| Liaocheng located in the west of Shandong province, ws the primary wheat production regions in the west of Shandong. Frequent and serious drought happened in the whole wheat growth period under the effect of latitude, sea and land location and terrain factors. Based on the daily meteorological data of eight stations in Liaocheng from 1970 to 2012, soil data, wheat growth data, drought statistics and the statistical yearbook data of Liaocheng, the monthly drought conditions of Liaocheng during 43 years were analyzed in this paper by the precipitation anomaly, SPI, Z index, soil moisture, relative humidity index and crop water deficit rate. In the combination with the affected area in the wheat drought disaster, most suitable drought index of wheat in Liaocheng was obtained with the inundated area analysis. With GIS technology, spatial visualization was realized by a comprehensive analysis of the risk degree of wheat drought in the region combining dangerous degree of disaster, disaster-pregnant sensitivity, vulnerability of hazard-affected bodies and defense capability based on the theory of natural disaster assessment. This article main content included:(1) In the arid climate elements from 1970 to 2012,the linear trend of precipitation was-6.07mm/10a,showing an overall downward trend and the uneven distribution of rainfall from the northwest to the southeast region increased gradually;the temperature linear trend was 0.37℃/10a,showing an increasing trend; the average of wind speed of-0.38 m/s·10a showed a downward trend; the annual average of sunshine hours linear trend was -145h/la, showing a downward trend. Relative humidity linear trend was 0.01 mm/10 a, present a weak downward trend. Affected by temperature, wind speed and other climatic factors, the reference evapotranspiration of Liaocheng city showed a significant downward trend, with the average of -62mm/10a, the average annual evaporation was 1095 mm in 43years. Reference crop evapotranspiration average was 319 mm in spring,417 mm insummer,234 mm in autumn,100 mm in winter; During the 43 years, the fastest decline in summer was 25.7 mm/10a,17.8 mm/10a followed by the spring,in autumn it was 12.7 mm/10a and the slowest was in winter, which was 3.7 mm/10a.(2) Drought months, the number and the drought degree in Liaocheng from 1970 to 2012 were worked out by precipitation anomaly, standardized precipitation index (SPI), precipitation Z index, relative humidity, relative humidity index and crop water deficit rate. The results showed that the most frenquent drought based on precipitation anomaly index distributed in Donge, Shiping and Yanggu. The most serious drought was mainly in January and Desember. Drought based on SPI index mainly distributed in Linqing, Gaotang and Yanggu, mostly occurred in September and December. Drought based on Z index mainly distributed in Guanxian, and Xinxian and mostly occurred in April and May. Drought based on Relatively humid index mainly distributed in Linqing, Gaotang, mostly occurres in January and December.Most suitable drought index of wheat in Liaocheng was obtained by comparing the applicability of the indicators and disastrous situation in wheat growth period.(3) According to the time, place and the duration that wheat disaster happened, drought level and drought magnitude accord were obtained through the analysis of the advantages and disadvantages of each index:The precipitation anomaly index were 59.25%,25.9%; Z index were 48.14%,11.1%; SPI index were 44.4%,11.1%; Index of relative wetting degree were 85.18%,51.8%; Crop water deficit rate index were 81.48%,74.1%; The soil relative humidity were 45%,15%.(4)Critical value of wheat drought was determined, as well as the intensity and frequency of drought. The main drought area and the space distribution were ascertained. The non engineering measures included weather forecast, the government policy. The wheat drought risk assessment figure of Liaocheng was obtained by analyzing the two effects on wheat drought evaluation in detail. |
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