Tropical Climates | Drainage Basin & Hydrographs | Flooding | Sustainable Urban Development |
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Sahara Desert, Atacama Desert, Namib Desert, Alice Springs
Name two examples of places with BWh climate.
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Overland flow, throughflow and base flow
Name the three flows that bring rainwater into the river channel.
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When river discharge exceeds bankfull discharge
When does flooding occur?
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Essential needs of the world's poor, and the needs of both current and future generations
What do "needs" in sustainable development refer to?
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Rainfall: Low total annual rainfall (250 to 630 mm), some rainfall in summer when ITCZ is near
Temp: High mean annual temp, ATR and DTR are larger than A climates
What are the climatic characteristics of BSh climates?
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Rising limb, falling limb, peak discharge, lag time
What are the four key components of a hydrograph?
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Recharge of groundwater, deposition of nutrients onto floodplains
Name one positive impact of flooding.
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The land area and natural resource capital on which the city draws to sustain its population and production structure (i.e., to produce the resources used and absorb the waste generated)
What is ecological footprint?
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Wet season: summer --> ITCZ migrates over --> brings rainfall due to convective and convergent lifting
Dry season: winter --> STH migrates over --> dry conditions due to sinking air
Why do Aw climates have wet and dry seasons?
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Lack of vegetation to shield the surface from the force of falling raindrops which dislodge soil particles and clog up pores, leading to an impermeable surface
What is the raindrop impact?
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Creation of highly impermeable and smooth surfaces (e.g., concrete) which promotes IEF that flows quickly and in large volumes into the channel; dense network of surface drains and underground sewers, deliver large volumes of water more rapidly to the river channel
How does urbanisation contribute to floods?
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Rapid rural-urban migration, inability of urban authorities to cope with the large influx of migrants, persistent poverty
Why are slums common in cities in LDCs?
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NH summer, overhead sun at Tropic of Cancer --> land heats up quickly --> ITCZ migrates northwards over heated land where pressure is low due to rising air --> SE trade winds blowing towards ITCZ deflect to the right after crossing into the NH and become SW monsoon winds
How do the SW monsoon winds form?
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IEF occurs when rainfall intensity exceeds infiltration capacity, typically in areas where infiltration is limited.
SOF occurs after the soil is saturated, in areas where infiltration is high. SOF comes from both direct rainfall falling on saturated soil and return flow.
What is the difference between IEF and SOF?
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Can only manage floods within the magnitude the dam is designed to hold; cause worse flooding if it fails
Name one limitation of dams in managing floods.
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Promote some form of circular metabolism by turning waste into energy input, but not entirely as potentially reusable and recyclable resources are burnt instead
How does incineration affect urban metabolism of a city?
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West Pacific (Australia, Indonesia): warm surface waters --> convective lifting --> rainfall (A climates)
East Pacific (S America): upwelling of cold water + sinking air --> dry conditions (B climates)
How does the Walker Circulation affect rainfall in the tropics?
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High rainfall intensity, ground surface being baked dry, lack of vegetation to promote infiltration and reduce raindrop impact. All of these promote IEF which flow into the channel quickly and in large volume.
Why are hydrographs in an arid climate likely to be flashy?
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For tropical cyclones to develop, there should be ocean waters with temperatures of 26-27°C or higher and sufficient depth (about 60 m) of warm water. Cyclones develop in late summer as it takes time for water at depth to heat up sufficiently (due to the high specific heat, mobility and transparency of water).
Why do tropical cyclones form during late summer?
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Difficult to provide attractive alternative transport to driving, especially during peak hours; cars are status symbol and offer greater comfort and convenience; congestion charging may not be sufficient to deter drivers of high SES
Why is traffic congestion difficult to resolve?
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