Abstract
Droughts remain a threat to grape yields in South Africa. Previous studies on the impacts of climate on grape yield in the country have focussed on the impact of rainfall and temperature separately; meanwhile, grape yields are affected by drought, which is a combination of rainfall and temperature influences. The present study investigates the impacts of drought on grape yields in the Western Cape (South Africa) at district and farm scales. The study used a new drought index that is based on simple water balance (Standardized Precipitation Evapotranspiration Index; hereafter, SPEI) to identify drought events and used a correlation analysis to identify the relationship between drought and grape yields. A crop simulation model (Agricultural Production Systems sIMulator, APSIM) was applied at the farm scale to investigate the role of irrigation in mitigating the impacts of drought on grape yield. The model gives a realistic simulation of grape yields. The Western Cape has experienced a series of severe droughts in the past few decades. The severe droughts occurred when a decrease in rainfall occurred simultaneously with an increase in temperature. El Niño Southern Oscillation (ENSO) appears to be an important driver of drought severity in the Western Cape, because most of the severe droughts occurred in El Niño years. At the district scale, the correlation between drought index and grape yield is weak (r≈−0.5), but at the farm scale, it is strong (r≈−0.9). This suggests that many farmers are able to mitigate the impacts of drought on grape yields through irrigation management. At the farm scale, where the impact of drought on grape yields is high, poor yield years coincide with moderate or severe drought periods. The APSIM simulation, which gives a realistic simulation of grape yields at the farm scale, suggests that grape yields become more sensitive to spring and summer droughts in the absence of irrigation. Results of this study may guide decision-making on how to reduce the impacts of drought on food security in South Africa.
Abstract from the paper’s OpenAlex record; open copy licensed other-oa. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 9
Claim · model-written summary
APSIM realistically simulated farm-scale grape yields.
Not reportedComparatorValue
Verbatim
t0“grape”
e0“The model gives a realistic simulation of grape yields.”
Claim · model-written summary
Western Cape experienced several severe droughts over recent decades.
Not reportedTaxon
Verbatim
e0“The Western Cape has experienced a series of severe droughts in the past few decades.”
Claim · model-written summary
Severe droughts coincided with lower rainfall and higher temperature.
- Outcome
- severe droughtse0
- Qualifier
- a decrease in rainfall occurred simultaneously with an increase in temperaturee0
Not reportedTaxonSettingDirection
Verbatim
e0“The severe droughts occurred when a decrease in rainfall occurred simultaneously with an increase in temperature.”
Claim · model-written summary
Most severe Western Cape droughts occurred in El Niño years.
Not reportedTaxonDirection
Verbatim
e0“most of the severe droughts occurred in El Niño years”
e1“The Western Cape has experienced a series of severe droughts”
Claim · model-written summary
At district scale, drought index and grape yield were weakly correlated (r≈−0.5).
Verbatim
t0“grape”
e0“At the district scale, the correlation between drought index and grape yield is weak (r≈−0.5)”
Claim · model-written summary
At farm scale, drought index and grape yield were strongly correlated (r≈−0.9).
Verbatim
t0“grape”
e0“at the farm scale, it is strong (r≈−0.9)”
e1“correlation between drought index and grape yield”
Claim · model-written summary
Poor farm-scale grape yield years coincided with moderate or severe drought periods.
Verbatim
t0“grape”
e0“At the farm scale, where the impact of drought on grape yields is high, poor yield years coincide with moderate or severe drought periods.”
Claim · model-written summary
Simulations indicate grape yields become more sensitive to spring and summer drought without irrigation.
- Taxon
- grapet0
- Treatment
- absence of irrigatione0
- Outcome
- grape yieldse0
- Direction
- more sensitivee0
- Qualifier
- spring and summer droughtse0
Not reportedComparator
Verbatim
t0“grape”
e0“grape yields become more sensitive to spring and summer droughts in the absence of irrigation”
Claim · model-written summary
Authors infer that irrigation management mitigates drought impacts on grape yields.
Verbatim
t0“grape”
e0“many farmers are able to mitigate the impacts of drought on grape yields through irrigation management”
The same questions in other papers
irrigation · yield · VitisResults differ
30 papers in the same direction as this paper · 52 in the opposite direction
- positive
- positive
- positive
79 papers more in this group
See all 83 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.