Pie are squared. Do the math to see what the difference is in interior area of each pipe. BUT that won't help you unless you know how many gallons of water you will see during a storm, and that's where the NRCS comes into play.

How much water you see is determined by the watershed, and what is or is not growing on that watershed.

THAT will help you determine the water velocity. You will need that number to calculate how much water a certain culvert size will handle.

https://calculator.academy/culvert-capacity-calculator/

Or you can just go to the local NRCS office for the answer.

www.hoosierpondpros.com

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).