Introduction

Archived Climate and River data can be used to understand changes to the snow, average temperature, and river flow over time.  Important (federally funded – i.e. your tax dollars) data includes USGS stream gauge (https://waterdata.usgs.gov/nwis/rt) and NOAA climate data (https://www.ncdc.noaa.gov/cdo-web/).  Placing the climate and river data into a geological context can be useful for understanding how the data can be used to benefit humans, sustainability practices, wildlife management, for example.

 

Geological Setting

Northwest Colorado includes the area west of the Park Range (REP and Mount Zirkel labels denote geomorphic features in the North Park Range – white to light pink elevation color).

Northwest Colorado Elevation Map

Figure 1: The Digital Elevation surface (colored surface) is a national endeavor to accurately map elevation for the nation using a combination of ground surveys and satellite imaging: https://nationalmap.gov/elevation.html. A subset, can be obtained fro the Colorado Geological Survey: http://coloradogeologicalsurvey.org/geologic-mapping/gis-data/. The stream lines (medium blue) and stream drainage basins (light blue) are obtained from the digital elevation models (DEMs) and stores on the Hydrosheds website: http://www.hydrosheds.org/. Town and Cities are denoted with black dots and labels.

NW_Colorado_DEM

 

 

Part of the Yampa River Drainage Basin is shown in light blue on Figure 1).  The Yampa river and tributaries collect runoff (water from rain or melted snow) from the western Northern Park Range and White River Uplift (labeled Flat Top Wilderness on Figure 1).  The Yampa River Drainage Basin ultimately flows into the Green River Drainage Basin (in Dinosaur National Monument – near the Colorado/Utah border) which adds river flow to the Colorado River Basin.

 

Methods

The USGS (United States Geological Survey) and NOAA (National Oceanographic and Atmospheric Administration) have collected and archived river flow and climate data for the country.  USGS stream gauge (https://waterdata.usgs.gov/nwis/rt) and NOAA climate data (https://www.ncdc.noaa.gov/cdo-web/).  Some of the data have been recorded for over 100 years which make them valuable for climate change studies.

 

Figure 2: Topography or Elevation of the area of the city of Steamboat Springs

Figure 3: Photo of USGS river gauging station at 5th Street in Steamboat Springs

 

 

 

 

 

 

 

 

 

 

 

 

You can observe the stream gauging station at 5th Street in Steamboat Springs (the brick building on the southwest side of the river).  This is one of the longest continuously monitored gauging stations in the country (over 100 years of record).

Figure 4: Schematics and data for River gauging stations and Climate data collection stations.  Upper left, a diagram from the USGS that illustrates how a stream gauging station measures water flow.  Lower left, a photo of the Yampa river and USGS stream gauging station across the stream.  Upper right, photo from NCDC-NOAA climate data measuring station.  Lower right, example of tabulated climate data (NCDC-NOAA).

 

Data and Results:

 

Figure 5:  Daily Snowfall (mm and in), River flow (discharge in cfs – cubic feet per second and cms – cubic meters per second), Minimum daily temperature (degrees Celcius and degrees Fahrenheit).

Century-long records provide information about annual to decadal changes in climate and river flow.  Individual snow fall events range from a few inches to ~a foot.  Spring river discharge ranges from ~ 100 cms to 160 cms.  Minimum Daily Temperature values range from commonly ~50°F in the summer to commonly -20°F in the winter.  A subtle, yet interesting, change becomes apparent.  During the 1st half of the 20th century, the lowest winter temperatures occasionally approached -45 to -50°F.  During the second half of the 20th century, the annual low extremes did not exceed -40°F.  These are observations apparent from the data.  Interpretations of what causes this change to warmer minimum temperatures could range from global climate change to natural decadal- to century-scale oscillations in climate/temperature trends.  With this data alone, we cannot be certain.  But when placed into context with data collected around the world, we might draw a conclusion that Steamboat Springs is showing warming trends consistent with the global climate.

