4.1.1.2 - Can undulating land be irrigated?
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Border-check irrigation is best suited to relatively flat land. Three issues affect the suitability of undulating land for border-check irrigation – the slope, the depth of the topsoil, and the volume of earthmoving needed to achieve the desired layout:
- Slope – Slopes of 1:100 to 1:800 can be used to irrigate perennial pasture, with perhaps 1:300 to 1:600 being an optimum. For more information see the Agnote “Border-check Irrigation Design”.
- Depth of topsoil - Removal of the topsoil is a serious problem associated with landforming. It results in exposure of low fertility sub-soils with poor soil structure and texture. Where shallow topsoils (as in much of the northern Victorian irrigation areas) are landformed, they should be stripped, temporarily stockpiled and replaced after landforming.
- Earthmoving – Slopes can be changed, minor undulations can be smoothed out, and cross slope can be removed with earthmoving equipment. However, this is expensive, and an economic assessment is needed to determine if a particular option is feasible.
You may choose to undertake relatively expensive earthworks to achieve the desired layout, or you may decide against developing a particular section of the farm to border-check irrigation. Alternative irrigation systems might be better suited to such areas or they may be left dry, perhaps to grow trees, or for habitat/biodiversity purposes.
© The State of Victoria, 1996 - 2009.
This document was last reviewed on 20/10/2009