Rainfall Files

GeoSWMM’s rain gage objects can utilize rainfall data stored in external rainfall files. The program currently recognizes the following formats for storing such data:

• Hourly and fifteen-minute precipitation data from over 5,500 reporting stations retrieved using NOAA’s National Climatic Data Center (NCDC) Climate Data Online service (www.ncdc.noaa.gov/cdo-web) (space-delimited text format only).
• The older DS-3240 and related formats used for hourly precipitation by NCDC.
• The older DS-3260 and related formats used for fifteen minutes precipitation by NCDC.
• HLY03 and HLY21 formats for hourly rainfall at Canadian stations, available from Environment Canada at www.climate.weather.gc.ca.
• FIF21 format for fifteen minutes rainfall at Canadian stations, also available online from Environment Canada.
• a standard user-prepared format where each line of the file contains the station ID, year, month, day, hour, minute, and non-zero precipitation reading, all separated by one or more spaces.

When requesting data from NCDC’s online service, be sure to specify the TEXT format option, make sure that the data flags are included, and, for 15-minute data, select the QPCP option and not the QGAG one.

An excerpt from a sample user-prepared Rainfall file is as follows:

S01   2001  7     12    00    00    0.12

S01   2001  7     12    01    00    0.09

S01   2001  7     22    15    00    0.17

When a rain gage receives the rainfall data from a file, the user must supply the name of the file and the name of the recording station referenced in the file. For the standard user-prepared format, the rainfall type (e.g., intensity or volume), recording time interval and depth units must be supplied also as rain gage properties. For the other file types these properties are defined by their respective file format and are automatically recognized by GeoSWMM.