GEOS1100 Lecture Notes - Lecture 8: Canterbury Plains, Sustainable Yield, Southern Tablelands
29 May 2018
School
Department
Course
Professor
WEEK 8
LECTURE 1
Catchment processes and management II - Groundwater and salinity
Catchment processes and management I - rivers
Water as a resource
• Freshwater only 2.6% of world water supply (of this - 3/4 ice, 14 ground water, 1% surface
water)
• Surface water that is "biologically - available" for terrestrial organisms (only 0.014% of tatl
water (lakes, soil moisture, atmosphere, rivers, biota
• 1/3 of available freshwater (0.005% of total) is soil moisture (biologically available but not
much direct use to humans)
• 1/2 of available freshwater (0.007% of total) is in lakes only 0.0001% of total in rivers
Australian Variability in Water Availability
• Water availability in Australia highly non-seasonal
• Australian rivers have the most variable flow regime in the world
Impacts of Australian rainfall 1
• In Ireland, 14 consecutive days without rainfall is a drought
• 30 days supply is held by Dublin's reservoirs
Irrigation Use
• Irrigation underpins the existence of an approximately $14.6 billion agricultural industry in
2013/14, $7.5 billion of which based in the Murray-Darling Basin
• Prolong drought over ten years to 2009 severely impacted on agricultural production e.g.
2006/2007 drought wiped an estimated $6 billion off the national economy \
Hydrological Cycle
Catchments - The unit of management
Runoff Pathways
Flood Hydrograph
Flow components combine to control the discharge of a river
• Base flow: the normal flow in a channel in the absence of recent rain
• Through flow - flow through soil/regolith
• Overland flow - surface runoff
What is a river?
River: A periodic or permanent channelized water flow
Floodplain: Area over which the river flows when it is in flood
Channel: Area where river flows under 'normal' conditions
Levee: A bank of fine sediment on the edges
Basic Concepts
• Base level control
o Sea level
o Lake
Equilibrium Profile
• If you change the base level the river will erode or aggrade until a new equilibrium profile is
achieved
Tectonic uplift modifies base-levels
