Evaluation of watershed conservation
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Transcript of Evaluation of watershed conservation
Evaluation of Watershed Conservation Management Practices to Reduce
Pollutant Loads in Grand Lake St. MarysUsing AnnAGNPS
• Ronald L. Bingner, USDA-ARS, Oxford, MS• Yongping Yuan, USEPA, Las Vegas, NV• Henrique Momm, Middle TN State Univ.,
Murfreesboro, TN• Milo Anderson, USEPA, Chicago, IL• Martin Locke, USDA-ARS, Oxford, MS
Grand Lake St. Marys in northwestern Ohio is experiencing toxic levels of algal blooms resulting from nutrient input from agricultural runoff.
Problem
Grand Lake St Marys, Ohio
Grand Lake St Marys, Ohio
GLSM - Tributaries
Objective
To determine where and if conservation practices can be placed and/or adopted to reduce phosphorus loadings to Grand Lake St Marys, Ohio.
AnnAGNPS
Agricultural Research ServiceA partnering effort between the USDA:
andNatural Resource Conservation Service
National Sedimentation Laboratory
AnnAGNPS: USDA pollutant loading (PL) model
Erosion, yield, & loadings by type of PL:• Waterrainfall, snowmelt, irrigation, & point sources.
• Sediment by particle size-class and source: clay; silt; sand; small aggregate; and large aggregate.
• Chemicals (attached & dissolved): nutrientsnitrogen, phosphorous, & organic carbon; and pesticidesany number, any kind.
Necessary Datasets
►Terrain
►Soils
►Climate 1893 - 2010
►Landuse
Climate Stations
GLSM 3 Meter DEM
GLSM - Soils
GLSM – Landuse
GLSM – Landuse
SoybeansCornUrbanWheatPasture
Woods
2006
Alfalfa
25.8%35.0%9.0%3.4%5.2%
1.9%2.7%
Water 17.0%
GLSM Feedlots
3214 AnnAGNPS Cell Subdivision for GLSM
Average Annual Monthly Precipitation & RunoffConventional Tillage
30 Year Average Annual Loads to Grand Lake St. Marys Tillage Effects
Practice Runoff (in)
SedimentLoad (t/ac)
Total N (lb/ac)
Attached P
(lb/ac)
Dissolved P
(lb/ac)
Total P
(lb/ac)
Existing Tillage
12.4 0.98 18.45 5.70 0.53 6.23
Minimum Tillage
9.8 0.69 13.73 4.46 0.46 4.92
No-Tillage
8.7 0.61 12.43 4.11 0.43 4.54
30 Year Average Annual Loads to Grand Lake St. Marys Riparian Buffer Effects
Practice Runoff (in)
SedimentLoad (t/ac)
Total N (lb/ac)
Attached P
(lb/ac)
Dissolved P
(lb/ac)
Total P
(lb/ac)
50 meter Grass Buffer
12.4 0.317 9.28 3.48 0.44 3.92
No Buffer
12.4 0.975 18.45 5.70 0.53 6.23
Average Annual Monthly Phosphorus LoadingVarious Scenarios
Phosphorus Load Reduction From Conservation Practices
A. Conventional Tillage
B. Minimum Tillage
C. No-Tillage
D. Buffers w/ Conv. Till.
E. Rye Cover w/ Conv. Till.
F. Clover Cover w/ Conv. Till.
G. Wheat Cover w/ Conv. Till.
H. Vetch Cover w/ Conv. Till.
I. Radish Cover w/ Conv. Till.
J. No-Till w/ Radish Cover
w/ Buffers
Phosphorus Loads to GLSMExisting Conditions – 30 Year Simulation
lb/ac
Contributed Phosphorus Load vs. Contributing Drainage Area
26% of the GLSM Watershed Contributes 50% of the Phosphorus Load
Areas Contributing 50% of the Phosphorus Load to GLSMExisting Conditions – 30 Year Simulation
lb/ac
Phosphorus Loads to GLSMWinter Wheat Cover – 30 Year Simulation
lb/ac
53% Phosphorus
Load Reduction to GLSM withWinter Wheat
Cover
Summary 26% of the watershed contributes 50% of the P
loads to GLSM.Many P loads entering GLSM originate near the
lake boundary. Reducing these loads alone would have a significant impact on reducing the total P loads into the lake.
Cover crops can reduce P loads by over 50% and up to 70%.
Riparian buffers can reduce P loads to the lake by up to 37%.
SummaryMinimum tillage and no-tillage conservation
practices can reduce P loads by up to 27%. Integrated conservation practices as part of an
overall watershed management plan could be implemented on high potential P loading source areas to minimize the economic impact and maximize the impact on reducing P loads.
Additional investigations can help understand how the changing lake boundary since 1938, with changing urbanization, has effected P loads into the lake.
Thank you
Observed versus SimulatedRunoff, sediment, total P, and SRP
Base conditions scenarioPBIAS, RSRS, NSE and r2
Load PBIAS RSR NSE r2
Runoff -10.8 0.87 .24 0.53
Sediment 637 7.8 -60 0.37
Total P 416 5.1 -25 0.50
SRP -20 0.77 0.4 0.66
30 Year Average Annual Loads to Grand Lake St. Marys Cover Condition Effects
Practice Runoff (in)
SedimentLoad (t/ac)
Total N (lb/ac)
Attached P
(lb/ac)
Dissolved P
(lb/ac)
Total P
(lb/ac)
Clover 6.7 0.58 14.18 3.25 0.18 3.43
Radish 7.5 0.28 6.77 1.67 0.12 1.79
Rye 7.4 0.59 13.93 3.26 0.17 3.43
Vetch 7.7 0.46 11.17 2.66 0.15 2.81
Wheat 12.6 0.52 10.77 2.80 0.15 2.95
Coldwater Creek554 μg/L Total Phosphorus
430 μg/L DRP (77.6%)
Beaver Creek1140 μg/L TP
846 DRP (74%)@2.9 cfs
Prairie Creek458 μg/L TP
433 μg/L DRP (94.5%)
Chickasaw Creek769 μg/L TP
611 μg/L DRP (79%)
@~4 cfs
Barnes Creek645 μg/L TP
532 μg/L DRP (82%)
GLSM Spillway Discharge 265 μg/L TP
12 μg/L DRP (4.5%)
GLSM Tributary Phosphorus Concentrations
September 27, 2011
Little Chickasaw Creek448 μg/L TP
370 μg/L DRP (83%)
A typical Ohio stream with a mixture of land uses has a phosphorus concentration of 50 μg/L
Burntwood Creek249 μg/L TP
183 μg/L DRP (83%)@1.8 cfs
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