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Southern China is an important agricultural planting region of China, but the seasonal drought severely impacted the regional agricultural production. Based on the 1981-2007 meteorological data from 13 typical meteorological stations in the seasonal drought areas in southern China and the data of related crops growth period and yield, three precipitation year types (drought year, potato-double cropping rice, and the suitable patterns in southwest area were the triple cropping systems with drought-resistant crops, such as winter wheat-rice-sweet potato, winter wheat-maize-sweet potato, and potato-double cropping rice. From the aspect of maximally utilizing water and heat resources, triple cropping would be the best choice, with the rice and upland crop rotation as the main and with the rice arranged in pairs in wet year. normal year, and wet year) were classified based on the yearly precipitation, and by using five indices (coupling degree of water requirement and precipitation during crop water critical stages, meteorological crop yield, output value per unit area, and water use efficiency and precipitation during whole growth period), the comprehensive benefit of all possible cropping patterns in each typical region was evaluated, and the optimal cropping patterns in the different regions of southern China in different precipitation years were obtained. In the semi-arid region, the optimal cropping patterns in dry year included potat-maize-sweet potato and winter wheat-rice-sweet potato. In the semi-humid region and during dry year, winter wheat-rice-sweet potato was the best choice, and rape seed-rice-sweet potato was the second one. In the warm and humid region (the typical region where seasonal drought happened), the best cropping pattern in Jiangnan area in different precipitation years was [ABSTRACT FROM AUTHOR]

Zoning seasonal drought based on the study of drought characteristics can provide theoretical basis for formulating drought mitigation plans and improving disaster reduction technologies in different arid zones under global climate change. Based on the National standard of meteorological drought indices and agricultural drought indices and the 1959-2008 meteorological data from 268 meteorological stations in southern China, this paper analyzed the climatic background and distribution characteristics of seasonal drought in southern China, and made a three-level division of seasonal drought in this region by the methods of combining comprehensive factors and main factors, stepwise screening indices, comprehensive disaster analysis, and clustering analysis. The first-level division was with the annual aridity index and seasonal aridity index as the main indices and with the precipitation during entire year and main crop growing season as the auxiliary indices, dividing the southern China into four primary zones, including semi-arid zone, sub-humid zone, humid zone, and super-humid zone. On this basis, the four primary zones were subdivided into nine second-level zones, including one semi-arid area-temperate-cold semi-arid hilly area in Sichuan-Yunnan Plateau, three sub-humid areas of warm sub-humid area in the north of the Yangtze River, warm-tropical sub-humid area in South China, and temperate-cold sub-humid plateau area in South-west China, three humid areas of temperate-tropical humid area in the Yangtze River Basin, warm-tropical humid area in South China, and warm humid hilly area in Southwest China, and two super-humid areas of warm-tropical super-humid area in South China and temperate-cold super-humid hilly area in the south of the Yangtze River and Southwest China. According to the frequency and inensity of multiple drought indices, the second-level zones were further divided into 29 third-level zones. The distribution of each seasonal drought zone was illustrated, and the zonal drought characteristics and their impacts on the agricultural production were assessed. Accordingly, the drought prevention measures were proposed. [ABSTRACT FROM AUTHOR]

Based on the 1959-2008 meteorological data from 249 meteorological stations in south-ern China, and by using crop water deficit index (CWDI) as the agricultural drought index, this paper calculated the drought frequency and drought stations ratio in this region, and analyzed the spatiotemporal distribution characteristics of drought for spring maize and summer maize during their growth periods. As for the spatial pattern of drought frequency, the drought for spring maize was more severe in the north of Huaihe River, northern Yunnan, and southern South China, but was lighter in the other regions. Except that the drought for summer maize at its late developmental stage was more severe in the middle-lower reaches of Yangtze River, northern South China, and eastern Southwest China, the drought for summer maize at its other developmental stages within southern China was lighter. As for the variation trend of drought intensity and drought area, the drought in-tensity of spring maize from its seven-leaf stage to jointing stage in the middle-lower reaches of Yan-gtze River increased obviously, while the drought intensity and drought area of the spring maize from its late spinning stage to milky maturity stage presented a decreasing trend. The drought of summer maize from its late jointing stage to tasseling stage and from late spinning stage to milky maturity stage all showed a decreasing trend. In Southwest China, the drought intensity and drought area for spring maize and summer maize had no clear trend. From the viewpoint of the inter-annual and dec-adal variability of drought intensity and drought area, there was a larger variation for the summer maize in the middle-lower reaches of Yangtze River, but less difference in Southwest China. [ABSTRACT FROM AUTHOR]

