Posts Tagged ‘oliverea’

5‑Year Flood Event in Oliverea

Posted on: November 1st, 2021 by Tim Koch

The Eso­pus Creek head­wa­ters and Birch Creek both expe­ri­enced a 5‑year flood event as a result of heavy rains on Octo­ber 25th and 26th. The McKin­ley Hol­low bridge was briefly over­topped due to downed trees block­ing the inlet. Oliv­erea Road (Coun­ty Route 47) was closed for a num­ber of hours due to flood­ing in a low lying area where the road and stream are at the same ele­va­tion. Ulster Coun­ty DPW prompt­ly respond­ed to reopen the bridge and road. 

McKin­ley Hol­low bridge after large trees were removed from the inlet and placed on the down­stream side of the bridge. 
Ulster Coun­ty DPW crews at work reopen­ing a low-lying sec­tion of Oliv­era Road.

A 5‑year flood event is the dis­charge that has a 20% chance of occur­ring in any giv­en year, based on sta­tis­ti­cal analy­sis of at least 10 years of con­tin­u­ous flow data from a USGS stream gage. The “100-year flood” has a 1% chance of occur­ring in any giv­en year. 

The longer the peri­od of record at the gage, the more accu­rate the prob­a­bil­i­ties will be for a flood of a giv­en mag­ni­tude. The Ashokan Reser­voir water­shed is one of the most heav­i­ly mon­i­tored water­sheds in New York State, both in terms of the num­ber of gages and the length of time.

The Eso­pus Creek gage at Allaben has con­tin­u­ous flow data since 1968 (53 years) and the Birch Creek at Big Indi­an gage has been in oper­a­tion since 1998 (23 years). The Eso­pus Creek at Cold­brook gage has been con­tin­u­ous­ly mon­i­tor­ing flow since 1931 (90 years), with month­ly flow data dat­ing back to 1914, when the Olive­bridge dam and the Ashokan Reser­voir were still being constructed. 

USGS stream gage on the Eso­pus Creek at Cold­book, in con­tin­u­ous oper­a­tion for 90 years. Pho­to cour­tesy of USGS.

The Ashokan Water­shed Stream Man­age­ment Pro­gram is con­tin­u­ing to assess this flood event and assist­ing local high­way depart­ments with emer­gency stream repairs as request­ed. If you need advise on how to man­age flood­ing or ero­sion on your prop­er­ty in the Ashokan Reser­voir water­shed, call the stream pro­gram office at (845) 688‑3047.

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What is a Stream Feature Inventory (SFI)?

Posted on: July 7th, 2020 by Tim Koch

Hold on tight for a bit of reverse engineering:

The Ashokan Water­shed Stream Man­age­ment Pro­gram (AWSMP) is a col­lab­o­ra­tion between Cor­nell Coop­er­a­tive Exten­sion of Ulster Coun­ty, the Ulster Coun­ty Soil & Water Con­ser­va­tion Dis­trict, and the New York City Depart­ment of Envi­ron­men­tal Protection.

All of the AWSM­P’s stream man­age­ment activ­i­ties are under­tak­en in coor­di­na­tion with a local Stake­hold­er Coun­cil. The Stake­hold­er Coun­cil uses rec­om­men­da­tions from Stream Man­age­ment Plans to guide their deci­sion mak­ing. Man­age­ment plans con­tain a com­pre­hen­sive review of stream char­ac­ter­is­tics, data, maps, and rec­om­mend­ed man­age­ment strategies.

The large amount of data and obser­va­tions required to write a man­age­ment plan for a stream come from a Stream Fea­ture Inven­to­ry (SFI). This is where the rub­ber meets the road, or, where the wad­ing boots meet the stream bed.

Dur­ing a SFI, AWSMP staff from the Ulster Coun­ty Soil & Water Con­ser­va­tion Dis­trict walk a stream from top to bot­tom, col­lect­ing data on erod­ing stream banks, log­jams, and infra­struc­ture. These data are then ana­lyzed and ulti­mate­ly used to write a stream man­age­ment plan.

Join AWSMP Stream Edu­ca­tor Tim Koch as he joins the assess­ment crew on a SFI of the Elk Bushkill Creek in the Town of Shan­dak­en. This SFI is part of a larg­er effort by AWSMP to assess mul­ti­ple head­wa­ter trib­u­taries of the Eso­pus Creek, includ­ing McKin­ley Hol­low Creek and Lit­tle Peck Hol­low Creek. These trib­u­taries may be con­tribut­ing exces­sive sed­i­ment loads to the upper Eso­pus  Creek in the Oliv­erea val­ley. Excess sed­i­ment sup­ply leads to aggra­da­tion, or sed­i­ment “fill­ing in” the stream, which can sub­se­quent­ly trig­ger bank ero­sion and raise flood ele­va­tions.  SFI’s of the Eso­pus Creek head­wa­ters may help to locate and pri­or­i­tize restora­tion project sites aimed at reduc­ing the sed­i­ment sup­ply reach­ing the valley.

Stay tuned in the com­ing months for a SFI report on the Eso­pus Creek Head­wa­ters and for a new stream man­age­ment plan for the Lit­tle Beaver Kill in the Town of Woodstock.

 

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