BANK EROSION PINS By Dave Derrick Potomologist VP

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 3 the bank.

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. Bank Erosion Rate Measurement e c a r t g e Thalw 5 ft long rebar bank erosion pins 0 4 , s e i r a v e c n a Dist al to 200 ft typic On shorter banks only two erosion pins would be needed, not three

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. Bank Erosion Rate Measurement 20 ft e c a r t g e Thalw 5 ft long rebar Stakes 0 4 , s e i r a v e c n a Dist al to 200 ft typic 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. 6

Travelute Site, Little Blue River, KS. 21 ft of lateral migration in one month! Stake was placed 25 ft from breaking edge of top bank one month ago 7

This Power. Point presentation was developed & built by Dave Derrick. Any questions or comments, call my personal cell @ 601 -218 -7717, or email @ d_derrick@r 2 d-eng. com For questions involving erosion pin installation, call or email Phil Balch, riverworker@yahoo. com Wildhorse Riverworks, Inc. , 11821 NW 13 th St. Topeka, Kansas 66615 Mobile 785 -213 -3778; Office 785 -478 -4886

CLEOPHUS SPEED ELVIS DERRICK, WITH FRIENDS