Climatological Perspecve on Extreme Hydrological Events in the and Valley

Allan Frei Department of Geography, Hunter College, City University of CUNY Instute for Sustainable Cies

Collaborators: Adao Matonse (NYCDEP), NYCDEP BWS Water Quality Modeling Group, NYSERDA, colleagues at CUNY Instute for Sustainable Cies, Rutgers University

Presented at 5th Annual Ashokan Watershed Conference Ashokan Center, Olivebridge, NY, April 2014 Presentaon Outline

• Background • How Unique were Irene and Lee? • Changing Frequency of Extreme Events in our Region • Conclusions

Tannersville, photo by Sean Mahoney Main Street, Margaretville hp://www.wnyc.org/blogs/wnyc-newsblog/2011/aug/31/focus- hp://www.buzzfeed.com/mjs538/frightening-hurricane- shis-people-stranded-catskills-flood-waters-recede/ irene-destrucon-photos

Irene in

Windham New Windsor the Catskills hp://www.buzzfeed.com/mjs538/frightening-hurricane-irene- hp://en.wikipedia.org/wiki/ destrucon-photos File:Forge_Hill_Road_bridge_washout_aer_Hurricane_Irene,_ New_Windsor,_NY.jpg Irene in the Catskills: EB Delaware, Margaretville

Main Street

Above: Immediately aer Irene, Sep 1, 2011, photo by Dannyelle Davis, NYCDEP Right: during Irene hp://www.buzzfeed.com/mjs538/frightening-hurricane-irene-destrucon-photos Irene in the Catskills: , Prasville

Above: Immediately aer Irene, Sep 1, 2011, photo by Dannyelle Davis, NYCDEP Extreme Events and Turbidity in the Catskills

Oulow from Shandakan Tunnel into , May 2012, photos by A. Frei Warner Creek (tributary of Stony Clove Creek), sediment entering creek under calm condions, October 2013

photos by A. Frei IPCC AR5 WG1 Fall, 2013 (welcome to my world of acronyms) Kunkel et al, BAMS, 2013

Change in 20-yr precipitaon return value units are Z-score (standard dev.); Larger dots have greater stascal significance 1910 1930 1950 1970 1990 2010 1910 1930 1950 1970 1990 2010

NOAA Climate Extremes Index (CEI) for the Northeast US hp://www.ncdc.noaa.gov/extremes/cei/ NYSERDA funded study : Hydrology, Vulnerability and Adaptaon Implicaons of Hurricane Irene and Tropical Storm Lee: Case Study of the Mid-Hudson Valley and Greater Catskills

Emergent Vulnerabilies as Perceived by Stakeholders [based on interviews, public meeng transcripts, press arcles and leers to the editor from local newspapers, community e-message boards, blogs, ...]

1) Transportaon, agricultural and tourism sectors were the most heavily impacted

2) Flooding in previously un-flooded (according to local knowledge) areas (e.g. in higher elevaon areas that are not floodplains)

3) predicted return interval for floods not a good indicator of actual frequency.

4) infrastructural weaknesses (e.g. road washouts)

5) Disproporonate socioeconomic effects (on availability of affordable housing) Study of Irene, Lee, and changes over me: Study Area and Staon Locaons

Map by David Lounsbery, NYCDEP Monthly Climatologies of Extreme (95th %le) Events

a) 10 inches 25 warm season

) 20 y a d / m

c 15 Unimodal ( Daily n o i

t (peak in Fall) a

t 10 Precipitaon i p i c e r

P 5

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

b) 32,000 CFS 900 warm 800 season

) 700 s /

m 600 . Bimodal u c

( 500

Daily w (peaks in

o 400 l f

m 300 Streamflow a Spring & Fall) e r t 200 S 100

0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Precipitaon Recurrence Intervals for Irene and Lee

Record Period Irene Annual Irene Warm Lee Annual Lee Warm Station ID for Frequency Return Period Return Period Number Station Name (County) Analysis Period (yrs) Return (yrs) Period (yrs) Return (yrs) 300254 Arkville (Delaware) 1952 - 2011 n/a n/a 2 4 302036 Delhi (Delaware) 1952 - 2011 7 7 4 5 302060 Deposit (Delaware) 1962 - 2011 2 2 7 7 302582 Ellenville (Ulster) 1952 - 2011 n/a n/a 2 3 304731 Liberty (Sullivan) 1952 - 2011 16 20 2 2 305310 Middletown (Orange) 1952 - 2011 n/a n/a 7 8 305426 Mohonk Lake (Ulster) 1952 - 2011 407 387 <2 2 306774 Port Jervis (Orange) 1952 - 2011 9 11 2 2 307274 Rosendale (Ulster) 1958 - 2011 472 449 <2 2 307799 Slide Mtn (Ulster) 1952 - 2011 88 169 <2 2 308932 Walton 2 (Delaware) 1956 - 2011 2 2 6 6 309292 West Point (Orange) 1952 - 2011 7 9 <2 2 Precipitaon Contours and Recurrence Hurricane Irene (26-29 Aug., 2011) Tropical Storm Lee (5-8 Sep., 2011) Intervals >34 cm (13 in) Precipitaon-Difference Contours and Staon Locaons Irene minus Lee

Lee > Irene Irene > Lee Irene & Lee Precipitaon Percenles and Ranks (Warm Season)

