Solving Ponding and Runoff Problems in the Desert
Figure 1. Mark Dunn and behind him is the landformed pivot field with newly planted alfalfa.
The client is in Central Nevada and grow alfalfa and wheat under center pivots.
"This particular field was never properly levelled (landformed) and the many low and high spots cause ponding and runoff issues as well as increased disease and pest pressures in the low/tight spots."
The Existing Topography shows the undulating field and the low lying areas can clearly be seen as confirmed by the Drainage Analysis below.
Figure 2. Existing Topography (left) and Existing Drainage Analysis (right). Drag the slider left or right to view each.
Figure 3. Existing Topography (left) and Proposed Topography (right). Drag the slider left or right to view each.
An OptiSurface 4Way was used to design the field. This surface type allows water to flow across the field and exit to the boundary.
The minimum slope was set to 0.10% to improve drainage. This is higher than the usual 0.05% minimum as the pivot wheel tracks can create small furrows so increasing the minimum slope helps.
The maximum slope was set to 1.0% to reduce the risk of runoff particularly at the extents of the pivot where the application rate is highest. And a smoothing of 300 ft/% to improve overall design avoiding rapid slope changes.
Figure 4. Proposed Cut/Fill Map.
The design was fairly straight forward - only the parameters in the boundary were used and no subzones were needed. Earthworks ended up at 177 yd³/ac (334 m³/ha).
So, even in a desert with center pivots there is a strong benefit to Optimum Surface Landforming™.
Mark summarized by saying:
No more ponding, damping off, salt accumulation. The water goes in as evenly as it goes on. This is a completely different field!