Using soil-moisture drought indices to evaluate key indicators of agricultural drought in semi-arid Mediterranean Southern Africa.
Using soil-moisture drought indices to evaluate key indicators of agricultural drought in semi-arid Mediterranean Southern Africa.
复制标题
利用土壤水分干旱指数评估半干旱地中海南部非洲农业干旱的关键指标。
DOI：
10.1016/j.scitotenv.2021.152464
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
S. Kralisch
中科院分区：
文献类型：
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作者：
A. Watson;Jodie Miller;A. Künne;S. Kralisch
干旱是每年影响全球大量人口的自然灾害。虽然存在不同形式的干旱，但其严重程度和范围取决于临界点。了解这些突发事件对于水、粮食和能源安全以及制定气候变化适应战略至关重要。本研究利用JAMS/J2000水文模型，以土壤水分亏缺指数（SMDI）侦测农业干旱。南非地中海地区的贝格河流域被用作试点研究区域，该区域在2015年至2018年期间经历了严重的干旱，气象干旱演变为农业干旱，导致农业部门的作物大幅减产和失业。为了应对气象短缺的影响，水资源管理部门选择限制农业水库的泄水，迫使农民依赖地下水。模拟结果说明了在集水区内检测源头压力的重要性，在2015/2017年，源头地区在35年的模拟中首次受到影响。此外，地下水系统的区域变化，在此期间，模拟了严重到极严重的SMDI值（-3到-4），被认为是由广泛的地下水过度使用造成的，导致冬季（JJA）减少47%，春季（SON）减少68%。观测到的径流量立即减少，说明这些系统对气象和农业干旱的复原力较低，以及用水行为变化的影响。通过使用SMDI结合一个约束良好的水文模型，可以检测到关键的干旱发生的触发因素以及用水行为的临界点。由于气候变化导致世界许多地区气象干旱发生率增加，了解严重长期影响的进展情况对于制定有效的适应战略以促进水、粮食和能源安全至关重要。
Droughts are natural disasters that globally affect large numbers of people each year. While different forms of drought exist, their severity and extent are dependent on critical points of onset. Understanding these onsets is crucial for water, food and energy security, as well as to develop climate change adaptation strategies. This study used the JAMS/J2000 hydrological model to detect agricultural drought using the Soil Moisture Deficit Index (SMDI). The Berg River catchment in Mediterranean South Africa was used as the pilot study area, which experienced a severe drought between 2015 and 2018 and where meteorological drought progressed into agricultural drought that resulted in significant crop reductions and job losses within the agricultural sector. To combat the effects of meteorological shortfalls, water resource management opted to curb agricultural reservoir releases, forcing farmers to rely on groundwater. Modelling results illustrated the importance of detecting headwater stress within the catchment, where in 2015/2017 headwater areas were affected for the first time over the 35-year simulation. Furthermore, regional changes to the groundwater system, during which severe to extremely severe SMDI values (−3 to −4) were simulated, is postulated to be caused by wide-spread groundwater overuse resulting in a 47% reduction in winter (JJA) and a 68% reduction in spring (SON) streamflow. Immediate streamflow reductions were observed, illustrating the low resilience of these systems to meteorological and agricultural droughts, as well as the impacts of water use behavioural changes. By using SMDI in conjunction with a well constrained hydrological model, crucial drought onset triggers can be detected as well as tipping points regarding water use behaviour. As climate change drives an increase in the occurrence of meteorological droughts in many parts of the world, understanding the advance of severe long-term effects is important for the development of effective adaption strategies to promote water, food and energy security.