WinTR-20 Project Formulation Hydrology Computer Program Overview Prepared by Quan D. Quan Hydraulic Engineer, NRCS Legislative Office Building Hartford, Connecticut October 26, 2010 WinTR-20 - Overview

Objectives Background of the development: WinTR-20 computer program Provide a brief description of the program Give an overview of the model, including its capabilities and limitations The objectives for this first lesson are: 1. To provide some background information on where the program came from. 2. To provide a very brief description of the program. 3. To give an overview of the model including its capabilities and limitations. In other words, to begin to discuss its applicability and talk about the conditions for which the model is useful. 4. And finally, to review some basic hydrology concepts and definitions. WinTR-20 Overview October 2010 WinTR-20 - Overview

Background Technical Release 20 Computer Program for Project Formulation Hydrology (TR-20) was first released in 1965 Revised in 1982, 1983, and 1986 Revision in February 1992 Major revision late 1998 Technical Release 20 Computer Program for Project Formulation Hydrology (TR-20) was first released in 1965 as a main frame FORTRAN program. Technical Release 20 Computer Program for Project Formulation Hydrology (TR-20) was revised and released in 1965 to assist Engineers in various calculations: - Hydrologic evaluation of flood events. - Analyze up to nine different rainstorm distributions. - 200 reaches, and 99 structures in any continuous run. - TR-20 is written in FORTRAN IV computer language. - Hydrology Branch of the SCS, Hydrology Laboratory, ARS, and C-E-I-R Inc. Revised in February 1983. -Appendix I – Data Check Computer -Table 4.1 – Alternates Compared Revision in February 1992. Major revision late 1998. WinTR-20 Overview October 2010 WinTR-20 - Overview

Background (continued) Major revision in late 1998 - WinTR-20 team was formed. - WinTR-20 team charge was to: 1. Modernize and revise the TR-20 computer software. 2. Upgrade the source code to Visual Basic. 3. Change the philosophy of data input. 4. Provide plots. 5. Windows interface and output post-processor. - First version of Windows based WinTR-20 was released in late September 2004. WinTR-20 Overview October 2010

WinTR-20 New Features Muskingum-Cunge Channel Routing replaces ATT-KIN Sub-Area / Reach Routing Concept replaces old Standard Control Runoff Curve Number (RCN) Calculation Option Time of Concentration (Tc) Calculation Option WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 New Features (continued) Graphics - Hydrographs - Reach / Structure Rating - Schematic WinTR-20 Overview October 2010

Model Overview WinTR-20 System Controller / Editor Capabilities / Limitations Minimum Data Requirements We’ll review now the capabilities and limitations of the computer program; look at an important consideration for this model, that being the WinTR-20 Controller/Editor window; talk about watershed schematics and their importance in hydrologic modeling; review some basic hydrology terms and concepts; and discuss the minimum data requirements for a WinTR-20 run. WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 System Controller / Editor - File - New WinTR-20 File - Open Existing WinTR-20 File - ReOpen Last Session - Convert Old Data - Import HEC-RAS - Import NOAA-NRCC Data - Local Land Use - Local Soil / HSG - Save - Save As - Exit New! WinTR-20 Overview October 2010

WinTR-20 System Controller / Editor - View - Schematic - Input File - Printed Page File - Error File - Debug File - Hydrograph File - FloodEcon File - Smoothed NOAA File WinTR-20 Overview October 2010

WinTR-20 System Controller / Editor - Run WinTR-20 Overview October 2010

WinTR-20 System Controller / Editor - Plots - Hydrograph - Storm - Peak Flow - Time Analysis - Alternate - Location WinTR-20 Overview October 2010

WinTR-20 System Controller / Editor - Help Diagram - Overview - Help Facilities - Getting Started - About Controller / Editor - Smoothing NOAA 14 Data WinTR-20 Overview October 2010

WinTR-20 System Controller / Editor – Data Section Alternate Analysis: Dimensionless Unit Hydrograph: Duration Increment: Global Output: Input Hydrograph: Rainfall Distribution: Stream Cross Section: Stream Reach: Storm Analysis: Structure Rating: Sub-Area: Time Analysis: WinTR-20: Version 1.11 Verification: WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 Identifier Window WinTR-20: Version 1.11.11 - Input Units Code: - Output Units Code: - Minimum Hydrograph Value: - Watershed Description: WinTR-20 Overview October 2010

