CONUS NG-IDF Data Sets

The NG-IDF data sets are developed for characterizing extreme events relevant to hydrologic design over water years 1951‒2013, at a 1/16th-degree (~6 km) resolution for over 200,000 locations across the conterminous United States (CONUS). The data sets are prepared in comma-separated value (.csv) format.

The data sets include:

• list_location.csv
  • Content: geographic coordinates and (snow parameterization) cluster ID of 207,173 locations over the CONUS land surfaces. 
  • Dimension: 207,173 (Rows) x 3 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3: cluster ID (ranging from 1‒5) 
• IDF/
  • Content: discrete IDF values, i.e. magnitude of extreme events, corresponding to different event durations and returned periods, driven by different hydrometeorological mechanisms (i.e., rain, snowmelt, and rain-on-snow [ROS])
  • Dimension: 207,173 (Rows) x 9 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3‒9 (unit: mm): IDF values corresponding to return periods of 2 , 5, 10, 25,  50, 100, and 500 year
• trend/
  • Content: Sen's slope of Mann-Kendall trend in annual maximum series driven by different hydrometeorological mechanisms over water years 1951‒2013
  • Dimension: 207,173 (Rows) x 3 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3:Trend. Unit is mm/year for all files but ROS_freq.csv that has a unit of # of events per year.
• Dom-Driver/
  • Content: Dominant driving mechanism of extreme W events with different durations (24, 48 and 72 hours) and return periods (10, 50, and 100 years)
  • Dimension: 207,173 (Rows) x 3 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3: Dominant driver IDs (1=rainfall, 2=ROS, 3=melt).
• risk/
  • Content: Design risk associated with PREC-IDF estimated 100-year extreme events
  • Dimension: 207,173 (Rows) x 3 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3: Bias (%) in PREC-IDF estimated extremes relative to NG-IDF
• SI/
  • Content: Seasonality of annual maximum W events with 24-, 48-, and 72-hr durations
  • Dimension: 207,173 (Rows) x 4 (Columns)
  • Format: C1: Latitude; C2: Longitude; C3: Mean data (=1 if Oct 1); C4: Seasonality index

Abbreviations used in folder/file names:

• W = water reaching the land surface during rain, snowmelt, and ROS events
• P = precipitation 
• R = rainfall
• ROS = rain-on-snow
• M = snowmelt