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How to Model Augmentation Plans

A well augmentation plan is typically the result of an engineering analysis that allows a well to divert out-of-priority and replace the river depletions with one or more replacement water sources in order to avoid injury to senior water rights. StateMod calculates the depletion at a river associated with well pumping in the current time step and all future time steps based on the amount pumped, the efficiency of its use, and its associated depletion pattern (e.g. unit response function). If a well water right is tied to an augmentation plan, any depletion associated with out-of-priority pumping (i.e. augmentation requirement) is stored in that plan in the current and all future time steps. The augmentation requirement is the difference between the well’s depletion on the river and the accretions from any associated return flows. These augmentation requirements may be “offset” by a number of supplies, including:

  • Depletions that accrue to the river in the current time step in-priority; accounted for automatically by StateMod
  • In-priority depletions that accrue to the river from pumping in prior time steps.
  • Accretions from decreed recharge areas or canal seepage
  • Releases from a reservoir
  • Pumping from Augmentation or Recharge Wells

A Special Augmentation Plan, discussed in more detail below, is used to account for depletions associated with a well or group of wells that are not required to be augmented. Examples include pumping in Designated Basins or pumping by wells decreed to be non-tributary (e.g. Coffin Wells). A Special Augmentation Plan can track these depletions, however does not generate an “augmentation requirement” and therefore does not have associated supplies.

Modeling Tips: * See the How to Model Well Operations section for information on how to include wells in a StateMod modeling scenario. * Refer toan existing model, such as the South Platte Model, for more information on how to include augmentation plans and operations in a StateMod model. * StateMod only accounts for the augmentation requirement and supplies used to offset the requirement; it does not limit well pumping if the supplies are insufficient to meet the full plan demand. The plan demand and supplies are reported in the plan summary (*xpl) file and it is up to teh user to confirm, if appropriate, that the full augmentation requirement is being offset. * Historical records of recharge supplies are limited in HydroBase, and when available, can be quite variable. The user may consider using a release limit plan to provide an overall limit to all of the recharge supplies, basing the monthly and annual limits on the recent or average total of all recharge supplies.