Close Window Buttons Two choices are given on most screens: Accept Changes (Close) – All data shown will written to the input file. Selecting this accepts the data you’ve entered and returns you to the previous screen. No Changes (Close) – None of the changes made to items in that window will be written to the input file. Select this to keep the original data and return to the previous screen. WinTR-20 Overview October 2010

Sub-area/Reach Concepts Watershed - system of sub-areas and reaches Sub-areas - watersheds that generate runoff - feed into the upstream end of reaches Reaches or Routing Elements- represent watershed stream flow paths or structures Channel Routing elements - Stream Reaches Structure Routing elements - Reservoir/Structure Reaches Watershed Outlet -final reach (required for all watersheds) I said before the concept of sub-areas and reaches is one that is very important in modeling and you will see it emphasized several times today and tomorrow, so you’ll have a lot of opportunity to ask questions about it if you don’t quite understand yet. To emphasize the important points here: For modeling purposes, a watershed can be thought of as a system of sub-areas and reaches. Sub-areas are those smaller subwatersheds that generate runoff and feed into the upstream end of reaches. Reaches are routing elements through which water is conveyed. There are two types of reaches: Channel routing elements or Stream reaches, and Structure routing elements or structure reaches. All watersheds are required to have an identified Watershed Outlet. Do not confuse the Watershed Outlet with outlets for individual sub-areas. We’ll move on now to talk a bit about schematics and their importance when building hydrology models. WinTR-20 Overview October 2010 WinTR-20 - Overview

Sub-area/Reach Concepts Watershed - system of sub-areas and reaches Sub-areas - watersheds that generate runoff Reaches - represent watershed flow paths (stream channels) or structures One of the most important concepts that must be understood when using WinTR-20 is how sub-areas and reaches are defined. As we go through the training today and tomorrow, this point will be emphasized several times. Let’s take a look at it now. A watershed can be split up into multiple sub-areas and reaches. Look closely at our watershed map and notice how the parts of the watershed are identified. Sub-areas are those land areas that can be thought of as generating runoff. This is a fairly simple concept to grasp. From the figure shown here, look at Sub-area 1. Imagine rain falling over the watershed. As the water hits the ground, a portion of it runs off the ground surface and ultimately ends up at a point in which we are interested, for example at the structure site at the outlet of Sub-area 1. You should easily see how all of Sub-area 1 is contributing runoff at the structure site. Reaches are watershed flow paths within the watershed through which runoff is conveyed in a concentrated manner. For example, from our watershed map above, the runoff from Sub-area 2 would accumulate at the outlet of Sub-area 2. To get to the Watershed Outlet, that water must pass through Sub-area 3. In this case, the water from Sub-area 2 passes through the stream channel which just happens to flow through the middle of Sub-area 3. We identify this stream channel segment as a REACH. Stream reaches are the most easily identifiable of reaches, however, within WinTR-20, one may also have structure reaches. If we are modeling runoff that is conveyed through a structure, we identify a “Structure Reach.” From our watershed map, the water that accumulates at the outlet of Sub-area 1 (at the structure site location) must be conveyed through that structure before it can join the runoff from Sub-area 2 and flow through the stream reach in Sub-area 3 to reach the Watershed Outlet. To route that water through the structure, we identify the structure itself as a REACH. Another important consideration is how runoff from sub-areas and water conveyed through reaches are combined to produce hydrographs. Again, looking at our watershed map, we have developed a runoff hydrograph from Sub-area 1, and routed it through our structure reach, resulting in a hydrograph at the outlet of Sub-area 1. We have also developed a runoff hydrograph from Sub-area 2. We combine those two hydrographs at the top of the stream channel reach that runs through the middle of Sub-area 3 and route that, using a stream channel reach to the Watershed Outlet. However, at this point, we’ve not yet accounted for the runoff form Sub-area 3. The next step is to develop a runoff hydrograph for Sub-area 3. This hydrograph is then combined with the previous hydrograph to develop a total hydrograph for the watershed at the WATERSHED OUTLET. WinTR-20 Overview October 2010 WinTR-20 - Overview

