characterizing tidal inundation of wetlands in the ... · 1/14/2009 · thermal imaging in the...

Characterizing Tidal Inundation of Wetlandsin the Murderkill Estuary (Kent County, DE)

Thermal Imaging

in the Murderkill Estuary (Kent County, DE)

Tom McKennaDelaware Geological Survey Can temperature

University of Delawarep

be used as an indicator of inundation?

LiDAR

Surface Elevation

TidalInundation

Supported by Kent County & Delaware DNRECJanuary 14, 2009

What causes low DO in the tidal Murderkill River?Issue: low DO (EPA “impaired waters”)

i / h bi h i l i t ti ?

ssue o O ( pa ed ate s )Question: appropriate TMDLs for nutrients? (EPA “pollution control strategy”)

river / marsh biogeochemical interaction?

Webbs Marsh July 3, 2008 low tideWWTP

extensive salt marsh

Waste Water Treatment Plant?NJ

DEBay

DE

Primary Research Question

What processes sources and sinks controlWhat processes, sources, and sinks control low DO in the tidal Murderkill River?

site specific concept al models and

Numerical Water-Quality Modelingsite-specific conceptual models and

input data

parameterizations of processes that

De laware Bay

McGinnis Pondp pare difficult to model explicitly and/or require information not easily obtainable

Andrews La ke

tidal inundation of marshesbiogeochemical cycling in marshesnutrient fluxes in/out marshes

Course y Pond

primary productivitysediment oxygen demand

M cColley Pond

WWTP

Tidal inundation of marshesThe flow of water on salt marsh platforms is still poorly characterized. New conceptual models are being developed

uplandconceptual models are being developed. marsh

platformsecondary

tidal channelChallenges:

i t h

primary tidal

microtopographygroundwater / surface-water interaction anthropogenic alteration (since late 1600s)inundation / vegetation relationship primary tidal

channelinundation / vegetation relationshipvery dynamic systemdense vegetationoverland flow in estuary-scale models

“Discrepancies in tidal phase and elevation in a numerical model can be

overland flow in estuary scale models

p paccommodated by the modeling calibration process but can severely limit the explanatory power and predictive capabilities of the model.” (French, 2003)

Methods for determining inundationHydrodynamic

Model(Overland Flow)

Tide Gages ElevationSurvey

VegetationSurvey

Comment

( )

Model based on distribution of vegetation communities (indirect)

No Few Yes Yes assumes correct

conceptual modelNo No No Yes

Model based on tide and ground-surface elevation (direct)

Yes Many ground-based Yes “Cadillac”

Yes/No Many/Few ground-based or LiDAR

Yes/No

No Few LiDAR No TemperatureNo Few LiDAR No p

Components of common x,y,z datum

“apples to apples” pInundation Studyelevation

marsh surface (LiDAR)very low reliefvery low reliefminimize error and remove bias

instrument locations (e.g. tide level)

preliminary inundation modelhighly parameterized

d t ldata loggerswater level, temperature, and salinity

time-series to document inundation and develop & test modelsair temperature & pressure, solar radiationtemperature on marsh platform (air/water)

Can we use temperature as an indicator of inundation?

thermal imagingCan we use temperature as an indicator of inundation?

Model for tidal inundationPreliminary model makes VERY simple (and wrong) assumption of Instantaneous inundation of entire marsh based on water elevation at Bowers Beach How wrong?Bowers Beach. How wrong?

Working towards more complex representation:

tidal propagation: function for instantaneous tide level for specifiedtidal propagation: function for instantaneous tide level for specified reaches of Murderkill River using data from tide gages at Frederica and Bowers Beach TLr = f(xr,t)

assign TLr to a subset of marshes along the reach

marsh subset inundated based on TLr and set of spatial parameters representing (raster layers):representing (raster layers):

• marsh elevation• attenuation/amplification of tidal amplitude• phase shift of tide based on distance from river/creek/ditch

Testing model of tidal inundationDirect measurement: water level, temperature, and salinity in tidal creeks / ditches using data loggers (time and instrument intensive). Marsh platform

g

g gg ( ) pinstrumentation?

