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Jessica J Walker

Jessica started with the USGS as a Mendenhall Postdoctoral Researcher in 2014.

Jessica's broad research interests center on the analysis of landscape change using remote sensing data.  Past projects have included tracking the vegetative trajectories of areas recovering from fire events, both in the semi-arid, high-elevation forests of Arizona and the boreal forests of Alaska.  Additional recent work includes examining surface inundation patterns via Landsat and MODIS imagery as part of the PLACE project (Patterns in the Landscape - Analyses of Cause and Effect).

 

 

 

Education and Certifications

  • 2012 - Ph.D. Geospatial and Environmental Analysis, Virginia Tech

    2000 - M.A. Geography, University of Arizona, Tucson

    1991 - B.A. Applied Math, Williams College

     

Science and Products

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USGS science for a changing world logo

Investigation of Lidar Data Processing and Analysis in the Cloud

Lower technical and financial barriers have led to a proliferation of lidar point-cloud datasets acquired to support diverse USGS projects. The objective of this effort was to implement an open-source, cloud-based solution through USGS Cloud Hosting Solutions (CHS) that would address the needs of the growing USGS lidar community. We proposed to allow users to upload point-cloud datasets to CHS-ad
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Community for Data Integration (CDI)
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Investigation of Lidar Data Processing and Analysis in the Cloud

Lower technical and financial barriers have led to a proliferation of lidar point-cloud datasets acquired to support diverse USGS projects. The objective of this effort was to implement an open-source, cloud-based solution through USGS Cloud Hosting Solutions (CHS) that would address the needs of the growing USGS lidar community. We proposed to allow users to upload point-cloud datasets to CHS-ad
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Views from Siuslaw National Forest

Patterns in the Landscape – Analyses of Cause and Effect

Understanding the rates and causes of land-use/land-cover (LULC) change helps answer questions about what, where, how, and why the Earth’s surface is changing. Land-surface change results from human activities or natural processes like floods, droughts, and wildfires, and many of these change processes are observable in satellite imagery. The growing historical catalog of satellite images allows...
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Climate Research and Development Program, Western Geographic Science Center
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Patterns in the Landscape – Analyses of Cause and Effect

Understanding the rates and causes of land-use/land-cover (LULC) change helps answer questions about what, where, how, and why the Earth’s surface is changing. Land-surface change results from human activities or natural processes like floods, droughts, and wildfires, and many of these change processes are observable in satellite imagery. The growing historical catalog of satellite images allows...
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Wetlands in the state of Arizona

We created a single map of surface water presence by intersecting water classes from available land cover products (National Wetland Inventory, Gap Analysis Program, National Land Cover Database, and Dynamic Surface Water Extent) across the U.S. state of Arizona. We derived classified samples for four wetland classes from the harmonized map: water, herbaceous wetlands, wooded wetlands, and non-wet
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Western Geographic Science Center

County-level maps of cropland surface water inundation measured from Landsat and MODIS

This dataset represents a summary of potential cropland inundation for the state of California applying high-frequency surface water map composites derived from two satellite remote sensing platforms (Landsat and Moderate Resolution Imaging Spectroradiometer [MODIS]) with high-quality cropland maps generated by the California Department of Water Resources (DWR). Using Google Earth Engine, we exami
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Climate Research and Development Program, Western Geographic Science Center

National Surface Water Maps using Daily MODIS Satellite Data for the Conterminous United States, 2003-2019

Members from the U.S. Geological Survey (USGS) Patterns in the Landscape - Analyses of Cause and Effect (PLACE) team are releasing monthly surface water maps for the conterminous United States (U.S.) from 2003 through 2019 as 250-meter resolution geoTIFF files. The maps were produced using the Dynamic Surface Water Extent (DSWE) algorithm applied to daily Moderate Resolution Imaging Spectroradiome
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Climate Research and Development Program, Western Geographic Science Center

DSWEmod surface water map composites generated from daily MODIS images - California

USGS researchers with the Patterns in the Landscape ? Analyses of Cause and Effect (PLACE) project are releasing a collection of high-frequency surface water map composites derived from daily Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Using Google Earth Engine, the team developed customized image processing steps and adapted the Dynamic Surface Water Extent (DSWE) to generate s
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Climate Research and Development Program, Western Geographic Science Center

Data release associated with the journal article "Solar and sensor geometry, not vegetation response, drive satellite NDVI phenology in widespread ecosystems of the western United States"

This dataset supports the following publication: "Solar and sensor geometry, not vegetation response, drive satellite NDVI phenology in widespread ecosystems of the western United States" (DOI:10.1016/j.rse.2020.112013). The data release allows users to replicate, test, or further explore results. The dataset consists of 4 separate items based on the analysis approach used in the original publicat
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Climate Research and Development Program, Western Geographic Science Center

