5.2B CS - The Nile

Question 1

Define porosity

Answer 1

refers to the total volume of pore spaces within a rock (greatest within coarse grained clastics such as Sandstone)

Question 2

Define pervious

Answer 2

rocks are those with distinct jointing patterns and bedding planes along which water can flow (e.g. Limestone or Causeway Basalt Colonnade)

Question 3

Describe impact of climate on the nile

Answer 3

• Precipitation north of Sudan is less than 20mm per year.
• Contrast to Ethiopian Highlands (2,300mm per year) – concentrated in summer months as ICTZ migrates north.
• Channel flow very small for rest of the year upstream.
• Evaporation also increases in summer (esp. in wide flat expanse of Sudd Wetlands)

Question 4

Describe geology in ethiopia

Answer 4

largely volcanic lavas (but highly pervious due to weathering)

Question 5

Describe geology in uganda

Answer 5

Uganda - Mix of Pre-Cambrian igneous / metamorphic and younger sedimentary.

Question 6

Describe geology in sudan&egypt

Answer 6

predominantly Sandstone overlain by Quaternary sediments (extensive groundwater storage)

Question 7

Describe vegetation in river nile

Answer 7

• River Nile - provides Egypt with only vegetation (irrigated crops)
• Vegetation density increases as you move south into wet highlands (closer to ITCZ).
• High interception and evapo-transpiration in summer monsoon months.

Question 8

Describe relief in nile

Answer 8

• Steep topography in the Ethiopian Highlands
• Contributes to greater surface run-off (opposite to flat lowlands)
• high levels of mechanical weathering at altitude
• Leads to erosion of dark top soil (hence ‘Blue Nile’)

Question 9

Describe soils in nile

Answer 9

• Blue Nile carries fertile volcanic silts during monsoon months (saturated overland flow)
• White Nile - light coloured clay sediment - limited infiltration and sediment load.

Means low permeability and limited groundwater storage

Question 10

Describe the nile

Answer 10

Travels through 11 different countries on its journey to the Mediterranean Sea.

Has two major tributaries – The ‘White Nile’ travels further, originating from the Great Lakes in Central Africa.

The ‘Blue Nile’ flows from Lake Tana in the Ethiopian Highlands – joining the White Nile at Khartoum, Sudan.

Annual monsoonal rainfall over Ethiopian Highlands during May-Aug – floods the Nile in lower reaches.