Rock Check Dam Spacing
Spacing between rock check dams in a channel or swale, where the toe of each upper dam sits at the crest of the next.
Example
You enter
- Effective dam height, crest above channel (ft) 2
- Channel longitudinal slope (%) 4
- Channel reach to protect (ft) 300
You get
- Spacing (crest to toe) 50 ft
- Dams for the reach 6
Checked against published worked examples from: Iowa SUDAS.
Details, formula, and sources
Scopespacing = dam height / channel slope, dams = ceil(reach / spacing). A 2 ft dam in a 4% channel spaces at 50 ft (6 dams over 300 ft); on an 8% grade the spacing halves and the count doubles. Small channels only; the AHJ governs.
Formula or tablespacing_ft = dam_height_ft / (channel_slope_pct / 100); dams = ceil(reach_length_ft / spacing_ft).
Source and editionCrest-to-toe check-dam spacing identity by name (the toe of each upper dam at the crest of the next); first-principles geometry.
Free accessThe crest-to-toe spacing rule is public erosion-control practice.
What governsEstimate. AHJ and licensed professional govern.
API field namesdam_height_ft, channel_slope_pct, reach_length_ft, spacing_ft, dams
- Spacing rule spacing = dam effective height / channel slope (toe of each upper dam at the crest of the next)erosion-control practice
- Scope small channels and swales only; not a perennial stream without a permitAHJ