Posts Tagged ‘stream stability’

Monday’s Bankfull Flows

Posted on: December 4th, 2020 by Tim Koch

Mon­day Novem­ber 30th, 2020 was a rainy day in the Ashokan water­shed. A home rain gauge in Boiceville mea­sured approx­i­mate­ly 4 inch­es over the course of the day. 

In response to the sig­nif­i­cant pre­cip­i­ta­tion the Beaver Kill, Lit­tle Beaver Kill, Bushkill, and Eso­pus Creek at Cold Brook reached bank­full dis­charge. Bank­full dis­charge is the stream flow that com­plete­ly fills the chan­nel in a geo­mor­phi­cal­ly sta­ble stream. Any flow that exceeds bank­full will put water onto the adja­cent floodplain. 

Cross sec­tion of a geo­mor­phi­cal­ly sta­ble stream where the entire chan­nel is filled dur­ing a bank­full flow.

Streams that have berms or lev­ees, are incised, or oth­er­wise unsta­ble do not have such a clear rela­tion­ship between bank­full dis­charge and chan­nel geometry.

In the North­east, a bank­full or greater flow hap­pens once every 1.5 years, on aver­age. How­ev­er, “on aver­age” means that some years see mul­ti­ple bank­full events while oth­ers have none. Mon­day’s event was the sec­ond time in 2020 that the Lit­tle Beaver Kill has equaled or exceed­ed its bank­full dis­charge of 909 cubic feet per sec­ond (cfs).

2020 Hydro­graph of the Lit­tle Beaver Kill. From USGS.

Bank­full flow events are impor­tant because over time, these flows move more sed­i­ment than any oth­er dis­charge, larg­er or small­er. This is because bank­full flows hap­pen reg­u­lar­ly, every 1.5 years on aver­age, as opposed to big floods that move a lot of sed­i­ment but are more infrequent. 

Due to the geo­mor­phic impor­tance of bank­full dis­charge events, the AWSMP reg­u­lar­ly vis­its stream restora­tion sites, cul­vert replace­ment projects, and oth­er stream reach­es fol­low­ing bank­full events to take pho­tographs and mon­i­tor any changes observed in the channel. 

AWSMP staff from the Ulster Coun­ty Soil & Water Con­ser­va­tion Dis­trict inspect a restora­tion site on Wood­land Creek fol­low­ing a bank­full flow in Novem­ber 2019. Pho­to by Tim Koch.

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New Video on Stream Channel Stability

Posted on: May 6th, 2020 by Tim Koch

The AWSMP office might be phys­i­cal­ly closed, but our edu­ca­tion staff have been hard at work gen­er­at­ing online stream based con­tent for both youth and adults.

AWSMP Educators Matt Savatgy, Brent, Gotsch, Tim Koch, and Amanda Cabanillas.

AWSMP Edu­ca­tors (from left to right) Matt Savat­gy, Brent Gotsch, Tim Koch, and Aman­da Caban­il­las dur­ing a snow­shoe stream walk in 2019.

 

AWSMP Stream Edu­ca­tor Tim Koch has just released a new video on stream chan­nel sta­bil­i­ty: what it is, and why it is impor­tant to main­tain and improve the sta­bil­i­ty of our rivers and streams. This 9‑minute video is meant for landown­ers, munic­i­pal offi­cials, con­ser­va­tion advi­so­ry coun­cil mem­bers, and any­one else inter­est­ed in or involved in stream management.

 

This video can also be viewed direct­ly from AWSM­P’s YouTube Chan­nel.

AWSMP Water­shed Youth Edu­ca­tor Matt Savat­gy and Pro­gram Assis­tant Aman­da Caban­il­las are cur­rent­ly pro­duc­ing a series of edu­ca­tion­al videos and at-home activ­i­ties for stu­dents. Fol­low along at home as they dis­cuss dif­fer­ent types of rocks, assess a cul­vert, and inves­ti­gate stream fea­tures in a chan­nel cross-section.

 

Screenshot of CCE Ulster Youth Education Video Series Website

Screen­shot of CCE Ulster Youth Sci­ence Edu­ca­tion Video Series Website

 

The online sci­ence series can be found at the Cor­nell Coop­er­a­tive Exten­sion of Ulster Coun­ty web­site and on the AWSMP web­site under Videos.

Check back with us in the com­ing weeks, espe­cial­ly if you are a stream­side landown­er or own prop­er­ty in the Spe­cial Flood Haz­ard Area as Resource Edu­ca­tor Brent Gotsch will be pro­duc­ing a series of short videos on flood­plains, flood­proof­ing, and all things flood insur­ance. In these upcom­ing videos, Brent will teach view­ers how to read a flood insur­ance rate map (FIRM) and the work­ings of the Nation­al Flood Insur­ance Pro­gram (NFIP) among oth­er flood relat­ed topics.

As always, our edu­ca­tion and tech­ni­cal staff are avail­able to answer any stream, flood­plain, or ripar­i­an buffer relat­ed ques­tions! Call the AWSMP office main line at (845) 688‑3047 for assis­tance or email info@ashokanstreams.org.

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