Sub-area Connectivity Sub-area Receiving Reach A1 R1 (storage) A2 R2 (stream) A3 Outlet One of the most important concepts that must be understood when using WinTR-20 is how sub-areas and reaches are defined. As we go through the training today and tomorrow, this point will be emphasized several times. Let’s take a look at it now. A watershed can be split up into multiple sub-areas and reaches. Look closely at our watershed map and notice how the parts of the watershed are identified. Sub-areas are those land areas that can be thought of as generating runoff. This is a fairly simple concept to grasp. From the figure shown here, look at Sub-area 1. Imagine rain falling over the watershed. As the water hits the ground, a portion of it runs off the ground surface and ultimately ends up at a point in which we are interested, for example at the structure site at the outlet of Sub-area 1. You should easily see how all of Sub-area 1 is contributing runoff at the structure site. Reaches are watershed flow paths within the watershed through which runoff is conveyed in a concentrated manner. For example, from our watershed map above, the runoff from Sub-area 2 would accumulate at the outlet of Sub-area 2. To get to the Watershed Outlet, that water must pass through Sub-area 3. In this case, the water from Sub-area 2 passes through the stream channel which just happens to flow through the middle of Sub-area 3. We identify this stream channel segment as a REACH. Stream reaches are the most easily identifiable of reaches, however, within WinTR-20, one may also have structure reaches. If we are modeling runoff that is conveyed through a structure, we identify a “Structure Reach.” From our watershed map, the water that accumulates at the outlet of Sub-area 1 (at the structure site location) must be conveyed through that structure before it can join the runoff from Sub-area 2 and flow through the stream reach in Sub-area 3 to reach the Watershed Outlet. To route that water through the structure, we identify the structure itself as a REACH. Another important consideration is how runoff from sub-areas and water conveyed through reaches are combined to produce hydrographs. Again, looking at our watershed map, we have developed a runoff hydrograph from Sub-area 1, and routed it through our structure reach, resulting in a hydrograph at the outlet of Sub-area 1. We have also developed a runoff hydrograph from Sub-area 2. We combine those two hydrographs at the top of the stream channel reach that runs through the middle of Sub-area 3 and route that, using a stream channel reach to the Watershed Outlet. However, at this point, we’ve not yet accounted for the runoff form Sub-area 3. The next step is to develop a runoff hydrograph for Sub-area 3. This hydrograph is then combined with the previous hydrograph to develop a total hydrograph for the watershed at the WATERSHED OUTLET. WinTR-20 Overview October 2010 WinTR-20 - Overview

Reach Connectivity Upper Reach Receiving Reach R1 (res.) R2 (stream) R2 (stream) Outlet R1 R2 One of the most important concepts that must be understood when using WinTR-20 is how sub-areas and reaches are defined. As we go through the training today and tomorrow, this point will be emphasized several times. Let’s take a look at it now. A watershed can be split up into multiple sub-areas and reaches. Look closely at our watershed map and notice how the parts of the watershed are identified. Sub-areas are those land areas that can be thought of as generating runoff. This is a fairly simple concept to grasp. From the figure shown here, look at Sub-area 1. Imagine rain falling over the watershed. As the water hits the ground, a portion of it runs off the ground surface and ultimately ends up at a point in which we are interested, for example at the structure site at the outlet of Sub-area 1. You should easily see how all of Sub-area 1 is contributing runoff at the structure site. Reaches are watershed flow paths within the watershed through which runoff is conveyed in a concentrated manner. For example, from our watershed map above, the runoff from Sub-area 2 would accumulate at the outlet of Sub-area 2. To get to the Watershed Outlet, that water must pass through Sub-area 3. In this case, the water from Sub-area 2 passes through the stream channel which just happens to flow through the middle of Sub-area 3. We identify this stream channel segment as a REACH. Stream reaches are the most easily identifiable of reaches, however, within WinTR-55, one may also have structure reaches. If we are modeling runoff that is conveyed through a structure, we identify a “Structure Reach.” From our watershed map, the water that accumulates at the outlet of Sub-area 1 (at the structure site location) must be conveyed through that structure before it can join the runoff from Sub-area 2 and flow through the stream reach in Sub-area 3 to reach the Watershed Outlet. To route that water through the structure, we identify the structure itself as a REACH. Another important consideration is how runoff from sub-areas and water conveyed through reaches are combined to produce hydrographs. Again, looking at our watershed map, we have developed a runoff hydrograph from Sub-area 1, and routed it through our structure reach, resulting in a hydrograph at the outlet of Sub-area 1. We have also developed a runoff hydrograph from Sub-area 2. We combine those two hydrographs at the top of the stream channel reach that runs through the middle of Sub-area 3 and route that, using a stream channel reach to the Watershed Outlet. However, at this point, we’ve not yet accounted for the runoff form Sub-area 3. The next step is to develop a runoff hydrograph for Sub-area 3. This hydrograph is then combined with the previous hydrograph to develop a total hydrograph for the watershed at the WATERSHED OUTLET. WinTR-20 Overview October 2010 WinTR-20 - Overview

