watershed hydrology & sediment dynamics...• assess river character. stage 2 data analysis •...
TRANSCRIPT
Watershed Hydrology & Sediment DynamicsSediment Transport in Stream Assessment and DesignMonday, August 1, 2016Patrick Belmont
“It is hard to imagine that a transport estimate made in the absence of a sound understanding of watershed history and dynamics would be of much use at all.”
A. Alabyan and A. Sidorchuk. Siberia G. Parker. Browns Gulch, Montana
G. Parker. Fly River, Papua New Guinea.
J. I
mra
n. B
rahm
aput
ra R
iver
, Ban
glad
esh.
Great diversity in channels and watersheds...
...emerging from complex interactions
Wheaton et al., 2011
How much and what type of sediment is being delivered to this channel?
What information do you need to answer those questions?
Is sediment supply a BIG number or SMALL number?
Interception Storage
Surface Storage
Unsaturated Zone Storage
Saturated Zone Groundwater Storage
Channel StoragePlan
t Sto
rage
trans
pira
tion rain, snow, condensation
stemflow, canopy drip
infiltration
percolation
outlet
plant uptake
Atmospheric Moisture
Hydrology matters...
Land use matters...
Soils and surficial geology matter...
Trimble, 1999
Sediment transport throughwatersheds is complicated
Natural and human-caused‘legacy effects’
Storage matters...
Grain size matters
Sediment type and grain size fractionation matter...
Bed and lower point bars made of bed material load
Banks and levees made of suspended load
Floodplains preserve old channel deposits + overbank
Floodplain
Coarse and fine load often have different sources/transport paths
Sediment type and grain size fractionation matter...Coarse and fine load often have different sources/transport paths
All else held constant, aggradation on the bed causes… aggradation on the floodplains
Sediment type and grain size fractionation matter...Coarse and fine load often have different sources/transport paths
All else held constant, aggradation on the floodplain… increases shear stress on the bed
So while the sources may be independent, effects on channel morphology and hydraulics are linked
A few key messages up front…Predicting sediment supply at any given location is difficult, but tractable
Ideally we want to know locations, mechanisms, and rates of erosion and deposition
Size matters…boulders, cobbles, gravel, sand, mud play distinct roles
Spatial and temporal variability over wide range of scales
Interactions of multiple non-linear processes
Many biological influences: veg-hydro-geomorph, beavers, human alterations
Simplified models can be useful or misleading
Many new tools available, none are comprehensive or bullet-proof
In many cases, all that is needed/feasible is to know if supply is a big # or small #
Roadmap
Push-button GeomorphologyThe geek approach. What computer models can and can’t tell you.
Basin-average erosion rates: The cosmo methodMillennial-scale landscape rates of erosion.
Reservoir and pond sedimentation ratesTime- and space-integrated measurements that may be useful.TOM
OR
RO
W
Watershed Sediment BudgetTools and techniques for robust constraints on sources and sinks.
Basic ReconnaissanceWith a tight budget, what do you really need to know?
Forget rates. What can we learn from basic form-process relationships?Continuity and discontinuity. Geomorphic Assessments.
TOD
AY’S
TO
PIC
S
A bit of hydrologyTargeted modeling and metrics. Stationarity Assumption?
Interception Storage
Surface Storage
Unsaturated Zone Storage
Saturated Zone Groundwater Storage
Channel StoragePlan
t Sto
rage
trans
pira
tion rain, snow, condensation
stemflow, canopy drip
infiltration
percolation
outlet
plant uptake
Atmospheric Moisture
Hydrology matters...
Clark et al. (2015) A unified approach for process‐based hydrologic modeling: 1. Modeling concept. Water Resources Research 51(4): 2498-2514.
Excellent perspective on the frontier of hydrologic modeling
Hrachowitz, et al. (2013). A decade of Predictions in Ungauged Basins (PUB)—a review. Hydrological sciences journal, 58(6), 1198-1255.