4-day Precipitaon 30-day Antecedent 4-d Precip 30-d Historical antecedent Rank of 2011 warm Historical season 60-d Rank of 2011 Irene Lee Irene Lee Irene %le Lee %le Irene %le Lee %le Precip60-d Precip Arkville na >99 na na na Delhi >98 >99 >95 >97 1 Deposit >98 >99 >91 >93 1 Ellenville na >99 na na na Liberty >99 >99 >85 >95 2 Middletown na >99 na na na Mohonk >99 >99 >91 >98 1 Port Jervis >99 >98 >91 >98 1 Rosendale >99 >97 >87 >97 1 Slide Mt. >99 >99 >61 >96 1 Walton >99 >99 >75 >93 2 West Pt. >99 >99 >98 >99 1 Percenle values in bold >= 98 percenle Percentage of Seasons During Which Extreme 4-day Precipitaon Events Occur Within 12 days of each other (prior to Irene and Lee)

Values are ranges across all staons. Changes over Time in the Frequencies of Extreme Events

Warner Creek, Near Stony Clove, Catskills, May 2012

Headcut incised during storms of 2011 exposing glacial ll that has probably not been exposed in 15-20K yrs. Course sediment is being recruited from upstream, but channel bed now at a lower base level than prior to Irene.

These sorts of fluvial geomorphological changes are related to the frequency and magnitude of extreme events, as well as human impact on channel condions. Human impacts up- or down- stream can also play a role.

Photos and geomorphological informaon from Dannyelle Davis, NYCDEP Changes over Time in the Frequencies of Extreme Events

Warner Creek (tributary of Stony Clove Creek, Esopus Creek)

May 2012 November 2013 exposed pleistocene proglacial lake sediment Post treatment probably has been only intermiently exposed throughout the Holocene (D. Davis, NYCDEP)

Photos by A. Frei Changes over Time in the Magnitudes of Events of Different Recurrence Intervals

Example from one stream gauge staon, daily streamflow

Tremper Kill

Data Used 56,500 CFS 1600 All Hist. 1940-1970 1400 1950-1980 1960-1990 1970-2000

) 1200

s 1980-2011 /

m Each color is a .

u 1000

c different (

w

o 800 overlapping l f

m 30-year period a

e 600 r

t starng 10 S 400 years apart Y-axis shows magnitude

200

0 Return Period 2 5 10 25 50 100

X-axis shows Recurrence Interval (years) Changes over Time in the Frequencies of Extreme Events

All Events 5 highest values Example from one staon (Ellenville 4-day Precipitaon) 95 %le value

Cold Season Warm Season Changes over Time in the Frequencies of Extreme Events

Number of 95%le values per year max smooth value Example from one staon (Ellenville 4-day Precipitaon) Smooth (11-yr mean)

Cold Season Warm Season Changes over Time in the Frequencies of Extreme Events

Number of 95%le 4-d precipitaon values per year: all staons

Cold Season Warm Season max smooth value Smooth (11-yr mean)

1985, 2006 Changes over Time in the Frequencies of Extreme Events

Number of 95%le daily streamflow values per year: all staons

Cold Season Warm Season max smooth value Smooth (11-yr mean)

1985, 2006 Number of 95%le values per year: all staons Cold season Warm season

4-day Precipitaon

1-day Streamflow Intergovernmental Panel on Climate Change Special Report on Extreme Events: SREX (2012)

Projected recurrence intervals for daily Tmax equal to 20-year recurrence during the late 20th Century. Different colors = different scenarios Intergovernmental Panel on Climate Change Special Report on Extreme Events: SREX (2012)

Projected recurrence intervals for daily Precip equal to 20-year recurrence during the late 20th Century. Different colors = different scenarios IPCC AR5: WG1,Fall 2013

WG2, Spring 2014

WG1

WG2

WG2 Intergovernmental Panel on Climate Change Special Reports: SREX (2012)

dryer wetter

Projected changes in soil moisture compared to the late 20th Century. Conclusions

• The events of Fall 2011 were unprecedented in this region due to a combinaon of: - the magnitude of precipitaon in each event - the proximity in space and me of the two events - antecedent and subsequent precipitaon

• As a result, Fall 2011 had the highest 60-day precipitaon total on record in this region Conclusions (cont’d)

• Geomorphological evidence suggests the recent period has had more frequent extreme events compared to condions during the last 10,000 yrs

• Since 1900, the frequency of extreme warm season hydrologic events peaked during the last 1-2 decades

• Since 1900, the frequency of extreme cold season hydrologic events peaked in the 1970s – 1980s

• Climate models predict that the trend toward more extreme events will connue through the 21st century

Minor Conclusion

• Standard parametric analysis (recurrence interval) is the appropriate tool for infrastructure planning, but may be insufficient for climatological understanding (it is based on annual maxima, and it requires >=30 years of data). Perhaps it needs to be adapted for non- staonary climate. Deep gorge created in Frost Valley (Ulster County Route 47) when floods aer Hurricane Irene blew out a culvert below the road in Oliverea, NY. hp://en.wikipedia.org/wiki/Effects_of_Hurricane_Irene_in_New_York#Orange_County Number of 95%le values per year: all staons 30 day results Cold season Warm season

30-day Precipitaon

30-day Streamflow Number of 95%le values per year: all staons 60 day results Cold season Warm season

60-day Precipitaon

60-day Streamflow