the hydrologic cycle
DESCRIPTION
The Hydrologic Cycle. Salt water vs. fresh water. In this class, we will be mostly Concerned with fresh water (terrestrial). Less than 1% of the Earth’s freshwater is on the surface at any time. 20% of the freshwater flows through the ground – groundwater. - PowerPoint PPT PresentationTRANSCRIPT
The Hydrologic Cycle
Salt water vs. fresh
waterIn this class, we will be mostlyConcerned with fresh water(terrestrial).
http://www.jhuccp.org/pr/m14/m14figs.stm
Less than 1% of the Earth’s freshwater is on the surface at any time.
20% of the freshwater flows through the ground – groundwater.groundwater.
Basic Cycle
Ocean
EvaporationEvaporation (ET)
runoff
Precipitation
Aquifer
Infiltration
Evaporation
PrecipitationEvaporation/ETSurface WaterGroundwater
Water Residence Times
Get this image from the mac to place here http://www.unep.org/vitalwater/05.htm
StreamStream: body of running water that is confined to a channelchannel and moves downhill due to gravity
Drainage BasinDrainage Basin: total area drained by a stream. Larger streams have larger drainage basins.
The size and composition of the sediment carried by the stream The size and composition of the sediment carried by the stream depends on the nature of the drainage basin.depends on the nature of the drainage basin.
Dissolved LoadDissolved Load Suspended LoadSuspended Load
Bed LoadBed Load
Braided Channel
Meandering Channel
Straight Channel
Fig. 10.18
Braided StreamsBraided Streams
Streams with high sediment loads deposit lots of channel bars. The stream moves around the bars, finding its way through the barriers.
Usually found near sediment source areas and/or areas with easily eroded substrate.
Braided Stream
Fig. 10.06
Meandering Meandering StreamStream
DepositionDeposition occurs on point barspoint bars, where stream velocity is low
ErosionErosion occurs on cutbankscutbanks, where stream velocity is high
Fig. 10.06
Meandering Meandering StreamStream
DepositionDeposition occurs on point barspoint bars, where stream velocity is low
ErosionErosion occurs on cutbankscutbanks, where stream velocity is high
Figure 14.14
Fig. 10.24
Meandering StreamsMeandering Streams
oxbow lakeoxbow lake
Fig. 10.27
Flood Plain:Flood Plain: area habitually flooded by a stream at high water. Contains fine-grain sediment deposited during flooding
Natural levee:Natural levee: low ridges formed along sides of main stream channel during flooding.
Fig. 10.27
Flood Plain:Flood Plain: area habitually flooded by a stream at high water. Contains fine-grain sediment deposited during flooding
Natural levee:Natural levee: low ridges formed along sides of main stream channel during flooding.
Water In (Inflow)
Surface runoff
Groundwater influx
Discharge from upstream
Direct precipitation
Water Out (Outflow)
Capacity (shape-dependent)
Rate (slope-dependent)
93 m
150 m
I <=> O normally
I > O channel fills
If channel fills completely, river can overflow banks and flood
Stream Budget
Flooding
Flooding at Flooding at River Park, River Park, Rock HillRock HillSeptember, 2004
Flooding along the Flooding along the Catawba river was Catawba river was caused by extreme caused by extreme rainfall resulting rainfall resulting from an unusual from an unusual series of powerful series of powerful hurricanes and hurricanes and tropical storms.tropical storms.
Precipitation – the basic water resource
GW
GW
GW
GW
GW
Adapted from: GWP (M. Falkenmark), 2003, Water Management and Ecosystems: Living with Change
Blue & Green Water - perspective
Why so much for agriculture?
• Most countries want/need to feed themselves.• No water = no plants = no food
Photosynthesis
6CO2 + 6H2O C6H12O6 + O2
• C3 plants – 1 gram biomass per 650-800 grams water transpired
• C4 plants – 1 gram biomass per 250-350 grams water transpired
• CAM plants – 1 gram biomass per 100-200 grams water transpired
Water use and farms• Average water needed per acre of crop
– Soybean (C3 plant) = 737,100 liters H2O– Corn (C4 plant) = 862,500 liters H2O
Considering that many farms are hundreds to thousands of acres…that’s a lot of water!!
---Note that corn is a more massive crop. ---Also note that CAM plants are primarily habit the desert and are not
irrigated.
Typical Domestic Water Use
• 10 – 40 L/person/day (water scarce)
• 50 – 100 L/person/day (low-income)
• 100 – 600 L/person/day (high-income)
– Differences in domestic freshwater use:
• Piped or carried• Number/type of• appliances and sanitation
Water Stress Index• Based on human consumption and linked to population growth• Domestic requirement:
– 3.65 - 14.6 m3/person/year (water scarce)– 36.5 - 219 m3/person/year (high-income)
• Associated agricultural, industrial & energy need:– 20 x domestic requirement– 73 – 292 m3/person/year– 730 – 4380 m3/person/year
• Total need:– 77 – 307 m3/person/year (water scarce)– 767 – 4599 m3/person/year (high-income)
Water Stress per International River Basin
http://www.transboundarywaters.orst.edu
Colorado River Basin• Colorado River water
usage– Water “rights” from river (in
million acre feet)• Colorado 3.85• New Mexico 0.84• California 4.4• Arizona 2.8• Nevada 0.3• Utah 1.7• Mexico 1.5Total 15.39
http://www.crwua.org/
Average River Flow = 15.5
• Population growth in Colorado River Basin