1. Subwatershed Prioritization in Arkansas - A Modeling Approach Presented by: Dharmendra Saraswat Co-Authors: N. Pai, M. Daniels, and M. Leh ANRC Task Force Meeting, September 21, 2010 Reviewed by: U of A Division of Agriculture Environmental Task Force

2. MODELING OBJECTIVE To assist in assessing the relative risk of sub-watersheds (12-digit hydrologic unit code) for sediment and nutrients contribution from selected 8-digit HUC priority watersheds using State-of-the Art modeling techniques ANRC Task Force Meeting, September 21, 2010 Priority Watersheds12-digit HUC 12-digit HUC Priority

3. MODELING TASKS a)Collect and organize watershed specific input data for setting up the Soil and Water Assessment Tool (SWAT) model b)Calibrate and validate the SWAT model for flow, sediment, and nutrients (total phosphorus and nitrate-nitrogen) ANRC Task Force Meeting, September 21, 2010

4. MODEL PHILOSOPHY Public Domain, supported by USDA-ARS, Worldwide Users and developers base, 682 published articles ANRC Task Force Meeting, September 21, 2010

5. MODEL PROCESS- LAND PHASE For smallest modeling scale, SWAT simulates spatially-variable soil and water processes that influence movement of nutrients and sediment from land to water (Source: Neitsch et al. 2005) ANRC Task Force Meeting, September 21, 2010

6. MODEL PROCESS- LAND PHASE Major Simulation Elements  Weather  Hydrology  Plant growth  Erosion  Nutrients (N, P)  Pesticides  Management (Source: Neitsch et al. 2005) ANRC Task Force Meeting, September 21, 2010

7. MODEL PROCESS- IN-STREAM ( Source: Neitsch et al. 2005) ANRC Task Force Meeting, September 21, 2010

8. MODELING INPUTS- SPATIAL DATA SWAT 2009 Elevation (DEM-10/30m) USGS Boundary (12 Digit HUC) Soil Data (SSURGO) Landuse (MULTIPLE YEARS) Streams (NHD) NEXRAD RADAR/Weather gages ANRC Task Force Meeting, September 21, 2010

9. MODELING INPUTS- TABULAR DATA SWAT 2009 Non-Point Source Agricultural Land-use practices for each county Point source discharge ANRC Task Force Meeting, September 21, 2010 Average daily loadings for:  water,  sediment,  ammonia,  Carbonaceous biochemical oxygen demand  dissolved oxygen and  phosphorus

10. MODEL EVALUATION PROTOCOL Six components of model evaluation:  Model examination  Algorithm examination  Data evaluation: quality of data  Sensitivity analysis: highest influence  Validation: system performance  Uncertainty analysis (recent trends) (Source: American Society for Testing and Materials, 1984) ANRC Task Force Meeting, September 21, 2010

11. WHY TAKE ALL THIS TROUBLE?  Reduce potential modeler bias  Provide a road map to follow  Allow other to repeat the study  Improve acceptance of model results ANRC Task Force Meeting, September 21, 2010

12. 1.Arrange simulated annual pollutant concentration 2. Sort low to high 3. Calculate rank 4. Calculate percentile rank Tied Rank functionality in Excel 2010 Low To High PERCENTILE RANKING ANRC Task Force Meeting, September 21, 2010

13. CASE STUDY  Beaver Reservoir  Lake Conway Point Remove (LCPR)  Bayou Bartholomew  Illinois River Drainage Area in Arkansas (IRDAA) ANRC Task Force Meeting, September 21, 2010

