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John C. Hammond, PhD

John Hammond works as a Research Hydrologist for the USGS MD-DE-DC Water Science Center.

John studies hydroclimatic variability and trends, seasonal snow dynamics, empirical streamflow relationships across scales, and incorporates satellite data into hydrologic models. Current projects include improving snow process representation in hydrologic models, characterizing hydrologic drought, developing drought early warning systems, and drivers of non-perennial flow, and DC StreamStats.

I obtained my PhD in Watershed Science at Colorado State University in 2018 where I studied hydrologic change across the intermittent-persistent snow transition of the western U.S. is response to snow loss. This work assessed the effects of snow persistence on streamflow generation and soil moisture through a combination of remote sensing, surface station data analysis, hydrologic modeling, and geospatial statistics.

Research interests include:

  • Runoff forecasting in snow-dominated watersheds
  • Input partitioning through the critical zone
  • Hydroclimatic and cryospheric trend detection
  • Low-cost sensors for snow and streamflow monitoring
  • Intermittent snow and streamflow occurrence and prediction

Consulting experience:

  • Remote sensing of snow occurrence timing and distribution
  • Flood innundation mapping
  • Hydrologic and meteorologic equipment installation and maintenance

 

Professional Experience

  • Hydrologist, U.S. Geological Survey (USGS)

    March, 2019 to Present: Surface water hydrologist (Water Science Center, Water Mission Area)

  • Colorado State University: Fort Collins, CO, US

    December, 2018 to March, 2019: Research Affiliate - Department of Ecosystem Science and Sustainability

  • Colorado State University: Fort Collins, CO, US

    August, 2015 to December, 2018: Graduate Research Assistant - Snow hydrology, soil science, and water yield

  • U.S. Geological Survey (USGS)

    November, 2014 to December, 2015: Surface Water Research Contractor

Education and Certifications

  • 2018. PhD, Geosciences: Watershed Science, Colorado State University. Dissertation: Effects of snow persistence on soil moisture and streamflow generation in mountain regions of the western U.S.

  • 2014. M.S., Water Resources Science, Oregon State University. Thesis: Trends in streamflow above and below dams across the Columbia River Basin from 1950 to 2012: assessing sub-basin sensitivity.

  • 2012. B.S., Environmental Science & Policy, University of Maryland, College Park. Concentration: Global Environmental Change. Citation: College Park Scholars – Environmental Studies. Cum Laude.

Science and Products

Filter Total Items: 13

High resolution SnowModel simulations reveal future elevation-dependent snow loss and earlier, flashier surface water input for the Upper Colorado River Basin

Continued climate warming is reducing seasonal snowpacks in the western United States, where >50% of historical water supplies were snowmelt-derived. In the Upper Colorado River Basin, declining snow water equivalent (SWE) and altered surface water input (SWI, rainfall and snowmelt available to enter the soil) timing and magnitude affect streamflow generation and water availability. To adapt effec
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Water Resources Mission Area, Colorado Water Science Center, New Mexico Water Science Center, Wyoming-Montana Water Science Center

Going beyond low flows: Streamflow drought deficit and duration illuminate distinct spatiotemporal drought patterns and trends in the U.S. during the last century

Streamflow drought is a recurring challenge, and understanding spatiotemporal patterns of past droughts is needed to manage future water resources. We examined regional patterns in streamflow drought metrics and compared these metrics to low flow timing and magnitude using long-term daily records for 555 minimally disturbed watersheds. For each streamgage, we calculated streamflow drought duration
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Water Resources Mission Area, Maryland-Delaware-D.C. Water Science Center, Nevada Water Science Center, New England Water Science Center, Oregon Water Science Center

Evaluating hydrologic region assignment techniques for ungaged basins in Alaska, USA

Building continental-scale hydrologic models in data-sparse regions requires an understanding of spatial variation in hydrologic processes. Extending these models to ungaged locations requires techniques to group ungaged locations with gaged ones to make process importance and model parameter transfer decisions to ungaged locations. This analysis (1) tested the utility of fundamental streamflow st
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Water Resources Mission Area, Alaska Science Center, Wyoming-Montana Water Science Center

Assessing placement bias of the global river gauge network

Knowing where and when rivers flow is paramount to managing freshwater ecosystems. Yet stream gauging stations are distributed sparsely across rivers globally and may not capture the diversity of fluvial network properties and anthropogenic influences. Here we evaluate the placement bias of a global stream gauge dataset on its representation of socioecological, hydrologic, climatic and physiograph

Peak-flow and low-flow magnitude estimates at defined frequencies and durations for nontidal streams in Delaware

