Avoiding Geohazards in the Mid-Atlantic Highlands by Using “Natural Stream” Principles J. Steven Kite, WVU Neal Carte, WVDOT Will Harman, Michael Baker Corp. Donald D. Gray, WVU
Photo: W. Gillespie North Fork South Branch Potomac River, Hopeville, WV “Natural Stream” Principles? Fluvial Geomorphology Applied with Goal of Maintaining River & Stream Channels & Floodplains in Equilibrium.
Developed from Relatively Unimpaired Streams
“Packaged” by Dave Rosgen.1 Must Be Fine Tuned to Region’s flood meteorology, topography, geology, ecology, land-use, politics, & culture.
1Rosgen, D. L. 1996, Applied River Morphology, Wildland Hydrology, Pagosa Springs, Co. Why Use Natural Stream Principles in Engineering & Construction? 1. Aesthetics 2. Ecosystem Support 3. Long-Term Cost Effectiveness 4. Reduce Flood Hazard – In Face of Increasing
Flood Severity Image from Will Harman, Michael Baker Corp. Floodplain = Part of River
Floodplain: Low Energy
We should not be surprised when, sooner or later, the River exerts its authority over its whole domain.
Channel: High Energy
Photo: J.S. Kite Mill Creek, Canaan Valley, W. Va What is the “Work” of a Stream?
1. Water Delivery
Little Conemaugh River, Johnstown, PA Photo: J.S. Kite “Work” of a Stream?
Todd Petty Photo Todd Petty Photo
2. Framework for
Ecosystem Constructed Floodplain Structure Mitchell River Basin, NC Michael Baker Corp “Work” of a Stream? 3.3. SedimentSediment TransportTransport
IgnoreIgnore SedimentSediment Transport:Transport:
OtherOther SystemsSystems DoDo NotNot WorkWork Photo: J.S. Kite “Grade” Delicate Balance between sediment supply & system’s ability to transport sediment
Ω sediment
stream resistance power
J.S. Kite Wolman-Miller Dominant Flow Hypothesis
t
r Dominant Flow
o
t (1-3 Year)
p
r
s
o
n
p
a
s
r Entrainment
n
T
a Threshold
t
r
y
n
T
c
e
t
n
n
e
m
i
e
u
d
q
m
e
i
e
S
r
d
F
e
e
S
v
i
t
t
n a
l
e
u
v
E m
u
C
0.2 1 2 10 20 200100 Graphic: S. Kite, WVU Recurrence Interval (Years) Bank-Full = Dominant Flow Controlling Hydraulic Geometry
Overbank Silt Loam Bank-Full Stage Sand & Gravel Channel Deposits Bedload
Bedrock
Graphics: J.S. Kite,J.S. WVU Kite Road Crossings Conventional Culverts May Be Migration Barriers & Block Sediment Transport
Photo: J.S. Kite Culvert Area - Bankfull Channel Area Ratio
Addresses Culvert’s Ability to Pass “Floods”
D
Culvert Area - Bankfull Channel Area Ratio =
AreaCulvert / AreaBankfull Channel
Graphics: J.S. Kite,J.S. WVU Kite Channel Area vs. Culvert Area: Non-aggrading and Aggrading Reaches 10 9 8 7 6 5 4
Culvert Area Culvert 3 2 No Aggradation Reaches Aggradation Reaches 1 Linear (1:1 Ratio) 0 0246810
Shavers Fork, W.Va. Approx. Channel Area White, J.A., 2004, MS Arch Culvert
Photo: J.S. Kite Lower Culvert Allows Bank-Full Flow, Sediment Transport, Fish Migration
Constructed Floodplain
Higher Culverts for Image from Will Harman, Flood Passage Michael Baker Corp.
e
g
d
i r Floodplain
Constructed B
≈
s
Michael Baker Corp.
t r
Image from Will Harman,
e
v
l
u
C
Channel x
Constructed
o
B
e
t
e
r
c
n
o
C
b
a
f
e
r P Floodplain Constructed Dev o tio n R o ad (R t. 1 33 0)
Bank Erosion Hazard Mitchell River Basin, NC Michael Baker Corp. Photo Natural Stream Design May Rely on Structures (e.g. Cross Veins)
Flow Directed to Mid-Channel to Reduce Bank Shear Stress
Constructed Reach WVU Stream Design Workshop, Photo: J.S. Kite Mitchell River Basin, NC Good “Design” Must Address Dominant (1-3 Year) Flow, Not Just Big (10-200 Year) Floods
Bank-Full “Flood” = Dominant Flow
Constructed Channel Reach WVU Stream Design Workshop, Mitchell River Basin, North Carolina J.S. Kite, WVU Mitchell River at Devotion Road (Rt. 1330), End of Construction
Floodway for Extreme (e.g. 50 year) Floods
Channel for Dominant (e.g. 1-3 year) Floods Photo by Will Harman Michael Baker Corp. Color Overlay: J.S. Kite Common Flood Mitigation Error – Over-Widening of Channel
Overbank Silt Loam Bank-Full Stage Sand & Gravel Channel Deposits Bedload
Bedrock
Graphics: J.S. Kite, WVU Common Flood Mitigation Error – Over-Widening of Channel
Old Bank-Full Stage
Old Bank-Full Flow Can’t Fill Banks & Can’t Transport Sediment
Bedrock Ω sediment
Graphics: J.S. Kite, WVU Common Flood Mitigation Error – Over-Widening of Channel
Old Bank-Full Discharge Becomes a Flood
Old Bank-Full Stage Old Bank-Full Flow Can’t Fill Banks & Can’t Transport Sediment
Bedrock
Graphics: J.S. Kite, WVU Common Flood Mitigation Error – Over-WideningOld Flood Becomes aof Worse Channel Flood
Old Bank-Full Stage Old Bank-Full Flow Can’t Fill Banks & Can’t Transport Sediment
Bedrock No Matter What the Mayor Says! Don’t Over-Widen Channels after a Flood. Re-Construct Bank-Full Channel Dimensions for Sediment Transport J.S. Kite, WVU Base Level & Profile Equilibrium Base Level = Lowest elevation to which a stream can erode (e.g. Sea Level, Lake, Falls, Downstream Reach, etc.)