Farmer, W. H., & Vogel, R. M. (2016). On the deterministic and stochastic use of hydrologic models. Water Resources Research.
Hydrologic modeling
Have flows changed?
Lytle and Poff, 2004
A basic lexicon of flow regime characteristics
Lytle and Poff, 2004
Changes (or not) in Flow Duration Curves
1940 - 1975
1976 - 2009
Slide modified from
Schottler, 2011 WR
C C
o
10
100
1000
10000
0 20 40 60 80 100
Flow
exceedance probability
Elk
1
10
100
1000
0 20 40 60 80 100
Flow
exceedance probability
Whetstone
10
100
1000
10000
0 20 40 60 80 100
exceedance probability
10
100
1000
10000
0 20 40 60 80 100
Blue Earth
10
100
1000
10000
0 20 40 60 80 100
exceedance probability
Le Sueur
1. Sort big to small2. Rank (m) from 1 to n
3. Compute EP = m/(n+1)
FDCs: Choose your axes carefully
Illustrating shifts in FDCs
Laue
r et a
l., in
revi
ew
1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 20110
10
20
30
40
50
60
70
Date
Pre
cipi
tatio
n-m
m p y
Making sense of highly variable hydrologic dataHourly Data for Precipitation: 1948-2011
1948-1977: Early Period
1977-2011: Late Period
An increase in highand extreme totalstorm amounts.
1. Sort big to small2. Rank (m) from 1 to n
3. Compute EP = m/(n+1)
http://cran.r-project.org/web/packages/waterData/waterData.pdfhttp://cran.r-project.org/web/packages/waterData/vignettes/vignette.pdfhttp://cran.r-project.org/web/packages/waterData/index.html
R package forautomated download of USGS flow databasic streamflow metric analysis & plots
See flood frequency document distributed with electronic course materials for a detailed explanation of probability and statistics that go into flood frequency analysis
TP 1=
QTQT KQ logloglog σµ +=
𝑄𝑄𝑇𝑇 = 10𝑙𝑙𝑙𝑙𝑙𝑙𝑄𝑄𝑇𝑇
T = Return Period or Recurrence Interval
P = Probability of Exceedance
QT = Discharge you are computing
σlogQ = Standard deviation of the log transformed annual peak flow series
KT = Frequency factor (from table, = f (skew and return period)
µlogQ = Mean of the log transformed annual peak flow series
Flood frequency analysis
FDC and FF spreadsheet
USGS Peak FQ Programhttp://water.usgs.gov/software/PeakFQ/
USDA Flood Frequency Calculationhttp://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/national/water/?&cid=stelprdb1042910
Alternative flood frequency tools
Stout, 2012
Site not gaged? Develop a regional curve
StreamStats
Frequencies of hydrologic phenomena (e.g., precipitation, streamflow) can be represented by a time-invariant PDF that can be estimated from historic record.
These PDFs provide the basis for evaluation of risks to water supplies, floodplain development, infrastructure.
Hornberger, 1998
The stationarity assumption in hydrology
30 35 40 45 50 55 60 65 70 75 80 85 90 95
Hornberger, 1998
In some places, these PDFs are systematically changing
The stationarity assumption in hydrology
Non-stationary conditions
Interception Storage
Surface Storage
Unsaturated Zone Storage
Saturated Zone Groundwater Storage
Channel StoragePlan
t Sto
rage
trans
pira
tion rain, snow, condensation
stemflow, canopy drip
infiltration
percolation
outlet
plant uptake
Atmospheric Moisture climate non-stationarity
land use non-stationarity
Standard practice for predicting flood frequency/magnitude assumes stationarity(Interagency, 1982)
Review of techniques to adjust for non-stationarity provided by Gilroy & McCuen (2012)
Streamstats assumes stationarity
National Flood Insurance Program assumes stationary flood flows
Stuck on stationarity?
