Chapter 16: Watershed Management Flashcards
Forests are an important source of this resource
Water
Forest regulate this
Streamflow
Forests are living filters that do this
Clean water
Forestry practices impact this
Water quality
Good forest management addresses this
Water
Topography influences these two aspects of water
Movement and collection
This is the total area that drains through a point on a river or a stream
Watershed
Watershed boundaries are defined by these
Highest elevations around a lake or river segment
Do watersheds have implied spatial extent?
No
Are watersheds hierarchical?
Yes
What are two other names for watersheds?
Catchment and drainage
These serve as natural units for land management
Watersheds
What are four goals of watershed management?
- Preserving water supply; 2. Controlling rate of water flow; 3. Controlling erosion/flooding; 4. Maintaining water quality
What are the six types of forest hydrology?
- Interception; 2. Stemflow; 3. Canopy drip; 4. Throughfall; 5. Channel interception; 6. Evapotranspiration
This type of forest hydrology involves the capture of precipitation by vegetation and litter
Interception
What are two ways that water can go in canopy interception?
Evaporate to atmosphere or become stemflow/canopy drip
What determines what happens to water during interception?
Vegetation properties
In this type of forest hydrology, water flows down branches and trunks
Stemflow
In this type of forest hydrology, precipitation is redirected to the crown edge
Canopy drip
This type of forest hydrology is precipitation that reaches the forest floor
Throughfall
Throughfall is a combination of these two water sources
Canopy drip and direct precipitation
What does throughfall depend on?
Vegetation properties
In this type of forest hydrology, precipitation falls on stream surfaces
Channel interception
What determines channel interception?
Stream surface area
In this type of forest hydrology, water loss is due to evaporation and transpiration
Evapotranspiration
During what time of the year can evapotranspiration be substantial?
Growing season
On what does evapotranspiration depend?
Vegetation properties
This process plays a large role in forest hydrology
Canopy interception
This describes the amount of water a canopy can hold
Interception capacity
Canopy interception rises rapidly during a storm until this happens
Interception capacity is reached
What happens when interception capacity is reached on tree leaves?
Weight of precipitation exceeds the surface tension holding water on leaves
Interception capacity is a function of these four factors
- Tree form; 2. Leaf area index; 3. Stem density; 4. Forest strata
What percentage of rainfall do conifers intercept annually?
25-35%
What percentage of rainfall do broadleaf trees intercept annually?
15-25%
In canopy interception, this is the portion of intercepted precipitation that does not reach the soil
Interception loss
What happens to most of interception loss?
It is evaporated
What happens to some of interception loss?
It is absorbed by tree through bark
Forests influence these two forest stream conditions
Streamflow and water quality
This describes the flow of water in streams
Streamflow
What are the two types of streamflow?
Baseflow and stormflow
This type of streamflow is the contribution from ground water
Baseflow
This type of streamflow is the the surge from storm precipitation and surface runoff
Stormflow
What are three ways forests improve stream water quality?
- Reducing sedimentation; 2. Increasing nutrient retention; 3. Reducing surface runoff
What are the two components of stormflow response?
Peak flow rate and lag time
How do forests improve baseflow?
By enabling baseflow to continue during prolonged dry periods
How do forests improve stormflow?
By reducing peak discharge and lengthening lag time
Do forests reduce flood risk from stormflow?
Yes
Does water yield decrease as a forest ages?
No
Which forestry activity contributes the most to forest soil erosion?
Roads/skid trails
What are five effects of silviculture on hydrology?
- Expose mineral soil; 2. Reduce plant transpiration; 3. Increase soil temperature; 4. Increase wind exposure/evaporation; 5. Increase erosion/sedimentation
What are five effects of forest roads on forest hydrology?
- Expose mineral soil; 2. Create impermeable surface; 3. Increase surface runoff; 4. Channelize surface flows; 5. Increase erosion/stream sedimentation
These parts of forest roads are especially bad for forest hydrology
Stream crossings
Do tree harvest and roads have an equal effect on peak sediment loads?
Yes
Do roads have a longer effect on sediment loads and soil erosion?
Yes
This federal legislation governing water pollution was passed in 1972
Clean Water Act
The original Clean Water Act only addressed this type of pollution
Point source pollution
In what year did an amendment add nonpoint sources to the Clean Water Act?
1987
These practices were identified as nonpoint sources and subject to regulation by the Clean Water Act 1987
Forestry practices
What two things does the Clean Water Act require each state to do?
- Identify best management practices and 2. Implement and monitor BMPs
What are the 8 categories for water quality and forest operations established by the EPA?
- Preharvest planning; 2. Streamside management zones; 3. Forest wetlands; 4. Road construction; 5. Timber harvesting; 6. Fire management; 7. Revegetation; 8. Forest chemical management
What is the best management practice for preharvest planning?
To plan for harvesting, site prep, and roads
What are three best management practices for streamside management zones?
- Maintain SMZs along surface waters; 2. SMZs protect water temperatures/quality; 3. SMZs should be sufficiently wide
What are two best management practices for forest wetlands?
- Minimize activity surrounding wetlands; 2. Use low-impact practices
What are four best management practices for road construction?
- Minimize sediment from construction; 2. Use drainage structures and turnouts; 3. Install proper stream crossings; 4. Construct during dry periods
What are three best management practices for timber harvesting?
- Harvesting should be done in accordance with harvest plan; 2. Avoid steep terrain and use SMZs; 3. Harvest during dry periods if possible
What are two best management practices for fire management?
- Reduce sediment from controlled burn; 2. Reduce nonpoint pollution during fire suppression
What is a best management practice for revegetation?
Revegetate quickly to reduce erosion
What is a best management practice for forest chemical management?
Minimize chemical use through appropriate management/application
