Add waterdata.get_field_measurements_metadata

[thodson-usgs]

Adds a thin wrapper around the OGC /collections/field-measurements-metadata collection. Returns one row per (location, parameter) field-measurement series describing its period of record, units, etc., without the underlying observations — that's what get_field_measurements is for.

Discrete-measurement analogue to get_time_series_metadata (which describes daily / continuous series). Primary use case is inventory queries: "what field-measurement parameters does this site have, and over what date range?"

Implementation

Mirrors R's read_waterdata_field_meta, with the same output_id ("field_series_id") and parameter list. Body is the standard service-agnostic dispatch through get_ogc_data — no new infrastructure required.

Live API examples (verified)

from dataretrieval.waterdata import get_field_measurements_metadata

# All series at a surface-water site
df, md = get_field_measurements_metadata(monitoring_location_id="USGS-02238500")
# 2 rows: parameter_code 00060 (discharge) and 00065 (gage height),
# both with begin in 1943 and end in 2026.

# Multi-site narrowed to discharge
df, md = get_field_measurements_metadata(
    monitoring_location_id=["USGS-07069000", "USGS-07064000", "USGS-07068000"],
    parameter_code="00060",
)
# 3 rows, one per site.

Test plan

• test_get_field_measurements_metadata — single-site happy path; asserts field_series_id, begin, end columns.
• test_get_field_measurements_metadata_multi_site — exercises the multi-site POST path.
• Live verification against api.waterdata.usgs.gov.

Related

Part of the v1.1.4 release-staging series; will be linked from a tracking issue.

[thodson-usgs]

Tracked in the v1.1.4 release-staging issue: #270.