Handbook for Irrigation of Wine Grapes in South Africa

Chapter 4

FIGURE 4.23. Example of an overhead sprinkler permanently attached to a trellis post. Figure 4.24 Figure .24

A

B

FIGURE 4.24. An example where grapevines were established under overhead sprinklers (A) and later irrigated by means of drippers (B).

4.2.4 FLOOD IRRIGATION Flood irrigation is applied over the full surface, and is also referred to as “border” or “rill” irrigation. It is primarily applied on the alluvial soils along rivers where water is supplied via irrigation schemes. Since flood irrigation has the lowest irrigation system efficiency (Table 4.1), it is only sustainable if ample, relatively cheap irrigation water is available. Furthermore, it requires intensive, skilled labour to apply flood irrigation effectively (Fig. 4.25). In addition to high evaporation losses while irrigation is being applied, water infiltration is usually uneven along flood irrigation beds. Since irrigation water flows for a longer period through the head of the bed, water tends to infiltrate deeper, compared to the rest of the bed.

IRRIGATION OF WINE GRAPES 87