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Hydrology and Sediment Calibration Status

Hydrology and Sediment Calibration Status. Gary Shenk Jing Wu Lewis Linker Ross Mandel Doug Moyer Jeff Keaton Hui Liu Jeff Raffensperger Modeling Subcommittee 4/4/05. Hydrology Calibration. Method has been stable for months Received final land use Final check of parameters

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Hydrology and Sediment Calibration Status

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  1. Hydrology and Sediment Calibration Status Gary Shenk Jing Wu Lewis Linker Ross Mandel Doug Moyer Jeff Keaton Hui Liu Jeff Raffensperger Modeling Subcommittee 4/4/05

  2. Hydrology Calibration • Method has been stable for months • Received final land use • Final check of parameters • New elevation data • Received upgraded rainfall • Ran iteration routine

  3. BMP Factor Edge of Stream Land Acre Factor Delivery Factor In Stream Concentrations Sediment Pathway in Phase 5 Edge of Field

  4. BMP Factor Edge of Stream Land Acre Factor Delivery Factor In Stream Concentrations Sediment Pathway in Phase 5 Edge of Field Targets

  5. Forest Harvested Forest Natural grass Extractive Barren Pervious Urban Impervious Urban Pasture Bad Pasture Hay High till with manure High till no manure Low till with manure Needed EOF targets for 13 land uses Agriculture Other

  6. NRI gave estimates of Pasture and Cropland for each county Pasture Bad Pasture Hay High till with manure High till no manure Low till with manure Needed EOF targets for 13 land uses Agriculture

  7. Pasture => Pasture Bad Pasture => 9.5 * Pasture Hay => 1/3 Crop (P4 NRI) High till with manure => 1.25 * Crop High till no manure => 1.25 * Crop Low till with manure => 0.75 * Crop Needed EOF targets for 13 land uses Agriculture 9% 0.05% 7% 4% 1% 4%

  8. Forest Harvested Forest Natural grass Bare Extractive Pervious Urban Impervious Urban Needed EOF targets for 13 land uses Other 65% 0.65% 0.65% 0.52% 0.11% 7.1% 1.2%

  9. FOREST • NRI estimates exist for phase 4 for the CB watershed. Use these where available • Southern Virginia • Calculate forest rate using USLE • Ratio the results so that the range is equal to the rest of the CB watershed

  10. HARVESTED FOREST • Bare ground erosion rates of forest soils 3 to 4 orders of magnitude greater than base forest erosion rates • Current practice in Mid-Atlantic Region does not reduce forests to bare ground except for roads and harvest machinery • Use 3.4 t/ac/yr as target rate—one order of magnitude greater than base forest rate

  11. NATURAL GRASS(fallow land, horse pasture) RECOMMENDATION: Use Basin-wide average Pasture erosion rate for 1982-1997, inclusive = 1.5 t/ac/yr

  12. BARE = CONSTRUCTION • 38 – 78 t/ac/yr (Guy and Ferguson, 1962) • 7.2 – 500 t/ac/yr ( U. S. EPA, 2002) • 35 – 45 t/ac/yr (MWCOG, 1987) • Choose 40 t/ac/yr

  13. EXTRACTIVE(mines, sand and gravel pits) • Active Operations: Permit limits of 70 mg/l TSS ≈ 0.16 t/ac/yr • Abandoned Mines: Waste piles and non-vegetated area more like construction areas • Assume average of one-fourth construction site erosion rate: 10 t/ac/yr

  14. URBAN • Post-construction urban sediment loads primary due to channel erosion from increased concentrated flow from impervious surfaces • Use Langland and Cronin (2003) estimates of urban EOS erosion rates by land use category

  15. Forest => Use P4 NRI Harvested Forest => Mean Forest * 10 = 3.4 t/ac/yr Natural grass => Mean Pasture = 1.5 t/ac/yr Bare => 40 t/ac/yr Extractive => 10 t/ac/yr Pervious Urban => 0.74 t/ac/yr Impervious Urban => 5.18 t/ac/yr Needed EOF targets for 13 land uses Other

  16. ATMOSPHERIC DEPOSITION ON WATER RECOMMENDATION: Use Constant Daily Rate of 10 lb/ac/day (Langland and Cronin, 2003)

  17. BMP Factor Edge of Stream Land Acre Factor Delivery Factor In Stream Concentrations Sediment Pathway in Phase 5 Edge of Field Method

  18. Wash off Generation Attachment Rainfall Detachment Land Sediment Simulation Detached Sediment KSER KRER AFFIX NVSI Soil Matrix (unlimited) 4 parameters, 1 target

  19. Rule 1 - Zero Detached Sed after Large Storms vanSickle and Beschta (1983) Allen Gellis (pers communication)

  20. Decision Rules for Four Key land Parameters: Rule2 – Detached Sediment Storage Reaches 90% of its Max in 30 Days AFFIX = 0.07673

  21. Generation Rainfall Detachment Rule3 – Generation makes up significant portion of Detached Sediment Detached Sediment KRER NVSI Soil Matrix (unlimited) • NVSI = [significant fraction] * target load

  22. Detached Sediment Wash off Generation KSER Attachment Rainfall Detachment KRER AFFIX NVSI Soil Matrix (unlimited) Strategy: Reduce the Parameter Set 1. Assume ratio of NVSI : EOF target 2. Assume ratio of KSER : KRER 3. Adjust KSER to meet target

  23. Two strategies to optimize ratios: • Does the model correctly capture the dynamic of land process? • Do the different land calibrations make a difference in the correlation between simulated and observed?

  24. - Dynamic of land process Land segment A42033 - pasture, KSER/KRER = 5 Detached Storage goes down to zero sometimes

  25. - Dynamic of land process Land segment A42033 - pasture, KSER/KRER = 5 Detached Storage remains high, never goes down to zero

  26. Status and expected steps • Computer programs ready • EOF calibration can be done in two weeks once final hydrology parameters are available.

  27. In Stream Concentrations Land-River Connection Edge of Field BMP Factor Edge of Stream Land Acre Factor Delivery Factor

  28. Proposed method: Relate delivery to average distance from land to river by segment

  29. Single factor for each land use in each segment • Related to watershed size • Unique for each Land use • Assume mean distance is the radius of a circle A = π*(mean distance)^2 DF = 0.417762 * A -0.134958 - 0.127097

  30. In Stream Concentrations Land-River Connection Edge of Field BMP Factor Edge of Stream Land Acre Factor Delivery Factor

  31. Outflow Inflow Deposition Scour River Cohesive Sediment Simulation Suspended Sediment Bed Storage (unlimited)

  32. Goals of River Calibration • Find sensitive parameters • Find numeric calibration measures • Make system of rules for their interaction

  33. Data • Calibrating now with 50 stations • Have data coming in for approx 200 stations

  34. Default Values

  35. Reduce Erodibility • Adjust M values only to 0.4

  36. Reduce frequency of Scour • Scour Tau and deposition tau setto 99th percentile • M = 0.4

  37. High frequency / Low Mass Scour • Adjust deposition and scour to 95th percentile. • M = 0.4 • Depositional 95% of time and erosional 5% of time.

  38. Low Frequency / High Mass Scour • M set to default • Tau scour set to 99th percentile

  39. Strategy for completion • Extra staff • Investigate various strategies • KS test • Shear Stress vs Error • Optimize 1:1 plot • Develop decision tree method that can be followed by calibrator or automated

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