1. MEASURING, DOCUMENTING, AND INTERPRETING THE FLOOD OF 2010 AP Photo/ Charles Krupa and Stew Milne

2. PRESENTATION OVERVIEW Long-term USGS hydrologic network Streamflow measurements during the flood Stage-discharge rating curve extension and changes USGS, NWS, and other agencies cooperation during the flood Probability of exceedance of the flood USGS, FEMA, RIEMA, and ACOE and other agencies cooperation after the flood Identification of high-water marks Surveying high-water marks Where do we go from here – other studies

3. REAL-TIME DATA FEBRUARY 20 – APRIL 5, 2010

4. PRECIPITATION FROM LATE FEBRUARY – APRIL 2010

5. PRECIPITATION MARCH 13-15, 2010 Data Courtesy of NWS-Taunton

6. PRECIPITATION MARCH 22-23, 2010 Data Courtesy of NWS-Taunton

7. March 29 th -30 th, 2010 PRECIPITATION MARCH 29-30, 2010 Data Courtesy of NWS-Taunton

8. TOTAL PRECIPITATION LATE FEB. – EARLY APRIL 2010 Data Courtesy of NWS-Taunton

9. USGS RHODE ISLAND STREAMFLOW-GAGING NETWORK

10. STREAMFLOW MEASUREMENTS

11. PAWTUXET RIVER AT CRANSTON

13. HYDROACOUSTICS - ADCP

14. PAWTUXET RIVER AT CRANSTON Discharge (Ref: BT) Left to RightNmb. of Ens. 411 Start Time09:13:30Duration 153.75 [s] Top Q963.10 [ft³/s]Measured Q 5771.38 [ft³/s] Bottom Q 1050.74 [ft³/s] (T+M+B) Q 7785.22 [ft³/s] Total Q 8978.00 [ft³/s]

15. PAWTUXET RIVER AT CRANSTON Previous max. GH = 14.50 ft (June 7, 1982) for 70 years GH=14.98 ft GH=20.79 ft

16. PAWTUXET RIVER AT CRANSTON Previous max. Q = 5,440 cfs (June 7, 1982) for 70 years Q=5,380 cfs Q=14,100 cfs

17. DURING THE FLOODS 21 of the 27 network streamgages had the highest discharge measurement made in the period of record 16 stage-discharge rating were extended during the floods to assist the NWS – Advanced Hydrologic Prediction Service (AHPS)

18. NWS NORTHEAST RIVER FORECAST CENTER

19. FORECASTING STREAM STAGE AND DISCHARGE

20. STAGE-DISCHARGE RATING CHANGES Rating 42 was prior to the March 30-31 flood with a max. GH = 15.00 ft and Q = 5,200 cfs Rating 42.1 extended to max. GH = 20.00 ft and Q = 9,600 cfs during the flood Rating 43 new – revised with Q measurements during flood with a max. GH = 22.00 ft and Q = 17,200 cfs Note: new Rating 43 had to be extend to a GH of 22 ft, which 7 ft higher than previous ratings.

21. STAGE-DISCHARGE RATING CHANGES Rating 27 was prior to the March 30-31 flood with a max. GH = 11.00 ft and Q = 2,700 cfs Rating 27.1 extended to max. GH = 16.00 ft and Q = 5,100 cfs during the flood Rating 28 new – revised with Q measurements during flood with a max. GH = 14.00 ft and Q = 5,700 cfs Note: with new Rating 28 at a GH = 11.00 ft – the Q = 3,530 cfs about a 31% increase in Q

22. S. BRANCH PAWTUXET R. AT WASHINGTON Previous max. Q = 1,980 cfs (June 6, 1982) for 69 years Q=2,060 cfs Q=5,280 cfs

23. PAWCATUCK RIVER AT WOOD RIVER JUNCTION Previous max. Q = 1,860 cfs (June 7, 1982) for 69 years Q=3,580 cfs

24. WOOD RIVER AT HOPE VALLEY Q=5,470 cfs Previous max. Q = 2,390 cfs (June 6, 1982) for 69 years

25. DURING THE FLOODS Equipment at 1 streamgage (Big River at Rt. 3) was damaged and 1 streamgage (Congdon River) structure and equipment was lost when the bridge washed out Assistance from the CT and NH-VT WSCs

26. DURING THE FLOODS Equipment at 1 streamgage (Big River at Rt. 3) was damaged and 1 streamgage (Congdon River) structure and equipment was lost when the bridge washed out

27. DURING THE FLOODS Q meas. made 3/30 at 16:45 Data stopped 3/30 at 20:15 Gage re-started At new location 300 ft upstream At new control

28. NEW PEAKS OF RECORD 17 of the 21 streamgages with at least 10 years of record had a new peak of record 11 of the 15 streamgages with new peaks of record have from 30-70 years of record (8 of 8 in Pawcatuck River Basin and 2 of 2 in the Pawtuxet River Basin)

29. FREQUENCY “The flood is considered to be anywhere between a 100 and 500 year flood… that means for the people here this is a once in a lifetime disaster” (Elysia Rodriguez, WWLP.com 22 News - http://www.wwlp.com/dpp/news/worst- flooding-in-ri-in-100-years)http://www.wwlp.com/dpp/news/worst- flooding-in-ri-in-100-years “We had two 100-year floods in two weeks,” Capone, Taunton NWS said. “This will be much higher than a 100-year flood” (http://www.usatoday.com/weather/floods/2010-03-31- flood_N.htm)http://www.usatoday.com/weather/floods/2010-03-31- flood_N.htm

