Research On Drought Assessment And Effect Of Drought On Yield Of Winter Wheat In Jinghuiqu Irrigation District

Drought disasters in numerous natural disasters with its influence scope, intensity and frequency, as the main natural disasters affect crop growth, the crop losses caused by the drought is higher than the sum of losses caused by other adversity stress. Therefore, to master the drought inducement and internal mechanism, accurately assess the occurrence and evolution of drought, and timely feedback to the agricultural irrigation and other measures to control and alleviate drought and promote agricultural production is of great significance. This paper selects Jinghuiqu irrigation district as the study area, select Standardized Precipitation Index(SPI) and Standardized Precipitation Evapotranspiration Index(SPEI) to analyze years of drought in irrigated areas and its evolution characteristics; optimizing trend yield simulation method, analysis of the relationship between drought and irrigated crop production, establish quantitative relationship of drought index and the winter wheat climate yield, a critical threshold effect of crop climate productivity and the biggest potential yield; research on temperature, precipitation and other meteorological factors on the effect of agricultural drought, and drought index on drought evaluation of the rationality and accuracy in irrigation district, analyze the inherent mechanism of the agricultural drought, scientific and reasonable implementation agriculture irrigation and drought measures provide a theoretical basis, the conclusions are as follows:(1) Through using the method of the linear regression method, the polynomial fitting method and the five point moving average method to simulate the trend of the winter wheat yield, separation of climate yield, with the trend of winter wheat yield simulation method suitable for irrigation district. One is from the perspective of trend yield comparative analysis: the significant test of regression trend yield and actual yield, the regression relationship of the five point sliding average method is the best. In addition, the simulation results more in line with the actual changes. The second is from climate yield of reasonableness analysis: in similar climate analysis, meteorological yield and the ratio of actual production, the key of the winter wheat growth period average temperature and precipitation affect time analysis, five moving average method can be more accurate than other two methods comprehensively reflect the research to the climate characteristics and characteristics of winter wheat growth. In summary, five point moving average method in the overall applicability of the optimal Jinghuiqu Irrigation district.(2) Using the data of precipitation, sunshine hours and temperature analyzed drying process of irrigation district: precipitation of irrigation district, 1953-1984 for more rain period, 1985-2008 for less rain period, 1975-1984 was the flucyuation period from pluvial period to brief rain period, the annual precipitation at a speed of 29.6 mm/10 a decrease; sunshine hours of irrigation district, 1961-1980 for more sunshine period, 1981-2001 for less sunshine period, annual sunshine time at a speed of 81.79 h/10 a decrease; temperature of irrigation district, 1953-1962 for warmer period, 1963-1993 for colder period, 1994-2008 was another warmer period. In particular, the temperature change trend of irrigation district was divided into two stages, 1953-1980 years for the cooling stage, 1981-2008 in the heating stage. Overall, the annual precipitation and sunshine hours decreased, the average temperature of the first decreased and then increased, reflecting the trend of drought in the Jinghuiqu Irrigation district.(3) Drought situation analysis of irrigation district based on drought indices. Through the wavelet analysis of drought index discover implicit in the arid area change cycle: 1.5 years of drought period in spring; and summer for 1.5 years and 3 years of drought cycle; 6.5 years of winter drought cycle. Irrigation district heating period all the time scales, the drought cycle compared with the cooling period have different degree of relationship, drought frequency of occurrence from the 25.0%~32.1% rose to 55.6% ~64.3%, the drought index showed a downward trend, revealing the drought trend in the irrigation district.(4) Based on the drought index of drought and crop yield research, to the most relevant SPI, SPEI drought index and regression analysis, obtained yield drought threshold and maximum yield potential. when the SPI24-11 value between 0.295 ~ 6.160 yield a positive climate, namely on the trend of yield increase, when the SPI24-11 = 2.933, the biggest increase 198.056 Kg/hm2;When SPEI24-11 values between 0.416 ~ 4.136 yield a positive climate, when SPEI24-11 = 1.860, the biggest increase 130.194 Kg/hm2;When SPI6-2 value between 0.331 ~ 4.880 yield a positive climate, when SPI6-2 = 2.274, the biggest increase 175.222 Kg/hm2;When SPEI6-2 value between 0.306 ~ 3.680 yield a positive climate, when SPEI6-2 = 1.687, the biggest increase of 149.320 Kg/hm2.(5) The evaluation of SPI and SPEI performance contrast indicate:(1) Warm period SPI and SPEI difference(SPI-SPEI) is positive, that SPEI determined drought conditions compared to determine which of the SPI drought conditions drier, relatively cold on the contrary.(2)Warming up stage, the annual scale and the spring and summer SPEI index sequence of the trend test is significantly better than the SPI index.(3) In assessment of drought occurrence frequency, SPEI determine drought seasons are spring and winter, and SPI index to judge drought seasons are winter and summer, in combination with the actual situation of irrigation area, the irrigation area belongs to continental semi-arid monsoon climate zone, rainy summer, winter spring is dry, so SPEI index evaluation results more accurate.(4) SPI and SPEI and positive sequence arrangement of precipitation and antitone array temperature sequences corresponding relations are good, SPEI response than SPI strongly to temperature fluctuations.(5) SPI index correlation with yield of winter wheat climate than SPEI index. Overall speaking, under the background of climate warming in irrigation district and SPEI showed more sensitive and accurate drought monitoring performance than SPI, but in the impact assessment of drought and crop yield of SPEI did not exhibit more excellent than SPI performance evaluation.