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TRANSCRIPT
Novel Data Visualization Tools and Analysis Reveal Patterns of Tidal Influence on a Coastal Wetland
Ryan E. Sleeper1
Samuel P. Parker1Michael Reynolds1
Alex Schiavoni1Nigel Goulding1
1EHS Support, LLC.
13 February 2019
• Introduction– A common scenario: A wetland wedged between a tidal
waterbody and a landfill.– Case study context.
• Methods– What is R?
• Results– The interactive visual aided qualitative times series analysis.– Spectral analysis numerically supported qualitative observations.
Presentation Overview
1
A Common Scenario
2
Key Questions
• Under what tidal conditions result in wetland inundation?
• Is inundation variable in time and space?
• Can we use this information to inform surface and shallow subsurface constituent transport dynamics?
HistoricalLandfill Wetland
TidalWaterbody
Case Study Context
3
• 3 wetland water level gauges installed and left to log hourly for 3 – 5 months.
• 1 open-ocean tidal gauge data downloaded from nearby station.
• Installed along a gradient of ocean connectivity.
Gauge 3
“… a free [and open source] programming and software environment for statistical computing and graphics.” – The R Foundation
What is R?
4
∑
Video of Interactive Visualization
5
• Interactivity allows for the quick exploration of timeseries data at multiple temporal scales
Click here for Interactive Visualization of the image below:
• A measured time series can be constructed as a function of many individual sine and cosine functions.
• The Fast Fourier Transformation moves a timeseries from the time domain to the discrete frequency domain.
• The Spectral Density is calculated providing a measure of the relative strength of the various frequencies in explaining the variance of the original time series. (Think of it as an R2)
Spectral Analysis and the Fast Fourier Transformation
6
Source: stackoverflow.com
periodogram(data)
Inundation vs Non-Inundation Periods
7
Open OceanTidal Gauge
12
24
Gauge 3Non-Inundation
24
12
Evapotranspiration dominated
Inundation
12
24
Tidal dominated
• The frequency signature of wetland water levels resembles that of the open ocean during apparent inundation events, whereas during non-inundation events the signature flips and becomes evapotranspiration dominated.
8
Combining Spatial and Temporal Information
Gauge 1
Gauge 2Ocean
N
• Animation of an inundation event highlights preferential flow paths
Click here to see Animation
Gauge 2Channel
CoastalDune
Landfill
Ocean
Barr
ier
9
Gauge 2Channel
CoastalDune
Landfill
Ocean
Barr
ier
Gauge 2Channel
CoastalDune
Landfill
Ocean
Barr
ier
Conceptual Surface Water and Shallow Groundwater Hydrology
Notes: Key:Figure not to scale.
Wet Season or Inundation Event(Direct Tidal Connectivity)
Seasonal Transition or Floodwater Recession(Channel Tidal Connectivity)
Dry Season or Persistent Dry Period(Groundwater Connectivity)
Tidal Variation Unable to
Breach Inlet
Direct Tidal Connectivity (e.g., dune topping,
channelized and overland flow)
LowerEvapotranspiration (ET)
ChannelFlow
Moderate ET
Higher ET
Channel Tidal Connectivity (e.g., channelized flow)
OverlandFlow
ChannelFlow
ChannelFlow
ChannelFlow
Surface Water Flux
Groundwater FluxTotal Water Flux
IncreasingWater Flux
IncreasingFlux Duration
Takeaways and Future Direction
10
• The software, R, provides powerful graphical and statistical tools to visually and numerically assess complex timeseries with ease (for free!)
• The coastal wetland floods regularly due to a combination of long-term (biweekly) tidal cycles and weather.
• Short-term (<24hr) variation in water level in the wetland was driven primarily by tides during inundation and by evapotranspiration during dry periods.
• Data still being collected may model flooding recurrence.