Implementation of a Surface Water Extent Model using Cloud-Based Remote Sensing - Code and Maps

This data release comprises the raster data files and code necessary to perform all analyses presented in the associated publication. The 16 TIF raster data files are classified surface water maps created using the Dynamic Surface Water Extent (DSWE) model implemented in Google Earth Engine using published technical documents. The 16 tiles cover the country of Cambodia, a flood-prone country in So
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Western Geographic Science Center

Phenology pattern data indicating recovery trajectories of ponderosa pine forests after high-severity fires

This tabular, machine-readable CSV file contains annual phenometrics at locations in ponderosa pine ecosystems across Arizona and New Mexico that experienced stand-clearing, high-severity fire. The locations represent areas of vegetative recovery towards pre-fire (coniferous/pine) vegetation communities or towards novel grassland, shrubland, or deciduous replacements. Each sampled area is associat
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Climate Research and Development Program, Western Geographic Science Center

Datasets for analyzing stream gage discharge and Landsat imagery integration in the greater Central Valley, California from 1984 to 2015

This data release comprises the data files and code necessary to perform all analyses presented in the associated publication. The *.csv data files are aggregations of water extent on the basis of the European Commission's Joint Research Centre (JRC) Monthly Water History database (v1.0) and the Dynamic Surface Water Extent (DSWE) algorithm. The shapefile dataset contains the study area 8-digit
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Western Geographic Science Center

Data - Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA

Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the central Cascade Mountain area, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous Change De
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Western Geographic Science Center
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Using Landsat and MODIS satellite collections to examine extent, timing, and potential impacts of surface water inundation in California croplands☆

The state of California, United States of America produces many crop products that are both utilized domestically and exported throughout the world. With nearly 39,000 km2 of croplands, monitoring unintentional and intentional surface water inundation is important for water resource management and flood hazard readiness. We examine inundation dynamics in California croplands from 2003 to 2020 by i
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Britt Windsor Smith, Christopher E. Soulard, Jessica J. Walker, Anne Wein
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Western Geographic Science Center

Analysis of surface water trends for the conterminous United States using MODIS satellite data, 2003–2019

Satellite imagery is commonly used to map surface water extents over time, but many approaches yield discontinuous records resulting from cloud obstruction or image archive gaps. We applied the Dynamic Surface Water Extent (DSWE) model to downscaled (250-m) daily Moderate Resolution Imaging Spectroradiometer (MODIS) data in Google Earth Engine to generate monthly surface water maps for the conterm
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Roy Petrakis, Christopher E. Soulard, Eric K. Waller, Jessica J. Walker
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Climate Research and Development Program, Western Geographic Science Center

DSWEmod - The production of high-frequency surface water map composites from daily MODIS images

Optical satellite imagery is commonly used for monitoring surface water dynamics, but clouds and cloud shadows present challenges in assembling complete water time series. To test whether the daily revisit rate of Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery can reduce cloud obstruction and improve high-frequency surface water mapping, we compared map results derived fro
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Christopher E. Soulard, Eric Waller, Jessica J. Walker, Roy Petrakis, Britt Windsor Smith
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Climate Research and Development Program, Western Geographic Science Center

Tamm review: Postfire landscape management in frequent-fire conifer forests of the southwestern United States

The increasing incidence of wildfires across the southwestern United States (US) is altering the contemporary forest management template within historically frequent-fire conifer forests. An increasing fraction of southwestern conifer forests have recently burned, and many of these burned landscapes contain complex mosaics of surviving forest and severely burned patches without surviving conifer t
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Jens T. Stevens, Collin Haffey, Jonathan D. Coop, Paula J. Fornwalt, Larissa Yocom, Craig D. Allen, Anne Bradley, Owen T. Burney, Dennis Carril, Marin E. Chambers, Theresa B. Chapman, Sandra L. Haire, Matthew D. Hurteau, José M. Iniguez, Ellis Margolis, Christopher Marks, Laura A. E. Marshall, Kyle C. Rodman, Camille S. Stevens-Rumann, Andrea E. Thode, Jessica J. Walker
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Ecosystems Mission Area, Climate Research and Development Program, Fort Collins Science Center, Western Geographic Science Center

Solar and sensor geometry, not vegetation response, drive satellite NDVI phenology in widespread ecosystems of the western United States

Satellite-derived phenology metrics are valuable tools for understanding broad-scale patterns and changes in vegetated landscapes over time. However, the extraction and interpretation of phenology in ecosystems with subtle growth dynamics can be challenging. US National Park Service monitoring of evergreen pinyon-juniper ecosystems in the western US revealed an unexpected winter-peaking phenologic
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Jodi R. Norris, Jessica J. Walker
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Climate Research and Development Program, Land Change Science Program, Western Geographic Science Center

