Transcript Water Resources - Rhodes University

Water Resources
GEOG 201
15th – 26th April 2002
Alistair McMaster, Rm 69
Lecture 1
• Global availability and distribution of water
resources.
• South African spatial and temporal distribution of
water resources.
• Utilisation of the water resource in SA
• Future options for water availability
• Water as a social, economic and environmental
commodity – Case study of Mhlatuzi Catchment.
Accessible Freshwater: Global Proportions
Freshwater in terms of global
volumes
Freshwater Resources –
Global Distribution of Mean Annual Runoff (MAR)
Introduction: Water Resources:
International Distribution
MAR:
Distribution
in Africa
Mean Annual Precipitation (MAP) - South
Africa
Potential Evaporation – South Africa
MAR – South Africa
Variability of Rainfall in SA
SA Water Usage
Utilised
Available
Lost
20 350 million m3/y
13 250 million m3/y
16 550 million m3/y
Major Dams and
Interbasin Transfers
Total volume of dams:
approx 27 000 million m3
Resource Use vs Resource Potential
Conclusion:
• Freshwater in South Africa is a scarce resource,
increasingly becoming a highly valued
commodity.
• As such, water is being treated more and more in
economic (tradeable water rights), social and
political, and environmental terms. (E.g. Sand and
Sabie river, Mhlatuzi river).
• Often, these different needs are in direct
competition.
• Thus, the sustainable and equitable management
of freshwater has become a national issue of
paramount strategic importance.
Alternative Sources of Water
• Desalination of Seawater
– Technically feasible, but very expensive.
• Weather Modification
– Feasible: can increase yield by 150 million m3/y, but
big politics.
• Shipping of freshwater
– Feasible, and competitive with desalination
• Icebergs
– Unresolved technical details
• Suppression of evaporation
– Not feasible
Alternative Sources of Water
• Importation of water
– Zambezi, Lesotho.
• Greater re-use of water
– Especially effluent.
• Water Conservation
–
–
–
–
Water demand management (savings of 10%)
Increased efficiency
Reduced leakages
Removal of alien vegetation
• Virtual or embedded water
• Reallocation of Water
Case Study:
• Mhlatuzi Catchment: Strategic
Environmental Assessment.
• http://www.dwaf.gov.za/sfra/
• (or Mhlatuzi SEA executive summary in
Geog Library)