View
3
Download
0
Category
Preview:
Citation preview
WaterQualityBuffersforWatersandWetlands
2008Nor’easter:IndianRiverBay
ProgressTowardsPollutionReductionGoalsfortheInlandBays
1,471
2,427
Nitrogen(lbs.perday)
Achieved Remaining
93
Phosphorus(lbs.perday)
Achieved
WaterQualityBuffersare…natural areas between development and wetlands or waterbodies; they are managed for the primary purposes of:
1.sustainable removal of pollutants entering wetlands or waterbodies,
2. to protect wetlands or waterbodies against encroachment and physical alterations, and
3. to allow wetlands or waterbodies to maximize their own natural capacities to reduce pollution.
Forested Buffer
~ 200’
BufferConsiderations
• Extent• Vegetation• FieldDitches• Views• ApprovalandEnforcement• Width
Headwaters(smallstreams)makeup~75%oftotalwaterwaylength
Headwatersaremoreefficientatremovingpollutionthanlargerstreams
Turf
Forest
VegetationType
Turfvs.Forest
• Forestedbuffersremove36%morenitrogenonaveragethangrassedbuffers
• Forestedbufferstakeup11– 37lbsofnitrogenand2– 5lbsofphosphorusperacreperyearintowood
• Soilorganicmatterisovertwiceashighinforestedbuffers
• Forestedbuffersimproveinstreamprocessingofnutrients
• Forestedbufferssupportwildlifehabitatanddon’tcontributepollution
Effect of Buffer Width on Nitrogen Removalfrom 17 Atlantic Coastal Plain Riparian Buffers
Buffer Width (ft.)
0 100 200 300
% N
itrog
en R
emov
al
-60
-40
-20
0
20
40
60
80
100
120
140
y=-7915.6564+((8015.6442x)/(0.1813+x))Rsqr = 0.67p = 0.0005---- = 95% Confidence Int.
EffectofBufferWidthonNitrogenRemovalfor17AtlanticCoastalPlainRiparianBuffers
BAY
MARSH
UPLAND
BAY
MARSH
UPLAND
BAY
MARSH
UPLAND
DEVELOPMENT
BAY
MARSH
UPLAND
DEVELOPMENT
BAY
MARSH
UPLAND
DEVELOPMENT
BAY
MARSH
UPLAND
DEVELOPMENT
SHORELINE ARMOR
BAY
MARSH
UPLAND
DEVELOPMENT
SHORELINE ARMOR
BAY
MARSH
UPLAND
DEVELOPMENT
SHORELINE ARMOR
BAY
MARSH
UPLAND
DEVELOPMENT
Mouth of Guinea Creek
Bay ShorelineUpland/Wetland Boundary
Bay ShorelineUpland/Wetland Boundary
Slope of Adjacent Upland Indian River BayRehoboth
BayGradual (<0.08 rise/run) 5.25 ft/yr 6.07 ft/yr
Steep (>0.09 rise/run) 1.44 ft/yr 0.82 ft/yr
Rates of tidal wetland migration derived from metric mapping analysis 1926-1989
FieldDitches
ApprovalandEnforcement
NewCastleCo.,DE
KentCo.,DE
SussexCo.,DE
NewJersey MarylandCriticalAreas
CIBAdequate
CIBOptimum
TidalWetlands&Waters
100ft. 100ft. 50ft. 300ft. 200ft. 80-300ft. 150-500ft.
NontidalWetlands 50ft. 25ft. 0ft. 0– 150ft. 25ft. 50 100
Headwaters 100ft. 50ft. 0ft. 300ft. 100ft. 35- 80 35-150
Larger/PerennialWaterways
100ft.or50ft.fromfloodplain
100ft. 0– 50ft. 300ft. 100ft. 80 150
VegetationType Natural/Forest
Natural
/Forest
Natural/
Forest
ExistingVegetationorNatural
/Forest
Natural
/Forest
Natural
/Forest
Natural
/Forest
VegetationPreservation
Existingnativevegetation
Existingnaturalbuffers
Existingnaturalbuffers
Existingvegetation
Existingnatural
vegetation
Existingnativevegetation
Existingnativevegetation
BufferMgmt.Plan No No No Yes Yes Yes Yes
BufferOrdinanceComparison
AnalysisofRecommendationsAppliedtoDevelopments
• 11randomlyselectedPLUSapplications:’04-’06.
l Separated into large (>75th percentile) & small projects (<50th
percentile) and by watershed region
l Estimated % developable acreage as buffer by waterbody type and buffer alternative
WellDrainedRegion
PoorlyDrainedRegion
Results• Onaverage,bufferswerewithinrangeofcurrentCountyopenspacerequirements
• Adequate=13.8%ofdevelopableacreage• Optimum=33.2%ofdevelopableacreage
• Siteswithtidalwetlandsbylowlyinguplandshadverylargeareasasbuffers
• Encouragefillingorintegrationintostormwatercontrolsthoseditchesunnecessaryfordrainage.
• Smallerbufferwidthsshouldbeafforded(>35’)onshallowditches(<3ftdeep)toallowbufferingofotherfeatures
Site Characteristics
Adequate A
lternative
Optim
um A
lternative
Applying R
ecomm
endations: Bethany W
oods
Acreage 12Developable Ac. 9% Dev. Ac. in Buffer (Adequate) 61% Dev. Ac. in Buffer (Optimum) 89
TidalNontidal Wtlnds
Nontidal WaterwayNontidal WetlandTidal Wetlands
Buffer TypesWaterbody Type
Development
Major Ditches
Site Characteristics
Adequate A
lternative
Optim
um A
lternative
Acreage 314Developable Ac. 309% Dev. Ac. in Buffer (Adequate) 1.8% Dev. Ac. in Buffer (Optimum) 3.7
TidalNontidal Wtlnds
Nontidal WaterwayNontidal WetlandTidal Wetlands
Buffer TypesWaterbody Type
Development
ApplyingRecommendations:Bridlew
ood
Indian River Bay Rehoboth Bay
Upland Buffer Width
Gradual Slope
Steep Slope
Gradual Slope
Steep Slope
50’ 10 35 8 6175’ 14 52 12 91100’ 19 69 17 122200’ 38 139 33 244300’ 57 208 49 366400’ 76 278 66 488500’ 95 347 82 610
Yearsbuffersofdifferentwidthsareestimatedtoprovideprotectiontotidalwetlands
derived from metric mapping analysis 1926-1989
Recommended