River Regimes

Geography: Edexcel A Level, topic 7.1.4

The Yukon

Different rivers experience different variation in discharge. The following factors affect flows of the Yukon:

The Yukon River flows through Alaska.
Conditions in Alaska are highly variable across the seasons. In the winter, conditions are near polar, but temperatures soar in the summer.
The Yukon River flows through different types of climate including tundra and mountain.

In winter, precipitation is frozen.
This causes the Yukon's flow to be low.
In summer, there is precipitation that does not freeze and also snowmelt of the winter’s precipitation.
This causes the Yukon's flow to be high.

As the area is a largely natural landscape, there is very little human influence on the river’s flow.

Different rivers experience different variation in discharge. The following factors affect flows of the Amazon:

The Amazon River flows through the Amazon rainforest where the climate is tropical.
Although the Amazon has a relatively consistent high temperature and rate of precipitation, there is some seasonal precipitation that leads to a lower river discharge.
The temperature and high biodiversity lead to very high levels of evapotranspiration.

Consistent temperatures and rainfall create a largely consistent river flow. Some lower rainfall in September and December leads to a lower river flow.
La Niña and El Niño years also produce changes in rainfall, which affects river discharge levels.

Deforestation affects interception, infiltration and surface runoff increasing the flow.
Large dams used by Brazilian cities for both hydroelectric power and irrigation can cause more discharge above the dam and a reduced flow below the dam.

Different rivers experience different variation in discharge. The following factors affect flows of the Murray-Darling:

The Murray-Darling is in Australia where the climate is seasonal sub-tropical.
Most of the Murray-Darling's basin is in a rain shadow.
This means that the basin is surrounded by mountains that collect most of the region's rain. This can cause periods of prolonged drought.
The tributaries to the north experience a monsoon climate, whilst the southern tributaries experience temperate climate.
There are wet (Aug-Nov) and dry (Jan-Apr) seasons that cause high and low river flows respectively.

There is a high seasonal variability for the Murray-Darling’s discharge because of the clear wet and dry seasons.
The river is also impacted by the changes in rainfall patterns during La Niña and El Niño years.
La Niña brings cooler than normal sea surface temperatures and wetter weather to Australia.
El Niño brings the opposite; less rainfall.

Water is drawn from the Murray-Darling for use in Australia’s cities and also to irrigate farms.
The natural flow paths of the river have been altered for human access, which has led to loss of habitat for local animals and a decline in quality of water.

What happens to the Yukon River in summer?
Why are human influences on the Yukon River minimal?
Which of the following types of landscape does the Yukon river flow through?
Which of the following is a human influence on the Amazon River discharge?
What process happens due to the high temperatures and high levels of biodiversity found in the Amazon rainforest?