Jump to content
GMS, SMS, and WMS User Forum

Process for specifying constant head in top model layer


Recommended Posts

Hi all,

I am not a constant user of GMS so I am often re-learning data processing techniques.  I am looking for help with a procedure to accomplish the following objective. 

I have a 10 layer, steady state flow model of a coastal plain. The top layer predominantly represents a confining clay layer (material 1 in brown) with several small discontinuous regions where the underlying aquifer is exposed (material 2 in green) and some inactive regions (in red). Regions where the underlying aquifer are exposed have specified values for recharge (using polygon feature objects derived from shapefile). Other BC's are defined on the top layer: (CHD for ocean - in cyan; rivers in blue; drains appearing only in material 2 - not shown).

I would like to specify a constant head in layer 1 equal to (TOP-1m) for every cell where clay is present but not interfere with other BCs subject to the following constraints:

If (TOP -1) > BOT,

   Constant head = TOP - 1

Else

   Constant head = BOT + (TOP - BOT) * 0.1

Any help on a process for accomplishing this task would be greatly appreciated.

Thanks

Ted

2019-09-13_11-21-51.png

Edited by tlillys
Link to post
Share on other sites
  • 1 month later...

My solution was to use QGIS to first create a raster from the DEM that followed the rules above. Then I created a polygon shape for the entire grid and then used the Difference algorithm to cut away the other features in the region that are represented by polygon shapes, one by one, first the ocean, rivers, green and red areas, leaving a polygon that represented the exposed clay layer at the surface.  I imported the polygon shapes and used the raster to define the CHD head stage value.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...