30. RECURRENCE INTERVALS Station Name 2010 Peak Flow (cfs) Probability of Exceedance (%) Recurrence interval (years) Period of record (years) Branch River at Forestdale 5,2604-225-5070 Blackstone River at Woonsocket* 14,9004-225-5081 Woonsaquatucket River at Centerdale 1,7504-225-5069 S.B. Pawtuxet River at Washington* 5,2800.5-0.2200-50070 Pawtuxet River at Cranston* 14,100<0.2> 50071 Hunt River near East Greenwich 2,4200.5-0.2200-50070 Pawcatuck River at Wood R. Jct. 3,5800.5-0.2200-50070 Wood River at Hope Valley 5,470<0.2> 50069 Pawcatuck River at Westerly 9,3300.5-0.2200-50069 * STREAMFLOWS EFFECTED BY REGULATED

31. USGS HYDROLOGIC NOTIFICATION SERVICE New USGS Hydrologic Notification Service (HNS) sends e-mail or test messages for user defined thresholds of real-time data –Surface water –Groundwater –Water quality –Precipitation –http://water.usgs.gov/rt-hns/

32. NEW STREAMGAGES ? Pawtuxet River at Fiskville (outflow of Scituate Reservoir) ? Pocasset River at Rt. 2 ? Eastern RI – Adamsville Brook ? Reservoir elevation gages for Scituate and Flat River Reservoirs ?

33. QUESTIONS USGS InformationUSGS Information –http://water.usgs.gov/http://water.usgs.gov/ –http://ri.water.usgs.gov/http://ri.water.usgs.gov/ –http://water.usgs.gov/rt-hns/http://water.usgs.gov/rt-hns/ USGS ContactsUSGS Contacts –Phil Zarriello (MA-RI WSC) pzarriel@usgs.govpzarriel@usgs.gov (508) 490-5010(508) 490-5010 –Gardner Bent (MA-RI WSC) gbent@usgs.govgbent@usgs.gov (508) 490-5041(508) 490-5041

34. USGS-FEMA-RIEMA CHARTERIZING THE FLOOD HWM Identification Survey HWMs into NAVD88 Calculate flood frequency at gages ? Calculate flow at ungaged sites using indirect methods ? Develop regression equations for estimating flood frequency at ungaged sites ? Compare HWM elevations to flood profiles and new flood frequencies with existing Flood Insurance Studies ?

35. IDENTIFICATION OF HWMs PHOTOS

36. IDENTIFICATION OF HWMs PHOTOS

37. FLAGGING HWMs – USGS and USACE Blackstone River Basin –Mainstem Blackstone from Pawtucket to WoonsocketUSACE –Branch River to headwatersUSACE Moshassuck River Basin USACE Pawcatuck River Basin –Mainstem Pawcatuck from Westerly to Worden PondUSGS –Ashaway River to CT borderUSGS –Wood River to Rt. 165USACE –Tomaquag RiverUSGS –Meadow BrookUSACE –Beaver River USACE –Usquepaug-Queen RiverUSGS –Chipuxet RiverUSGS Pawtuxet River Basin –N. Branch Pawtuxet to Scituate Res. to headwatersUSGS –Mainstem from North and South Branch to Cranston USGS –Mainstem from Cranston streamgage to mouthUSACE –S. Branch Pawtuxet to Flat River Res. to headwatersUSACE –Pocasset RiverUSGS Woonasquatucket River Basin USGS

38. SITE MAP HWMs MAP

39. HWM DATABASE Over five days from April 2-7 about 274 HWMs were identified at about 134 sites by USGS USACE during same period had about 175 HWMs identified at about 90 sites

40. SURVEYING HWMs RI

41. FLOOD FREQUENCY STUDY ? Johnson, C.G., and Laraway, G.A., 1976, Flood magnitude and frequency of small Rhode Island streams: U.S. Geological Survey Open-File Report 76-883, 22 p. The regression equations developed are for estimating peak discharges with recurrence intervals of 2 and 5 years The 10-, 25-, and 50-year floods are computed as ratios of the 2-year peak discharge The regression equations were developed from peak- discharge records from 1966-1971 for 38 stations and are applicable only to rural streams having no significant storage with drainage areas less than 10 square miles

42. RI FLOOD 2010 STUDY ? Flood profiles ? Frequency analyses of HWM sites ? Comparison to existing Flood Insurance Studies ?

44. Sources: projo.com; wunderground.com; dot.ri.gov; abc6.com Providence Journa/Kris Craig Warwick Waste Water Treatment Facility

46. HIGH FLOW DATA FEBRUARY 20 – APRIL 5, 2010

47. S. BRANCH PAWTUXET R. AT WASHINGTON Previous max. GH = 5.30 ft (June 6, 1982) for 69 years GH=5.42 ft GH=9.22 ft

48. Schutt and Cranston Mayor Allan Fung surveyed the flood from a helicopter. "From the sky, you can see how far the Pawtuxet exceeded its banks," Schutt said. "It's now in those areas (the Federal Emergency Management Agency) designated as a one-in-500-years flood event."Federal Emergency Management Agency The river at Cranston crested Wednesday at 20.7 feet. Flood stage is 9 feet, according to the National Weather Service. Rivers in Connecticut, Massachusetts and New Hampshire will crest through the weekend, said Ed Capone, service coordination hydrologist at the Northeast River Forecast Center.National Weather Service Massachusetts Flooding elsewhere is forecast to cover roads and inundate some buildings, but around Cranston, Warwick and West Warwick, the flooding is unprecedented, Capone said. The river gauge at Cranston registered a flow of 14,000 cubic feet per second Tuesday night, compared with the last record flood two weeks ago of 5,000 cubic feet per second, he said. Normal is 750 to 1,000 cubic feet per second. "We had two 100-year floods in two weeks," Capone said. "This will be much higher than a 100-year flood.“ (http://www.usatoday.com/weather/floods/2010-03-31-flood_N.htm)

49. HYDROACOUSTICS