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Colin A Penn

Colin is an Hydrologist with the Colorado Water Science Center

 

 

Education and Certifications

  • Colorado School of Mines Hydrologic Science and Engineering Graduate Program

    M.S. Hydrology - May 2014

  • B.S. Environmental Sciences: Water Resources Concentration, Minor Statistics - May 2009
    Honors College Graduate
    University of Vermont Rubenstein School of Environment and Natural Resources

Science and Products

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Snowpit Loch Vale Watershed in Rocky Mountain National Park

Rocky Mountain Regional Snowpack Chemistry Monitoring Study

Snowpacks collect atmospheric deposition throughout the snowfall season and offer a unique opportunity to obtain a composite sample of the chemistry of most of the annual precipitation at high elevations [> 1,800 meters]. The purpose of the snowpack network is to determine annual concentrations and depositional amounts of selected nutrients and other constituents in snow resulting from atmospheric...
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Colorado Water Science Center
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Rocky Mountain Regional Snowpack Chemistry Monitoring Study

Snowpacks collect atmospheric deposition throughout the snowfall season and offer a unique opportunity to obtain a composite sample of the chemistry of most of the annual precipitation at high elevations [> 1,800 meters]. The purpose of the snowpack network is to determine annual concentrations and depositional amounts of selected nutrients and other constituents in snow resulting from atmospheric...
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Rio Grande, Upper Canyons

Upper Rio Grande Basin Focus Area Study

USGS is undertaking a 3-year study of water use, availability, and change in the Upper Rio Grande Basin in one of several national “Focus Area Studies” in the Department of Interior’s WaterSMART initiative. The Upper Rio Grande study area runs 670 miles from its headwaters in Colorado through New Mexico and northern Mexico to Ft. Quitman, Texas. Along its river corridor, it is a primary source of...
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Oklahoma-Texas Water Science Center
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Upper Rio Grande Basin Focus Area Study

USGS is undertaking a 3-year study of water use, availability, and change in the Upper Rio Grande Basin in one of several national “Focus Area Studies” in the Department of Interior’s WaterSMART initiative. The Upper Rio Grande study area runs 670 miles from its headwaters in Colorado through New Mexico and northern Mexico to Ft. Quitman, Texas. Along its river corridor, it is a primary source of...
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USGS scientist recording data near alpine waterway

Water, Energy, and Biogeochemical Budgets (WEBB): Loch Vale Watershed

Loch Vale is an alpine/subalpine watershed in Rocky Mountain National Park where the U.S. Geological Survey has been conducting research since the 1980s. Our research has focused on the effects of climate change and atmospheric pollutants on water, soil, vegetation, and aquatic life. The alpine/subalpine ecosystem in Loch Vale is sensitive to changes in climate and air pollution. Our long-term...
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Colorado Water Science Center
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Water, Energy, and Biogeochemical Budgets (WEBB): Loch Vale Watershed

Loch Vale is an alpine/subalpine watershed in Rocky Mountain National Park where the U.S. Geological Survey has been conducting research since the 1980s. Our research has focused on the effects of climate change and atmospheric pollutants on water, soil, vegetation, and aquatic life. The alpine/subalpine ecosystem in Loch Vale is sensitive to changes in climate and air pollution. Our long-term...
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Daily streamflow performance benchmark defined by D-score (v0.1) for the National Hydrologic Model application of the Precipitation-Runoff Modeling System (v1 byObs Muskingum) at benchmark streamflow locations

This data release contains the D-score (version 0.1) daily streamflow performance benchmark results for the National Hydrologic Model Infrastructure application of the Precipitation-Runoff Modeling System (NHM) version 1 "byObs" calibration with Muskingum routing computed at streamflow benchmark locations (version 1) as defined by Foks and others (2022). Model error was determined by evaluating pr
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Water Resources Mission Area

Streamflow benchmark locations for hydrologic model evaluation within the conterminous United States (cobalt gages)

A list of stream gages within the conterminous United States that will serve as the initial list of sites (version 1.0) used for streamflow benchmarking of hydrologic models. Sites within this list were chosen based on their presence in the GAGES-II dataset, their availability of modeled streamflow data from the most recent version of the National Hydrologic Model application of Precipitation-Runo
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Water Resources Mission Area

Model input and output for hydrologic simulations in the Rio Grande Headwaters, Colorado, using the Precipitation-Runoff Modeling System (PRMS)

The U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) was used to assess the effects of changing climate and land disturbance on seasonal streamflow in the Rio Grande Headwaters (RGHW) region. Three applications of PRMS in the RGHW were used to simulate 1) baseline effects of climate, 2) effects of bark-beetle induced tree mortality, and 3) effects of wildfire, on components of th
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Colorado Water Science Center

Base flow estimation via optimal hydrograph separation at CONUS watersheds and comparison to the National Hydrologic Model - Precipitation-Runoff Modeling System by HRU calibrated version

Optimal hydrograph separation (OHS) is a two-component, hydrograph separation method that uses a two-parameter, recursive digital filter (RDF) constrained via chemical mass balance to estimate the base flow contribution to a stream or river (Rimmer and Hartman, 2014; Raffensperger et al., 2017). A recursive digital filter distinguishes between high-frequency and low-frequency discharge data within
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Water Resources Mission Area

Groundwater Watch - Colorado Active Water Level Network

The Active Groundwater Level Network contains water levels and well information from wells in Colorado

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Colorado Water Science Center

SnowModel simulations and supporting observations for the north-central Colorado Rocky Mountains during water years 2011 through 2015

