| There is a serious shortage of water resources and uneven spatial and temporaldistribution in our country. Especially in the northwest region of China, drought is animportant factor of restricting the sustainable development of local agriculture, economy andsociety. Xinjiang far from the sea and located in the inland has a typical temperate continentalarid climate, including long time-sunshine, large diurnal variation of temperature, smallrainfall, strong evaporation and dry climate, and climate characteristics have significantdifference in time and space. Water shortages caused by drought is a key factor in affectingthe ecological balance and restricting the sustained and stable development of the nationaleconomy in Xinjiang region. Therefore, studying on the changes of drought and crop waterrequirement in the future under climate change scenarios in Xinjiang region, it has importantreference value on disaster prevention and mitigation, agricultural water use planning, theadjustment of agricultural structure and ecological environment construction in the future.In this paper, daily meteorological data of42weather stations in Xinjiang during1961-2010and Penman-Monteith equation were used to estimate ET0at daily time scale.Drought index AI was calculated combined with ET0and precipitation, and waterrequirements of cotton and sugar beet were calculated combined with the crop coefficient Kcat daily time scale. Statistical downscaling model was used to predict daily sequence data of P,ET0, AI, water requirements of cotton and sugar beet at each station under A2and B2scenarios during2011-2099. Making use of software ArcGIS10’s inverse distance weightedspatial interpolation analysis function, the spatial distribution of average annual P, ET0, AI,water requirements of cotton and sugar beet in the growth period in Xinjiang region during1961-2010and2011-2099can be obtained. Mann-Kendall method combined with the areaweighting factors for all station was used to analyze the change trends of P, ET0, AI, waterrequirements of cotton and sugar beet in the growth period in Xinjiang region. The mainconclusions were as follows:(1) The overall trend of average annual precipitation’s spatial distribution in Xinjiangduring1961-2010was that precipitation in northern Xinjiang was more than that in southernXinjiang, the northwest more than the southeast and the mountains more than plains andbasins. Average annual precipitation under A2scenario was lower than that under B2scenario during2011-2099, but the overall trend of average annual precipitation’s spatial distributionunder both scenarios was similar to that during1961-2010. Average daily precipitation had anupward trend in all Xinjiang region during1961-2010, and was predicted to continue to riseduring2011-2099.(2) The overall trend of average annual ET0’s spatial distribution in Xinjiang during1961-2010was that ET0in southern Xinjiang was more than that in northern Xinjiang, plainsand basins more than the mountains. The overall trend of average annual ET0’s spatialdistribution in Xinjiang during2011-2099was similar to that during1961-2010, whichshowed a decreasing trend from south to north. Average daily ET0had a downward trend inXinjiang during1961-2010, and was predicted to continue to decline during2011-2099,declining almost compared with that during1961-2010.(3) A trend of decreasing from southern to northern region in average annual AI inXinjiang during1961-2010. According to grade index for drought, we can see climate variedfrom semi-arid to arid, to extreme drought from northern to southern region in Xinjiang, andTurpan basin was the most arid region which had the least precipitation in Xinjiang. Theoverall trend of average annual AI’s spatial distribution in Xinjiang during2011-2099still hada trend of decreasing from southern to northern region. Average daily AI had a downwardtrend in Xinjiang during1961-2010, and was predicted to continue to decline during2011-2099, declining less than that during1961-2010.(4) A trend of decreasing from southern to northern region in average annual waterrequirement of cotton and sugar beet in the growth period in Xinjiang during1961-2010,which was similar to that during2011-2099. Cotton water requirement in the growth periodhad a fluctuating downward trend in Xinjiang during1961-2010, and was predicted tocontinue to decline during2011-2099, declining almost compared with that during1961-2010.Water requirement of sugar beet in the growth period had a fluctuating downward trend inXinjiang during1961-2010, and was predicted to continue to decline during2011-2099, butthe decline was small. The decrease of water requirement of cotton and sugar beet will havegreat significances on reducing the irrigation quantity of cotton and sugar beet, developingwater-saving agriculture and the planning and management of water resources. |
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