This article discusses recommended design parameters like slopes and smoothing for your landform designs.
Dry Areas - 0.05%
Wet Areas - 0.10%
For Drains - can go flatter down to 0.01%
Rule of Thumb
- For furrow irrigated fields, try to make the minimum and maximum slopes as close as possible without increasing the earthworks too much, but there is a trade off there. We recommend the maximum slopes not more 2x the minimum slopes.
- For dryland, we've seen analysis that shows slopes over 1% have reduced yield due to runoff, so keeping maximum slopes not more than 1% probably has yield benefits. The other factor is erosion, especially if the catchment area upstream is large 1% can be too steep.
Recommended Minimum - 100 m/% or 300ft/%