14. CASE STUDY ILLINOIS RIVER DRAINAGE AREA IN ARKANSAS (IRDAA) ANRC Task Force Meeting, September 21, 2010

15. MODEL SETUP- COMPARISON Model: SWAT2005 DEM: 10 m Soil: SSURGO Land Use: 2006 HRUs: Criteria (10% land use, 5% soil type, 0% slope) Ponds: 9019 (3831 acres) Study Period: Calibration: 1996-2005(1992- 95) Validation: 2006-2007 Flow at three gages, sediment and nutrients at outlet  Nitrate-nitrogen yield from a few forestry dominated subwatersheds in southern part of IRDAA did not match with expected yield  Lack of all forms of nitrogen data from point sources could result in higher loading from landscape. ANRC Task Force Meeting, September 21, 2010

16. Model: SWAT2009 DEM: 10 m Soil: SSURGO Land Use: 1992, 1993, 1999, 2001, 2004, and 2006 HRUs: 848 Ponds: 9019 (3831 acres) Study Period: Calibration: 1996-2005(1992- 95) Validation: 2006-2008 Flow at total seven gages, sediment and nutrients at three MODEL SETUP- COMPARISON  Few studies have used watershed models in spatially distributed fashion  Spatially distributed calibration and validation account for hydrologic patterns in subwatersheds* * Qi and Grunwald, 2005 ANRC Task Force Meeting, September 21, 2010

17. Weather * NOAA -NWS DATA USED NEXT GENERATION RADAR (NEXRAD ) ANRC Task Force Meeting, September 21, 2010

18. ETF Recommendation: 4%, 21%, and 75% for ammonia-, organic-, and nitrate-nitrogen- based on ETF recommendation Point Source Loading DATA USED ANRC Task Force Meeting, September 21, 2010

19. Poultry litter application adjusted -Litter application rate adjusted for type of grasses and temporally as well* -Cool-season: 2 ton/ac Warm season: 3 ton/ac -January 2004 onwards, rate declined to 1 ton/ac Management Data DATA USED (*Sharpley et al., 2009) ANRC Task Force Meeting, September 21, 2010

20. CALIBRATION/VALIDATION Subwatershed#16- ~44%, (80%) #19- ~60% (~89%), #18- 24% (~65%) ANRC Task Force Meeting, September 21, 2010

21. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Urban % Pasture % Forest % 144.335.514.6 25.362.124.9 413.967.714.1 531.154.510.9 125.356.933.4 2346.035.912.7 Soil under Hydrologic Group C & D- 73.4%) ANRC Task Force Meeting, September 21, 2010 HOC, MFL, LOC, SC,MC,SC

22. Sub watershed# Urban % Pasture % Forest % 73.958.932.1 112.536.158.7 151.527.967.2 165.340.347.7 250.522.873.5 Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Lowest priority: Slopes > 8%- 46.4% Soil under Hydrologic Group C & D- 67.6%) ANRC Task Force Meeting, September 21, 2010 UBC, CH, LW, UMF, UEC

23. Sub watershed# Urban % Pasture % Forest % 2*44.335.514.6 37.252.834.8 413.967.714.1 5*31.154.510.9 18*11.456.325.8 23*46.035.912.7 Percentile Approach – Total Phosphorus SUBWATERSHED IDENTIFICATION  Highest priority: *Point source affected *23- 303(d) list Soil -C & D- 74% ANRC Task Force Meeting, September 21, 2010 MFC, HFC, LOC,SC, GC, SC

24. Sub watershed# Urban % Pasture % Forest % 64.735.655.6 112.536.158.7 151.527.967.2 165.340.347.7 Percentile Approach – Total Phosphorus SUBWATERSHED IDENTIFICATION  Lowest priority: ANRC Task Force Meeting, September 21, 2010 LF, CH, LW, UMF

25. Sub watershed# Urban % Pasture % Forest % 25.362.124.9 413.967.714.1 5*31.154.510.9 64.735.655.6 73.958.932.1 Percentile Approach – Nitrate-Nitrogen SUBWATERSHED IDENTIFICATION  Highest priority: *point source affected, 5 is in 303(d) for nitrate Slopes > 8%- 9.6% ANRC Task Force Meeting, September 21, 2010 MFC, LOC, SC, LF, UBC