Finding Hydrologic DataPrecipitation:PRISMhttp://www.prism.oregonstate.edu/
NOAA: Frequency Duration Datahttp://hdsc.nws.noaa.gov/hdsc/pfds/
NOAA: NNDC datahttp://www7.ncdc.noaa.gov/CDO/dataproduct
NRCS: Snotelhttp://www.wcc.nrcs.usda.gov/snow/
NRCS: SCANhttp://www.wcc.nrcs.usda.gov/scan/
Streamflow:USGS: Water Watchhttp://waterwatch.usgs.gov/
USGS: NWIShttp://waterdata.usgs.gov/nwis
Many state agencies, consortiums
Groundwater:USGS: NWIShttp://waterdata.usgs.gov/nwis/gw
Soil Moisture:NWS: CPChttp://www.cpc.ncep.noaa.gov/soilmst/w.shtml
Effective Discharge
Discharge
Flood flows, bankfull, and effective discharge
So what is bankfull?The elevation at which water spills out of the channel and onto the floodplain
(so it only occurs where you have well defined banks and a floodplain)
Elevation of the top of bank If banks are at different elevations, it is the top of the lower bank
It is typically identified at a visible break in slope between the channel and floodplainOften it is the transition from unvegetated to (woody) vegetated surface
Roadmap
Push-button GeomorphologyThe geek approach. What computer models can and can’t tell you.
Basin-average erosion rates: The cosmo methodMillennial-scale landscape rates of erosion.
Reservoir and pond sedimentation ratesTime- and space-integrated measurements that may be useful.TOM
OR
RO
W
Watershed Sediment BudgetTools and techniques for robust constraints on sources and sinks.
Basic ReconnaissanceWith a tight budget, what do you really need to know?
Forget rates. What can we learn from basic form-process relationships?Continuity and discontinuity. Geomorphic Assessments.
TOD
AY’S
TO
PIC
S
A bit of hydrologyTargeted modeling and metrics. Stationarity Assumption?
How would you describe these channels?
Insightful books for watershed analysisand stream restoration
Stage 1 Data Compilation (description and mapping)• Derive watershed boundary conditions• Determine landscape units• Assess river character
Stage 2 Data Analysis• Define and interpret River Styles• Explain contemporary character/behavior• Assess river history
Stage 3 Predict future river structure
Stage 4 Prioritize watershed management issues
Stage 5 Identify target conditions for river
Stages of a River Styles Assessment
River Styles HierarchyWatershed Watershed area determined by drainage divide. Determines
the boundary conditions within which rivers operate.
Geomorphic Unit Instream and floodplain landforms (pools, bars, levees, backwaters, etc.) that reflect distinct form-process associations.
River Style Length of channel with a characteristic assemblage of geomorphic units.
Landscape Unit Topographic unit determined on the basis of local relief, valley slope and morphology. Defines the valley-setting.
Hydraulic Unit Uniform patches of flow and substrate material within a geomorphic unit.
Microhabitat Individual elements (e.g., logs, rocks, gravel patches) within a stream.
Grabowski et al. 2014
Many other classification schemes out there
Montgomery and Buffington, 1997
Many other classification schemes out there
Modified from Montgomery, 2004
Time & Space scales of change are linked
Tools for geomorphic assessments
USU Fluvial Habitats CenterJoe Wheaton, Nick Bouwes, Wally MacFarlane, Gary O’Brien etc.http://etal.joewheaton.org/
Topotoolbox (requires Matlab)https://topotoolbox.wordpress.com/
Stream Profiler (requires ArcGIS and Matlab)http://geomorphtools.org/tools.htm
UMass-Amherst: Collection of Frameworks and Protocolshttp://extension.umass.edu/riversmart/fluvial-geomorphology-assessment-methods
River Styles tree developed for NSW, Australia
Brierley et al., 2002
YOU decide how to divide up the river network!
Visual representation of River Styles tree for NSW, Australia
These are each different‘process domains’
Different ecological functionshydro-geomorphic processessensitivities to changepotential for recovery
At the watershed scale, what are the primary gradients?
