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
419-448-2204
http://www.heidelberg.edu/academiclife/distinctive/ncwqr
THANK YOU!
