounts of temperature and precipitation.
What are some environmental impacts of flooding
Intense flooding can lead to over supplies of sediment and nutrients.
Floods can recharge groundwater systems.
Flooding can lead to pollution from chemicals, nitrates and heavy metals.
What are some socio economic impacts of flooding
Floods between 1990-2010 were responsible for 200,000 deaths and impacting 3 billion.
Income from tourism is disrupted.
Structural damage to properties in all countries.
What are physical causes of the Bangladesh floods 2007
Bangladesh is a low lying country, at the base of the Himalayan mountains.
Collapse of old earth dams in Pradesh, India caused further flooding.
Long duration of heavy rainfall saturated soil, increased surface runoff and increased discharge.
What are human causes of the Bangladesh floods 2007
Experienced urbanisation in recent years, e.g. capital, Dhaka, has over 1 million people.
One of the poorest countries in the world, GDP is around $300 per person.
What are social effects of Bangladesh floods 2007
Children lost out on education as 4,000 schools were affected, 44 destroyed.
At least 10.5 million people were estimated to have been displaced.
Estimated 25 million made homeless.
What are the economic effects of Bangladesh floods 2007
550,000 hectares of land couldn’t be planted with rice at peak time, basmati rice rose in price by 10%.
$290 million in crops were damaged.
Debt increased, both individually (farmers) and nationally (government).
What are the environmental effects of Bangladesh floods 2007
Transport and other infrastructure disrupted, emergency supplies couldn’t get through.
2.2 million acres of damaged cropland.
10,000km of roads destroyed.
What are some facts about storm Desmond 2015
2 deaths. 16,000 properties flooded. £24m spent on emergency payments. £200m in additional funding for flood recovery. Footpaths and walls washed away, ground eroded. Millions of tons of sediment was transported by the river and deposited on floodplains.