Community for data integration 2018 funded project report

The U.S. Geological Survey Community for Data Integration annually funds small projects focusing on data integration for interdisciplinary research, innovative data management, and demonstration of new technologies. This report provides a summary of the 10 projects funded in fiscal year 2018, outlining their goals, activities, and accomplishments.
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Leslie Hsu, Caitlin M. Andrews, John B. Bradford, Daniel D. Buscombe, Katherine J. Chase, Wesley M. Daniel, Jeanne M. Jones, Pam Fuller, Benjamin B. Mirus, Matthew E. Neilson, Hans W. Vraga, Jessica J. Walker, Dennis H. Walworth, Jonathan Warrick, Jake Weltzin, Daniel J. Wieferich, Nathan J. Wood
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Ecosystems Mission Area, Science Synthesis, Analysis and Research Program, Science Analytics and Synthesis (SAS) Program, Community for Data Integration (CDI), Wetland and Aquatic Research Center , Science Data Management

Implementation of a surface water extent model in Cambodia using cloud-based remote sensing

Mapping surface water over time provides the spatially explicit information essential for hydroclimatic research focused on droughts and flooding. Hazard risk assessments and water management planning also rely on accurate, long-term measurements describing hydrologic fluctuations. Stream gages are a common measurement tool used to better understand flow and inundation dynamics, but gage networks
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Christopher E. Soulard, Jessica J. Walker, Roy E. Petrakis
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Climate Research and Development Program, Land Change Science Program, Western Geographic Science Center

Phenology patterns indicate recovery trajectories of ponderosa pine forests after high-severity fires

Post-fire recovery trajectories in ponderosa pine (Pinus ponderosa Laws.) forests of the US Southwest are increasingly shifting away from pre-burn vegetation communities. This study investigated whether phenological metrics derived from a multi-decade remotely sensed imagery time-series could differentiate among grass, evergreen shrub, deciduous, or conifer-dominated replacement pathways. We foc
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Jessica J. Walker, Christopher E. Soulard
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Climate Research and Development Program, Western Geographic Science Center, Wildland Fire Science

Integrating stream gage data and Landsat imagery to complete time-series of surface water extents in Central Valley, California

Accurate monitoring of surface water location and extent is critical for the management of diverse water resource phenomena. The multi-decadal archive of Landsat satellite imagery is punctuated by missing data due to cloud cover during acquisition times, hindering the assembly of a continuous time series of inundation dynamics. This study investigated whether streamflow volume measurements could b
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Jessica J. Walker, Christopher E. Soulard, Roy E. Petrakis
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Climate Research and Development Program, Land Change Science Program, Western Geographic Science Center

Differential changes in the onset of spring across US National Wildlife Refuges and North American migratory bird flyways

Warming temperatures associated with climate change can have indirect effects on migratory birds that rely on seasonally available food resources and habitats that vary across spatial and temporal scales. We used two heat-based indices of spring onset, the First Leaf Index (FLI) and the First Bloom Index (FBI), as proxies of habitat change for the period 1901 to 2012 at three spatial scales: the U
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Eric K. Waller, Theresa M. Crimmins, Jessica J. Walker, Erin E. Posthumus, Jake Weltzin
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Species Management Research Program

Forest harvest patterns on private lands in the Cascade Mountains, Washington, USA

Forests in Washington State generate substantial economic revenue from commercial timber harvesting on private lands. To investigate the rates, causes, and spatial and temporal patterns of forest harvest on private tracts throughout the Cascade Mountains, we relied on a new generation of annual land-use/land-cover (LULC) products created from the application of the Continuous Change Detection and
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Christopher E. Soulard, Jessica J. Walker, Glenn E. Griffith
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Western Geographic Science Center, Land Change Monitoring, Assessment, and Projection

Continuous 1985-2012 Landsat monitoring to assess fire effects on meadows in Yosemite National Park, California

To assess how montane meadow vegetation recovered after a wildfire that occurred in Yosemite National Park, CA in 1996, Google Earth Engine image processing was applied to leverage the entire Landsat Thematic Mapper archive from 1985 to 2012. Vegetation greenness (normalized difference vegetation index [NDVI]) was summarized every 16 days across the 28-year Landsat time series for 26 meadows. Dist
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Christopher E. Soulard, Christine M. Albano, Miguel L. Villarreal, Jessica J. Walker
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Climate Adaptation Science Centers, Western Geographic Science Center

DSWE_GEE v1.0.0

Code for implementation of the Dynamic Surface Water Extent algorithm in Google Earth Engine. Multiple scripts allow the creation of single-scene or composited Dynamic Surface Water Extent (DSWE) images from Landsat and MODIS data. All code is written for use in the JavaScript API.
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Western Geographic Science Center
Integrating stream gage data and Landsat imagery to complete surface water records

Integrating stream gage data and Landsat imagery to complete surface water records

This article is part of the Spring 2020 issue of the Earth Science Matters Newsletter. 

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