WATERSHED MANAGEMENT

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WATERSHED MANAGEMENT

• DEFINITION
• Analysis, protection, repair, utilization, and
  maintenance of drainage basins for control and
  conservation of water resources
• RELATED TERM Hydrology

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WATERSHED MANAGEMENT

• Important for foresters because
• Water necessary for wildlife
• Water necessary for humans
• Silviculture affects water quality quantity

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WATERSHED MANAGEMENTOUR TOPICS

• The Hydrologic Cycle
• Water Use and the Law
• Management Issues

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THE HYDROLOGIC CYCLE (Figs. 16.1 16.2)

• Hydrologic Cycle Equation P Q ET S
• P precipitation
• Q runoff (streamflow)
• ET evapotranspiration
• S watershed storage change
• Assuming S 0 and rearranging
• Q P - ET

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THE HYDROLOGIC CYCLE

• Precipitation (P)
• Interception (I)
• Throughfall
• Channel Interception (CI)
• Infiltration (F)
• Subsurface Storm Flow (SSSF)
• Base Flow (ground water flow, BF)
• Surface Runoff (SRO)
• Evapotranspiration (ET)
• Potential ET
• Actual ET
• Watershed Storage Changes (S)

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THE HYDROLOGIC CYCLE

• Precipitation (P)
• Determined by factors external to watershed
• Interception (I)
• Precipitation landing on plants may
• Evaporate
• Become stemflow
• Become canopy drip
• Determined by vegetation characteristics

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THE HYDROLOGIC CYCLE

• Throughfall
• Precipitation reaching the forest floor (canopy
  drip direct precipitation)
• Determined by vegetation characteristics
• Channel Interception (CI)
• Precipitation falling on stream surfaces
• Determined by stream surface area

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THE HYDROLOGIC CYCLE

• Infiltration (F)
• Water entering soil
• May percolate (move down through soil)
• May become
• Subsurface storm flow (SSSF)
• Base flow (ground water flow, BF)
• Watershed storage change (S)
• Surface runoff (SRO) occurs if soils maximum
  infiltration rate is exceeded
• Determined by watershed factors

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THE HYDROLOGIC CYCLE

• Evapotranspiration (ET)
• Evaporation transpiration
• Potential ET may exceed actual ET
• Determined by climate watershed factors

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THE HYDROLOGIC CYCLE

• Watershed Storage Changes (S)
• Snow ice fields
• Water in surface depressions
• Soil moisture (groundwater)
• Determined by climate watershed factors

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THE HYDROLOGIC CYCLE

• Remember our runoff (streamflow) equation?
• Q P - ET
• Another runoff (streamflow) equation
• Q CI SRO SSSF BF
• Rapid response if SRO and/or SSSF high
• BF maintains streamflow between storm events

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HYDROLOGIC MEASUREMENTS

• Rain gauges
• http//www.srh.noaa.gov/tlh/cpm/srg_page.html
• http//www.chilbolton.rl.ac.uk/weather/raingaugede
  tails.htm
• Weirs
• Etc.

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Photos Alex Cherry
Throughfall
Stemflow
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Photo Alex Cherry
Weir at Robinson Forest
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SURFACE WATER USE LAW

• General Principles
• No one owns water
• One may own right to use water
• Two systems in U.S.
• East Riparian Law
• West Doctrine of Prior Appropriation

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SURFACE WATER USE LAW EAST

• Riparian Law
• Water use rights belong to owners of land
  touching lake or stream
• Water must pass downstream unchanged in
• Quantity
• Quality
• Regimen (timing)
• Exceptions
• Use for household, livestock garden
• Payment of compensation

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SURFACE WATER USE LAW WEST

• Doctrine of Prior Appropriation
• First claimant has first right to use
• Earliest claims have priority if supply exceeded
• Claims limited to beneficial use
• Ownership of land physically touching water
  source not required
• Water rights lost if not used