26. Percentile Approach – Nitrate-Nitrogen SUBWATERSHED IDENTIFICATION  Lowest priority: Sub watershed# Urban % Pasture % Forest % 92.038.155.9 2133.729.129.4 2240.528.721.5 263.236.654.6 272.239.654.3 ANRC Task Force Meeting, September 21, 2010

27. CASE STUDY BEAVER RESERVOIR WATERSHED (BRW) ANRC Task Force Meeting, September 21, 2010

28. Model: SWAT2009 Delineation: USGS 12-digit HUC DEM: 30 m Soil: SSURGO Land Use: 1992, 1999, 2001, 2004, and 2006 Subwatersheds: 76 HRUs: 2199 (5% land use, 10% soil type, 0% slope) Ponds: 6100 (4857 acres) Study Period: Calibration: 1996-2005 (2003-2005) Validation: 2006-2008 Point Sources: 23 MODEL SETUP ANRC Task Force Meeting, September 21, 2010

29. Weather * NOAA -NWS DATA USED NEXT GENERATION RADAR (NEXRAD ) ANRC Task Force Meeting, September 21, 2010

30. MONITORING GAGES ANRC Task Force Meeting, September 21, 2010

31. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Pasture % Urban % 1* 49385 8* 65166 15 41472 16 43461 17 65212 46 572016 47 491629 59 62291 60 73191 61 70231 62 47396 63 282 64* 513110 66 37532 67 57343 ANRC Task Force Meeting, September 21, 2010 West Fork - 303(d) – sediment since 1998, TMDL * PS

32. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Lowest priority: Sub watershed# Forest % Pasture % Urban % 2* 38474 7 45412 10 60280 12 61119 20 8070 22 8412 24 76144 26 8242 27 5835 32 56294 34 83102 41 70201 44 73191 45 57322 71 80114 * flatter topography results in lower sediment loss ANRC Task Force Meeting, September 21, 2010

33. Percentile Approach – Total P SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Pasture % Urban % 3* 24576 4 21612 6 26523 8* 65166 9 37464 11 48352 13 61714 15 41472 16 43461 17 65212 45 57322 63 282 64* 513110 65 43454 66 37532 * Point source affected ANRC Task Force Meeting, September 21, 2010

34. Percentile Approach – Total P SUBWATERSHED IDENTIFICATION  Lowest priority: Sub watershed# Forest % Pasture % Urban % 7 45412 22 8412 24 76144 26 8242 32 56294 35 80131 36 84111 39 79141 40 73181 42 72181 69 9150 71 80114 72 8186 73 9530 74 9531 75 9071 ANRC Task Force Meeting, September 21, 2010

35. Percentile Approach – Nitrogen-N SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Pasture % Urban % 1* 49385 3 24576 4 21612 5 45402 6 26523 8* 65166 9 37464 10 60280 11 48352 16 43461 17 65332 45 57322 64* 513110 65 43454 66 37532 * Point source affected ANRC Task Force Meeting, September 21, 2010

36. SUBWATERSHED IDENTIFICATION Sub watershed# Forest % Pasture % Urban % 2 38474 20 8071 22 8412 35 80131 36 84111 40 73181 51 82121 52 50309 53 82131 56 83120 69 81121 71 80114 73 9530 74 9531 75 9071 76 8872 Percentile Approach – Nitrogen-N  Lowest priority: ANRC Task Force Meeting, September 21, 2010

37. CASE STUDY LAKE CONWAY POINT REMOVE WATERSHED (LCPRW) ANRC Task Force Meeting, September 21, 2010

38. Model: SWAT2009 Delineation: USGS 12-digit HUC DEM: 10 m Soil: SSURGO Land Use: 1999, 2004, and 2006 Subwatersheds: 29 HRUs: 2668 (0% land use, 5% soil type, 0% slope) Ponds: 6100 (4857 acres) Study Period: Calibration: 2001-2005(Flow) Validation: 2006-2008 (Flow) Point Sources: 34 MODEL SETUP ANRC Task Force Meeting, September 21, 2010

