Handbook for Irrigation of Wine Grapes in South Africa

Chapter 1 t r 1

temperature variation of the Coastal region (Bonnardot et al. , 2002). The altitude and distance to the ocean can be used to estimate MFT for localities where there are no weather stations by means of the following equation: MFT = 20.9 - 0.0052341A + 0.06369D (R 2 = 0.9983; s.e. = 0.04°C) Eq. 1.1 where A is the altitude (m) and D is the distance to the Atlantic Ocean (km). In practical terms, the model shows that MFT declines at a rate of ca. 0.5°C with a 100 m increase in altitude, and that air temperature increases by ca. 0.6°C per 10 km increase in distance to the ocean. According to Equation 1.1, the MFT at the Atlantic Ocean coastline is estimated to be around 20.9°C. t r t r ri ti f t t l r i ( r t t l. , ). ltit i t t t t ti t f r l liti r t r r t r t ti f t f ll i ti : . - . . (R 2 . ; . . . ° ) . . r i t ltit ( ) i t i t t t tl ti ( ). I r ti l t r , t l t t li t r t f . . ° it i r i ltit , t t ir t r t r i r . . ° r i r i i t t t . r i t ti . , t t t

tl ti

tli

i ti

t t r

. ° .

Figure 1.4

No Station

District

MFT (°C) 23.0 24.7 18.9 22.9 25.0 19.1 20.6 24.0 24.2 23.6 24.4 23.4 24.3 23.7 22.8 24.5 23.2

1 Lutzville

Lutzville Klawer

1

Lutzville

2 Klawer Winery

2

3 Nortier

Lamberts Bay

4 Graafwater Co-op Graafwater

3

5 Ideal hill 6 Heldervue

Piketberg Piketberg

4

7 Vredenburg Co-op Vredenburg 8 Mo P rreesburg Co-op Mo P rreesburg

9 Porterville Co-op

Porterville

10 Langgewens

Mo P rreesburg

St. Helena Bay

6 5

11 Riebeeck Wes Co-op Riebeeck Wes

7

12 Grasrug 13 Landau 14 HS Boland 15 Philadelphia 16 Nederburg

Malmesbury Wellington Agter Paarl Philadelphia

Vredenburg

9

Porterville

8 10

11

Paarl Paarl

12

17 Bellvue

13

Atlantic Ocean

14

15

18 Bien Donne 19 Elsenburg

Groot Drakenstein

22.6

18 16

17

Stellenbosch 21.8 20 Mountain Vineyard Groot Drakenstein 22.5 21 La Motte Franschhoek 22.8 22 Nietvoorbij Stellenbosch 21.5 23 Helderfontein Helderfontein 21.8 24 Bethlehem Groot Drakenstein 22.1 25 Welgevallen 4 Stellenbosch 22.1

19

22

24 20 21

Table Bay

23

25

False Bay

30

Kilometers 30

0

FIGURE 1.4. The variability in mean MFT as recorded at selected weather stations in the Coastal region of the Western Cape (after Myburgh, 2005). I 1.4. The varia ility in ean FT as recor e at selecte eather stations in the Coastal region of the estern Cape (after yburgh, 2005).

IRRIGATION OF WINE GRAPES 21

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