What is it?
Also referred to as the Coefficient of Permeability, the conductivity is a measure of a liquid’s ability to move through a porous media. Conductivity is derived from the relationship between specific discharge (v = Q/A) and the hydraulic gradient (dh/dl) defined in Darcy’s law. The coefficient K is expressed in units of [L]/[T], commonly as m/d, cm/s or ft/d.Source: Adapted from Domenico and Schwartz (1990).
How to use it:
A. Single Effective ValueB. M4W Data Center Layer
C. DataNET Layer
D. User Raster
E. Anisotropy Ratios
F. TP Geostatistical Simulation
A. Single Effective Value
Assign spatially-constant, effective horizontal (Kxx) values and implicitly assign vertical (Kzz) and north-south (Kyy) conductivities through prescribing vertical and horizontal anisotropy ratios (Kxx/Kzz and Kxx/Kyy, respectively) - more on this below. The value is applied throughout the model domain, expect in areas where zone-based refinement is being applied.B. M4W Data Center Layer
Hydraulic Conductivity (K) can be represented with spatially variable 2D data-layers available on the MAGNET4WATER Data Center. Most layers are geographically limited. An option with global coverage is available.1. Michigan Glacial-Screen to 1st Confining Unit
This layer covers the State of Michigan (United States) and represents the vertically-averaged K of the surficial glacial deposits based on estimates of K from water well records, from the well screen to the first confining unit encountered.2. Michigan Glacial-Entire Drift Sediment
Another layer for the State of Michigan (United States) representing average K of the surficial glacial deposits, but computed from K estimates from water well records spanning the entire glacial drift sediment (i.e., from the well screen to the static water level / land surface).3. Global Surficial K
Estimates of average K of surficial aquifers (global spatial coverage). Spatial resolution: ~90 square km, rasterized to 540m grid cells. Estimates are from Huscroft et al. (2018) as part of the GLHYMPS 2.0 project: "Compiling and Mapping Global Permeability of the Unconsolidated and Consolidated Earth: GLobal HYdrogeology MaPS 2,0 (GLHYMPS 2.0)".4. Michigan Bedrock T
Transmissivity of the subcropping bedrock geological unit for the State of Michigan, completed using spatial interpolation of transmissivity estimates from analysis of aquifer pumping test data. Spatial resolution: 540m.NOTE: IGW-NET will use the modeled aquifer thickness and given transmissivity estimates to compute model hydraulic conductivity.
5. USA Glacial K
800m resolution dataset representing estimated hydraulic conductivity of the glacial deposits for the glaciated regions of the northern United States. Originally published in USGS data release by Bayless et al. (2017): "Maps and grids of hydrogeologic information created from standardized water-well drillers' records of the glaciated United States".6. USA/Canada T
1km resolution dataset of transmissivity of aquifer presented in de Graaf et al. (2020) for the continental United States and Canada. Originally published by de Graaf et al. (2020): "Hyper-resolution continental-scale 3-D aquifer parameterization for groundwater modeling".NOTE: IGW-NET will use the modeled aquifer thickness and given transmissivity estimates to compute model hydraulic conductivity.
C. DataNET Layer
This option allows users to import from MAGNET4WATER DataNET a WCS data layer as a raster file of aquifer recharge. A "linked" DataNET page needs to be opened to be able to send a WCS layer from DataNET into IGW-NET (a prompt will appear if that is the case, allowing the user to open a new DataNET page to be linked).Once the WCS layer is transferred into IGW-NET, it will be converted into a geotiff raster file uploaded to your user folder.
See the 'DataNET-based Model' Quick Tutorial for an example.
D. User-provided Raster
User raster files can be used to assign Kxx values across the model domain. To do this, check the box next to the ‘Import’ link, then select the link to open a file browser.The following raster file formats are supported for import of user hydraulic conductivity data layers:
1 - Ascii format with the same projection (PRJ) as your model PRJ
2 - Geotiff (.tif) format with PRJ information embedded in the .tif file
3 - IMG format with PRJ information embedded in the .tif file
E. Anisotropy Ratios
This section also allows assigning anisotropy ratios in both horizontal and vertical directions, i.e., Kxx/Kyy and Kxx/Kzz, respectively, where Kxx is the X- (west-east) direction horizontal conductivity, Kyy is the Y- (north-south) direction horizontal conductivity, and Kzz is the vertical hydraulic conductivity within the current conceptual / aquifer layer.Note that the ratios are assumed to be 1 if these checkboxes are not selected.
Also note that the anisotropy ratios apply to both a single value or a raster approach for assigning hydraulic conductivity.