Transcript Riparian Forest Buffers Def.

Riparian Forest Buffers
• Def. – land adjacent to a
waterway is referred to as
the “riparian zone.”
• Other terms used –
riparian management
zones (RMZ) or
streamside management
zone (SMZ)
Benefits
• Control surface runoff
and shallow ground
water
– Nutrients
– Sediment
• Shade streams
• Ameliorate effects of
some pesticides
• Provide dissolved and
particulate organic food
for aquatic and
terrestrial systems
Sheet erosion on crop land
Shallow Groundwater
• Frequently occurs in
riparian areas
• Saturated condition
which occur near or
within the root zone of
trees and other woody
vegetation and at
relatively shallow depths
where bacteria, oxygen,
and soil contribute to
denitrification
Nonpoint Source
Pollution
• NPS pollution is caused by
rainfall or snowmelt moving
over and through the
ground.
• As the runoff moves, it
picks up and carries away
natural and human-made
pollutants, finally depositing
them into lakes, rivers,
wetlands, coastal waters,
and even our underground
sources of drinking water.
Nonpoint Source
Pollution (NPS)
• NPS Pollutants include:
– Excess fertilizers, herbicides, and insecticides from agricultural
lands and residential areas;
– Oil, grease, and toxic chemicals from urban runoff and energy
production;
– Sediment from improperly managed construction sites, crop and
forest lands, and eroding stream banks;
– Salt from irrigation practices and acid drainage from abandoned
mines;
– Bacteria and nutrients from livestock, pet wastes, and faulty
septic systems;
– Atmospheric deposition and hydromodification.
NPS:
Hydromodification
• Hydrography:
– Configuration of an
underwater surface
including its relief,
bottom materials,
coastal structures, etc.
– Description and study
of seas, lakes, rivers,
and other waters.
NPS: Hydromodification
Before
During
Bear Creek, Blackfoot River, Montana
• Hydrologic modification:
– The alteration of the natural
circulation or distribution of
water by the placement of
structures or other activities
After
NPS: Hydromodification
• Alteration of the hydrologic characteristics of coastal and
noncoastal waters, which in turn could cause degradation of
water resources
Undersized and perched culvert on
McCabe Creek before restoration
Open bottom box culvert on McCabe
Creek after restoration
Example of
Hydromodification
• Streambed
scouring and
bank erosion
resulting from
storm surges
within
urbanized
watersheds
NPS: Sediment
• Total suspended solids (TSS), i.e., sediment
is major NPS pollution of concern
NPS Contribution of Total Suspended
Sediment (TSS), 1980
Background
26%
Forest
5%
Other
6%
Pasture and
range
25%
Cropland
38%
NPS: Phosphorus
• Major nutrient
leading to water
pollution
• Leads to low
dissolved
oxygen from
excessive plant
growth
• Binds to soil
particles
Sources of NPS Phosphorus
Background
28%
Forest
2%
Other
1%
Pasture and
range
28%
Cropland
41%
NPS: Nitrogen
• Water soluble
• Some converted
to gaseous forms
by microbial
action
• Enters surface
and goundwater
Sources of NPS Nitrogen
Background
25%
Forest
4%
Pasture
25%
Other
3%
Cropland
43%
Underlying Principles
of Buffers
• Vegetation and soil
filters sediments
• Vegetation takes up
nutrients which can be
removed from portion
of site by harvesting
timber and forage.
Clearfield Creek in PA, stable structure
but polluted by mine drainage
Streamside Forest as
Sediment Filter
• Sediment settles as
speed of surface flow
reduced by forest floor
• Sediment is filtered
out as sediment loaded
water percolates into
porous forest floor
Riparian Forest Buffer
• Forest dominated
landscapes
– Leave continuous
unharvested forest
along waterways
• Agriculture
dominated
landscapes
– Create 3 zone buffer
along waterways
Riparian Forest Buffer
• Where to use
– Adjacent to permanent
or intermittent streams
occurring at lower edge
of upslope crop land,
grassland or pasture, or
harvested forest
– Margin of lake or
ponds
Riparian Forest Buffer
• Where to use
– Margin of intermittent
or permanently
flooded,
environmentally
sensitive open water
wetlands
– On karst formations at
margins of sinkholes
and other groundwater
recharge areas
A deep sinkhole
Riparian Forest Buffer
• Use to protect any water
body which will not be,
– Routed through a natural or
artificial wetland serving as
an adequate nutrient sink
– Where concentrated flows
will not otherwise be
converted to sheet flow and
routed through a forest
buffer at a lower point in the
watershed.
Need to exclude livestock,
provide access by piping
water to tank, and planting
buffer.
Riparian Forest Buffer: Design
• Objective - encourage
sheet flow and
infiltration and impede
concentrated (stream
like) flow
• Consist of 3 zones
– Undisturbed forest
– Managed forest
– Grassland
Riparian Forest Buffer: Design
Riparian Forest Buffer: Zone 1
• Location – from top
of stream bank
outward at least 15 ft.
• Purpose – create
stable ecosystem
adjacent to waterway
– Shade watercourse
– Contribute detritus and
large woody debris to
steam ecosystem
Riparian Forest Buffer: Zone 1
• Function – handle sheet
and subsurface flows only
• Limits –
– No subsurface drains that
bypass this zone
– No grazing but maintained
stream crossings allowed
• Vegetation – mix of native
riparian tree and shrub
species
Riparian Forest Buffer: Zone 1
• Management
– Large over mature trees
left to fall
– Occasional removal of
high value trees permitted
if disturbance is very
limited
– Equipment excluded
except for necessary
stream crossing and
stabilization work
Riparian Forest Buffer: Zone 2
• Location – Minimum of
60 ft. beyond edge of zone
1
• Purpose –
– Provide necessary contact
time
– Provide carbon energy
source for buffering and
long-term sequestering of
nutrient
• Function
– Handle sheet and
subsurface flows
Buffered rangeland.
