Calculation Details and Supporting Documentation

Adapted Chesapeake Nutrient and Sediment Load Reduction Model

John Dawes avatar
Written by John Dawes
Updated over a week ago

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

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 having a geographic footprint outside the Land River Segment delineation will return a no load reductions.

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

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

1. User relates their project to a grant program that has this model enabled (If you are having trouble getting to this step, see the following article: Create a new project

2. User creates a site with geography and attributes (If you are having trouble getting to this step, see the following article: Add a New Site ).

3. User creates a new practice and draws geographic footprint as defined by the practice (If you are having trouble getting to this step, see the following article: Add a New Practice ).

4.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 and 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 is helpful in creating 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.  

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