Reach 1 (storage routing) Schematics Sub-area 2 Reach 2 (Reach Routing) Outlet Reach 1 (storage routing) Sub-area 3 Sub-area 1 Storage Area Sub-Area Inflow Points Legend Schematics are simply line drawing representing the elements of a watershed model. Remember we said that watersheds consist of a series of sub-areas and reaches. The idea behind building a schematic is to show how these elements are combined to represent our watershed as we build our computer model for that watershed. Schematics are extremely important in that a well done schematic will allow you to come back to a particular model years from now, be able to pick it up, and by reviewing the schematic be able to tell exactly what you did when you developed the model. It also allows another user who has never looked at your model before to pick it up and see what you’ve done. This is especially important when, long after you are retired and moved away, another modeler has to come back and look at your work. The following explanation of the schematic will also provide a review of the sub-area reach concepts we just talked about. As I mentioned, t the schematic is a simple line drawing representing the elements of a watershed model. Let’s take a look at one now that has been developed to represent the watershed on the map we looked at previously. The individual who developed this schematic has identified for us two symbols in the legend to tell us that red triangle represent storage areas (or STRUCTURE reaches) and that blue squares represent sub-area inflow points. Starting with Sub-area 1, we might draw a line to represent the Sub-area. We will develop a runoff hydrograph for that sub-area. The blue square then shows us that this is where the inflow (runoff hydrograph) from Sub-area 1 enters our watershed system. We then route the runoff from sub-area 1 through the structure (red triangle) at the outlet of Sub-area 1 and label it a structure reach: in this case, REACH 1. Next we develop a runoff hydrograph for Sub-area 2 which is represented by a line and show the point at which this runoff enters the watershed system (blue square). The water from REACH 1 (the structure) and Sub-area 2 are combined then at the TOP of REACH 2 (which is the stream reach running through the middle of Sub-area 3). This entire hydrograph is then routed through the stream reach, REACH 2 towards the watershed outlet. We next develop a runoff hydrograph for Sub-area 3, showing the location at which that runoff enters the watershed system as an blue square. The water from REACH 2 and Sub-area 3 are then combined into one total hydrograph at the WATERSHED OUTLET. WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 Schematics WinTR-20 Overview October 2010

Sub-Area: Window Sub-Area: Land Use Details Tc Details - Sub-Area Identifier: - Sub-Area Reach Identifier: - Sub-Area Rain Gage Identifier: - Sub-Area Peak Output Code: - Sub-Area Hydrograph Output Code: - Sub-Area Time Analysis Code: - Sub-Area Hydrograph File Code: Land Use Details Tc Details WinTR-20 Overview October 2010

Help Window Click on text variable name. Click on it again to remove the help. WinTR-20 Overview October 2010

Stream Reach: Window WinTR-20 Overview October 2010

Stream Cross Section: Window WinTR-20 Overview October 2010

Structure Rating: Window WinTR-20 Overview October 2010

Storm Analysis: Window WinTR-20 Overview October 2010

Global Output: Window WinTR-20 Overview October 2010

Rainfall Distribution: Window WinTR-20 Overview October 2010

Input Hydrograph: Window WinTR-20 Overview October 2010

Dimensionless Unit Hydrograph: Window WinTR-20 Overview October 2010

Alternate Analysis: Window WinTR-20 Overview October 2010

Verification: Window WinTR-20 Overview October 2010

Output Graphical Tabular WinTR-20 Overview October 2010

File Management within WinTR-20 Input file “example.inp” Output file “example.out” Hydrograph file “example.hyd” Error file “example.err” Debug file “example.dbg” WinTR-20 Overview October 2010 WinTR-20 - Overview

