Modeling of Critical Areas for DRP Runoff and Targeting Strategies

Rem Confesor Jr.Research Scientist

NCWQR, Heidelberg University

Team Meeting #5 Great Lakes Protection Fund Grant

A Phosphorus Soil Test MetricTo Reduce Dissolved Phosphorus Loading to Lake Erie

July 24, 2013

Watershed Modeling

CONSTRAINTS:

SPACE & TIMEresolution

Precipitation

Infiltration Runoff flow

Yearly Runoff flow = (x)Precipitation + y(Infiltration) + Constant

Spatially lumped across the whole watershed, Yearly time step

Issues:

a. One precipitation value for the whole watershed.

b. Model is not a good representation of reality.

c. Coefficients are unknown: need for calibration.

A very simple conceptual model…

Precipitation (P)

Infiltration (I)Runoff

Flow (R)

Evapo-transpiration (ET)

Groundwaterrecharge (G)

Lateral subsurface

Flow (L)

Evaporation (E)

Soilstorage

(S)

S = P - ET - E - I - R; I = G + L;Discharge (Q) = (a)R + (b)L + c

Basic spatial unit

A little bit of improvement…

Digital elevation model(slope/terrain)

Land use/ crop cover

Soil typeHydrologic Response Units (HRUs)

+

+

The hydrologic response unit (HRU)- basic spatial unit:unique combination of slope, landuse, & soil.

 

Terrain

Weather

Soil

Land use/crop cover

Agricultural practices & mgt.: tillage, fertilizer, etc. 

Flow, sediment,

nutrients (N & P), etc.

The SWAT Model:

Physically-based.

Daily time step.

Long-term simulation of effects of changes in ag. management.

“RELATIVE” output changes due to these management changes.

SWAT SETUP: CROP ROTATION

2006, Corn

2007, Soybean

2008, Corn

2009, Soybean

Baseline to NoTill + IncBaseline to NoTill

Change in DRP, lb/acre P2O5

Change in DRP, lb/acre P2O5

NoTill + In TO Disc Plowed + InNoTill + Bcast TO NoTill + In

Change in Particulate P, lb/acre P2O5

Baseline to NoTill + InBaseline to NoTill

NoTill + In TO Disc Plowed + InNoTill + Bcast TO NoTill + In

Change in Particulate P, lb/acre P2O5

Rem Confesorrconfeso@heidelberg.edu

419-448-2204

http://www.heidelberg.edu/academiclife/distinctive/ncwqr

THANK YOU!