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68 Units of Measure Â°C degree(s) Celsius cfs cubic feet per second cms, m3/s cubic meter(s) per second ft foot or feet ft/ft feet per foot ft/s feet per second ft2 square feet H:V horizontal:vertical in. inch(es) kg/m3 kilogram(s) per cubic meter kg/s kilogram(s) per second km2 square kilometer(s) m meter(s) m/m meter(s) per meter m/s meter(s) per second m/s2 meter(s) per second squared m2 square meter(s) m2/s square meter(s) per second m3/s/m cubic meter(s) per second per meter mm millimeter(s) ppm parts per million W/m2 Watt(s) per square meter Statistical Terms a best-fit regression parameter b best-fit regression parameter; sediment rating curve parameter p-value probability t Mann-Kendall test statistic Acronyms and Initialisms CEM Channel Evolution Model CN curve number CSR capacity-supply ratio CSR Tool CSR Stable Channel Design Tool Abbreviations, Acronyms, Initialisms, and Symbols
Abbreviations, Acronyms, Initialisms, and Symbols 69 DOT Department of Transportation eRAMS Environmental Resource Assessment & Management System FDC flow duration curve GHCND Global Historical Climatology Network â Daily HEC-20 Hydraulic Engineering Circular No. 20 HEC-RAS Hydrologic Engineering Center River Analysis System NCHRP National Cooperative Highway Research Program NRCS Natural Resources Conservation Service O on the order of PDF probability density function R-B Richards-Baker Flashiness Index RGA rapid geomorphic assessment SRP stream response potential SWAT-DEG Soil and Water Assessment Tool â channel DEGradation SWMM Storm Water Management Model USGS U.S. Geological Survey Symbols D16, D75, D84, D90 particle size for which 16%, 75%, 84%, and 90% of all sediments is smaller [m], respectively D50 median grain diameter of the bed material [m] Dg geometric mean grain diameter [m] Fs approximate fraction of sand in bed sediments g gravitational acceleration [m/s2] G specific gravity of sediment (2.65 is typically assumed) i day kd erodibility factor n Manningâs roughness coefficient n total number of days in the flow record n total number of data points q daily-averaged discharge [m2/s] Q median annual peak flow (Q2) [m 3/s] Q water discharge rate [m3/s] Q1.5, Q2 1.5-year and 2-year, return interval discharges [m 3/s], respectively Qeff effective discharge [m 3/s] Qs sediment discharge rate [kg/s] Qs50, Qs75, Qs90 discharge associated with 50%, 75%, and 90% of cumulative sediment transport over the sorted flow record [m3/s], respectively RB Richards-Baker Flashiness Index S channel slope [m/m] Sv valley slope [m/m] w channel top width at bankfull [m] w/h width/depth ratio r density of the fluid mixture [kg/m3] sg geometric standard deviation of particles sizes t* dimensionless shear stress w specific stream power [W/m2] (w = rgQS/w) w* dimensionless specific stream power
Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACIâNA Airports Council InternationalâNorth America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing Americaâs Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation