GroundWater Desktop

KT3D_H2O

Though kriging is widely used as the preferred method for constructing gridded water level datasets suitable for contouring, residuals arising from using the most common (linear) drift to krige water levels in the vicinity of extraction wells often indicate large local departures from the linear drift, which correlate with areas of drawdown. These are evident in plan view and cross-section.

Using linear-log kriging, ground water levels measured in the vicinity of pumping wells are kriged using a regional-linear and point-logarithmic drift, the latter derived from the Thiem equation. Hence, the combined regional-linear and point-logarithmic drift accounts for drawdowns (or mounding, in the case of injection wells) using a logarithmic approximation for the curvature of the potentiometric surface. Since the drift model approximates the principal physical processes that govern ground water flow and govern the auto-correlation of ground water elevation data, this approach produces maps of contoured water levels that more realistically represent physical conditions and that allow for improved interpretation of measured water-level data. Additional benefits include an improved estimate of the background hydraulic gradient and generation of an grid suitable for two-dimensional particle tracking.

KT3D_H2O allows to generate gridded maps of water level elevations that include the following elements that have important influence on the shape of the mapped surface and are usually ignored by other gridding software applications:

  • Point Sink or Source of Known Strength (Well Drift): accounts for mounding (or drawdown) in response to injection (or extraction) at a known rate at one or more wells.
  • Horizontal Line Sink, Source or Barrier: accounts for mounding (or drawdown) in response to finite-length horizontal linear features such as interception trenches, infiltration galleries and hydraulic barriers.
  • Leaking Pond of Known Strength: accounts for the potentiometric response of a water table (unconfined) aquifer to infiltration through the base of a perched circular or irregular shaped pond.

Experimental and theoretical variogram modeling and visualizations

Support for multi monitoring event variograms.

Kriged results can be used to complete the following types of hydrogeologic analyses maps for single or multiple monitoring events:

  • Maps of water level elevations
  • Maps of Kriging Variances
  • Maps of Cross validation results
  • Particle tracking for approximate capture zone delineation.

KT3D_H2O produced water-level maps are used for particle tracking that can be used to evaluate approximate flow directions and rates, approximate advective(-dispersive) transport and approximate the extent of capture.

Particle tracking uncertainty, associated with the physical process of hydrodynamic dispersion and mixing, is incorporated through a random walk component. The random walk movements are added to the advective displacements, providing an indication of the expected uncertainty in particle location due to dispersion.

The combined results of the approximate capture zone analyses can be used to evaluate the robustness of hydraulic capture, and identify areas where capture may be compromised by creating the Capture frequency maps. Capture frequency maps are generated by:

  • Processing multiple water level events, each with unique pumping rate data; producing groundwater elevation contours for each event;
  • Undertaking particle tracking on each surface and recording the fate of each particle; and,
  • Summarizing the results in terms of the fraction of the events for which each particle was removed at an extraction well.

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