Spatial Environmental Assessment Toolkit (SEAT) Plugin in QGIS
Contents
Introduction
The SEAT incorporates device specific parameters, site-specific hydrodynamic conditions, and local receptor information to assess the potential for environmental change within a system. Results from a successful SEAT application informs developers and regulators on the risk of environmental change associated with deploying a device or array in a site of interest. There are four modules available that assess different physical aspects of the impact of instruments on environmental conditions:
- Shear Stress Module: Analysis of spatial change in bed mobility
- Velocity Module: Analysis of spatial change in larval motility
- Acoustics Module: Analysis of acoustic propagation and thresholds
- Power Module: Analysis of power generated by WEC/CEC array
For this tutorial we will be using the Shear Stress Module on a coastal region of interest in Canada. This region is the Cow Bay/Eastern Passage area, south of Dartmouth.
Download and Install Plugin
To download and install the SEAT plugin for QGIS, follow the instructions on the page linked below.
https://sandialabs.github.io/seat-qgis-plugin/installation.html
Download Datasets
a) Bathymetry
Download CHS bathymetric grid for ou study area (east coast of Canada). Download as GeoTIFF.
Visit site: https://data.chs-shc.ca/dashboard/map
Select Bathymetric region, for this tutorial the Eastern Passage coast south of Dartmouth.
b) Hydrodynamic Data
Download a hydrodynamic model that has depth-averaged or near-bed velocity (u, v), time series covering at least one full tidal cycle, and is a grid or mesh file
c) Seabed Sediment Data
Download seabed sediment data in the form of a seabed classification map.
Preprocess Data
Before preprocessing data we need to define our study area in QGIS. We first need to set our CRS (EPSG:6663)
Create study area polygon
a) Bathymetry
Load bathymetry into QGIS
Layer --> add layer --> add raster layer
Reproject bathymetry
Select the set CRS of your study area
Clip bathymetry to study area
Resample to resolution of 100
Use the raster projection(warp) again to set resolution.
Apply NoFill to data
b) Hydrodynamic Model Outputs
Import hydrodynamic model outputs
Layer --> add layer --> add raster layer
Select NetCDF and load u_velocity and v_velocity
Reproject velocity layers
Use same method as for bathymetry
Clip velocities to study area
Use same method as for bathymetry
Match grid to bathymetry
Raster --> align raster
Reference layer is bathymetry, align U velocity and V velocity
c) Sediment Layer
Integration into SEAT
Before opening the SEAT tool, confirm you have the bathymetry, velocity, and roughness (sediment) raster layers. Make sure that resolution, extent, and CRS is the same for all rasters.
Open SEAT tool
Processing → Toolbox → SEAT → Hydrodynamics → Bed Shear Stress
Input rasters
Input:
- Bathymetry raster
- U and V velocity files. You will need to select depth averaged velocity and specify time handling.
- Roughness raster
Other specifications
Set water density to ρ = 1025 kg/m³
Create a dedicated folder for output
Run the tool
Analyze Output
Visualise
Right-click output --> Properties --> Symbology
Use Singleband pseudocolor, Color ramp: Magma
Set Min/Max to 2 and 98
Look for where high and low τ values are
Numerical Assessment
Right-click --> Properties --> Information
For τ (N/m²), <0.05 = Very low energy, 0.05–0.2 = Moderate, 0.2–0.5 = High, >0.5 = Very high (tidal jets)