39.  LEAST MONITORED, MOST RAINGAGES Weather DATA USED ANRC Task Force Meeting, September 21, 2010

40.  Row Crops : Dominant Crop- Soybean Management Data DATA USED DateOperationRate May 1 - May 15 Tillage couple days before planting Disk 2X and Float 1X May 1 - May 15Planting May 15 - May 30Fertilization with 0-0-60 100 lb/acre May 15 - July 15 Pesticide glyphosate once per month 1 lb/acre/month July 15 - Sep 15Irrigation ~3 inches/month Oct 1 - Oct 20Harvest and kill ANRC Task Force Meeting, September 21, 2010

41. Arkansas River as Inlet DATA USED  USGS gauge near Dardanelle (# 07258000)  Stage-Discharge relationship: Discharge (cfs) = 7408 x Stage (feet) - 30234; R 2 = 0.77 +/- 23% error in estimating missing data should be expected (J.E. Funkhouser, USGS) ANRC Task Force Meeting, September 21, 2010

42. CALIBRATION/VALIDATION  Flow calibration: 2001-2005, Validation: 2006-2008  Land Use of covered subwatersheds: Forests: 61.7% - 98.4% Pasture: 1.2% - 35.2% Urban: 0.1% - 2.7%  Forest (~54%) and Pasture (~22%)  Flow missing: October 2004- September 2005 October 2007 – September 2008 ANRC Task Force Meeting, September 21, 2010

43. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Crop % Pasture % Urban % 142044.620.45.5 1858.8-16.93.9 2539.3-39.116 2636.2-29.65.8 2814.444.730.19.4 2942.717.823.410.8 ANRC Task Force Meeting, September 21, 2010 Subwatershed #18- Beaverdam Creek

44. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION  Lowest priority: Sub watershed# Forest % Crop % Pasture % Urban % 176.8-20.61.6 298.4-1.20.1 364.2-29.03.2 452.5-35.23.8 1972.8-15.25.3 ANRC Task Force Meeting, September 21, 2010

45. Percentile Approach – Total Phosphorus SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Crop % Pasture % Urban % 142044.620.45.5 18*58.8-16.93.9 2539.3-39.116.0 2636.2-29.65.8 2814.444.730.19.4 2942.717.823.410.8  Soils C & D  *Low streamflow ANRC Task Force Meeting, September 21, 2010

46. Percentile Approach – Total Phosphorus SUBWATERSHED IDENTIFICATION  Lowest priority: Sub watershed# Forest % Crop % Pasture % Urban % 176.8-20.61.6 298.4-1.20.1 452.5-35.23.8 766.1-31.11.9 975.0-23.41.1 ANRC Task Force Meeting, September 21, 2010

47. Percentile Approach – Nitrate-Nitrogen SUBWATERSHED IDENTIFICATION  Highest priority: Sub watershed# Forest % Crop % Pasture % Urban % 633.38.631.620.0 1420.044.620.45.5 1733.2-26.135.8 19*72.8-15.25.3 2539.3-39.116.0 2636.2-29.65.8  #6- Whig Creek (10 mi)  #17- City of Conway WWTP ANRC Task Force Meeting, September 21, 2010

48. Sub watershed# Forest % Crop % Pasture % Urban % 298.41.20.1 452.535.23.8 1569.9-26.62.6 1646.1-45.56.2 2942.717.823.410.8 Percentile Approach – Nitrate-Nitrogen SUBWATERSHED IDENTIFICATION  Lowest priority: ANRC Task Force Meeting, September 21, 2010