This data release includes simulation output from SnowModel (Liston and Elder, 2006), a well-validated process-based snow modeling system, and supporting snow, meteorological, and streamflow observations from the water years 2011 through 2015 (October 1, 2010, through September 30, 2015) across a 3,600 square kilometer model domain in the north-central Colorado Rocky Mountains. For each water year
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Colorado Water Science Center

Spatial variability in seasonal snowpack trends across the Rio Grande headwaters (1984 - 2017)

This study evaluated the spatial variability of trends in simulated snowpack properties across the Rio Grande headwaters of Colorado using the SnowModel snow evolution modeling system. SnowModel simulations were performed using a grid resolution of 100 m and 3-hourly time step over a 34-yr period (1984–2017). Atmospheric forcing was provided by phase 2 of the North American Land Data Assimilation
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Water Resources Mission Area, Climate Research and Development Program, Land Change Science Program, Colorado Water Science Center

Groundwater levels in the Denver Basin bedrock aquifers of Douglas County, Colorado, 2011–19

Municipal and domestic water users in Douglas County, Colorado, rely on groundwater from the bedrock aquifers in the Denver Basin aquifer system as part of their water supply. The four principal Denver Basin bedrock aquifers are, from shallowest to deepest, the Dawson aquifer (divided administratively into “upper” and “lower” Dawson aquifers in Douglas County), the Denver aquifer, the Arapahoe aqu
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Water Resources Mission Area, Colorado Water Science Center

Changes in climate and land cover affect seasonal streamflow forecasts in the Rio Grande headwaters

Seasonal streamflow forecast bias, changes in climate, snowpack, and land cover, and the effects of these changes on relations between basin‐wide snowpack, SNOw TELemetry (SNOTEL) station snowpack, and seasonal streamflow were evaluated in the headwaters of the Rio Grande, Colorado. Results indicate that shifts in the seasonality of precipitation and changing climatology are consistent with period
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Water Resources Mission Area, Climate Research and Development Program, Colorado Water Science Center

Estimation of base flow by optimal hydrograph separation for the conterminous United States and implications for national-extent hydrologic models

Optimal hydrograph separation (OHS) uses a two-parameter recursive digital filter that applies specific conductance mass-balance constraints to estimate the base flow contribution to total streamflow at stream gages where discharge and specific conductance are measured. OHS was applied to U.S. Geological Survey (USGS) stream gages across the conterminous United States to examine the range/distribu
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Water Resources Mission Area, Maryland-Delaware-D.C. Water Science Center, Colorado Water Science Center

Groundwater-Level Elevations in the Denver Basin Bedrock Aquifers of Elbert County, Colorado, 2015–18

Public and domestic water supplies in Elbert County, Colorado, rely on groundwater withdrawals from five bedrock aquifers in the Denver Basin aquifer system (lower Dawson, upper Dawson, Denver, Arapahoe, and Laramie-Fox Hills) to meet water demands. Increased pumping in response to regional population growth and development has led to declining groundwater levels in neighboring Douglas County. The
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Water Resources Mission Area, Colorado Water Science Center

Snow sublimation in mountain environments and its sensitivity to forest disturbance and climate warming

Snow sublimation is an important component of the snow mass balance, but the spatial and temporal variability of this process is not well understood in mountain environments. This study combines a process‐based snow model (SnowModel) with eddy covariance (EC) measurements to investigate (1) the spatio‐temporal variability of simulated snow sublimation with respect to station observations, (2) the
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Water Resources Mission Area, Colorado Water Science Center

Numerical experiments to explain multiscale hydrological responses to mountain pine beetle tree mortality in a headwater watershed

The effects of mountain pine beetle (MPB)-induced tree mortality on a headwater hydrologic system were investigated using an integrated physical modeling framework with a high-resolution computational grid. Simulations of MPB-affected and unaffected conditions, each with identical atmospheric forcing for a normal water year, were compared at multiple scales to evaluate the effects of scale on MPB-
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Water Resources Mission Area, Colorado Water Science Center

Water-quality response to a high-elevation wildfire in the Colorado Front Range

Water quality of the Big Thompson River in the Front Range of Colorado was studied for 2 years following a high‐elevation wildfire that started in October 2012 and burned 15% of the watershed. A combination of fixed‐interval sampling and continuous water‐quality monitors was used to examine the timing and magnitude of water‐quality changes caused by the wildfire. Prefire water quality was well cha
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Water Resources Mission Area, Climate Research and Development Program, Land Change Science Program, Colorado Water Science Center

Non-USGS Publications**

Penn, C. A., Wemple, B. C. and Campbell, J. L. (2012), Forest influences on snow accumulation and snowmelt at the Hubbard Brook Experimental Forest, New Hampshire, USA. Hydrol. Process., 26: 2524–2534. doi: 10.1002/hyp.9450

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Precipitation Runoff Modeling System (PRMS)

The Precipitation-Runoff Modeling System is a deterministic, distributed-parameter, physical process based modeling system developed to evaluate the response of various combinations of climate and land use on streamflow and general watershed hydrology.

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Water Resources Mission Area

Hydrologic Model Evaluation and Time-Series Tools (HyMETT) R-package

Hydrologic Model and Evaluation Time-series Tools (HyMETT) software facilitates the analysis and evaluation of hydrologic model output and time-series data with functions focused on comparison of modeled and observed data, period-of-record statistics, and trends.
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Water Resources Mission Area, Oregon Water Science Center

Science and Products