5.3 -River Regimes

Question 1

What do river regimes indicate

Answer 1

River regimes indicate the annual variation of discharge of a river at a particular point . River regimes are measured in cumecs

Question 2

What is a simple river regime

Answer 2

A simple river regime is a regime that is usually in a temperate climate that rises in mountainous regions.

-With a simple river regime there are predictable seasonal changes in discharge

Question 3

What are complex river regimes

Answer 3

Complex river regimes are larger rivers that cross several different climatic zones and therefore experience the effects of different seasonal climatic events , as well as human factors which add to their complexities

Question 4

What are examples of rivers with complex regimes

Answer 4

The river Yukon in Alaska has a complex regime
The Amazon in Brazil has a complex regime
The Murray- Darling in Australia has a complex regime

Question 5

What are factors affecting the rivers regime

Answer 5

Factors affecting a rivers regime:
Size of river 
Humans
Vegetation
Geology and soil
Temperature 
Precipitation

Question 6

How does the size of the river affect its regime

Answer 6

• The longer the river ,the more complex the variables tend to be- making the regime more complex.
• The variables tend to be more complex as the river may cross several climatic zones and so may encounter very different land uses and population densities along its length. The river may also experience the effects of different seasonal climate events because of its length

Question 7

How can humans affect a rivers regime

Answer 7

Human factors can also contribute to the complexity of river regimes e.g damming rivers for energy or irrigation , damming rivers can regulate flow - making the regime more complex

Question 8

How can vegetation affect the regime

Answer 8

-The amount and type of vegetation cover can also affect the regime e.g wetlands can hold water and release it very slowly into the river Stetson

Question 9

How can geology and soil affect a rivers regime

Answer 9

Geology and soils can also affect the river regime- the permeability and porosity of soil are particularly important in affecting the regime

-e,g water is stored as groundwater in permeable rocks and is gradually released into the river as base flow. This tends to regulate the flow during dry periods

Question 10

How can temperature affect a rivers regime

Answer 10

Temperature can affect a rivers regime as evaporation will cause marked reductions in river discharge in summer as temperatures are warmer

Question 11

How can precipitation affect a rivers regime

Answer 11

Precipitation affects a rivers regime as regimes often reflect rainfall seasonal maximums of when the snow fields and glaciers melt ( for snow the peak period is in spring , for glaciers it is in early summer

Question 12

Describe the basic river regime of the Nile

Answer 12

• The Nile stretches in its basin across 35 degrees of latitude, with varied climatic zones from high rainfall tropical forest and grassland, to extensive wetland regions( the sudd ( vast swamp in South Sudan)) and the large desert area of the Sahara
• All hydrological characteristics of the Nile are affected by upstream geographical and climatic conditions as the majority of its drainage basin in the lower regions receives low precipitation ( nearly all the Niles water originates from 20% of the basin)

Question 13

Where does the Niles water originate from

Answer 13

The Niles water originates from two main sources - the white Nile (30%) in the Central African equatorial lake plateau and the Blue Nile ( 56%) which is in the Cape Horn highlands ( Ethiopia+ Eritrea).

-The river Atabara tributary which contributes to 14% of the Niles water

Question 14

What are the sources of water like from the blue and white Nile

Answer 14

• The blue Nile shows great variation seasonally due to summer rains and droughts
• The white Nile provides a very steady flow of water and there is less of an annual range due to the constant flow of water from the Great Lakes ( e.g lake Victoria) and swamplands in Uganda
• Despite their differences both the blue and white Nile lie in humid regions with a average of over 1,000 mm a year annual rainfall

Question 15

How do human factors affect the river Niles regime

Answer 15

Human factors have a great impact on the river Nile regime, such as through the disruption and abstraction caused by dams. For example the Aswan dam in southern Egypt has caused a reduced seasonal discharge variation and reduced floods since 1968.

-Lake nasser, formed behind the dam has also caused a change to the river regime by increasing infiltration and percolation into groundwater stores and multiplying levels of evaporation due to several factors