Queensland Contour Banks

Designing Erosion Control Contour Banks with the New Contour Bank Design Feature

Farmer: Tristan Nitschke
Location: Queensland, Australia
Field Area: 286 ha or 706 acres
Irrigation Method: none
Crops: Wheat, Chickpeas, Cotton

The design worked perfectly, vastly expediting the the project of draining the contour banks and minimizing necessary earthworks.

Tristan Nitschke
Farmer, Queensland, Australia

Problem

The client was looking for a way to improve the drainage of existing contour banks on his field and add more to reduce the risk of erosion.

The Runoff Analysis for a 1-in-10yr rainfall event below shows where there are high risk of erosion highlighted by the yellow to red runoff velocities.

Figure 1. Existing Topography (left) and Runoff Analysis (right). Drag the slider left or right to view each.

The field already have two contour banks installed in the field and the client is looking to add contour banks on the rest of the field. These banks will slope so that water falls and exit into the grassed waterways as shown below.

Figure 2. Google Earth Background (left) and Existing contour banks and waterways (right). Drag the slider left or right to view each.

Solution

The new feature called Contour Bank Design was used. The target slope is defined and the location of each contour bank is marked in the map using Pick and Calculate. Ridges were defined where the contour banks will fall away and exit to the waterways.

The contour banks will then be offset to create the crest of the bank and the water channel. This particular design requires variable height of the bank and water channel increasing in capacity as it reaches the waterway. This design approach reduces the earthworks and improves ease of farming over the banks.

The resulting contour banks are spaced 220mm vertically and slopes at 0.15% into the waterway as shown below in the Proposed Topography and Contour Bank Profile.

Figure 4. Proposed contour banks.

Figure 5. Water channel long section of one of the contour banks.

Figure 5. Bank crest long section of one of the contour banks.

Conclusion

The client was very happy and had this to say,

The design worked perfectly, vastly expediting the the project of draining the contour banks and minimizing necessary earthworks.

The design will also be very valuable in future bank and drain maintenance.


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