Final Forest Watershed Management

factors affecting runoff response

precipitation, storage, spatial distribution, flow pathway, land use

possible flow paths

infiltration excess overload flow

discharge of groundwater

shallow subsurface flow/interflow

saturation excess overland flow

channel interception

return flow

h2o can emerge from groundwater

variable source area (VSA)

the source of water in space changes over time

controls of infiltration capacity

land cover

soil texture

topography

flow attenuation

precipitation may not be uniform across the entire area.

good hydraulic conditions

high infiltration capacity

flooding is rare

poor hydraulic conditions

low infiltration capacity

flooding is high

soil erosion

detachment and transport of unconsolidated Earth material from one place to another where it is deposited

cyclic

happens every once in awhile

episodic

high in intensity, low in frequency

why is soil erosion important

nutrient loss

reduce infiltration

non-point source pollution

detachment

rain drops falling on bare ground and/or sheets of water flowing over soil surface can dislodge soil particles.

transportation

detached particles moved downhill, downslope, or down stream by floating, rolling, dragging, splashing

deposition

particles eventually accumulate somewhere either permanently or temporally

sheet erosion

relatively uniform erosion over entire soil surface, soil removed in uniform thin layers. requires overland flow

rill erosion (#1)

occurs when overland flow breaks up into small channels or micro rills. erosion intensity increases, greatest amount of soil loss globally

gully erosion

death is >0.3m, deep terrain. represents major sediment-producing process, generating 10-95%

what do mass movements require

gravity and steep terrain

triggers of mass movements

intense rainfall

rapid snowmelt

human disturbance

freeze/thaw cycles

earthquakes

volcanic eruption

landslide

downslope movment of soil or rock on a surface of rupture

safety factor of <1

imminent failure

safety factor of >1

increasing slope stability

Debis flow

form of rapid mass movement in which loose soil, rock, organic matter, air, and water mobilizes as a slurry downline

soil creep

very slow (mm/year) movement is ubiquitous widespread occurrence

ways to measure erosion

erosion pin

sediment trap

rainfall simulation

settling basin and tipping bucket

building a rating curve

management practices to reduce erosion potential

road location

timing of activities

mulching, seeding, stablizing

skid trails

landing size during logging

maintenance

riparian management zone (RMA)

the ground along a water of the state where the vegetation and microclimate are influenced by year round or seasonal water. associated with high water tables

RMA protection zone

riparian area protection zone where there are requirements for vegetation retention and certain practices are limited or modified. emphasis on providing water quality and fish/wildlife habitat

type F stream

fish bearing streams

type SSBT stream

small/medium type F that have salmon, steelhead, or bull trout the may be used for domestic water

type D stream

streams used for domestic water, not fish bearing

type N stream

non-fish bearing, non domestic water

type Np stream

small type N perrenial stream, no fish, no domestic use

small stream size

< 2cfs

medium stream size

2 - 10 cfs

large stream size

> 10 cfs

RMA delineation standard basal area targets depend on:

geographic region

stream type

stream size

harvest type

Oregon private forest accord

focus on threatened and endangered salmonid and salamander species in three major areas

ELZ

equipment limitation zones