ALTERNATIVE: Can observations of environmental temperature be used to capture spatio temporal dynamics of inundation (lessused to capture spatio-temporal dynamics of inundation (less expensive, more representative of spatial heterogeneity)?

W t fl d h t t fWater flow and heat transfer are highly-coupled processes.

7:19 DST

105

Temperature loggers on marsh platform

Environmental Thermography

Establishing a common vertical datumlow relief on marsh platforms so minimizing elevation error and bias is criticalp g

asset source datum vertical type datum

LiDAR monuments

USGSDELDOT

ellipsoidalellipsoidal

NAD83NAD83monuments

monumentsDELDOT

NGSellipsoidalellipsoidal

NAD83NAD83

monuments NGS orthometric NAVD88tide gages USGS orthometric NGVD29tide gages USGS orthometric NGVD29

tide prediction NOAA tidal MLLW

Geoid model: GEOID03 / VDATUM software (NOAA)convert between ellipsoid, orthometric, and tidal datums

Conducted least squares adjusted GPS-RTK survey8 reference monuments; minimally constrained

Survey correctionsElevation adjustments of up to 55 cm !

Significant for accurate modeling of marsh platform g g pinundation and hydrodynamics in river.

Correction (m)

Locationreference elevation

NGVD29 to

leastsquare

Total(m)Location

value NAVD88squareadjust

(m)

USGS Bowers gage -0.34 -0.24 +0.03 -0.55USGS Webbs gage -0.34 -0.24 +0.03 -0.55USGS Frederica gage 0.00 -0.24 +0.08 -0.16N Bowers ref. monument +0.03 +0.03Barretts Ch. ref. monument +0.08 +0.08LiDAR ref. monument +0.08 +0.08

ELEVATION MAPPINGLIDAR b USGS / NASALIDAR survey by USGS / NASA

Mark Nardi & Wayne Wright

2008; low spring tide; leaf-off

EAARLExperimental

Advanced Airborne Ranging LiDARg g

Digital Elevation ModelDigital Elevation ModelLiDAR survey

scale optimized for

M d kill

scale optimized for marsh topography

Murderkill River

salt marsh

Delaware Bay

uplands

LiDAR data collected for other b i l LiDAR

ypurposes by commercial LiDAR vendors is not optimal for mapping marsh topography.

Cumulative Probability of Tide Being Below an n

Tide Being Below an Absolute Elevation

n el

evat

ion

MTL

MLL

WM

LW

85% of time b l MHW

Bowers

elow

giv

en

75th %

HH

W

HW

below MHW3 gages (USGS)

FredericaWebbs Slough

tidal datums shown for Bowers ter l

evel

be

medianMHMH

45% of time below MTLtidal datums shown for Bowers

(VDatum)

of ti

me

wat

25th %

% fPreliminary model makes VERY

simple (and wrong) assumption of Instantaneous inundation based on

t l ti t B B h Elevation (m)-1.5Frac

tion

o 2% of time below MLW

water elevation at Bowers BeachBut how wrong?

Elevation (m)

Digital Elevation ModelLiDAR

Delaware Bay

Murderkill RiverRiver

uplands

salt marsh

uplands

salt marsh

elevation < mean tide level0 02 m NAVD88-0.02 m NAVD88LSA

using tide levels from Bowers Beach gage

elevation < 0.4 m0 4 m NAVD880.4 m NAVD88LSA


elevation < mean high water0 6 m NAVD880.6 m NAVD88LSA


elevation < mean highest high water 0 75 m NAVD880.75 m NAVD88LSA


elevation < 0.9 m 0 9 m NAVD88 (> MHHW)0.9 m NAVD88LSA (> MHHW)


Data Loggers in Webbs Marsh~ 1 year at 6-minute sampling interval

Murderkill R

temperature, salinity, leveltemperature

temperature, salinity, level, velocity, pH, DO R.

