Spatio-temporal Varations Of Cotton Agricultural Drought And Its Response To Climate Change In The Past 53 Years In North Xinjiang

Agricultural drought is an important risk source for agricultural production.Based on the data of 25 meteorological stations in the north Xinjiang and agricultural Drought Index,the paper explores the temporal and spatial evolution characteristics of agricultural drought and its relationship with meteorological factors in north Xinjiang in the past 1961?2013 years.The main results are as follows:(1)The spatial and temporal distributions of meteorological factors in north Xinjiang 1961?2013 years were studied,and the potential evapotranspiration,sunshine hours,mean wind speed and relative humidity of cotton were decreased,and the temperature increased.The potential evapotranspiration of cotton crops in different growth periods is characterized by the decreasing trend from southwest to northeast,the relative humidity was decreased from west to east,while the sunshine hours shows the trend of the north is larger than the south,and the mean wind speed is decreasing from north to south.(2)In the past 53 years,the drought index was decreased.and the change rate is-0.117/a,the whole Xinjiang drought Index in addition to Alate,alzshankou,Kelamayi and Danbancheng,the rest are low value distribution,the climate tendency rate is reflected by the trend of decline from west to east,according to the classification of drought level,Extreme drought distribution site only 3,indicating that the climate is turned warm and humid.Under the condition of climate change,drought gradually became light during tha past 53 years,especially exhibited more significant in south central region of north Xinjiang.Nevertheless,a noticeable point is that extreme drought happened frequently.(3)The change trend of north Xinjiang cotton water demand,irrigation water requirement and irrigation water requirement index in different growth periods is decreasing,and the crop water surplus deficit index and effective precipitation are increasing.According to the results of the periodic analysis,the water demand of cotton has a large period of 30 a and a 15?17a periodic scale,on the smaller interannual scale,there is no obvious periodic characteristic of crop water demand,in the space distribution,the crop water demand,crop water surplus deficit index and effective precipitation of cotton are generally decreased from west to east,The water demand of irrigation is characterized by low middle height,and most of the index of irrigation requirement is the low distribution of middle and high sides.(4)The results of climate analysis showed that the cotton crop water requirement and irrigation demand index were significantly positively correlated with the average wind speed,sunshine duration,and maximum temperature and the relative humidity showed a significant negative correlation.There is a positive correlation between crop water surplus deficit index,irrigation water requirement and relative humidity,and negative correlation with sunshine duration.