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WinTR-55 Small Watershed Hydrology

WinTR-55 Small Watershed Hydrology. Overview. Course Outline. Overview Historical Background Program Description Review of Hydrology Related Terms Model Capabilities and Limitations. Lesson Objectives. The objectives of this lesson are to: Review the background of WinTR-55

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WinTR-55 Small Watershed Hydrology

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  1. WinTR-55Small Watershed Hydrology Overview

  2. Course Outline Overview • Historical Background • Program Description • Review of Hydrology Related Terms • Model Capabilities and Limitations WinTR-55 Overview

  3. Lesson Objectives The objectives of this lesson are to: • Review the background of WinTR-55 • Provide a brief description of the Program • Review some basic hydrology concepts and definitions • Give an overview of WinTR-55 capabilities and limitations WinTR-55 Overview

  4. Background of WinTR-55

  5. Background • First issued in January 1975 • Manual Method • Simplified method for estimating Q and qpeak, and developing partial hydrographs • Collection of hydrology tools • RCN method to determine Q • Velocity based Tc method • Utilization of unit hydrograph theory to determine partial hydrographs and qpeak • Generalized stream channel routing • Simplified storage routing method WinTR-55 Overview

  6. Background • First issued in January 1975 • Generalized tables and graphs developed from TR-20 • Allowed rapid hand computations • Type II rainfall distribution only • Major revision in June 1986 • Types I, IA and III rainfall distributions added • First version of DOS computer program • Methods/procedures identical to the manual WinTR-55 Overview

  7. Background • Spring 1998 • Team formed to upgrade the computer program from DOS to Windows • August 2003 • First version of Windows based TR-55 (WinTR-55 version 1.0) is released WinTR-55 Overview

  8. Program Description

  9. Program Description • Single event model • Generates hydrographs • Routes hydrographs through channels and/or reservoirs • Models sub-areas WinTR-55 Overview

  10. Program Description • Program written in Visual Basic version 6.0 • WinTR-55 exists as a graphical user interface (GUI) to the WinTR-20 executable program WinTR-55 Overview

  11. Hydrology Related Terms

  12. Watershed Boundary The outline of the watershed on a map or the divide between watersheds. Reference Hydrology Related Terms WinTR-55 Overview

  13. Watershed The area contributing direct runoff to a stream. NEH 630, Chapter 22 Hydrology Related Terms WinTR-55 Overview

  14. Sub-Area (or Subwatershed) A watershed that is part of a larger watershed. NEH 630, Chapter 22 2 1 3 4 5 Hydrology Related Terms WinTR-55 Overview

  15. Stream Channel Reach A length of stream channel selected for use in hydraulic or other computations. NEH 630, Chapter 6 2 1 3 Reach 1 4 Reach 2 5 Hydrology Related Terms WinTR-55 Overview

  16. Stream Channel Reach A length of stream channel selected for use in hydraulic or other computations. NEH 630, Chapter 6 N Hydrology Related Terms Sub-area A Stream Reach 1 Stream Reach 2 Sub-area C Sub-area B WinTR-55 Overview

  17. Structure Reach A stream reach containing a hydraulic structure. Reference N Hydrology Related Terms Sub-area A Stream Reach 1 Structure Reach Stream Reach 2 Sub-area C Sub-area B WinTR-55 Overview

  18. Outlet The downstream end of the watershed. Reference N Hydrology Related Terms Sub-area A Stream Reach 1 Outlet Structure Reach Stream Reach 2 Sub-area C Sub-area B WinTR-55 Overview

  19. Time of Concentration (Tc) The time it takes water from most distant point (hydraulically) to reach the watershed outlet. NEH 630, Chapter 15 Hydrology Related Terms WinTR-55 Overview

  20. Time of Concentration (Tc) In hydrograph analysis, Tc is the time from the end of the excess rainfall to the point on the falling limb of the hydrograph (point of inflection) where the recession curve begins. NEH 630, Chapter 15 qp Excess Rainfall L Tc Discharge (q/qp) Q Tp Tr Tb Time (t/Tp) Hydrology Related Terms WinTR-55 Overview

  21. Sheet Flow Flow over plane surfaces Usually occurs in headwater of streams Very shallow flow depths (up to about 0.1 ft) 210-VI-TR-55, 2nd ed., June 1986 Photo courtesy of USDA-NRCS Hydrology Related Terms WinTR-55 Overview

  22. Shallow Concentrated Flow Flow regime existing between the sheet flow segment and open channel flow segment along the time of concentration flow path. 210-VI-TR-55, 2nd ed., June 1986 Photo courtesy of USDA-NRCS Hydrology Related Terms WinTR-55 Overview

  23. Photo courtesy of USDA-NRCS Open Channel Flow Water flowing in a defined channel. 210-VI-TR-55, 2nd ed., June 1986 Hydrology Related Terms WinTR-55 Overview

