Engineering Field Handbook Chapter 2: Estimating Runoff .

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 650Engineering Field Handbook Chapter 2: Estimating Runoff and Peak DischargesMassachusetts EFH-2 Supplement Number: MA-EFH2MA Supplement BackgroundThe purpose of this supplement is to assist Field staff in utilizing the most current rainfall data andrainfall distribution available for the design of conservation practices. These rainfall data weredeveloped by the Northeast Regional Climate Center (NRCC) and will replace rainfall data from WeatherBureau Technical Paper 40 (TP-40). Rainfall distributions were developed by the NRCS Water Qualityand Quantity Technology Development Team and replace the standard NRCS rainfall distributions Type IIand Type III.This supplement updates the rainfall depths and rainfall distribution types to be used in estimatingrunoff and peak discharges as described in NEH Part 650, Engineering Field Handbook Chapter 2 (EFH-2).This supplement includes information on the MA rainfall counties and sub-county areas and provides anexample application of the computer program, EFH-2. Appendices include additional information on thetwenty MA precipitation areas, procedures to update the EFH-2 rainfall amount data files, backgroundinformation on the four NRCC rainfall distribution types, and an example application of peak dischargecalculation using a chart.Effective upon receipt, NRCS MA staff are to use these updated rainfall depths and rainfall distributiontypes when estimating runoff and peak discharges described in NEH 650, Chapter 2. Theimplementation is in two parts, (1) updating NEH 650, Chapter 2 for Massachusetts and (2) updating thedata files for the EFH-2 computer program by replacing the county rainfall (county.MA) and rainfalldistribution types (type.rf) files.The EFH-2 computer program User Guide contains information, guidance, and examples concerningrunoff curve number, average watershed slope, watershed length, input/output operations, andlimitations. Additional technical information is available from the NRCC web site (www.precip.net) andNRCS technical directives such as National Engineering Handbook Part 630 – Hydrology, Chapter 4,Storm Rainfall Depth and Distribution.Rainfall DataThe NRCC has completed a rainfall-frequency analysis for data through December 31, 2008. This is thefirst comprehensive rainfall-frequency analysis for the northeast states since 1961, when TP-40 wascompleted. Data are available for specific locations from an interactive web site (www.precip.net).Alternatively, data for representative locations in Massachusetts counties are included in a rainfallamount data file (county.MA) for use with the EFH-2 computer program. The data contained in thedatabase are included in Appendix 1 of this Supplement.[MA 210 NEH 650 2, Amendment MA-1, March 2013]Page 1

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 650Rainfall DistributionsFour rainfall distributions have been developed for the northeast states (CT, MA, ME, NH, NY, RI, andVT). These rainfall distributions were developed based on the NRCC data. The state of Massachusetts ischaracterized by three rainfall distributions as indicated below in Figures 1 and 2. Appendix 1 includesdetailed maps of all towns in each county or sub-county rainfall area.Figure 1 - Location of types B, C, and D rainfall distributions[MA 210 NEH 650 2, Amendment MA-1, March 2013]Page 2

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 650Figure 2 - Massachusetts State map showing the twenty rainfall areasThe EFH-2 computer program uses equations to relate unit peak discharge (cubic feet per second perinch of runoff per acre of drainage area) to time of concentration in hours. The equations andcoefficients for the four northeast rainfall distributions are included in Appendix 3. Plots of the rainfalldistributions for Regions A, B, C, and D are included in Appendix 4. Appendix 5 includes a graph which isan alternative to running the EFH-2 computer program. Within the accuracy of reading the graph, theresult will be close to that derived from the EFH-2 computer program.Example Application of the EFH-2 Computer Program in MassachusettsFor this example, we select a small watershed in the Worcester Central region. The drainage area is 10acres, the curve number is 82, length is 800 feet, and watershed slope is 3 percent. From the rainfalldistribution map above, the rainfall distribution region is “D”.1. Open the EFH-2 program from the Engineering Applications programs. Open the “Basic Data”tab. In the State window enter MA. In the County window, use the pull-down menu to selectthe town of Worcester. The name “NRCC D” next to the county name designates this county isin NRCC Rainfall Distribution Type D region and that the rainfall data source is the NRCC website.[MA 210 NEH 650 2, Amendment MA-1, March 2013]Page 3