Reliable estimates of the magnitude of peak flows in streams are required for the economical and safe design of transportation and water conveyance structures. In addition, reliable estimates of the magnitude of low flows at defined frequencies and durations are needed for meeting regulatory requirements, quantifying base flows in streams and rivers, and evaluating time of travel and dilution of t

Pervasive changes in stream intermittency across the United States

Non-perennial streams are widespread, critical to ecosystems and society, and the subject of ongoing policy debate. Prior large-scale research on stream intermittency has been based on long-term averages, generally using annually aggregated data to characterize a highly variable process. As a result, it is not well understood if, how, or why the hydrology of non-perennial streams is changing. Here

Managing nonperennial headwater streams in temperate forests of the United States

Forest management guidelines are designed to protect water quality from unintended effects of land use changes such as timber harvest, mining, or forest road construction. Although streams that periodically cease to flow (nonperennial) drain the majority of forested areas, these streams are not consistently included in forest management guidelines. This paper reviews management guidelines for nonp

The drying regimes of non-perennial rivers and streams

The flow regime paradigm is central to the aquatic sciences, where flow drives critical functions in lotic systems. Non-perennial streams comprise the majority of global river length, thus we extended this paradigm to stream drying. Using 894 USGS gages, we isolated 25,207 drying events from 1979 to 2018, represented by a streamflow peak followed by no flow. We calculated hydrologic signatures for

Evaluating low flow patterns, drivers and trends in the Delaware River Basin

In the humid, temperate Delaware River Basin (DRB) where water availability is generally reliable, summer low flows can cause competition between various human and ecological water uses. As temperatures continue to rise, population increases and development expands, it is critical to understand historical low flow variability to anticipate and plan for future flows. Using a sample of 325 U.S. Geol
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Maryland-Delaware-D.C. Water Science Center, Pennsylvania Water Science Center

Spatial patterns and drivers of nonperennial flow regimes in the contiguous United States

Over half of global rivers and streams lack perennial flow, and understanding the distribution and drivers of their flow regimes is critical for understanding their hydrologic, biogeochemical, and ecological functions. We analyzed nonperennial flow regimes using 540 U.S. Geological Survey watersheds across the contiguous United States from 1979 to 2018. Multivariate analyses revealed regional diff

Zero or not? Causes and consequences of zero-flow stream gage readings

Streamflow observations can be used to understand, predict, and contextualize hydrologic, ecological, and biogeochemical processes and conditions in streams. Stream gages are point measurements along rivers where streamflow is measured, and are often used to infer upstream watershed‐scale processes. When stream gages read zero, this may indicate that the stream has dried at this location; however,
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Water Resources Mission Area, Maryland-Delaware-D.C. Water Science Center

Sub-annual streamflow responses to rainfall and snowmelt inputs in snow-dominated watersheds of the western U.S.

Streamflow generation in mountain watersheds is strongly influenced by snow accumulation and melt, and multiple studies have found that snow loss leads to earlier snowmelt timing and declines in annual streamflow. However, hydrologic responses to snow loss are heterogeneous, and not all areas experience streamflow declines. This research examines whether streamflow generation is different for rain
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Water Resources Mission Area, Maryland-Delaware-D.C. Water Science Center
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Loch Raven Reservoir

MD-DE-DC WSC Surface Water Capabilities

As an integrated part of the WSC, the Surface Water Team monitors and conducts investigative research to describe and improve our region's understanding of extreme hydrologic events - droughts, floods and flood hazards, and coastal or bay storm surge and inundation. They also facilitate measurement of precipitation, streamflow, stage and computation of streamflow at locations in Maryland, Delaware...
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Maryland-Delaware-D.C. Water Science Center
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MD-DE-DC WSC Surface Water Capabilities

As an integrated part of the WSC, the Surface Water Team monitors and conducts investigative research to describe and improve our region's understanding of extreme hydrologic events - droughts, floods and flood hazards, and coastal or bay storm surge and inundation. They also facilitate measurement of precipitation, streamflow, stage and computation of streamflow at locations in Maryland, Delaware...
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High Resolution Current and Future Climate SnowModel Simulations in the Upper Colorado River Basin

This data release contains SnowModel snow evolution simulation output on a 100-meter (m) geospatial grid for a 311 kilometer (km) × 300 km model domain in Colorado, United States, encompassing the Colorado and Gunnison River Basin headwaters in the Upper Colorado River Basin. Weather Research and Forecasting (WRF) Model convection-permitting and orography-resolving (4-km grid spacing) regional cli
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Colorado Water Science Center

U.S. Streamflow Drought During the Last Century: annual drought and low flow metrics, annual climate, and trends for the periods 1921-2020, 1951-2020 and 1981-2020