49. CASE STUDY BAYOU BARTHOLOMEW WATERSHED (BBW) ANRC Task Force Meeting, September 21, 2010

50. Model: SWAT2009 Delineation: USGS 12-digit HUC DEM: 10 m Soil: SSURGO Land Use: 1992, 1999, 2004, and 2006 Subwatersheds: 44 HRUs: 3657 (0% land use, 5% soil type, 0% slope) Study Period: Calibration: 1996-2005 Validation: 2006-2008 (2004- 2008)-Portland Point Sources: 9 MODEL SETUP ANRC Task Force Meeting, September 21, 2010

51. DATA USED Sub watershed WET_MXS A (ha) WET_NS A (ha) WET_MXVO L (m 3 ) WET_NVO L (m 3 ) WET_F R 1286861,432,403429,7210.04 22,55076512,751,1073,825,3320.27 37162153,579,1801,073,7540.09 41,0783235,391,3091,617,3930.16 61,2063626,028,5201,808,5560.16 78022414,009,6721,202,9020.13 91,0243075,119,6121,535,8840.15 107672303,837,0691,151,1210.10 116782033,391,5501,017,4650.06 129022714,510,0181,353,0050.17 131,8415529,205,2292,761,5690.17 1413641681,884204,5650.01 183,4231,02717,113,7015,134,1100.23 192,36871011,838,8903,551,6670.22 229552864,774,6851,432,4060.10 231,7245178,621,5012,586,4500.15 251,4104237,048,5462,114,5640.14 268472544,236,9761,271,0930.06 271,4124247,062,0412,118,6120.15 301,2603786,298,1871,889,4560.16 312,07762310,385,0293,115,5090.18 371,0803245,398,0671,619,4200.10 431,3654106,826,6682,048,0000.24 442,39571811,972,5653,591,7700.35  2001 NLCD land use map  24 of the 44 subwatersheds in BBW had some wetland surface area ANRC Task Force Meeting, September 21, 2010

52.  NEXRAD Weather * NOAA -NWS DATA USED ANRC Task Force Meeting, September 21, 2010

53. Percentile Approach – Sediment SUBWATERSHED IDENTIFICATION ANRC Task Force Meeting, September 21, 2010 Preliminary Results

54. SUBWATERSHED IDENTIFICATION ANRC Task Force Meeting, September 21, 2010 Preliminary Results Percentile Approach – Total Phosphorus

55. Percentile Approach – Nitrate-Nitrogen SUBWATERSHED IDENTIFICATION ANRC Task Force Meeting, September 21, 2010 Preliminary Results

56. OVERALL SUMMARY  State of the art modeling and latest data was used for calibrating and validating SWAT model  Total number of gages utilized varied from one to seven in different selected watersheds  NEXRAD data used for precipitation as per availability  Model outputs such as, total flow, surface flow, base flow, sediment, nitrate-nitrogen, and total phosphorus were rigorously evaluated using latest performance criteria  In most of the subwatersheds, generally land use, soils, and slope association seen with high/low concentrations for water quality constituents ANRC Task Force Meeting, September 21, 2010

57. OVERALL SUMMARY..C ONTD.  Uncertainty estimation to assess risk associated with model outputs is gaining ground. Quantification of input data uncertainty is desirable to assess model performance  The model output has been used to rank subwatersheds on a relative basis. Absolute conc. of water quality constituent may not be of concern  Data gaps noticed in LCPR  It is encouraged that modeling results are also compared with other local information for decision making purposes  Monitoring and Modeling are complimentary and monitoring data is required for having confidence in modeling results ANRC Task Force Meeting, September 21, 2010

58. ACKNOWLEDGMENTS ANRC Task Force Meeting, September 21, 2010 Dr. Robert (Bob) Morgan, Beaver Water District Dr. Srinivasan (Srini) Raghavan Dr.(s) Jeff Arnold, Mike White and Nancy Sammons Dr. Amy Apon and Mr Jeff Pummil, UA High Performance Computing Center

59. QUESTIONS?/ SUGGESTIONS  dsaraswat@uaex.edu ANRC Task Force Meeting, September 21, 2010