 

Detailed comparison of the minimum daily temperature, river discharge, and snowfall.  When the minimum daily temperature consistently rises above freezing, the river discharge peaks in April to June with the melt of the majority of the snow.

Figure 6: 2011 to 2016 minimum daily temperature, river discharge, and snowfall.  Dashed gray lines indicate the beginning of the peak discharge.

Using the ~century of data we can look for systematic changes over this time period.  for instance, the date of peak discharge in 1912 was June 5 as compared to the date of peak discharge in 2007 being May 15.  The date of peak discharge over the past ~ 100 years has ranged from May 25 to June 9

Figure 7:  Comparison of 2 years, 1912 and 2007 illustrating how peak discharge relates to minimum daily temperature and snowfall.  When the minimum daily temperature consistently rises above freezing, the river reaches peak discharge.

Extracting out the date of peak discharge or most significant snowmelt for each year and plotting that data shows us an interesting trend.  By adding a linear trend line, the data shows a progressive shift towards earlier peak discharge or significant snowmelt.  At the beginning of the 20th century, the peak discharge date was, on average, around June 5.  By the first decade of the 21st century, the peak discharge or significant snowmelt date is around May 26 or 10 days earlier.  Moreover 1974 marks the earliest snowmelt/peak discharge on April 26 whereas in 1983 the peak discharge/snowmelt date occurred on June 25.  Since the early 1990’s most peak discharge/significant snowmelt dates are in mid-May to the earliest June.  At the beginning of the 20th century (early 1900’s), the peak discharge/significant snowmelt events were latest May to mid-June.

 

 

 

 

 

 

 

 

 

 

Figure 8:  Date of peak discharge or significant snowmelt from 1904 to 2015 for the 5th street bridge USGS gauging station on the Yampa River, Steamboat Springs, CO.  Red dot marks the 1912 year whereas green dot marks the 2007 year with details shown in figure 7.  Bold black trend line indicates the average change in peak discharge/snowmelt.  Green dashed horizontal lines indicate the dates of significant snowmelt/peak discharge at the beginning of the 20th century (top green dashed horizontal line) and beginning of the 21st century (bottom green dashed horizontal line).

 

Summary:

 

Archived and digital climate data can be utilized to understand weather patterns and climate changes.  Steamboat Springs, a town in the mountains of Colorado has century-length climate records (temperature, snowfall, river flow).  These records can be used to 1) educate and 2) place into a regional to global context of climate change.  The changes can be utilized by climate modelers to understand how future changes in the atmosphere, hydrosphere and geosphere may interact to affect weather that people experience day to day.

In this article, we have included just a few of many possible graphs from the datasets.  Interesting findings within the data include a earlier average snowmelt date through time.  This may be related to global climate change patterns and may represent another line of evidence.  Future work may include adding additional data/graphs to investigate whether the minimum temperature is rising and does the daily minimum temperature rise above freezing earlier in the year?  What about total snowfall, are there trends?  Do trends observed in Steamboat Springs exist in other areas of the Rocky Mountains.  How does this affect the ski season for Steamboat Springs ski resort?

 

 

References:

Ray, A.J., Barsugli, J.J., Averyt, K.B., Wolter, K., Hoerling, M., Doesken, N., Udall, B., Webb, R.S., 2008, Climate Change in Colorado, A Synthesis to Support Water Resources Management and Adaptation; A Report by the Western Water Assessment for the Colorado Water Conservation Board, http://cwcb.state.co.us/public-information/publications/documents/reportsstudies/climatechangereportfull.pdf

Stream Gauge records from United States Geological Survey (USGS) http://waterdata.usgs.gov/nwis/inventory/?site_no=09239500&agency_cd=USGS

Climate records from NOAA National Climate Data Center (NCDC) http://www.ncdc.noaa.gov/cdo-web/cart?mr=t