Image Source: http://www.rustycans.com/OhioFalls.jpeg Stream Adjustments to Lower Base Level • Equilibrium - Concave Profile
Lake
Bedrock Outcrop
Graphics: J.S. Kite, WVU Stream Adjustments to Lower Base Level • Incision to Adjust Profile
Retreating Knickpoint
Graphics: J.S. Kite, WVU Lewis Run, Rockingham County, VA
Large Gravel Pit Operations Lowered Channel Causing Retreating Knickpoint
1987 Topo Map: TerraServer-USGS Graphics: J.S. Kite, WVU Lewis Creek, Rockingham Co., Va., 10 Nov 1985
Photo: J.S. Kite Key to Reducing Flood Damage: Bank Stability
Anthony Creek, Greenbrier Co., W.Va. Photo: J.S. Kite W.Va. Rt. 28/55, Near Champe Rocks: Before 1985 Flood
USGS Photo Graphics: J.S. Kite, WVU W.Va. Rt. 28/55, Near Champe Rocks: After 1985 Flood
WV DOT Photo Graphics: J.S. Kite, WVU W.Va. Rt. 28/55, Near Champe Rocks: Before 1985 Flood
Old Channels
USGS Photo Graphics: J.S. Kite, WVU Vegetation = Nature’s Bank Protection
Image from Will Harman, Michael Baker Corp. Photo by Will Harman, Michael Baker Corp. Dense Root Wads Reduce Bank Shear
Mitchell River Basin Photo: J.S. Kite Hydraulic Geometry in Plan View Sinuosity Rosgen Class Sinuosity = P = River Distance Along Thalweg / 1.0 - 1.2 Low 1.2 - 1.5 Moderate Straight-Line Distance 1.5 + High Meander-
Radius of Belt Width Curvature
λ = Meander Graphics: Wavelength J.S. Kite, WVU North Fork South Branch Potomac River, Hopeville: Before
USGS Photo North Fork South Branch Potomac River, Hopeville Anticline
Photo: J.S. Kite North Fork South Branch Potomac River, Hopeville: After
WV DOT Photo North Fork South Branch Potomac River, Hopeville: After
WV DOT Photo Graphics: J.S. Kite, WVU Rc= 250 m (800 ft)
Rc= 310 m (1020 ft)
Rc= 330 m (1080 ft)
North Fork South Branch Potomac River, Hopeville, WV, 1987 Graphics: J.S. Kite, WVU Rc= 290 m (950 ft)
Rc= 310 m (1020 ft)
Rc= 310 m North Fork South Branch (1020 ft) Potomac River, Photo: TerraServer-USGS Hopeville, WV, 1987 Graphics: J.S. Kite, WVU 7 Upstream Meanders
Mean Rc = 302 m
Rc= 315 m Rc= 135 m (440 ft) (1030 ft)
North Fork South Branch Potomac River, Hopeville, WV, 1987 Photo: TerraServer-USGS After Flood Mitigation Graphics: J.S. Kite, WVU 7 Upstream Meanders
Mean Rc = 302 m
Rc=302 m Rc= 315 m (990 ft) (1030 ft)
North Fork South Branch Potomac River, Hopeville, WV, 1987 After Flood Mitigation Graphics: J.S. Kite, WVU North Fork South Branch Potomac River, Hopeville 1985
1985 Flood
Rc= ~400 m (~1300 ft)
When ‘Rules of the River’ are not respected, adverse channel adjustments often result.” Photo: W. Gillespie (Luna Leopold, 1994) Graphics: J.S. Kite National Interactive Forum on Geomorphic Reclamation “Putting a New Face on Mining Reclamation” September 12-14, 2006 Farmington Civic Center Farmington, New Mexico Sponsored by the Office of Surface Mining, Western Region, and OSM’s National Technical Training Program www.ott.wrcc.osmre.gov/forums/Geomorphic%20Reclamation/nifgr.htm