Capabilities & Limitations Types of reaches Channel or Structure Channel Manning “n” 0.005-1.00 Reach Routing Muskingum-Cunge Sheet Flow Max. Length 100 feet Runoff Curve Number 30-100 Weighted Curve Number 30-100 Drainage Area 1 acre to 300 square miles Single sub-area min 1 acre - max 20 sq. miles As I mentioned previously, many of the capabilities and limitations in WinTR-20 were carried over from the original TR-20. This was done to limit its use to approximately the same types of watersheds that were being modeled using the original TR-20. WinTR-20 is capable of handling extremely large and complex watersheds. The result is a model that is fairly simple and straightforward to use. Reaches may be comprised of channel reaches or structure reaches. Channel reaches are those where hydrographs are routed through a length of stream channel, while structure reaches are those where hydrographs are routed through a structure. Again, we’ll talk more about reaches later. Reach routings are performed using the Muskingum-Cunge procedure. NRCS made changes in the TR-20 computation routine to now utilize Muskingum-Cunge as opposed to the previously utilized Att-Kin (Attenuation-Kinematic) Method. Sheet Flow maximum length. 100 feet in length is a new limitation. Maximum drainage area. The maximum drainage area is 300 square miles. There was a suggested single drainage area size of 1 acre to max 20 square miles. However, we would warn the user strongly to be highly suspicious of any intent to utilize this model for anything smaller than perhaps a 1 acre drainage area. WinTR-20 Overview October 2010 WinTR-20 - Overview

Minimum Data Requirements Data required for a single sub-area run can be entered on the WinTR-20 System Controller/Editor Main Window. These data include: WinTR-20 Identifier – Input and Output Units Code, Minimum Hydrograph Value, and Watershed Description Storm Analysis Identifier – Gage Rain Table (Type I, etc.), Gage Antecedent Runoff Condition, and Rainfall Data Sub-Area Identifier – Reach, Drainage Area, Weighted Curve Number, Time of Concentration (Tc), and Output Code (Peak, Hydrograph, Time Analysis, and Hydrograph File) Global Output (at least one item selected). We want to spend just a second talking about data requirements. For a single sub-area watershed run, the data can be entered on the WinTR-20 Main Window directly. These data include: WinTR-20 Identifier: which includes a Input and Output Units Code, Minimum Hydrograph Value, and Watershed Description of the watershed being modeled. Storm Analysis Identifier: which includes Gage Rain Table, Gage Antecedent Runoff Condition, and Rainfall Data. Sub-Area Identifier: which includes: Reach, Drainage Area, Weighted Curve Number, Time of Concentration (Tc), and Output Code (Peak, Hydrograph, Time Analysis, and Hydrograph File). And finally, Global Output: at least one item should be selected. WinTR-20 Overview October 2010 WinTR-20 - Overview

User Responsibility Results from the model can be sensitive to the input data. It is the user’s responsibility to ensure that all the input data (whether it is actually entered or implied through default values for blank data fields) is appropriate. WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 web sites NRCS users may find WinTR-20 by: Contact your state ITS for download Non-NRCS users may find WinTR-20 at: http://www.wsi.nrcs.usda.gov/products/W2Q/H&H/Tools_Models/WinTR20.html E-mail questions to: LO-OR-NRCS-TR20@one.usda.gov WinTR-20 Overview October 2010 WinTR-20 - Overview

WinTR-20 Development Team William H. Merkel Maryland 301-504-3956 Helen Fox Moody Maryland 301-504-3948 Quan D. Quan Maryland 301-504-3952 Dan Moore Oregon 503-414-3054 John McClung Arkansas 501-210-8902 Pete Cooper Minnesota 651-602-7884 Geoff Cerrelli Pennsylvania 717-237-2214 Thom Garday Arkansas 501-210-8905 Don Woodward NRCS-Retired Roger Cronshey NRCS-Retired WinTR-20 Overview October 2010

Summary Reviewed the background of the development for WinTR-20 Provided a brief description of the Program Gave an overview of the model including its capabilities and limitations The objectives for this first lesson are: 1. To provide some background information on where the program came from. 2. To provide a very brief description of the program. 3. To give an overview of the model including its capabilities and limitations. In other words, to begin to discuss it’s applicability and talk about the conditions for which the model is useful. 4. And finally, to review some basic hydrology concepts and definitions. WinTR-20 Overview October 2010 WinTR-20 - Overview

The End WinTR-20 Overview October 2010

WinTR-20 Overview October 2010