Salinisation in Pakistan: Causes (CS)

Question 1

Physical cause: geology

Answer 1

Former shallow tropical sea bed–> large store of chemical salts in regolith

Question 2

Physical cause: climate

Answer 2

• Evaporation rate exceeds precipitation totals–> capillary action combined with deposition of salts.
• Temperatures are above 40C

Question 3

Physical cause: geomorphology

Answer 3

-Indus basin is low lying with gentle slopes–> poor drainage and water logging

Question 4

Physical cause: groundwater

Answer 4

Pakistani quality of water is salt-rich in some places

Question 5

Human cause: history

Answer 5

19th century British modernized and large-scale irrigation project 650,000km2. Salinity is promoted here and water seeping down raises the water table to 3m below soil surface

Question 6

Human cause: Tube wells

Answer 6

used to lower the water table, but encouraged the use of saline water for irrigation
1964-1993: 25,000–>350,000 tube wells

Question 7

Human causes: vegetation clearance

Answer 7

In the Punjab region vegetation clearance has caused an increased rate of evaporation–> increased salinity

Question 8

Human causes: Intense farming

Answer 8

Indus irrigation designed for 65% cropping intensity: intensity is at 150%+ in some regions