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Wetland Extent Tool (WET)

NASA DEVELOP Spring 2019
WET Link: https://code.earthengine.google.com/c028d40c9d6d8de09af17fad5aa9bcc9

The Wetland Extent Tool (WET) was developed by the Great Lakes Water Resources Team to increase the efficiency of wetland mapping in Minnesota. WET is an automated tool hosted on Google Earth Engine (GEE) that maps wetland change and extent using Sentinel-1 C-SAR backscatter ratios, Landsat 8 (OLI) indices, and a LiDAR derived Topographic Wetness Index (TWI).

Getting Started

Prerequisites

WET was created for use within Google Earth Engine, an open source cloud computing platform, and was scripted in JavaScript. The GEE API can be accesed on the homepage, where users can sign up and request approval. Resources for getting started and navigating the platform can be found in the GEE user guide.

Inputs

Dataset Source Parameter Resolution
Landsat 8 (OLI) GEE TCWGD, MNDWI 30m
Sentinel-1 C-SAR GEE VV, VH 10m
DEM (LiDAR) Steve Kloiber TWI 3m
Field Data Steve Kloiber

Deployment

Classification Scheme

Classified maps can be inspected using GEE's inspector tool on the right panel. The Classified Clusters layer will return an indexed number indicating which landcover class the pixel belongs to.

Level-1 Classification Code Key Code Key Description
Upland 1 Dry land
Open Water 2 Includes rivers, lakes, ponds
Wetland 3 Inundated Area

Outputs

By default, the variable Classfied Clusters will contain the classified map for the date range that is specified, which by default is the growing season of 2017. Users can alter the date range in lines 11 and 12 of the code to create other classification outputs. We recommend only selecting dates within Northern Minnesota's growing season of 05/21 to 09/26, to avoid using imagery with snow.

Computation

If the region of interest is too large, the computation may time out on Google Earth Engine. To avoid this issue, users may instead export the output to their Google Drive. A function for doing this can be found in lines 981 to 988.

Authors

  • Erica O'Connor - Team Lead
  • Melissa Ferriter
  • Alice Lin
  • Christopher Notto

Contact

Acknowledgements

  • Erika Higa and Nega Kasraee
  • Bruce Chapman and Benjamin Holt
  • Our project partners at the US Fish and Wildlife Service, Minnesota Department of Natural Resources, Environmental Protection Agency, Ducks Unlimited, National Oceanic and Atmospheric Administration Office for Coastal Management, and the University of Montana