Groundwater chemistry#

client.chemistry gives access to SGU’s Grundvattenkvalitet, analysresultat och provplatser (version 2) API. The data comes as two collections:

Sampling sites (provplatser): wells and springs where samples are taken.
Analysis results (analysresultat): one measured value of one chemical parameter in one sample.

Identifying sites#

A sampling site has three identifiers:

Argument	API name	Example
`national_site_id`	`nationellt_provplatsid`	`359366`
`site_id`	`platsbeteckning`	`"TTK-442-M"`
`site_name`	`provplatsnamn`	`"Lena"`

Analysis results refer to sites only by national_site_id, so that is the fastest way to fetch results. Passing site_id or site_name instead works, but costs an extra request to look up the site and logs a warning.

from sgu_client import SGUClient

with SGUClient() as client:
    site = client.chemistry.get_sampling_site_by_name(site_id="TTK-442-M")
    national_site_id = site.properties.national_site_id  # 359366

Fetching analysis results#

Fetch results for one or more sites, optionally limited to a time range with tmin and tmax:

results = client.chemistry.get_results_by_site(
    359366,
    tmin="2020-01-01",
    tmax="2024-01-01",
)

# several sites in one request
results = client.chemistry.get_results_by_sites([359366, 378865], tmin="2020-01-01")

sampling_date and the other result dates are UTC datetimes, as are the site dates established_date, first_sample_date and latest_sample_date. See Dates and times.

When sites are given by site_id or site_name, a lookup that misses any requested site raises SGUNotFoundError naming them instead of returning partial results.

Filtering by parameter#

Parameters are identified by SGU’s Swedish parameter names (parameter_name, parameternamn). Some common ones:

Parameter name	Meaning
`pH`	pH
`Konduktivitet`	Electrical conductivity
`Klorid`	Chloride
`Svavelsulfat`	Sulfate
`Nitratkväve`	Nitrate nitrogen
`Bly`	Lead

# all lead measurements since 2020
lead = client.chemistry.get_results_by_parameter("Bly", tmin="2020-01-01")

# pH at a single site
ph = client.chemistry.get_results_by_parameter("pH", national_site_id=359366)

Querying the collections directly#

For anything the convenience methods don’t cover, query the collections with OGC API filters. filter_expr takes a CQL expression using the Swedish API field names:

sites = client.chemistry.get_sampling_sites(
    bbox=[12.0, 55.0, 16.0, 58.0],
    filter_expr="provplatstyp='brunn_ror'",
)

results = client.chemistry.get_analysis_results(
    filter_expr="parameternamn='Bly' AND provtagningsdatum>='2020-01-01'",
)

Note

The v2 chemistry API ignores the sortby parameter.