The Adapted Chesapeake Nutrient and Sediment Load Reduction Model is an algorithm in FieldDoc that allows users to estimate nutrient and sediment load reductions based on Phase 6 Chesapeake Bay Watershed Model practice names. Users supply a practice name, extent, or area treated based on practice, and the FieldDoc system returns isolation load estimates for the given practice. The Adapted Chesapeake Nutrient and Sediment Load Reduction Model was created from default efficiencies and designed to balance ease of data entry with scientific rigor. While it is not meant to replace or align with Bay Program scenario tools or TMDL reduction targets, it is useful in understanding a rough estimate of reductions if a practice were to be implemented based on size, type, and location.

Calculation Details

Default load efficiencies for edge of stream (EOS) nitrogen, phosphorus, and sediment reductions are provided at a practice scale by the Chesapeake Bay Program.

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IMPORTANT: This model only runs for practices with eligible scenarios occurring within the Phase 6 Chesapeake Bay Model Land River Segment delineation. Practices without scenarios or those that have a geographic footprint outside the Land River Segment delineation will not return load reductions estimates.

Source Data

The source data required to run the calculation can be found here:

C9-IsolationScenarioResults

Steps to apply the model to FieldDoc hosted-BMPs

The following steps outline how a FieldDoc user leverages the service within the FieldDoc.org application.

1. Within an Activity, assign the relevant Activity Type to the activity, and draw the geographic footprint as defined by the practice extent.

2. Open up the Edit Activity modal and navigate to the Metrics tab. Enter in the unit value and click Save inputs.

3. .If a valid scenario can be run, FieldDoc returns nutrient and sediment load reduction estimates based on the input data.

The following steps outline the behind-the-scenes process model for the Adapted Chesapeake Nutrient and Sediment Load Reduction Model

1. Based on the user practice input data, FieldDoc sends the practice footprint, matching practice name and practice extent (acres) to the Adapted Chesapeake Nutrient and Sediment Load Reduction Model Application Programming Interface (API) for processing.
2. The Adapted Chesapeake Nutrient and Sediment Load Reduction Model API compares the user-generated practice information to the Isolation Scenario Results Table (IsolationScenarioResults 20181203 - lrseg - EOS.xlsx) and looks up the appropriate Land River Segment ID based on the user-supplied practice geography, and matches practice name, revealing the appropriate isolation efficiencies for nitrogen, phosphorus, and sediment.
3. The Adapted Chesapeake Nutrient and Sediment Load Reduction Model API runs the following math and returns load reductions for the practice:

BMP Extent x Load Efficiency = Load Reduction

Use Cases and Limitations

This model is not appropriate for tracking load reductions that must align with the Chesapeake Bay Total Maximum Daily Load or the Chesapeake Assessment and Scenario Tool. This model helps create ballpark estimates to gain an understanding of how your respective work could impact load reductions. The Adapted Chesapeake Nutrient and Sediment Load Reduction Model was created from default efficiencies and designed to balance ease of data entry with scientific rigor.