  24. Rainfall Return Period The average time interval between rainfall events with a given or greater magnitude. Reference Hydrology Related Terms Described as 2-year, 5-year, 10-year, etc. events. 100 - Year Event  An event which has a 1 percent chance of occurrence IN ANY YEAR; NOT ONE event every 100 years. http://www.srh.noaa.gov/lub/wx/precip_freq/precip_index.htm WinTR-55 Overview

  25. Hydrologic Soil Group (HSG) Soil classification based on infiltration rate after prolonged wetting with all vegetation removed. HTS Module 103 – Runoff Concepts A group of soils having the same runoff potential under similar storm and cover conditions. NEH 630, Chapter 7 Hydrology Related Terms WinTR-55 Overview

  26. Hydrology Related Terms Runoff Curve Number (CN) A single parameter, combining hydrologic soil group and land use and treatment class, describing runoff potential of that single hydrologic soil-cover complex. NEH 630, Chapter 9 WinTR-55 Overview

  27. Antecedent Runoff Condition (ARC) The condition of a watershed, including soil wetness, vegetal condition, and land use at the beginning of a storm. NEH 630, Chapter 10 Hydrology Related Terms WinTR-55 Overview

  28. Hydrology Related Terms Impervious Areas Areas into which water cannot infiltrate, such as roads, roofs or parking lots. 210-VI-TR-55, 2nd ed., June 1986 Photo courtesy of USDA-NRCS WinTR-55 Overview

  29. Rainfall Distribution Distribution of rainfall with respect to time. 210-VI-TR-55, 2nd ed. June 1986 Hydrology Related Terms WinTR-55 Overview

  30. Hydrology Related Terms WinTR-55 Overview

  31. Mass Curve of Rainfall Accumulated rainfall total for a specific rainfall event. Reference Hydrology Related Terms WinTR-55 Overview

  32. Dimensionless Unit Hydrograph Discharge hydrograph resulting from 1 inch of direct runoff distributed uniformly over the watershed. NEH 630, Chapter 16 Hydrology Related Terms Q/Qp T/Tp WinTR-55 Overview

  33. Hydrograph A graph showing discharge and/or stage with respect to time at a given point in a watershed. NEH 630, Chapter 16 Discharge Time Hydrology Related Terms WinTR-55 Overview

  34. Storm Rainfall Data Rainfall amounts measured at rain gages, published, and statistically analyzed by NWS. NEH 630, Chapter 4 Hydrology Related Terms Photo courtesy of USDA-NRCS WinTR-55 Overview

  35. Peak Discharge The maximum discharge resulting from a rainfall event. NEH 630, Chapter 16 Peak Discharge Time Hydrology Related Terms WinTR-55 Overview

  36. Rainfall Depth Average depth of storm rainfall over the watershed area for a specified storm duration. NEH 630, Chapter 4 Hydrology Related Terms Photo courtesy of USDA-NRCS WinTR-55 Overview

  37. Runoff The portion of precipitation that makes its way to the watershed outlet. NEH 630, Chapter 10 Hydrology Related Terms Photo courtesy of USDA-NRCS Photos courtesy of USDA-NRCS WinTR-55 Overview

  38. Runoff Volume The volume of runoff resulting from a rainfall event. NEH 630, Chapter 10 The area under a discharge hydrograph. NEH 630, Chapter 16 Discharge Runoff Volume Time Hydrology Related Terms WinTR-55 Overview

  39. Capabilities & Limitations

  40. Maximum Area 25 sq. mi. Tc for any sub-area 0.1 hr < Tc< 10 hrs ARC 2 (average) CN for any sub-area 40 < CN < 98 Number of sub-areas 1-10 Number of reaches 0-10 Types of reaches Channel or Structure Reach Routing Muskingum-Cunge Capabilities & Limitations WinTR-55 Overview

  41. Structure Routing Storage-Indication Structure Types Pipe or Weir Structure Trial Sizes 1-3 Rainfall Depth Default or user-defined (range of 0-50 inches) Rainfall Distributions NRCS Type I, IA, II, III, NM distributions or user- defined Rainfall Duration 24-hour Dimensionless Unit Standard peak rate factor (484) Hydrograph or user-defined Capabilities & Limitations WinTR-55 Overview

  42. Methods based on open and unconfined flow Inappropriate for use in closed system pipe flows, such as storm sewers. Composite flood hydrographs should be compared to stream gage data where possible. At a minimum, compare peak discharges with data from USGS curves of peak flow versus drainage area. Capabilities & Limitations WinTR-55 Overview

  43. Questions?

  44. Summary • Reviewed the background of WinTR-55 • Provided a brief description of the Program • Reviewed some basic hydrology concepts and definitions • Gave an overview of WinTR-55 capabilities and limitations WinTR-55 Overview

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