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 6502. Enter the remaining data on this window. The Drainage Area and Runoff Curve Number couldalternatively have been entered by opening the RCN tab.[MA 210 NEH 650 2, Amendment MA-1, March 2013]Page 4

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 6503. Open the Rainfall/Discharge data tab. Select the rainfall type NRCC D from the pull downmenu. Once the rainfall type is selected, the peak discharges and runoff depths are calculated.4. To complete the project, click File Save and File Print.[MA 210 NEH 650 2, Amendment MA-1, March 2013]Page 5

Estimating Runoff and Peak DischargesEngineering Field Handbook – Chapter 2National Engineering Handbook Part 650Appendix 1. County rainfall database (county.MA). Table 1 lists the rainfall data compiled from theNRCC web site (www.precip.net) and imported into the EFH-2 executable program file “county.MA”.Table A1.1 Massachusetts rainfall data by town and county [inches]Town and CountyABINGTON PLYMOUTH COUNTY NRCC-CACTON MIDDLESEX COUNTY CENTRAL NRCC-DACUSHNET BRISTOL COUNTY NRCC-CADAMS BERKSHIRE COUNTY NORTH NRCC-BAGAWAM HAMPDEN COUNTY NRCC-CALFORD BERKSHIRE COUNTY SOUTH NRCC-CAMESBURY ESSEX COUNTY NRCC-DAMHERST HAMPSHIRE COUNTY NRCC-CANDOVER ESSEX COUNTY NRCC-DAQUINNAH DUKES COUNTY NRCC-CARLINGTON MIDDLESEX COUNTY SOUTH NRCC-DASHBURNHAM WORCESTER COUNTY NORTH NRCC-CASHBY MIDDLESEX COUNTY NORTH NRCC-CASHFIELD FRANKLIN COUNTY NRCC-CASHLAND MIDDLESEX COUNTY SOUTH NRCC-DATHOL WORCESTER COUNTY NORTH NRCC-CATTLEBORO BRISTOL COUNTY NRCC-CAUBURN WORCESTER COUNTY SOUTH NRCC-DAVON NORFOLK COUNTY NRCC-CAYER MIDDLESEX COUNTY NORTH NRCC-CBARNSTABLE BARNSTABLE COUNTY WEST NRCC-CBARRE WORCESTER COUNTY CENTRAL NRCC-DBECKET BERKSHIRE COUNTY SOUTH NRCC-CBEDFORD MIDDLESEX COUNTY CENTRAL NRCC-DBELCHERTOWN HAMPSHIRE COUNTY NRCC-CBELLINGHAM NORFOLK COUNTY NRCC-CBELMONT MIDDLESEX COUNTY SOUTH NRCC-DBERKLEY BRISTOL COUNTY NRCC-CBERLIN WORCESTER COUNTY CENTRAL NRCC-DBERNARDSTON FRANKLIN COUNTY NRCC-CBEVERLY ESSEX COUNTY NRCC-DBILLERICA MIDDLESEX COUNTY CENTRAL NRCC-DBLACKSTONE WORCESTER COUNTY SOUTH NRCC-DBLANDFORD HAMPDEN COUNTY NRCC-CBOLTON WORCESTER COUNTY CENTRAL NRCC-DBOSTON SUFFOLK COUNTY NRCC-DBOURNE BARNSTABLE COUNTY WEST NRCC-CBOXBOROUGH MIDDLESEX COUNTY CENTRAL NRCC-DBOXFORD ESSEX COUNTY NRCC-DBOYLSTON WORCESTER COUNTY CENTRAL NRCC-DBRAINTREE NORFOLK COUNTY NRCC-CBREWSTER BARNSTABLE COUNTY EAST NRCC-CBRIDGEWATER PLYMOUTH COUNTY NRCC-CBRIMFIELD HAMPDEN COUNTY NRCC-CBROCKTON PLYMOUTH COUNTY NRCC-CBROOKFIELD WORCESTER COUNTY CENTRAL NRCC-DBROOKLINE NORFOLK COUNTY NRCC-CBUCKLAND FRANKLIN COUNTY NRCC-CBURLINGTON MIDDLESEX COUNTY SOUTH NRCC-DCAMBRIDGE MIDDLESEX COUNTY SOUTH NRCC-DCANTON NORFOLK COUNTY NRCC-CCARLISLE MIDDLESEX COUNTY CENTRAL 482.642.642.692.58[MA 210 NEH 650 2, Amendment MA-1, March 8.688.348.807.298.628.628.808.36Page 6

