3/14/2017 Nutrient Monitoring Council Meeting: Vermilion Headwaters, Indian Creek, and Lake Springfield Projects Daniel Perkins, Ph.D.
Partners and Sponsors Lake Springfield and Indian Creek Watershed Projects Vermilion Headwaters (MRBI)
Table of contents MONITORING PRIORITY WATERSHEDS • Lake Springfield MODELING PRIORITY WATERSHEDS • Vermilion Headwaters • Lake Springfield Watershed • Indian Creek Watershed
Lake Springfield Watershed Monitoring
Watershed Monitoring Background and Goals • Lake Springfield Watershed Monitoring • Flow • Nitrate Concentration • Measurements collected April 2015-March 2016 • Goals • Determine spatial nitrate yield (lb/ac) – a form of yield • Understand seasonal trends 5
Lake Springfield Land Use • Corn-Soy is the major land use at all the sites (>80%) • Watershed is fairly flat with slopes < 1.5%, except near stream corridors > 5% 7
2015-2016 Monitoring Locations • Sites locations focus on pseudo-first order scale (single tributary) • Some concentration data were available – used this to prioritize a range of concentration observations 102 6 Site Square miles 15 6 28.3 104 107 8 25.9 8 15 21.9 102 10.3 104 47.4 107 64.0 8
Summary of Concentration Data 12 Average Concentration 10 8 Nitrate, ppm 6 Site 6 4 Site 8 Site 15 2 Site 102 102 Site 104 6 Site 107 15 107 0 104 8 Apr-Sept 2014 Oct-Mar 2015 Apr-Sept 2015 Oct-Mar 2016 Site Rank: 8>104>6>102>15>107 9
Average NO 3 -N Detections (ppm) – By Season Apr – Sep ‘14 Oct ‘14 – Mar ‘15 Avg. lakeside NO3-N Avg. lakeside NO3-N = 0.30 ppm = 0.68 ppm Concentrations near entrance to Lake <= 6.00 Springfield have 6.01 – 8.00 averaged < 8 ppm 8.01 – 10.00 10.01 – 12.00 since 2014 > 12.00 Apr – Sep ‘15 Avg. lakeside NO3-N Oct ‘15 – Mar ‘16 = 0.36 ppm Avg. lakeside NO 3 -N = 3.67 ppm On average, NO 3 -N concentrations were higher in 2015 than in 2014
Flow Event Sampling • Similar % of flow events were sampled in each season, so yield estimates should be comparable between seasons • 30 days April 2015 – March 2016 in LSW had significant rainfall events (>= 0.5” rainfall) • 21 days April 2015 – Sep 2015 • 9 days Oct 2015 – March 2016 • 13 sampling events occurred the day or two days after a significant rainfall event • 9 sampling events April 2015 – Sep 2015 (43%) • 4 sampling events Oct 2015 – March 2016 (44%) • 43-44% of flow events were captured across the two years 11
Discrete Yield (lbs/ac)
EXAMPLE: Discrete load – Site 15 Rainfall Load 35,000 0.0 30,000 0.5 Nitrate-Nitrogen yield (lb/day) 25,000 1.0 Rainfall (in/day) 20,000 1.5 15,000 2.0 10,000 2.5 5,000 0 3.0 4/1/15 5/27/15 7/22/15 9/16/15 11/11/15 1/6/16 3/2/16 12
Discrete Yield (lbs/ac/day) 6 8 15 102 104 107 4/14/2015 0.00 0.18 0.35 0.09 0.06 0.05 4/20/2015 0.25 0.62 1.30 0.01 0.63 5/13/2015 0.25 0.57 1.60 0.24 0.43 0.39 6/3/2015 0.15 0.33 1.01 0.70 0.03 0.18 6/9/2015 0.39 0.68 2.02 1.41 0.86 6/15/2015 0.28 0.36 0.41 0.35 0.21 0.16 6/22/2015 0.60 0.60 1.59 0.00 0.91 0.43 6/26/2015 1.40 1.33 0.00 0.71 0.51 6/29/2015 0.66 1.03 1.79 0.00 0.61 0.31 7/9/2015 0.58 2.08 0.00 0.65 0.51 102 7/13/2015 0.48 0.46 0.91 0.00 0.53 0.32 7/20/2015 0.19 0.23 0.47 0.00 0.19 0.07 6 7/30/2015 0.07 0.15 0.00 0.04 0.03 15 107 8/5/2015 0.03 0.05 0.06 0.00 0.02 0.02 104 8 8/10/2015 0.04 0.08 0.05 0.17 0.05 0.01 8/17/2015 0.02 0.02 0.05 0.93 0.01 0.01 8/28/2015 0.00 0.00 0.00 0.20 0.00 0.00 9/11/2015 0.00 0.00 0.00 0.14 0.00 0.00 9/19/2015 0.00 0.00 0.00 0.06 0.00 0.00 9/23/2015 0.00 0.00 0.00 0.43 0.00 0.00 10/1/2015 0.00 0.00 0.00 1.41 0.00 0.00 10/8/2015 0.00 0.00 0.00 0.91 0.00 0.00 10/12/2015 0.00 0.00 0.00 0.61 0.00 0.00 10/23/2015 0.00 0.00 0.00 0.53 0.00 0.00 10/28/2015 0.00 0.00 0.00 0.04 0.00 0.00 11/5/2015 0.00 0.00 0.00 0.05 0.00 0.00 11/12/2015 0.00 0.00 0.00 0.00 0.00 0.00 11/18/2015 0.01 0.49 0.01 0.00 0.09 0.01 11/25/2015 0.05 0.52 0.10 0.00 0.24 0.04 11/29/2015 0.11 0.42 0.18 0.00 0.17 0.17 12/7/2015 0.06 0.26 0.22 0.09 0.23 12/30/2015 0.95 1.05 0.74 0.00 1.61 0.87 1/6/2016 0.22 0.52 0.09 0.18 0.16 1/14/2016 0.17 0.48 0.17 0.17 0.17 1/29/2016 1.13 0.06 0.00 1.61 0.11 0.06 2/3/2016 0.14 0.29 0.44 0.17 0.30 0.07 2/19/2016 0.12 0.18 0.11 2/26/2016 0.10 0.07 0.00 3/11/2016 0.07 0.05 0.32 0.00 3/14/2016 0.14 0.10 0.46 0.11 0.07 0.16 13 3/25/2016 0.20 0.10 0.23 0.18 0.05