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SURFACE WATER USE LAW

• Watershed management is impacted by the two
  surface-water-use principles (Riparian Law,
  Doctrine of Prior Appropriation)
• Additional laws are based on the principles
• Regulations are based on the principles laws
• Court decisions are based on the principles, laws
  regulations

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WATERSHED MANAGEMENT ISSUES

• Water yield (quantity)
• Water regimen (timing)
• Water quality

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WATERSHED MANAGEMENT ISSUES (continued)

• Water Yield Regimen
• Managed by vegetation manipulation, e.g.
• Forest removal
• Decreases ET temporarily
• Increases snowpack accumulation
• Increases water yield (Q) temporarily
• May expand or compress flow regimen
• Change in species composition
• May increase or decrease water yield
• Water harvesting (seal soil surface)
• E.g., to fill livestock watering ponds

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See Fig. III-2 on p. iii-3 Greene County Soil
Water Conservation District Stream Restoration
Program. 2003. Section III Introduction to
stream management. Fig. III-2 on p. iii-3 in
Batavia Kill Stream Management Plan. http//www.g
cswcd.com/stream/bataviakill/smp/
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WATERSHED MANAGEMENT ISSUES (continued)

• Water Quality Issues
• Suspended sediment
• Dissolved nutrients
• Chemicals
• Nonpoint source pollution

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WATERSHED MANAGEMENT ISSUES (continued)

• Water Quality Issue Suspended Sediment
• Enters streams via soil erosion
• Reduces light penetration
• Inhibits aquatic plant growth
• Inhibits sight-feeding animals
• May cause fish gill damage
• Physical habitat damage
• Temperature changes

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WATERSHED MANAGEMENT ISSUES (continued)

• Water Quality Issue Suspended Sediment
• Seek to maintain natural equilibrium between
• Sediments entering stream
• Sediments transported out
• Goal minimize sediments entering stream
• Buffer areas between disturbance and surface
  waters
• Appropriate timing of disturbances
• Minimize soil compaction

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WATERSHED MANAGEMENT ISSUES (continued)

• Water Quality Issue Dissolved Nutrients
• Timber harvest reduces nutrient uptake
• Leads to increase in soil solution nutrients
• Nutrients may increase in surface waters
• Effect depends on ecosystem
• Effects temporary, reforestation ameliorates
• Uneven-aged silviculture may mitigate

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WATERSHED MANAGEMENT ISSUES (continued)

• Water Quality Issue Chemicals
• Fertilizers, herbicides, pesticides
• Need consider
• Precipitation
• Land surface
• Distance from application to surface water
• Soils

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WATERSHED MANAGEMENT ISSUES (continued)

• Watershed Quality Issue Nonpoint Source
  Pollution
• Pollution with no single source identifiable
• e.g., a forested watershed with many owners
• Managed by land use control
• Best Management Practices (BMPs)
• Usually a response to a specific problem
• Usually a combination of practices
• Usually developed with public input
• e.g., streamside buffers

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Sedimentation
Debris
Photos Dr. Jeff Stringer
Streamside Management Zone (SMZ)
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Slide courtesy Dr. Chris Barton
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NONPOINT SOURCE POLLUTION

• BMPs prevent or minimize problems
• Restoration costs are VERY high
• BMPs are preferred to restoration!

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KENTUCKY WATERSHED VIEWER

• http//eppcmaps.ky.gov/website/watershed/viewer.h
  tm

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WATER YIELD CALCULATION

• ASSUME that in a 200 ha forested watershed
• Preharvest forest ET (annually) 70 cm
• Postharvest ET (annually) 50 cm
• Rainfall (annually) 80 cm
• CALCULATE
• 1. Pre-harvest annual streamflow volume
• 2. Post-harvest annual streamflow volume
• 3. Increase in streamflow volume
• 4. Number of people supported by the increase
• (1 ha 10,000 m2 per capita annual human water
• consumption 212,000 liters)