water Flashcards
what is the global hydrological cycle driven by
by solar energy and gravitational potential energy
what percentage is all the worlds freshwater accessible to humans
1%
what are the inputs of the global hydrological cycle
-precipitation patterns and types (frontal, orographic and convectional)
what are the flows of the global hydrological cycle
-interception, infiltration, direct runoff, overland flow, throughflow, percolation, groundwater flow)
what are the outputs of the global hydrological cycle
evaporation, transpiration, channel flow
whats frontal rainfall
where a cold airmass reaches a warm airmass, the warm air is forced to rise over the denser cooler air, forming rain
whats orographic rainfall
where warmer, moist Atlantic air is forced to rise as it reaches uplands and then it cools, this produces heavy rain
whats convectional rainfall
typical in the UK summer, in high temps, the rainfall created is often intense and associated with electrical storms and thunder
what physical factors affect the inputs, outputs and flows of drainage basins
-climate (affects inputs and outputs)
-soils (affects flows e.g. soil moisture surplus)
-geology (affects flows)
-vegetation (affects flows)
-relief (affects flows)
what human factors affect drainage basins
-deforestation
-changing land use
-creating new water storage reservoirs
-abstracting water
How has deforestation disrupted the hydrological cycle
Deforestation= lowered humidity and rainfall.
Deforestation= reduces evapotranspiration and increases surface runoff
How does changing land use affect the hydrological cycle
Arable to pastoral= compaction of soil, other way around increases infiltration
What do water budgets show
Water budgets show the annual balance between inputs (precipitation) and outputs (evapotranspiration) and their impact on soil (soil moisture surplus or soil moisture recharge), water availability and are influenced by climate types (tropical, temperate or polar)
What do river regimes indicate?
River regimes indicate the annual variation of discharge of a river and result from the impact of climate, geology and soils.
What is the shape of a storm hydrograph impacted by?
Dependent on size, shape, drainage density, rock type, soil, relief, vegetation, land use and urbanisation
What is meteorological drought?
-a shortfall or deficiency in water over an extended period, usually at least a season
What is hydrological drought?
-reduced stream flow, lowered groundwater levels and reduced water stores
Is the Aral Sea hydrological or meteorological drought?
Its hydrological
Is the Sahel meteorological or hydrological?
Its meteorological
What has desertification in the sahel led to?
- Changing rainfall patterns
- Vegetation becomes stressed leading to bare soil
- Bare soil can be eroded by wind
- When rain does fall, it makes it difficult for soil to capture and store it
What did drought in Australia occur due to?
-occurred due to El Nino
What human factors can act as a positive feedback loop?
-population growth= pressure on land to grow more food
-overgrazing= destroys vegetation cover
-over cultivation= exhausts the soil and crops will not grow
-deforestation= trees cut down and soil health declines
How does drought affect forest ecosystems?
-responsible for a loss of infiltration, link to pinon pines, tree mortality increases, less resilience present
How does drought affect wetlands?
Water tables will decline. Wetlands act as temporary water stores and recharge aquifers
What are the human factors which can exacerbate flood risk?
-changing land use within the river catchment, mismanagement of rivers (channelisation, dams, river embankments) and using hard engineering systems.