USGS scientist John Fulton measures streamflow on Middle Fork Ranch Creek, Colorado using instream, conventional methods. USGS radar equipment is also shown recording non-contact river discharge.
Graham Sexstone
Graham Sexstone is a Research Hydrologist with the USGS Colorado Water Science Center
Graham investigates snow and hydrological processes in mountainous environments of the United States that are critically important for understanding water resources and availability for the nation. Current projects use a combination of field-based measurements, remote sensing observations, and physically based modeling over a range of spatial scales to better understand the spatial and temporal variability of snow water resources and how snow processes are linked with water availability and water budgets. Graham received his PhD in Watershed Science from Colorado State University in 2016 and studied the importance of snow sublimation to seasonal snowpack variability.
Professional Experience
2017 to present: Research Hydrologist, USGS Colorado Water Science Center
2018 to present: Affiliate Faculty, Geosciences, Colorado State University
2012 to 2017: Hydrologist, USGS Colorado Water Science Center
Education and Certifications
2016. PhD, Watershed Science, Colorado State University
2012. M.S., Watershed Science, Colorado State University
2007. B.A., Geography, University of Vermont
Science and Products
Streamflow timing and magnitude during snow drought depend on snow drought type and regional hydroclimate
Evaluating distributed snow model resolution and meteorology parameterizations against streamflow observations: Finer Is not always better
Modeling forest snow using relative canopy structure metrics
Aquatic carbon export and dynamics in mountain headwater streams of the western U.S.
Snowpack relative permittivity and density derived from near-coincident lidar and ground-penetrating radar
Snow surface roughness across spatio-temporal scales
High resolution SnowModel simulations reveal future elevation-dependent snow loss and earlier, flashier surface water input for the Upper Colorado River Basin
Upper Rio Grande Basin water-resource status and trends: Focus area study review and synthesis
Evaluating hydrologic region assignment techniques for ungaged basins in Alaska, USA
Black carbon dominated dust in recent radiative forcing on Rocky Mountain snowpacks
Snow depth retrieval with an autonomous UAV-mounted software-defined radar
Spatial variability in seasonal snowpack trends across the Rio Grande headwaters (1984 - 2017)
Rocky Mountain Regional Snowpack Chemistry Monitoring Study
Estimating the Future Effects of Forest Disturbance on Snow Water Resources in a Changing Environment
Linking water, carbon, and nitrogen cycles in seasonally snow-covered catchments under changing land resource conditions
Snowpack Sublimation - Measurements and Modeling in the Colorado River Basin
SnowModel Simulations for the 2022–23 Water Years, near Coal Creek, San Juan Mountains, Colorado, USA
Simulated snowpack and meteorology at multiple resolutions for three headwater study areas in Colorado, USA, water years 1980-2019
Lidar Point Clouds (LPCs), Digital Elevation Models (DEMs), and Snow Depth Raster Maps Derived from Lidar Data Collected on Small, Uncrewed Aircraft Systems in the Upper Colorado River Basin, Colorado, 2020-22
High Resolution Canopy Structure and Density Metrics for Southwest Colorado Derived from 2019 Aerial Lidar
Snow Measurements in Specific Canopy Structure Regimes for the 2022-2023 Water Years, North of Coal Creek, San Juan Mountains, Colorado, USA
NGWOS Ground Based Discrete Snowpack Measurements
High Resolution Current and Future Climate SnowModel Simulations in the Upper Colorado River Basin
Basin Characteristics and Streamflow Statistics for Selected Gages, Alaska, USA (ver. 2.0, September, 2022)
Historical simulated snowpack for the Lake Sherburne, MT watershed and vicinity, water years 1980-2019
National Hydrologic Model Alaska Domain parameter database, version 1
SnowModel simulations and supporting observations for the Rio Grande Headwaters, southwestern Colorado, United States, 1984 - 2017
Climatological data for the Loch Vale watershed in Rocky Mountain National Park, Colorado, water years 1992-2019

USGS scientist John Fulton measures streamflow on Middle Fork Ranch Creek, Colorado using instream, conventional methods. USGS radar equipment is also shown recording non-contact river discharge.
Rocky Mountain Regional Snowpack Chemistry Map
Science and Products
Streamflow timing and magnitude during snow drought depend on snow drought type and regional hydroclimate
Evaluating distributed snow model resolution and meteorology parameterizations against streamflow observations: Finer Is not always better
Modeling forest snow using relative canopy structure metrics
Aquatic carbon export and dynamics in mountain headwater streams of the western U.S.
Snowpack relative permittivity and density derived from near-coincident lidar and ground-penetrating radar
Snow surface roughness across spatio-temporal scales
High resolution SnowModel simulations reveal future elevation-dependent snow loss and earlier, flashier surface water input for the Upper Colorado River Basin
Upper Rio Grande Basin water-resource status and trends: Focus area study review and synthesis
Evaluating hydrologic region assignment techniques for ungaged basins in Alaska, USA
Black carbon dominated dust in recent radiative forcing on Rocky Mountain snowpacks
Snow depth retrieval with an autonomous UAV-mounted software-defined radar
Spatial variability in seasonal snowpack trends across the Rio Grande headwaters (1984 - 2017)
Rocky Mountain Regional Snowpack Chemistry Monitoring Study
Estimating the Future Effects of Forest Disturbance on Snow Water Resources in a Changing Environment
Linking water, carbon, and nitrogen cycles in seasonally snow-covered catchments under changing land resource conditions
Snowpack Sublimation - Measurements and Modeling in the Colorado River Basin
SnowModel Simulations for the 2022–23 Water Years, near Coal Creek, San Juan Mountains, Colorado, USA
Simulated snowpack and meteorology at multiple resolutions for three headwater study areas in Colorado, USA, water years 1980-2019
Lidar Point Clouds (LPCs), Digital Elevation Models (DEMs), and Snow Depth Raster Maps Derived from Lidar Data Collected on Small, Uncrewed Aircraft Systems in the Upper Colorado River Basin, Colorado, 2020-22
High Resolution Canopy Structure and Density Metrics for Southwest Colorado Derived from 2019 Aerial Lidar
Snow Measurements in Specific Canopy Structure Regimes for the 2022-2023 Water Years, North of Coal Creek, San Juan Mountains, Colorado, USA
NGWOS Ground Based Discrete Snowpack Measurements
High Resolution Current and Future Climate SnowModel Simulations in the Upper Colorado River Basin
Basin Characteristics and Streamflow Statistics for Selected Gages, Alaska, USA (ver. 2.0, September, 2022)
Historical simulated snowpack for the Lake Sherburne, MT watershed and vicinity, water years 1980-2019
National Hydrologic Model Alaska Domain parameter database, version 1
SnowModel simulations and supporting observations for the Rio Grande Headwaters, southwestern Colorado, United States, 1984 - 2017
Climatological data for the Loch Vale watershed in Rocky Mountain National Park, Colorado, water years 1992-2019

USGS scientist John Fulton measures streamflow on Middle Fork Ranch Creek, Colorado using instream, conventional methods. USGS radar equipment is also shown recording non-contact river discharge.
USGS scientist John Fulton measures streamflow on Middle Fork Ranch Creek, Colorado using instream, conventional methods. USGS radar equipment is also shown recording non-contact river discharge.