### Modeling ponding, infiltration

Posted:

**Thu Apr 11, 2019 9:15 am**Hello all,

I am trying to model the de-watering of a coal ash pond, followed by a brief period of time it is left open to the atmosphere. The total scenario runs for 92 days with 5cm of ponded water removed weekly beginning Day 1.

Here is a brief overview of the inputs for my model:

- Top BC: Variable Head 1: 30 cm w/ 5cm decreasing every 7 days, then 0 until day 92

- Sides: No flux BC

- Bottom: Free drainage/unit gradient BC; groundwater is assumed to be far below

My concern is when I check the "Boundary Flux" results, there is nothing displayed for the Actual Atmospheric Flux, Surface Runoff, Evaporation or Infiltration. Is there another way to implement this scenario?

My goal is to take the final pressure head values from this "pre-closure" scenario as input into models with constant flux top BCs representing different closure scenarios.

I am trying to model the de-watering of a coal ash pond, followed by a brief period of time it is left open to the atmosphere. The total scenario runs for 92 days with 5cm of ponded water removed weekly beginning Day 1.

Here is a brief overview of the inputs for my model:

**Soil Hydraulic Model**: van Genuchten - mualem**Soil Hydraulic Params:**1 Material, alpha= 0.036, n=1.64, l=-1**Time Variable Conditions**: Precipitation, evaporation inputs, hCritA: 1000; this was calculated to be higher, however results are not sensitive to changes above this**Initial Condition:**Fully saturated w/ h=0, and the top row of nodes h=-1 for stability purposes**Boundary Conditions:**- Top BC: Variable Head 1: 30 cm w/ 5cm decreasing every 7 days, then 0 until day 92

- Sides: No flux BC

- Bottom: Free drainage/unit gradient BC; groundwater is assumed to be far below

My concern is when I check the "Boundary Flux" results, there is nothing displayed for the Actual Atmospheric Flux, Surface Runoff, Evaporation or Infiltration. Is there another way to implement this scenario?

My goal is to take the final pressure head values from this "pre-closure" scenario as input into models with constant flux top BCs representing different closure scenarios.