23

1Murder-

kill R

WSR

Likely Temperature Signals from Inundation?

season temperature

air water

day nitespring warm cool warm/coolsummer warm cool warmfall cool cool warm/coolwinter cool cold coolwinter cool cold cool

Temperature signals of inundation at 3 sites on the marsh platform (over 7 days) inundation progresses through time from site 1 to site 3

Jun 1, 2008 Jun 8, 2008daynight start of

1daynight

oCstart of

inundationat site 1

start of inundation

at site 3

2oC

3oC

air temp.Water temperature @ Webbs Slough (WS)

oC

Webbs Slough (WS) tide

p

temperature difference (site 1 – site WS)

Webbs Slough (WS) tidem

Phase lag of inundation relative to tide level at Webbs Slough

area minutes

• secondary ditches 10-20• Spartina alterniflora 20-40

near ditches• Spartina alterniflora 60-90

away from ditches • Spartina patens 60-90p p

MULTI-SPECTRAL IMAGING

Reflected Energy Emitted EnergyThermal Bands

SWIR MWIR LWIRNIRUV Visible

1.7µm 3.0µm 5.0µm 14.0µm8.0µm1.0µm0.4µm

thi t dthis study

Environmental Thermography(Thermal Imaging of the Environment)

• measure “apparent” temperature of remote surfaces located centimeters to kilometers away

• absolute temperature can be calculated emissivity of a material (e.g. water, sediment, vegetation) y ( g , , g )geometry of the observing system

• can be usedcan be used as a quick investigative tool for detailed lab / field studies of dynamic processes

• natural engineered industrial• natural, engineered, industrial

Imagingg gPlatforms

Temperature Time Series of Tidal Mixing in Webbs Slough (May 15, 2008) 12 18°C

lift platform visual

5:49 DST 6:04 DST 6:19 DST5:34 DST

Cooler water from the Murderkill River flows into Webbs Slough during flood tide and back out during ebb tide

flood

6:34 DST

15 30 45

7:04 DST 7:19 DST

sunrise0 minflood tide

6:49 DST

60 90 10575

high tide

ebbtide60

7:34 DST 8:04 DST 8:19 DST7:49 DST

90 10575 tide

120 150 165 min135

Temperature Time Series Showing Inundation of Marsh Platform

visual8:44 PM ESTflood tidewarmer water (gray blue) oncolder (red)

marsh surface

12/13/2008BB

Amarsh surface

thermal imager location816-817A

9:04 PM ESThigh tideB

882-885A

9:42 PMebb tideB

July 31, 2008early evening

1062-1064A

Image of Marsh Platform Inundationwarmer water flowing onto

Webbs MarshDecember 13, 2008

high spring tide ld i ( bf i )

gcold marsh surface cold morning (subfreezing)

helicopter platform

inundated platform

is “warm” (orange)

A

AB

(orange)

AB

channels are “hot” (yellow)

Thermal ImageDifferentiating

Sources

cold water (black) ponded on marsh

Thermal ImageSources of Water

cold water (black) ponded on marsh platform after recent rain event

Visual Image

BB

A

B

A

warm water (white) in Brockonbridge Gut Webbs Slough and ditches

12/13/2008 9:56 AM high tide

Gut, Webbs Slough, and ditches

ConclusionsConclusions

S lt h l ti i M d kill E tSalt-marsh elevations in upper Murderkill Estuary (Frederica) are lower than lower estuary (Bowers Beach)

Common vertical datum is critical for quantifying tidal inundation using in-situ instrumentation.

Environmental temperature can be used to capture spatio-temporal dynamics of inundation.– inexpensive in-situ data loggersinexpensive in situ data loggers– environmental thermography

characterizing tidal inundation of wetlands in the ... · 1/14/2009 · thermal imaging in the...

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