MEASURING, DOCUMENTING, AND MEASURING, DOCUMENTING, AND INTERPRETING THE FLOOD OF 2010INTERPRETING THE FLOOD OF 2010

AP Photo/ Charles Krupa and Stew Milne

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

REAL-TIME DATA FEBRUARY 20 – APRIL 5, 2010

PRECIPITATION FROM LATE FEBRUARY – APRIL 2010

PRECIPITATION MARCH 13-15, 2010

Data Courtesy of NWS-Taunton

PRECIPITATION MARCH 22-23, 2010

Data Courtesy of NWS-Taunton

March 29th-30th, 2010PRECIPITATION MARCH 29-30, 2010

Data Courtesy of NWS-Taunton

TOTAL PRECIPITATIONLATE FEB. – EARLY APRIL 2010

Data Courtesy of NWS-Taunton

USGS RHODE ISLANDSTREAMFLOW-GAGING NETWORK

STREAMFLOW MEASUREMENTS

PAWTUXET RIVER AT CRANSTON

PAWTUXET RIVER AT CRANSTON

HYDROACOUSTICS - ADCP

PAWTUXET RIVER AT CRANSTON• Discharge (Ref: BT) Left to Right Nmb. of Ens. 411• Start Time09:13:30 Duration 153.75 [s]• Top Q 963.10 [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]

PAWTUXET RIVER AT CRANSTON

Previous max. GH = 14.50 ft (June 7, 1982) for 70 years

GH=14.98 ft GH=20.79 ft

PAWTUXET RIVER AT CRANSTON

Previous max. Q = 5,440 cfs (June 7, 1982) for 70 years

Q=5,380 cfs Q=14,100 cfs

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)

NWS NORTHEAST RIVER FORECAST CENTER

FORECASTINGSTREAM STAGE AND DISCHARGE

STAGE-DISCHARGE RATING CHANGESRating 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.

STAGE-DISCHARGE RATING CHANGESRating 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

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

PAWCATUCK RIVERAT WOOD RIVER JUNCTION

Previous max. Q = 1,860 cfs (June 7, 1982) for 69 years

Q=3,580 cfs

WOOD RIVER AT HOPE VALLEY

Q=5,470 cfs

Previous max. Q = 2,390 cfs (June 6, 1982) for 69 years

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

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

DURING THE FLOODS

Q meas. made 3/30 at 16:45

Data stopped 3/30 at 20:15

Gage re-started At new location300 ft upstreamAt new control

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)

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)

• “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)

RECURRENCE INTERVALS

Station Name2010 Peak Flow (cfs)

Probability of Exceedance

(%)

Recurrence interval (years)

Period of

record (years)

Branch River at Forestdale 5,260 4-2 25-50 70

Blackstone River at Woonsocket* 14,900 4-2 25-50 81

Woonsaquatucket River at Centerdale 1,750 4-2 25-50 69

S.B. Pawtuxet River at Washington* 5,280 0.5-0.2 200-500 70

Pawtuxet River at Cranston* 14,100 <0.2 > 500 71

Hunt River near East Greenwich 2,420 0.5-0.2 200-500 70

Pawcatuck River at Wood R. Jct. 3,580 0.5-0.2 200-500 70

Wood River at Hope Valley 5,470 <0.2 > 500 69

Pawcatuck River at Westerly 9,330 0.5-0.2 200-500 69

* STREAMFLOWS EFFECTED BY REGULATED

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/

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 ?

QUESTIONS

• USGS InformationUSGS Information– http://water.usgs.gov/

– http://ri.water.usgs.gov/– http://water.usgs.gov/rt-hns/

• USGS ContactsUSGS Contacts– Phil Zarriello (MA-RI WSC)Phil Zarriello (MA-RI WSC)

• pzarriel@usgs.govpzarriel@usgs.gov• (508) 490-5010(508) 490-5010

– Gardner Bent (MA-RI WSC)Gardner Bent (MA-RI WSC)• gbent@usgs.govgbent@usgs.gov• (508) 490-5041(508) 490-5041

USGS-FEMA-RIEMAUSGS-FEMA-RIEMA CHARTERIZING THE FLOOD 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 ?

IDENTIFICATION OF HWMs

• PHOTOS

IDENTIFICATION OF HWMs

• PHOTOS

FLAGGING HWMs – USGS and USACE• Blackstone River Basin

– Mainstem Blackstone from Pawtucket to Woonsocket USACE– Branch River to headwaters USACE

• Moshassuck River Basin USACE• Pawcatuck River Basin

– Mainstem Pawcatuck from Westerly to Worden Pond USGS– Ashaway River to CT border USGS– Wood River to Rt. 165 USACE– Tomaquag River USGS– Meadow Brook USACE– Beaver River USACE– Usquepaug-Queen River USGS– Chipuxet River USGS

• Pawtuxet River Basin– N. Branch Pawtuxet to Scituate Res. to headwaters USGS– Mainstem from North and South Branch to Cranston USGS– Mainstem from Cranston streamgage to mouth USACE– S. Branch Pawtuxet to Flat River Res. to headwaters USACE– Pocasset River USGS

• Woonasquatucket River Basin USGS

SITE MAP HWMs

• MAP

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

SURVEYING HWMs RI

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

RI FLOOD 2010 STUDY ?

• Flood profiles ?

• Frequency analyses of HWM sites ?

• Comparison to existing Flood Insurance Studies ?

• Sources: projo.com; wunderground.com; dot.ri.gov; abc6.com • Providence Journa/Kris

Craig Warwick Waste Water Treatment Facility

HIGH FLOW DATA FEBRUARY 20 – APRIL 5, 2010

S. BRANCH PAWTUXET R. AT WASHINGTON

Previous max. GH = 5.30 ft (June 6, 1982) for 69 years

GH=5.42 ftGH=9.22 ft

• 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."

• 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.

• 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)

HYDROACOUSTICS