How the STAC Phosphorous Review will Influence the CBP Phase 6 CBWM

Gary Shenk EPA/CBPO

Presentation to STAC

12/3/13

Concepts

• State of the review

• Phase 6

• Incorporation method

• Possible formulations

• Who Decides

STAC P Review – Preliminary Findings

• Soil P concentrations and how we manage P applications are the major drivers for P losses that we can control.

• The simulation process needs to capture the impact of management on key drivers of P transport which will drive collection of essential data.

Additional Detail

• Inputs – Soil P reservoir – Overall P balance – Apply fertilizer and manure at times, rates, and method based

on regional information

• Processes – Soil Type-specific isotherms – Account for P stratification in CNT – Consider interaction between tillage and manure applications – Account for differences in connectivity that affect delivery

efficiency – Describe the temporal dynamics of the effects of drawdown of

soil P on loads – Be capable of scaling down to provide segment by segment

guidance on drivers of P losses and needed practices – Dissolved P!

The Bottom Line

• Collect or estimate Soil P levels

• Make export a function of application method

6

Precipitation Fertilizer Manure Atmospheric deposition

Runoff

Phase 5

Hydrology submodel

Management filter

River Sediment submodel Phosphorus

submodel

Nitrogen submodel

hourly

7

Precipitation

Fertilizer Manure Atmospheric deposition (…)

Runoff

Phase 6

Hydrology submodel

Management filter: Panels using multiple lines of evidence

River Sediment submodel

Nutrient Submodels

Temporal Nutrient model

What could submodels look like?

What could submodels look like?

What could submodels look like?

What could submodels look like?

Export Load =

Storage * Coeff (soil, slope, location, tillage)

+

Annual application * Coeff (parameters)

Alisha Mulkey and Frank Coale are working on a model like this

A STAC recommendation in this format could be readily implemented

Who Decides? • WQGIT – Ultimate responsibility

• Ag, Forestry, Urban Workgroups – Can make recommendations on land use types, loading rates, BMPs, or any other aspect of modeling.

• Land Use Workgroup – primary responsibility to determine land uses and methods to map them. Can make recommendations on loading rates.

• Modeling Workgroup – primary responsibility to determine calibration methods and multiple model averaging methods

12

Chesapeake Bay Program Partnership

13

Agriculture Workgroup BMP Verification Committee Forestry Workgroup Land Use Workgroup Milestones Workgroup Trading and Offsets Workgroup Urban Stormwater Workgroup Wastewater Treatment Workgroup Watershed Technical Workgroup

Modeling Workgroup 255

Model related Membership as of 7/2013 – 365 individuals

39

29

42

14

Chesapeake Bay Partnership Models

Priorities

WQGIT Priorities for phase 6

15 Same is true for P processing, soils, etc

16

Precipitation

Fertilizer Manure Atmospheric deposition (…)

Runoff

STAC recs fit here if they are clear and feasible

Hydrology submodel

Management filter: Panels using multiple lines of evidence

River Sediment submodel

Nutrient Submodels

Temporal Nutrient model

18

Trees

Roots Leaves

Particulate

Refractory

Organic N

Particulate

Labile

Organic N

Solution

Ammonia

Nitrate

Solution

Labile

Organic N

Adsorbed

Ammonia

Solution

Refractory

Organic N

AGCHEM Nitrogen Cycle A

tmo

sph

eric

Dep

osi

tion

D

enit

rifi

cati

on

Export

Export Export Export Export Export Export

19

PQUAL loading model

SURFACE

INTERFLOW

Groundwater

flow * conc sed * factor

flow * conc

flow * conc

Complex vs Simple

• Calibration is complex and time consuming

• Calibration is imprecise

• Longer run time

• Simulated sensitivity to inputs

• Calibration is relatively simple and fast

• Calibration is precise

• Shorter run time

• Sensitivity to inputs must be specified (by multiple research models and methods)

20

-5%

0%

5%

10%

15%

20%

25%

30%

35%

40%

0% 10% 20% 30% 40% 50% 60% 70%

Exp

ort

Re

du

ctio

n

Atmospheric Deposition Reduction

Reduction in forest loads from 1985 to CAIR

21

Aber, et al, 2003

-5%

0%

5%

10%

15%

20%

25%

30%

35%

40%

0% 10% 20% 30% 40% 50% 60% 70%

Exp

ort

Re

du

ctio

n

Atmospheric Deposition Reduction

Reduction in forest loads 1985 to CAIR

DE

DC

MD

NY

PA

VA

WV

22

23

Regression of monthly nitrate yield – Preliminary Results

Deposition is Important in

the spring and fall

Disturbance is Important in the summer

24

Sensitivity incorporation

1. Determine generalized sensitivity from AGCHEM

2. Literature / model search for sensitivities to input

3. Decision on sensitivity approach from the Modeling Workgroup

4. Implementation of sensitivity in the phase 6 model