River Research & Design, Inc. BANK EROSION PINS By Dave Derrick, Potomologist & VP, River Research & Design, Inc.

BANK EROSION PINS A simple, inexpensive & accurate way to precisely measure bank erosion rates. Five ft long sections of ½ inch diameter rebar are driven horizontally into the toe, middle, & upper sections of an eroding bank until the river end of the rebar is flush with the face of the bank. Over time the length of rebar exposed shows the amount of erosion!! Wooden stakes are usually labeled (5 ft, 10 ft, etc) & driven at 5 ft intervals (5 stakes) on top bank above the rebar in case the rebar is washed away.

Phil Balch in KS installing bank pins The rebar is driven into the bank until the end is flush with the face of the bank. 3

Bank Erosion Rate Measurement 5 ft long sections of ½ inch diameter rebar is driven into the toe, middle, & upper bank until the rebar is flush with the face of the bank. Thalweg trace Distance varies, 40 to 200 ft typical 5 ft long rebar bank erosion pins On shorter banks only two erosion pins would be needed, not three

Bank Erosion Rate Measurement Distance varies, 40 to 200 ft typical 5 ft long sections of ½ inch diameter rebar is driven into the toe, middle, & upper bank until the rebar is flush with the face of the bank. Thalweg trace 20 ft 5 ft long rebar Distance varies, 40 to 200 ft typical Stakes Mark stakes with distance from edge of bank (5 ft, 10 ft, 15 ft, etc.), then measure back from edge of bank & drive stakes into ground at 5 ft intervals

Pins were originally installed with river ends flush with streambank surface Bank erosion pins Measure exposed length of rebar to determine amount of erosion, then divide by time since rebar was installed to determine the erosion rate. Convert this number to the erosion rate in feet per year. Bank erosion monitoring pins are pieces of rebar driven into the bank until the ends are flush with the streambank 6 6

Stake was placed 25 ft from breaking edge of top bank one month ago Travelute Site, Little Blue River, KS. Stake was placed 25 ft from breaking edge of top bank one month ago 21 ft of lateral migration in one month! On this site, the banks were 23 feet high. Two markers were set in the field; 1 – 29.1 feet from the bank, the other was set 28 feet from the edge. When checked in May; one pin was gone, the other was 7 feet from the edge. 7 7

This PowerPoint presentation was developed & built by Dave Derrick This PowerPoint presentation was developed & built by Dave Derrick. Any questions or comments, call my personal cell @ 601-218-7717, or email @ d_derrick@r2d-eng.com For questions involving erosion pin installation, call or email Phil Balch, riverworker@yahoo.com Wildhorse Riverworks, Inc., 11821 NW 13th St. Topeka, Kansas 66615 Mobile 785-213-3778; Office 785-478-4886 “Based on the interagency publication, Stream Corridor Restoration: Principles, Processes, and Practices, this introductory training covers: Stream corridor ecosystems and their components Ecological processes, structure & functions Characterization and analysis of stream corridors Development of a restoration plan Design, implementation, monitoring, and Integrated, iterative, adaptive, flexible approaches”.

CLEOPHUS SPEED ELVIS DERRICK, WITH FRIENDS