Discrete yield Summary and Limitations • Discrete flow and concentration measurements provide point-in- time snapshots of nitrate yield , but difficult to precisely calculate total seasonal yield • Sampling events are random w.r.t. flow events, so difficult to calculate flow between sampling events without continuous stage monitoring • Sites were monitored after Dec 27, 2015 event (> 2.5 in), sampling program missed a potential high nitrate yield • Nitrate concentrations may fluctuate throughout longer hydrographs 14
SWAT Modeling to Supplement Flow Limitations
SWAT Modeling to Supplement Monitoring • SWAT model was used to provide daily flow estimates, based on a calibration period, to ‘fill in’ stream flow between measurements • When daily flow is available, this increases accuracy of yield/yield estimates – but is still an estimate 16
SWAT Model • Offers the greatest number of management alternatives for modeling agricultural watersheds • Adopted as part of the USEPA Better Assessment Science Integrating Point and Nonpoint Sources (BASINS) software package for applications including support of TMDL analyses • Used by many US federal and state agencies , including the USDA Conservation Effects Assessment Project (CEAP), to evaluate the effects of conservation practices • A large number of previous peer-reviewed modeling studies have used SWAT to evaluate conservation practices around the globe • Waterborne is working closely with developers at Purdue University to actively expand capabilities of the model 17
Basics of the SWAT model Land Use Weather Slope SWAT Output (Flow, Sediment, HRUs Nutrients) Soil Class Crop management operations River Networks 18
SWAT Model Calibration • SWAT calibration parameters such as runoff (CN), tile flow (tile depth, distance between tiles, drainage coefficient), and tillage • SWAT was calibrated spatially at 6 sites using discrete flow measurements • Lake Springfield watershed was delineated in to 44 sub-basins • Sub-basin weighted NEXRAD rainfall data (2005 – April 2016) • Continuous corn-soybean rotations are assumed in the watershed; NASS (2013) was used to setup land use • SSURGO soils • Subsurface tiles were assumed in all corn and soybean land use 19
EXAMPLE: Daily Average Flow vs Snapshot Flow • SWAT simulated daily average flow matched well with measured flow (timing) • SWAT underestimated flow during July 7, 2015 event • Magnitude of flow varies with timing of the sample collected Site 107 90 Site 107 35 80 SWAT Simulated Grab Sampled Flow (cms) 30 Grab Sampled 70 R² = 0.7286 25 60 Flow (cms) 20 50 15 40 10 30 5 20 0 0 10 20 30 40 10 SWAT Simulated Flow (cms) 0 4/1/2015 5/31/2015 7/30/2015 9/28/2015 11/27/2015 1/26/2016 3/26/2016 20
Estimated Cumulative NO 3 -N Yield Summary Site 6 Site 104 Site 8 50 0 50 0 50 0 45 0.5 45 0.5 45 0.5 40 1 40 1 40 1 35 1.5 35 1.5 lb/acre Nitrate 35 1.5 lb/acre Nitrate lb/acre Nitrate Rainfall, in 30 2 30 2 30 2 25 2.5 25 2.5 25 2.5 20 3 20 3 20 3 15 3.5 15 3.5 15 3.5 10 4 10 4 10 4 5 4.5 5 4.5 5 4.5 0 5 0 5 0 5 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 Site 102 Site 107 Site 15 50 0 50 0 50 0 45 0.5 45 0.5 45 0.5 40 1 40 1 40 1 35 1.5 lb/acre Nitrate 35 1.5 lb/acre Nitrate 35 1.5 lb/acre Nitrate Rainfall, in 30 2 30 2 30 2 25 2.5 25 2.5 25 2.5 20 3 20 3 20 3 15 3.5 15 3.5 15 3.5 10 4 10 4 10 4 5 4.5 5 4.5 5 4.5 0 5 0 5 0 5 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 4/6/15 7/15/15 10/23/15 1/31/16 5/10/16 21
Cumulative NO 3 -N yield – lb/acre 6 8 15 102 104 107 25 20 Cumulative NO3-N yield (lbs/ac) 102 6 15 15 107 104 8 10 5 0 4/1/2015 5/27/2015 7/22/2015 9/16/2015 11/11/2015 1/6/2016 3/2/2016 22
Cumulative NO 3 -N yield • Cumulative nitrate yield (lbs/ac) Site # Apr-Sep 2015 Oct 2015-Mar 2016 6 16.8 18.7 102 6 8 18.6 25.1 15 107 104 8 15 19.5 15.3 102 16.1 15.9 104 16.0 19.7 107 16.1 15.8 • Site 8 had higher nitrate yields on per acre basis when compared to other sites (both 2015 and 2016) • Site 104 had higher nitrate yields in 2016 Recall: Concentration • Site 104 is downstream of Site 8 and had lower yields per Site Rank: acre in both 2015 and 2016 8>104>6>102>15>107 • Site 8 subbasin is contributing more than the rest of the Site 104 sub-basin 23
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