Water levels
A Water Level is a single static groundwater gauging reading taken at a Location — routine well monitoring, not a pumping or recovery event. Each reading captures how far below the well's measuring point the water sits, plus optional well-condition and free-product readings — LNAPL (Light Non-Aqueous Phase Liquid) that floats on the water table and DNAPL (Dense Non-Aqueous Phase Liquid) that sinks below it. Pumping and recovery readings belong to a Well Purge instead.
What a water level records
A water level is an aggregate root in its own right. It belongs to a Site and a Project (both required, both fixed once the reading is created), and it is recorded at a Location — the point on the Site where the gauging was taken — optionally naming a Well at that Location. As with the site's field parameters, the record is owned and queried at the Site level; the Location is the measurement point, not the scope it lives under. There is no measurement-type field — the record is the type. You don't choose "static" versus "pumping"; you record a Water Level for routine gauging and a Well Purge for purge events.
The two core numbers are the depth to water and the groundwater elevation:
- Depth to water (
DepthToWater) is the distance from the measuring point down to the water surface. It is signed — a negative value records an artesian (flowing) well, where water rises above the measuring point. - Groundwater elevation (
GroundwaterElevation) is the water surface expressed as an elevation, relative to the same vertical datum as the measuring point.
Both are optional, but a reading with no measurement value at all must explain itself: either mark the well dry, or supply a Qualifier or Notes, or the record is rejected.
The measuring point lives on the Well
A water level is referenced to the well's measuring point — the fixed mark (typically the top of casing) that depth is measured from. The reading stores MeasuringPointElevation, a single elevation value, but the measuring-point datum (the Well's vertical datum and top-of-casing elevation) belongs to the Well, not to the water level. This keeps every reading at a well consistent against one surveyed mark.
When the measuring-point elevation, depth to water, and groundwater elevation are all recorded, Erde checks that the groundwater elevation matches measuring-point elevation − depth to water within a unit-aware tolerance (0.05 ft / 0.02 m). A larger mismatch produces a warning, not a rejection — it flags a likely transcription error without blocking the save. The check is skipped when LNAPL is present, because floating product depresses the apparent water surface and a NAPL-corrected elevation legitimately diverges from the raw calculation.
Figure: A water level is gauged at a Location, optionally tied to a Well, and owned by a Project.
Duplicates are a warning, not a block
Erde does not enforce a unique constraint on water levels. If you record a second reading for the same Location, the same Well, and the same measurement date and time, Erde returns a warning — "Another water level reading already exists for this well and location at the same date and time." — and still saves the row.
The duplicate check matches on the Well as well as the Location and date, so legitimate well-cluster or nest gauging — several wells at one Location read on the same day — does not trip it. A future-dated reading is likewise a warning, never an error.
Units and method
Every reading carries a Unit, which is required and defaults to Feet. Method records the physical tool used and is optional.
| Field | Required | Values |
|---|---|---|
| Unit | Yes | Feet (default), Meters |
| Method | No | Electric Tape, Interface Probe, Pressure Transducer, Sonic / Acoustic, Visual Estimate, Airline, Steel Tape, Other |
A Pressure Transducer value here is a single spot reading off the transducer's display — it is one moment in time, not a continuous time series.
Free product, well condition, and personnel
Beyond the two core numbers, a reading can record floating or sinking free product, the well's total depth, a dry-well flag, and who took the reading. All of these fields are optional, and all are interpreted in the reading's Unit.
| Field | Required | Notes |
|---|---|---|
LNAPL thickness (LnaplThickness) | No | Thickness of light non-aqueous phase liquid floating on the water surface. Must be positive when supplied. |
Depth to LNAPL (DepthToLnapl) | No | Depth from the measuring point to the top of the LNAPL column. Non-negative. |
DNAPL thickness (DnaplThickness) | No | Thickness of dense non-aqueous phase liquid resting below the water. Must be positive when supplied. |
Depth to DNAPL (DepthToDnapl) | No | Depth from the measuring point to the top of the DNAPL column. Non-negative. |
Total depth (TotalDepth) | No | Sounded depth to the bottom of the well. Must be positive when supplied. |
Is dry (IsDry) | No | Marks the well as dry. Defaults to off. |
Dry reason (DryReason) | No | Free text explaining why the well is dry. Up to 200 characters. |
Measured by (MeasuredBy) | No | Name of the person who took the reading. Up to 200 characters. |
A few consistency rules govern these fields. A reading marked Is dry cannot also carry a depth to water or groundwater elevation — a dry well has no water surface to measure — and dry reason can only be set when the reading is marked dry. NAPL thickness and its matching depth are usually recorded together, and depth to water beyond the total depth, LNAPL below the water surface, or DNAPL above it each produce a warning to flag a likely transcription error; none of these warnings blocks the save.
How it fits together
| Aspect | Water Level | Well Purge |
|---|---|---|
| Records | Static (routine) gauging | Water purged before sampling |
| Created when | You gauge a well | Water is actually purged |
| Pumping / recovery readings | No — out of scope | Yes |
| Scope | Site and Project; recorded at a Location, Well optional | Site and Project; recorded at a Location, Well optional |
Water levels feed the Hydrograph tool, which charts groundwater levels over time. The full Field Monitoring set is described in the Field Monitoring overview.
Delete several at once
The Water Levels grid supports multi-select deletion. Tick the checkbox on each row you want (or use the header checkbox to select the whole page), then select Delete selected (N) above the grid and confirm. This grid loads a page at a time, so selection covers the current page — to remove a larger set, narrow it with a filter first. Search, filter, sort, and Export apply to the whole table; see Working with data grids.
Bulk deletion is permanent and cannot be undone. Each removed water level is recorded individually in the Audit Log. Bulk delete is unavailable while the Site is locked.