The R package cder provides a simple interface to the
CDEC Webservice. Getting CDEC data with cder is easy, just
pass a station code to cdec_query():
# get data for CDEC station NSL
cdec_query("NSL")The CDEC web service uses some default values for the duration code, sensor number, and start/end dates. However, these default values vary from station to station, and sometimes a station will return no data by default. It’s generally a good idea to specify these yourself:
station = "NSL"
duration = "event" # or "E"
sensor = 100 # electrical conductivity
start.date = "2023-01-01"
end.date = "2023-01-05"
cdec_query(station, sensor, duration, start.date, end.date)
#> # A tibble: 385 × 9
#> Stati…¹ Durat…² Senso…³ Senso…⁴ DateTime ObsDate Value
#> <chr> <chr> <int> <chr> <dttm> <dttm> <dbl>
#> 1 NSL E 100 EL COND 2023-01-01 00:00:00 2023-01-01 00:00:00 6015
#> 2 NSL E 100 EL COND 2023-01-01 00:15:00 2023-01-01 00:15:00 6019
#> 3 NSL E 100 EL COND 2023-01-01 00:30:00 2023-01-01 00:30:00 6075
#> 4 NSL E 100 EL COND 2023-01-01 00:45:00 2023-01-01 00:45:00 6151
#> 5 NSL E 100 EL COND 2023-01-01 01:00:00 2023-01-01 01:00:00 6283
#> 6 NSL E 100 EL COND 2023-01-01 01:15:00 2023-01-01 01:15:00 6310
#> 7 NSL E 100 EL COND 2023-01-01 01:30:00 2023-01-01 01:30:00 6360
#> 8 NSL E 100 EL COND 2023-01-01 01:45:00 2023-01-01 01:45:00 6408
#> 9 NSL E 100 EL COND 2023-01-01 02:00:00 2023-01-01 02:00:00 6425
#> 10 NSL E 100 EL COND 2023-01-01 02:15:00 2023-01-01 02:15:00 6444
#> # … with 375 more rows, 2 more variables: DataFlag <chr>, SensorUnits <chr>,
#> # and abbreviated variable names ¹StationID, ²Duration, ³SensorNumber,
#> # ⁴SensorTypeThe web service supports multiple stations and sensors:
# get data for CDEC stations NSL and HUN
stations = c("NSL", "HUN")
# get electrical conductivity and stage
sensors = c(100, 1)
start.date = "2023-01-01"
end.date = "2023-01-05"
cdec_query(stations, sensors, "hourly", start.date, end.date)
#> # A tibble: 388 × 9
#> Stati…¹ Durat…² Senso…³ Senso…⁴ DateTime ObsDate Value
#> <chr> <chr> <int> <chr> <dttm> <dttm> <dbl>
#> 1 NSL H 100 EL COND 2023-01-01 00:00:00 2023-01-01 00:00:00 6015
#> 2 NSL H 100 EL COND 2023-01-01 01:00:00 2023-01-01 01:00:00 6283
#> 3 NSL H 100 EL COND 2023-01-01 02:00:00 2023-01-01 02:00:00 6425
#> 4 NSL H 100 EL COND 2023-01-01 03:00:00 2023-01-01 03:00:00 6471
#> 5 NSL H 100 EL COND 2023-01-01 04:00:00 2023-01-01 04:00:00 6230
#> 6 NSL H 100 EL COND 2023-01-01 05:00:00 2023-01-01 05:00:00 5925
#> 7 NSL H 100 EL COND 2023-01-01 06:00:00 2023-01-01 06:00:00 4668
#> 8 NSL H 100 EL COND 2023-01-01 07:00:00 2023-01-01 07:00:00 3991
#> 9 NSL H 100 EL COND 2023-01-01 08:00:00 2023-01-01 08:00:00 3700
#> 10 NSL H 100 EL COND 2023-01-01 09:00:00 2023-01-01 09:00:00 4757
#> # … with 378 more rows, 2 more variables: DataFlag <chr>, SensorUnits <chr>,
#> # and abbreviated variable names ¹StationID, ²Duration, ³SensorNumber,
#> # ⁴SensorTypeCertain CDEC stations may store non-numeric data flags in the Value
column instead of in the DataFlag column, resulting in parsing issues.
For example, flow data at SGN (Sugar Creek near Callahan) will sometimes
use the codes “ART” and “BRT” to signify discharge at stages above or
below the available rating table. cder reexports
readr::problems() to allow you to view these parsing
problems, and additionally writes the problematic rows to a temporary
file to facilitate further investigation.
sgn = cdec_query('SGN', 20, start.date = "2022-07-02",
end.date = "2022-07-03")
#> Warning: One or more parsing issues, call `problems()` on your data
#> frame for details, e.g.:
#> dat <- vroom(...)
#> problems(dat)
#> Warning: Parsing problems detected. Output written to
#> C:\Users\michael\AppData\Local\Temp\RtmpqOnwQX\file478447f97f36.csv
problems(sgn)
#> # A tibble: 1 × 5
#> row col expected actual file
#> <int> <int> <chr> <chr> <chr>
#> 1 26 7 a double BRT C:/Users/michael/AppData/Local/Temp/RtmpqOnwQX/fi…That’s it! The CDEC Webservice currently does not support querying
station metadata. To browse station data, use the Station Search
tool or Locator
Map. These URLs can also be accessed by calling
cdec_search_stations() and cdec_map(),
respectively. See help("cdec-search") for more
information.To access the metadata page for a particular station, use
cdec_meta().