River longitudinal profile
Flow accumulation
Valley confinement
Valley confinement
Confined
Partially Confined
Unconfined
Downstream gradients in a textbook river
Downstream gradients in an escarpment river
QuiescentRills and gullies
Debris flows
Landslides
Other landscape scale considerations:How active are the hillslopes?
Which hillslopes are/aren’t connected?
Indicators of channel behavior
Channel planform
Bed material texture
Assemblage of geomorphic units that make up a reach
RiverStyles Form-Process Relationships
Metrics ofchannelplanform
Interpretations fromchannel planform
Kleinhans, 2010
Channel adjustment in different valley settings
Channel adjustment in different valley settings
Roadmap
Push-button GeomorphologyThe geek approach. What computer models can and can’t tell you.
Basin-average erosion rates: The cosmo methodMillennial-scale landscape rates of erosion.
Reservoir and pond sedimentation ratesTime- and space-integrated measurements that may be useful.TOM
OR
RO
W
Watershed Sediment BudgetTools and techniques for robust constraints on sources and sinks.
Basic ReconnaissanceWith a tight budget, what do you really need to know?
Forget rates. What can we learn from basic form-process relationships?Continuity and discontinuity. Geomorphic Assessments.
TOD
AY’S
TO
PIC
S
A bit of hydrologyTargeted modeling and metrics. Stationarity Assumption?
Rea
ch 1
Ste
ep h
illsl
opes
del
iver
sed
imen
t to
low
gra
dien
t val
ley
floor
Wea
k tu
ff an
d rh
yolit
e be
droc
k, re
cent
sev
ere
burn
Example: North Fork Cable Creek, Oregon
Rea
ch 2
Cha
nnel
inci
sed
into
a n
arro
w, h
igh-
grad
ient
val
ley
Cha
nnel
gra
dien
t ste
eper
, bed
mat
eria
l coa
rser
, les
s he
tero
gene
ity
Rea
ch 3
Valle
y w
iden
s, w
ell d
evel
oped
(and
con
nect
ed) f
lood
plai
nM
uch
grav
el d
epos
ition
and
het
erog
enei
ty in
bed
form
s
Rea
ch 4
Cha
nnel
cro
sses
faul
t and
ent
ers
onto
har
d C
olum
bia
Riv
er B
asal
tS
tep-
pool
to p
ool-r
iffle
mor
phol
ogy
Some history on the landscape we’ll beexamining this afternoon
Little Bear River Watershed
Seven high resolution, real-time flow/turbidity monitoring stations:http://littlebearriver.usu.edu/
Long profiles of EF, SF Little Bear and other drainages of the Bear River Range
Longitudinal profiles extracted with Stream Profiler Tool: geomorphtools.org
Little Bear East ForkLittle Bear – South Fork
Littl
e B
ear E
ast F
ork
Littl
e B
ear S
outh
For
k
Little Bear Flood Flows
Your assignment for this afternoon:
Work in groups of 3-4
Utah DNR has requested a map illustrating thedifferent reach types that occur along the river. This info will be used to determine which sites to prioritize for furthermonitoring and restoration.
The Little Bear Watershed is being targeted for a majorwatershed restoration project with the goal of restoringcutthroat and brown trout habitat.
Your assignment for this afternoon:1. Obtain GIS and/or Google Earth data
2. Peruse GIS data for 30 min. Identify points/areas of interest along the channel and throughout the watershed.
3. Spend ~30 min delineating distinct reaches of the mainstem Little Bear. Split lb_mainstem_to_edit at reach breaks and describe each reach wrt:1. valley confinement2. number of channels, sinuosity and lateral stability3. slope and/or discontinuities in the long profile4. notable sediment sources and sinks5. other relevant attributes
Turn in by tonight:Shapefile or screen-shot illustrating reach breaks<1 page document describing each reach, other key points/areas of interest, and any other observations made in the field