This dataset contains annual flow metrics quantifying drought and low streamflows for USGS GAGES-2 gages in the contiguous U.S. satisfying data completeness checks for the periods 1921-2020, 1951-2020, and 1981-2020. The dataset also contains annual climate variables from the USGS Monthly Water Balance Model (MWBM). The dataset provides trend analysis outputs for annual drought and low flow metric
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Maryland-Delaware-D.C. Water Science Center

Basin Characteristics and Streamflow Statistics for Selected Gages, Alaska, USA (ver. 2.0, September, 2022)

This data release documents the data used for the associated publication "Evaluating hydrologic region assignment techniques for ungaged watersheds in Alaska, USA" (Barnhart and others, 2022) The data sets within this release are stored in 14 files: (1) Streamflow observations and sites used. (2) Statistically estimated streamflow values computed for each site. (3) Streamflow statistics
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Wyoming-Montana Water Science Center

PeakFQ inputs and selected outputs for selected gages in or near Delaware

This data release contains input and output files for PeakFQ models for 122 selected streamgages in or near Delaware. For each PeakFQ model, we provide the input peak flow file (.txt), peak flow specification file (.psf), model outputs in the form of .PRT and .EXP files, and a plot of peak flow estimates with fit relationship (.EMF). The PeakFQ models provided are for the weighted skew option base
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Maryland-Delaware-D.C. Water Science Center

Magnitude and Frequency of Peak Flows and Low Flows on Nontidal Streams in Delaware: peak and low flow estimates and basin characteristics

This dataset contains four tables: (1) site, regression and weighted peak flow estimates (peak_flow_estimates.csv) (2) site, regression and weighted low flow estimates (low_flow_estimates.csv) (3) basin characteristics for peak flow sites (peak_basin_stats.csv) (4) basin characteristics for low flow sites (low_basin_stats.csv). These tables support the USGS report "Magnitude and Frequency of
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Maryland-Delaware-D.C. Water Science Center

Contiguous U.S. annual snow persistence and trends from 2001-2020

Snow persistence (SP) or the snow cover index (SCI), is the fraction of time that snow is present on the ground for a defined period. Cloud covered index (CCI) is the fraction of time that there is no data, cloud, or sensor saturation for the same period. SP and CCI were calculated on a pixel by pixel basis using MODIS/Terra Snow Cover 8-Day L3 Global 500m Grid, Collection 6 obtained from the Nati
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Maryland-Delaware-D.C. Water Science Center

National Hydrologic Model Alaska Domain parameter database, version 1

This data release contains input data for hydrologic simulations of the Alaska Domain application of the U.S. Geological Survey (USGS) Precipitation Runoff Modelling System (PRMS) as implemented in the National Hydrologic Model (NHM) infrastructure (Regan and others, 2018). The NHM Alaska Domain parameter database consists of 114 parameter files in ASCII format (CSV), two files needed to run the A
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Wyoming-Montana Water Science Center

Geospatial Fabric for the National Hydrologic Model Alaska Domain, version 1

This metadata record documents a geospatial dataset for the U.S. Geological Survey Precipitation Runoff Modeling System (PRMS) used to drive the National Hydrologic Model (NHM). The Alaska Geospatial Fabric v1 is the spatial representation of the hydrologic response units (HRUs) used for the PRMS NHM Alaska domain. These HRUs were generated using the twelve-digit Hydrologic Unit Code (HUC12) water
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Wyoming-Montana Water Science Center

Sub-annual streamflow responses to rainfall and snowmelt inputs in snow-dominated watersheds of the western U.S.

The data presented here contain quasi-event hydrologic response characteristics for quickflow response intervals (QRIs) calculated at 57 USGS GAGES-II reference watersheds in the western US. Each row in the attached csv contains characteristics for an individual QRI at one site. QRI characteristics include duration, antecedent flow, input, input rate,peak flow, potential evapotranspiration, quickf
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Maryland-Delaware-D.C. Water Science Center

Contiguous US and Global streamflow gages measuring zero flow

We report the site number and locations of 5798 streamflow gages displaying zero flow for at least one day in their daily records. 4891 of these gages are from the GRDC network, and 906 are USGS gages in the contiguous US. Additionally, provisional data for two USGS gages 1) Rio Puerco near Bernardo, NM (USGS site: 08353000) and 2) Agua Fria River Near Mayer, AZ (USGS site: 09512500) are provided
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Maryland-Delaware-D.C. Water Science Center
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USGS Studies Low-Flow Changes in the Delaware River Basin

USGS scientists published a new study of low flow in streams in the Delaware River Basin. In general, the low flows measured during 1980-2018...

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Science and Products