CAMELS: Large-Sample Hydrometeorological Dataset

This is a community data set of daily forcing and hydrologic response data for 671 small- to medium-sized basins across the contiguous United States (median basin size of 336 km2) that spans a very wide range of hydroclimatic conditions. Area-averaged forcing data for the period 1980 to 2014 was generated for three basin spatial configurations (with variable spatial resolution) - basin mean, hydrologic response units (HRUs) and elevation bands - by mapping daily, gridded meteorological data sets to the subbasin (Daymet) and basin polygons (Daymet, Maurer and NLDAS). Daily streamflow data was compiled from the United States Geological Survey National Water Information System.

The focus of this dataset is to (1) be available for community use and (2) provide a model performance benchmark using the coupled Snow-17 snow model and the Sacramento Soil Moisture Accounting Model, calibrated using the shuffled complex evolution global optimization routine. After optimization minimizing daily root mean squared error, 90% of the basins have Nash-Sutcliffe efficiency scores >=0.55 for the calibration period and 34% >= 0.8. This benchmark provides a reference level of hydrologic model performance for a commonly used model and calibration system, and highlights some regional variations in model performance. For example, basins with a more pronounced seasonal cycle generally have a negative low flow bias, while basins with a smaller seasonal cycle have a positive low flow bias. Finally, we find that data points with extreme error (defined as individual days with a high fraction of total error) are more common in arid basins with limited snow and, for a given aridity, fewer extreme error days are present as the basin snow water equivalent increases.

To Access Resource:

Questions? Email Resource Support Contact:

  • Andrew Newman
    UCAR/NCAR - Research Applications Laboratory

Temporal Range

  • Begin:  1980-01-01T00:00:00
    End:  2014-12-31T00:00:00


Resource Type dataset
Temporal Range Begin 1980-01-01T00:00:00
Temporal Range End 2014-12-31T00:00:00
Temporal Resolution Daily
Bounding Box North Lat 50
Bounding Box South Lat 25
Bounding Box West Long -125
Bounding Box East Long -66
Spatial Representation vector
Spatial Resolution N/A
Related Links

Dataset website : The website provides additional information, including related papers, regarding the dataset.

Additional Information N/A
Resource Format ASCII - Formatted for text attributes
Standardized Resource Format ASCII
Asset Size 15000 MB
Legal Constraints

When using this dataset, users acknowledge and accept the following: - Terms of Use ( - Copyright Issues ( - Privacy Policy ( - Publication and Information Dissemination ( - Public Access (

Access Constraints None
Software Implementation Language N/A

Resource Support Name Andrew Newman
Resource Support Email
Resource Support Organization UCAR/NCAR - Research Applications Laboratory
Distributor N/A
Metadata Contact Name Andrew Newman
Metadata Contact Email
Metadata Contact Organization UCAR/NCAR - Research Applications Laboratory

Author Andrew J. Newman
Kevin Sampson
Martyn P. Clark
Andrew Bock
Roland Viger
Dave Blodgett
Publisher UCAR/NCAR
Publication Date 2016-05-15
Digital Object Identifier (DOI)
Alternate Identifier A large-sample watershed-scale hydrometeorological dataset for the contiguous USA
Resource Version 1.2
Topic Category N/A
Progress onGoing
Metadata Date 2018-10-12T17:00:27
Metadata Record Identifier 03da9963-ccd8-11e8-a6b1-b808cf016134
Metadata Language eng
Suggested Citation Andrew J. Newman, Kevin Sampson, Martyn P. Clark, Andrew Bock, Roland Viger, Dave Blodgett. (2016). CAMELS: Large-Sample Hydrometeorological Dataset. 1.2. UCAR/NCAR. Accessed 22 September 2023.

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