Still about the result of saturation in normal simulation

[Zeyu Tang]

Dear everyone,

I am still have the problem where the computed saturation values are largely greater than 1, and the simulated pressure is significantly positive in regions that are not associated with river channels, as showed in the figure. I would like to understand the underlying cause of this phenomenon, where in areas exhibiting positive pressure values outside of river channel also tend to show saturation close to 1.

One possible cause I am considering is that the spatial resolution of my model domain is relatively coarse (dx = dy = 10,394 m), which may result in overly flat topographic gradients. This would lead to excessive water accumulation in regions where precipitation (P)  exceeds evapotranspiration (ET), so producing unrealistically high pressure and saturation values.

These documents are I used as input slope for both the x and y directions. I would greatly appreciate any suggestions or guidance on how to reduce the widely positive pressure values in non-river areas, particularly under  coarse spatial resolution settings.



Let me know if you'd like to get more the model input details.

[Reed M. Maxwell]

Hi- What are the vertical Ksat values for your soil cells (the top cells of the domain)?  Are they less than your precipitation values and causing excess infiltration?  Is the ponding just in the surface cell or deeper?

 

Reed M. Maxwell, Ph.D.
William and Edna Macaleer Professor

Department of Civil and Environmental Engineering

High Meadows Environmental Institute

Director, Integrated GroundWater Modeling Center

Princeton University

maxwell.princeton.edu

igwmc.princeton.edu

 

 

 

 

 

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[zitong jia]

Thank you very much for taking the time to respond to my previous inquiries despite your busy schedule, I'm the same author of the last question.

As shown in Figure 1, The maximum annual average PME is about 0.0017 m/h, and in areas prone to saturation, it ranges from 0.0007 to 0.0017 m/h. The dominant soil type (loam) has a vertical K value of 0.005 m/h, which  is larger than the PME into the grid per hour, indicating that infiltration should be sufficient.

I attempted increasing K to 0.158 m/h, but all four soil layers still remained saturated same to before, with saturation increasing with depth.

Initially, I suspected the FlowBarrier setting, but after I cancelled the flowbarrier and spin it into the formal simulation, oversaturation persisted. Based on the results (Figure 2), I suspect it is a combination of the slope and PME: grids near rivers with gentle slopes and high P–ET tends to saturation. Areas with low P–ET appear less saturated even with flat slopes.

I'm unsure how to adjust the model to mitigate this issue. I would greatly appreciate your guidance or any suggestions you may have.