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Hi all. I have a problem mapping recharge to MODFLOW-USG within GMS (version 10.2.4). My MODFLOW-USG model has multiple layers. Layer 1 pinches out to expose layer 2 at the surface, and similar for deeper layers (that's how GMS created the 3D grid from horizons and TINS etc). When I map recharge to MODFLOW (steady state rates for now, but will use transient rates later), GMS maps the recharge fine to the surface where layer 1 is exposed, but will not map anything to the surface where layer 2 (and below) is exposed. So only part of the recharge is mapped to MODFLOW. I have discussed this with GMS support, and they have suggested that I add a thin upper layer (a new layer 1) to the model over the whole model domain, and set this layer to inactive. Recharge would then map to this new layer 1, and pass through this inactive layer (if the right settings are selected) to the first active cell below. However, I also have a SFR2 coverage that needs to map to the uppermost layer, and this will not map to inactive cells. This also creates errors with river bed inverts passing below the bottom elevation of layer 1 cells. I therefore don't think this is a suitable solution. GMS support have been very helpful, but they are very busy and response times are long. Therefore, I was wondering if anybody else has had this issue arise, and if they have found an alternative work around. Is it a GMS mapping problem or a MODFLOW-USG limitation? I would have thought that having underlying layers outcrop to the surface is not uncommon, and so it would be unusual for MODFLOW-USG to not support this. Any help would be appreciated. Thanks.
Theo posted a topic in Using GMSDear All, I am struggling to figure out why my flow budget is not tabulating recharge as a "Flow In" value. Background: So I competed a steady state groundwater flow model, using NWT solver in GMS 8.3. The steady state flow model works perfectly (i.e.. flow budget shows a value as "flow in" for recharge, calibrated, heads, etc.) However, as soon as I change the steady state groundwater flow model to a transient model, using transient observation data, no value is "read" in the flow budget for recharge. So i played around to sort this out, using transient recharge data or single value recharge data. In the modflow package the recharge values are shown. All my dates/times for the stress periods, observation data and recharge are the same. So my question is what should I do to get the recharge "read" by modflow to be tabulated in the flow budget? Without the recharge value forming part of my modflow solution the observation heads can't be calibrated using transient data. Any suggestions will be great. Thanks in advance. Cheers, Theo