Estimating Runoff and Peak DischargesCARVER PLYMOUTH COUNTY NRCC-CCHARLEMONT FRANKLIN COUNTY NRCC-CCHARLTON WORCESTER COUNTY SOUTH NRCC-DCHATHAM BARNSTABLE COUNTY EAST NRCC-CCHELMSFORD MIDDLESEX COUNTY CENTRAL NRCC-DCHELSEA SUFFOLK COUNTY NRCC-DCHESHIRE BERKSHIRE COUNTY NORTH NRCC-BCHESTER HAMPDEN COUNTY NRCC-CCHESTERFIELD HAMPSHIRE COUNTY NRCC-CCHICOPEE HAMPDEN COUNTY NRCC-CCHILMARK DUKES COUNTY NRCC-CCLARKSBURG BERKSHIRE COUNTY NORTH NRCC-BCLINTON WORCESTER COUNTY CENTRAL NRCC-DCOHASSET NORFOLK COUNTY NRCC-CCOLRAIN FRANKLIN COUNTY NRCC-CCONCORD MIDDLESEX COUNTY CENTRAL NRCC-DCONWAY FRANKLIN COUNTY NRCC-CCUMMINGTON HAMPSHIRE COUNTY NRCC-CDALTON BERKSHIRE COUNTY NORTH NRCC-BDANVERS ESSEX COUNTY NRCC-DDARTMOUTH BRISTOL COUNTY NRCC-CDEDHAM NORFOLK COUNTY NRCC-CDEERFIELD FRANKLIN COUNTY NRCC-CDENNIS BARNSTABLE COUNTY EAST NRCC-CDIGHTON BRISTOL COUNTY NRCC-CDOUGLAS WORCESTER COUNTY SOUTH NRCC-DDOVER NORFOLK COUNTY NRCC-CDRACUT MIDDLESEX COUNTY NORTH NRCC-CDUDLEY WORCESTER COUNTY SOUTH NRCC-DDUNSTABLE MIDDLESEX COUNTY NORTH NRCC-CDUXBURY PLYMOUTH COUNTY NRCC-CEAST BRIDGEWATER PLYMOUTH COUNTY NRCC-CEAST BROOKFIELD WORCESTER COUNTY CENTRAL NRCC-DEAST LONGMEADOW HAMPDEN COUNTY NRCC-CEASTHAM BARNSTABLE COUNTY EAST NRCC-CEASTHAMPTON HAMPSHIRE COUNTY NRCC-CEASTON BRISTOL COUNTY NRCC-CEDGARTOWN DUKES COUNTY NRCC-CEGREMONT BERKSHIRE COUNTY SOUTH NRCC-CERVING FRANKLIN COUNTY NRCC-CESSEX ESSEX COUNTY NRCC-DEVERETT MIDDLESEX COUNTY SOUTH NRCC-DFAIRHAVEN BRISTOL COUNTY NRCC-CFALL RIVER BRISTOL COUNTY NRCC-CFALMOUTH BARNSTABLE COUNTY WEST NRCC-CFITCHBURG WORCESTER COUNTY NORTH NRCC-CFLORIDA BERKSHIRE COUNTY NORTH NRCC-BFOXBOROUGH NORFOLK COUNTY NRCC-CFRAMINGHAM MIDDLESEX COUNTY SOUTH NRCC-DFRANKLIN NORFOLK COUNTY NRCC-CFREETOWN BRISTOL COUNTY NRCC-CGARDNER WORCESTER COUNTY NORTH NRCC-CGEORGETOWN ESSEX COUNTY NRCC-DGILL FRANKLIN COUNTY NRCC-CGLOUCESTER ESSEX COUNTY NRCC-DGOSHEN HAMPSHIRE COUNTY NRCC-CGOSNOLD DUKES COUNTY NRCC-CGRAFTON WORCESTER COUNTY SOUTH NRCC-DGRANBY HAMPSHIRE COUNTY NRCC-CGRANVILLE HAMPDEN COUNTY NRCC-CEngineering Field Handbook – Chapter 2National Engineering Handbook Part .692.742.472.632.482.632.552.802.652.552.60[MA 210 NEH 650 2, Amendment MA-1, March 28.808.567.608.947.298.947.688.678.647.688.05Page 7