A 627ha (1550ac) cotton farm in Azerbaijan was looking to re-design their fields for bay irrigation. The farm was split into 7 fields. This case study focuses on one 95ha (235ac) field.

Figure 1. Satellite image of the farm area highlighted in yellow and the field highlighted in red.

The field was being furrow irrigated, however, there were many depressions in the field creating water logging problems and poor irrigation efficiency and uniformity.

The map below shows the drainage analysis results, incorporating the furrow height and direction in the existing topography. It shows where water will pond in the furrows, which will drown the crop and require excessive irrigation water to fill the depressions before the rest of the furrow will be irrigated. The depressions also create havoc with any machinery operations because 80% of the field is dry and ready to get planted, sprayed or harvested but the 10% of the field with depressions will remain wet for weeks longer than it should.

Figure 2. Existing Topography (left) and Drainage Analysis (right). Drag the slider left or right to view each.

The fields were designed using OptiSurface 1Way with main slopes set to a minimum of 0.10% and a maximum of 0.20% with zero cross slope and a smoothing factor of 100m/% was applied. The bays are split using the purple Excluson subzones which allow steps between the bays.

Figure 3. Existing Topography (left) and Proposed Topography (right). Drag the slider left or right to view each.

The earthworks were only 237 m³/ha excluding headland construction. Below you can see the Cut/Fill Map with the majority of cuts and fills less than 100mm.

Figure 4. Cut/Fill Map.

The inflow to the bays was supplied by head ditch and siphons. The head ditch was designed with steps to limit the height difference from the water level in the head ditch and the bay level. Siphon sizes were optimized for each bay to achieve optimal set times.

Figure 5. Head Ditch Profiles.

Here's a video where Graeme demonstrates the process of the bay irrigation design. (video will be replaced)

The flexibilty OptiSurface Designer allows the design of multuple bays together with variable main slope and zero cross slope to achieve an optimal balance between earthworks and irrigation uniformity.