Contour Plowing: Furrow Flow-Routing Simulator

Tillage Pattern

Furrow spacing 1.4 m

Furrow capacity medium

Slope angle 12°

Rainfall intensity medium

Field Readouts

Runoff velocity (outlet)

0.00 m/s

Sediment trapped

Cumulative sediment export

0 units

How it works

Real hillslope conservation design starts from the Universal Soil Loss Equation: soil loss A = R·K·LS·C·P, where R is rainfall erosivity, K soil erodibility, LS the slope length–steepness factor, C the cover-management factor and P the support-practice factor. Contour plowing is a P-factor practice: instead of tilling straight up-and-down (which turns every furrow into a chute), rows are cut along elevation contours so each furrow is a small level channel running across the slope.

This simulator drives that mechanism directly rather than just plotting the equation:

downhill accel  a = a0 · sin(slope)
furrow capacity  Cmax(row) = k_depth  (regenerates slowly, infiltration)
capture chance   captured if remaining(row) > flow load at crossing
runoff velocity  v(t+dt) = v(t) + a·dt   (only while not captured)

Contour Furrows ON — droplets crossing each ridge line are caught in a level furrow (capacity set by the slider) and held while it slowly drains; only overflow continues downhill. This is the physical reason contour plowing cuts erosion.
Contour Furrows OFF — the same field tilled straight down-slope: no lateral channels, every droplet accelerates unchecked to the outlet.
Furrow spacing / capacity — tighter, deeper furrows intercept more flow before it reaches erosive speed; this mirrors why real contour intervals shrink on steeper ground.
Rainfall intensity — raises droplet spawn rate, which fills furrow capacity faster and pushes more flow into overtopping, exactly as a storm outpaces furrow drainage in the field.

Runoff velocity and sediment export are read directly off the particle system: velocity is the mean speed of droplets crossing the outlet, sediment trapped is the fraction of all droplets ever captured by a furrow rather than reaching the outlet.

Runoff (flowing) Trapped in furrow

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