What is it?
This interface section is used to specify the bottom elevation of the aquifer (conceptual) layer.NOTE: The bottom surface of near surficial/unconfined aquifers is commonly represented as a data layer that follows the interface between unconsolidated sediments and consolidated rock material (usually assumed to be a ‘no-flow’ boundary condition when the yield of rock is expected to be low relative to that of the overlying sediments).
How to use it:
The bottom boundary of the model domain (aquifer bottom) can be assigned as:- a constant value prescribed by the user
- a surface following the aquifer top elevation surface such that the aquifer has a constant thickness
- a constant elevation that is a prescribed value below the minimum DEM elevation within the model domain
- a surface following the bedrock top surface raster on the MAGNET4WATER Data Center (see more below)
- a surface based on a user bedrock top surface raster file, which can be uploaded by checking the box next to ‘Import’ and then selecting the link to open a file browser (see more details below).
- a surface prescribed by a spatially-variable aquifer thickness from the MAGNET Data Center (see more below).
- a surface prescribed by a spatially-variable aquifer thickness from a user aquifer thickness raster file.
You can also import scatter points of bottom elevations using zone features.
Import Raster Options
The following raster file formats are supported for import of user aquifer thickness or bedrock top surface files: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 .img file
MAGNET4WATER Data Center Layers
1. Rock Top Elevation Michigan
A 500m resolution layer is available for the State of Michigan (United States) representing the top of the bedrock unit underlying the unconsolidated glacial sediments. The continuous surface was interpolated from bedrock elevations noted in lithologic records in Wellogic, a statewide database of water well records.Make sure the 'Min DEM Minus' suboption is selected (while also choosing 'Data Center' radio button option).
2. Global AQ Thick. 1000m
Global layer of surficial aquifer thickness (depth to bedrock top surface) from ORNL DAAC Soil Collection Archive, Pelletier at al. (2016) "Global 1-km Gridded Thickness of Soil, Regolith, and Sedimentary Deposit Layers."Make sure the 'Thickness' suboption is selected (while also choosing 'Data Center' radio button option).
3. Global AQ Thick. 250m
Global depth-to-bedrock dataset from the Land-Atmosphere Interaction Research Group, Sun Yat-sen University, Shangguan et al. (2017).Make sure the 'Thickness' suboption is selected (while also choosing 'Data Center' radio button option).
4. US Glacial AQ Thick.
A 800m resolution dataset representing the total thickness of glacial deposits for the glaciated regions of the northern United States. From USGS data release "Maps and grids of hydrogeologic information created from standardized water-well drillers' records of the glaciated United States".Make sure the 'Thickness' suboption is selected (while also choosing 'Data Center' radio button option).