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Showing results for tags 'flow budget'.
Currently you can not get cell to cell flow budgets with MODFLOW-USG. This is a feature that can really help troubleshoot problems and analyze if the model is behaving correctly. Any plans in providing this in MODFLOW-USG?
I want to simulate a Sheet Pile with permeable holes through the whole acquifer. STEP 1 The simplified model is a 10x10 m grid, with only two Boundary Conditions: from CHD 1.0 m (left side) to CHD 2.0 m (right side). As I've the HK for an equivalent Slurry Wall (width 1 m), I insert 3 polygon features: 1) HK representing the Slurry wall (width = 1 m): HK = 0.0041 m/day 2) HK representing the Slurry wall's holes, filled with gravel (width = 1 m): HK = 864 m/day 3) HK representing the aquifer: HK = 1.2 m/day I check the Flow Budget for all the model (run 1): 30.6 m3/day. The head value in the cells just before the HK is 1.45 m. STEP 2 Now I need to set an HK equivalent rapresenting the Slurry wall with holes. I use the parallel approach (Figure_3, in the xy plane): HK eq = (HK sw x Lenght sw + HK holes x Lenght holes) / (Lenght sw + Lenght holes) = 43 m/day I replace the Slurry wall with holes polygon with a new polygon with HK equivalent (43 m/day). I check the Flow Budget for all the model: 41 m3/day. Why is not the same value obtained from run 1? The head value in the cells just before the HK is 1.23 m, less than 1.45 (run 1). STEP 3 I change the HK equivalent for the Slurry wall: 0.38 m3/day. The Flow Budget for all the model: 30.8 m3/day. The head value in the cells just before the HK is 1.44 m. Why the HK equivalent are so different (100 times smaller)? What's wrong in my exercise? Thank you Daniele Figure 1: HK representing the Slurry wall (width = 1 m): HK = 0.0041 m/day Figure 2: HK representing the Slurry wall's holes, filled with gravel (width = 1 m): HK = 864 m/day Figure 3: Formula for calculate the Effective conductivity parallel to layers
Dear 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