To analyze the spatiotemporal characteristics and occurrence regularity of seasonal drought can provide theoretical basis for constituting the countermeasures of drought resistance and drought mitigation under the background of global climate change. Based on the 1959-2008 daily precipitation and atmospheric temperature data collected from the meteorological stations in 15 provinces (municipalities, and autonomous regions) of southern China, and using the percentages of precipitation anomalies (Pa) in the national standard "Meteorological Drought Classification", which were locally modified, the drought indices in southern China in 1959-2008 were calculated, and the spatial distribution characteristics of drought frequency in southern China in each year, each season, and each month, as well as the inter-annual changes of the drought intensity and the proportions of the stations with seasonal drought were analyzed. In the study period, the annual drought risk in southern China was generally low. There existed obvious seasonal differences in the spatial distribution characteristics of the drought. Autumn drought was most frequent and most intensive, mainly occurred in the middle and lower reaches of Yangtze River, South China and in the other major agricultural areas, winter drought was also frequent and intensive, mainly occurred in the west of Southwest China and the South China and other winter crop planting areas, while spring drought and summer drought were relatively less frequent or intensive. Spring drought mostly occurred in the southwest of Southwest China, the south of South China, and Huaibei area etc., and summer drought mostly occurred in the middle and lower reaches of Yangtze River, southeastern coastal area of Fujian, and northeast of Southwest China. The area with drought frequently occurred showed an obvious monthly fluctuation and space transformation, which was decreased with time from November to next May, increased with time from May to November, in the smallest range from April to June, and in the widest range from November to December. The annual drought area showed a slight decrease while the drought intensity should a slight increase, but the situation differed with season, i. e., spring drought area slightly decreased and the drought intensity weakened, summer drought area had an obvious decrease and the drought intensity weakened, autumn drought area increased obviously and the drought intensity increased, while winter drought area decreased and the drought intensity weakened. [ABSTRACT FROM AUTHOR]

In recent years, seasonal drought occurs frequently in southern China, giving severe impact on the production of local wintering crops. Based on the 1959-2009 meteorological data from 268 meteorological stations in southern China, and by using crop water deficit index (CWDI) as agricultural drought index, this paper analyzed the spatiotemporal characteristics of drought for winter wheat and rapeseed. The results showed that in southern China, drought happened more frequently in Southwest China, north Huaihe basin, and parts of South China during the developmental stages of wintering crops. In the mid-lower Yangtze basin, the intensity and extent of drought increased during the mid-late developmental stages of winter wheat, and became much heavier at its later developmental stages. For rapeseed, the intensity and extent of drought increased during the developmental stage before winter and the late developmental stages. In southwest part, the intensity and extent of drought increased significantly during the developmental stage before winter for winter wheat and rapeseed. Since the early 1990s, the intensity and extent of drought in southern China increased during the mid-late developmental stages of wintering crops. [ABSTRACT FROM AUTHOR]

Based on the 1959-2008 precipitation data from 262 meteorological stations in southern China, this paper analyzed the change characteristics of seasonal precipitation trend coefficient, precipitation variability, and annual and decadal precipitation standardized anomalies in this region. In the study period, there was a great difference among the trend of quarter precipitation. In most parts of the region, the precipitation in spring and autumn presented a decreasing trend but that in summer and winter was in adverse; only in southwest part, a slightly different trend was observed. In the whole region, the probability of spring drought decreased, but that of summer drought, autumn drought, and winter drought increased. Spring drought often occurred in south and southwest parts, summer drought and autumn drought often occurred in south part and the middle, lower reaches of Yangtze River, and winter drought expanded from south part to south part and the middle, lower reaches of Yangtze River. The precipitation in spring and autumn was below the normal level after the 1980s, while that in summer and winter was below the normal level before the 1990s, above the normal level in the 1990s, and below the normal level since the 21st century. The decadal change of the seasonal precipitation standardized anomaly in each part of the region was basically consistent, i. e. , decreased in autumn and increased in summer and winter. [ABSTRACT FROM AUTHOR]