The impact of climate variability and extreme weather events on agricultural productivity in arid environments has become a focal point in contemporary research. Monitoring crop water productivity (CWP) is critical and urgently required especially in the arid regions where agriculture consumes an above-average portion of the available fresh water resources. In this context, this study aimed to demonstrate the utility of remotely sensed data in assessing CWP and water use dynamics across diverse crop types in South Africa during the El Niño (2018/19) and non-El Niño (2021/22) events. In addressing the objective, the study also assessed the intra- and inter-annual variations in crop water productivity for diverse crop types including, grains, grapes, citrus fruits, teas, planted pastures, and oil seeds. The study used potential evapotranspiration and biomass derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite to estimate CWP from 2017 to 2021. This period included El Niño (2018/19) and non-El Niño (2021/22) years. The results showed that potential evapotranspiration (PET) derived from MODIS was related to the PET estimated from weather stations (R > 0.6; RMSE < 21.90; p-value < 0.001). In terms of water use, planted pastures had the highest water use 114 mm/month), while teas and citrus fruits had the lowest water use (6 mm/month). Citrus fruits, grapes and teas consistently had the lowest annual mean crop water productivity (<0.02 kg/m/annually), while oil seeds had the highest annual mean crop water productivity (>0.1 kg/m/annually). Lastly, there were no significant differences (p-value > 0.05) between the CWP for all the crops observed between El Niño (2018/19) and non-El Niño (2021/22) periods, suggesting the effectiveness of adaptation measures and interventions during this period. These results provide a simple, spatially explicit framework, relevant to understanding crop-water use, laying the groundwork for informed decision-making and sustainable agricultural practices. Integrating these findings into policy frameworks and agricultural strategies is paramount for ensuring food security and resilience in a changing climate.

中文翻译：

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南非极端天气事件期间遥感作物水分生产力和可持续农业用水

气候变化和极端天气事件对干旱环境下农业生产力的影响已成为当代研究的焦点。监测作物水分生产率 (CWP) 至关重要且迫切需要，特别是在农业消耗的可用淡水资源高于平均水平的干旱地区。在此背景下，本研究旨在展示遥感数据在评估厄尔尼诺（2018/19）和非厄尔尼诺（2021/22）事件期间南非不同作物类型的CWP和用水动态方面的效用。在实现这一目标的过程中，该研究还评估了不同作物类型（包括谷物、葡萄、柑橘类水果、茶叶、种植牧场和油料种子）作物水分生产力的年内和年际变化。该研究利用中分辨率成像光谱仪（MODIS）卫星的潜在蒸散量和生物量来估算2017年至2021年的CWP。这一时期包括厄尔尼诺（2018/19）年和非厄尔尼诺（2021/22）年。结果表明，MODIS 得出的潜在蒸散量 (PET) 与气象站估计的 PET 相关（R > 0.6；RMSE < 21.90；p 值 < 0.001）。用水量方面，种植牧场用水量最高，为114毫米/月），而茶叶和柑橘类水果用水量最低（6毫米/月）。柑橘类水果、葡萄和茶叶的年平均作物水分生产率始终最低（<0.02 kg/m3/年），而油籽的年平均作物水分生产率最高（>0.1 kg/m3/年）。最后，厄尔尼诺现象（2018/19）和非厄尔尼诺现象（2021/22）期间观察到的所有作物的 CWP 之间没有显着差异（p 值 > 0.05），这表明适应措施和干预措施的有效性在这段时期。这些结果提供了一个简单的、空间明确的框架，与了解作物用水相关，为明智的决策和可持续农业实践奠定了基础。将这些发现纳入政策框架和农业战略对于确保气候变化下的粮食安全和抵御能力至关重要。