干旱气象

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近50 a南方农业干旱演变及其影响

李祎君,吕厚荃   

  1. 国家气象中心,北京100081
  • 出版日期:2017-10-31 发布日期:2017-10-31
  • 作者简介:李祎君(1978—),女,内蒙古人,高工,主要从事农业气象研究. E-mail:daoshaodao@163.com。

Evolution of Agricultural Drought in Southern China and Its influence in Recent 50 Years

LI Yijun, LVHouquan   

  1. National Meteorological Centre of China, Beijing 100081, Chin
  • Online:2017-10-31 Published:2017-10-31
  • Supported by:

    国家重点基础研究发展计划(973计划)项目“气候变暖背景下我国南方旱涝灾害对水资源与农业的影响” (2013CB430205)及 “十二五”国家科技支撑计划项目(2011BAD32B01)共同资助

摘要:

干旱是威胁农业生产的最主要农业气象灾害之一,随着气候变暖,近年来干旱对中国南方地区的影响也越来越大。为了清楚地了解气候变化背景下,南方农业干旱的演变规律及其对农业的影响,以江南、华南和西南地区为研究对象引入安全种植指数、农业水资源承载力饱和度等概念来探讨干旱对南方农业及其种植结构的影响。结果发现,研究区域正处在气温显著上升阶段,变暖明显,蒸散增加。尽管农业干旱频率减小,但其危害程度显著增大(尤其是西南地区),并具有明显的季节性,危害的主要作物为南方双季晚稻和西南冬小麦。从农业水资源的利用情况来看,西南地区水资源饱和程度高,用水压力较大,近年干旱高发均与水资源不足、分布不匀关系密切。综合考虑研究区域水资源、作物耗水、干旱风险以及种植习惯等因素,建议西南区在保持当前种植规模不变的前提下,适当减少水稻种植、增加玉米面积,或减少冬小麦种植;江南和华南区,保持早稻种植规模或适当扩大,缩减晚稻规模,可改种玉米、豆类或薯类等耗水少的作物。

关键词: 双季稻, 农业干旱, 水分利用效率, 农业水资源承载力饱和度, 种植结构

Abstract:

Southern China is a major agricultural region with complex cropping systems, terrain and climate conditions. Though water resources in this region are relatively abundant, seasonal drought events occurred frequently due to unevenly temporal distribution of precipitation. Moreover, the more remarkable effect of climate warming on drought in south China occurred in recent years, which was an important agro-meteorological disaster. Crops may respond to climate change more intensely in southern China than that in other regions of China. In contrast, many plants in southern China have been at their maximum optimum temperature, while plants in other regions of China may be at the moderate optimum temperature, which provides more buffer space. In this paper, the agricultural drought and its effect on planting structure in south of the Yangzi River and southern China and southwest China were investigated, and the effects of seasonal droughts on agriculture in these regions were investigated too. Various water resource and drought indices during crop growth stages in each of the three sub-regions were calculated for the past 50 years by using meteorological observations. The results showed that significant climate warming and increasing evapotranspiration were found in study regions. Although occurring frequency of agricultural drought decreased, its damage to agricultural production increased significantly in these regions especially in southwest China. Drought of south China had an obvious seasonal characteristic which was main threat to late rice and winter wheat in study regions. This study indicated that droughts occurred frequently in winter wheat growth season in southwest China and at late rice stages in south China and the south of Yangtze River regions. Spring drought often occurred in southern and southwest parts of southern China, while summer drought and autumn drought often occurred in southern part and the middle and lower reaches of the Yangtze River. This study further investigated the drought impacts on early rice and late rice growth in south China and south of the Yangtze River regions and indicated that the largest impacts occurred during the critical stages, mainly for late rice. Although annual water balances are in surplus in most of southern China, seasonal droughts are a severe threat to certain individual crops at the critical stage. The impacts of seasonal agricultural droughts should be further investigated in more details using sophisticated crop models to understand the physiological processes and mechanisms. Inadequate resources and uneven distribution of precipitation resulted in high frequency of drought and saturation of water resource in recent years. Adjustments of planting structure were proposed based on regional water resources and crop water consumption, drought risk and growing habits and other factors. In order to protect water resource, the idea of reducing rice planting and increasing corn area was suggested. The water resources in parts of southern China had been a limiting factor for crop growth. Irrigation has been a useful technique to mitigate the impacts of water resource shortage. On the other hand, plant areas of early rice could be appropriately expanded, while planting areas of late rice also was expected to decrease in south of the Yangtze River and southern China. In order to decrease the consumption of regional agricultural water and keep sustainable development of water resources, adjustments of planting structure were expected in the study regions. Any mitigation approaches need to be considered in combination with future landscape changes due to urbanization that has speeded recently and will remain the trend in the near future. More water resources would be used for living and industrial needs instead of agricultural usages. This suggest that the impacts of droughts on water resources would become more critical for agriculture in southern China.

Key words:  agricultural drought, water use efficiency, saturation of agricultural water resource carrying capacity, planting structure