Riparian Forest Buffer: Zone 2
• Limits
– Any subsurface drains
should be converted to
sheet flow in zone 3
– No grazing, but maintained
stream crossing allowed
• Vegetation
– Native riparian tree and
shrub species
– No nitrogen fixers if
nitrogen buffering is needed
Riparian Forest Buffer: Zone 2
• Management
– Periodic harvesting and TSI to
maintain vigorous growth and
to remove sequestered
nutrients.
– Can manage for wildlife
habitat and aesthetics as long
as production of leaf litter,
detritus and large woody debris
is maintained
– Appropriate equipment allowed
as necessary
Riparian Forest Buffer: Zone 3
• Location –
– Minimum of 20 ft. beyond
edge of zone 2, or wider to
accommodate whatever
mowing equipment is to be
used
• Purpose –
– Sediment filtering
– Nutrient uptake
• Function –
– Convert concentrated flow to
uniform shallow, sheet flow
using grading, shaping,
diversions basins and level lip
spreaders
Well vegetated buffer in southwest US.
Riparian Forest Buffer: Zone 3
• Limits
– Activities that would damage
earthworks
• Vegetation
– Dense grass and forbs for structure
stabilization, sediment control and
nutrient uptake.
• Management
– Mow and remove, or use
controlled intensive grazing, to
maintain vigorous growth and
remove nutrients
– As necessary reshape earthworks,
remove accumulated sediment and
reestablish vegetation
Total Buffer
Width: Streamside
• Determine based on
– Soil hydrographic
group
– Total area of source
– Soil capability class
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Soil Hydrologic Groups
Type
Infiltration
capacity/permeability
Leaching
potential
Runoff
potential
Deep, well drained
sands and gravels
High
High
Low
Moderately deep to
deep, moderately
drained, moderate fine
to moderately coarse
texture
Moderate
Moderate
Moderate
Impeding layer, or
moderately fine to fine
texture
Low
Low
High
Clay soils, soils with
high water table,
shallow soils over
impervious layer
Very low
Very low
Very high
Total Buffer Width:
Streamside
• Soil Hydrologic Group
– Widen zone 2 to
include all group C and
D soils subject to
frequent flooding
– 75 ft. minimum for
zones 1 and 2 applies
to group A or B soils
adjacent to intermittent
or perennial streams
Total Buffer Width:
Streamside
• Source area
– Increase zone 2 for
combined zone 1
and 2 width of 1/3 of
slope distance from
stream bank to top
of pollution source
area, i.e.
– Total buffer between
field and forest will
be 1/3 of source area
Incomplete streamside buffer
Total Buffer Width:
Streamside
• Soil capability
class
– Increase width of
zone 2 to provide
combined width
of zone 1 and 2
of,
Soil Capability
Class
Buffer Width
Cap. I, II e/s, V
75 ft.
Cap. III e/s, IV e/s
100 ft.
Cap. VI e/s, VII e/s
150 ft.
Soil Capability Classes
• Indicates the suitability of soils for agriculture.
• The soils are grouped primarily by their capability
for sustained production of cultivated crops and
pasture plants. They are grouped by 2 levels, class
and subclass, to indicate the degree and kind of
major soil limitations.
• Classes -- the broadest groups (typically
designated by Roman numerals I to VIII); the
numeral indicate progressively greater limitations
and narrower choices for agriculture.
Soil Capability Classes
• Subclasses Groups of (soil) capability units within
classes of the land capability classification that
have the same kinds of dominant limitations for
agricultural use as a result of soil and climate.
• The four kinds of limitations recognized are:
–
–
–
–
risks of erosion (e);
wetness, drainage, or overflow (w);
other root zone limitations (s); and
climatic limitations (c).
Total Buffer Width:
Pond and Like-Side
• Buffer area should be at
least 1/5 drainage area of
cropland and pastureland
source area.
• Width determined by
creating uniform width
buffer of total required
area
• Hydrologic and capability
class methods for
streamside buffers applies.
Houses, not cropland, are major
source of lake pollution in midwest.
Total Buffer Width:
Wetlands
• Focus
– Wetlands adjacent to
open water and subject
to flushing, not those
functioning as nutrient
sinks
• Buffers should have
zones 1, 2 and 3 on
sides receiving runoff
Indiana BMP RMZ Width Recommendations
Total RMZ Width*
Watercourse
Chara.
0-5%
slope
5-10%
slope
10-20% 20-40%
slope
slope
40% +
slope
Primary
RMZ
Perenial 40’ wide
200
200
200
200
200
200
Perenial 40 - 20’
wide
75
75
75
105
105-165
75
Perenial 20’ wide
50
50
65
105
105-165
35
Intermittent
25
45
65
105
105-165
Sinkhole
openings
25
45
65
105
105-165
Water supply
75
90
130
210
210-300
75
Other lakes and
ponds
35
45
65
105
105-165
35
* Width in feet on each side of watercourse
Midwest Issue
• Field drain tiles empty
into drainage ditches
that flow directly to
waterways.
• Methods need to
buffer tile water before
it enters ditches.
Midwest Issue
• A solution being
studied
– Run ditch water
through constructed or
natural wetland before
entering waterway
– Use these wetlands for
production of
hydrophytic crops and
for-fee waterfowl
hunting
Forest wetlands can also
function as nutrient sinks.