Analysis Of Applicability Of Different Meteorological Drought Index In Gansu Province

Drought is the most serious natural disasters in global threat. It is harmful to human society economic development due to its universality and harm of persistence. The drought index of the research is becoming a hot spot of global change research direction. Gansu province is located in the inland arid areas of Northwest China, in the Tibet plateau, loess, coastal area of Inner Mongolia plateau, climate in Gansu were complex and diverse. By its special geographical location, underlying surface conditions and atmospheric circulation, the influence of such factors as severe drought disasters in Gansu province and differences in regional. As climate drying, the drought frequency was increasing high. Also China has different meteorological drought monitoring index of drought, but drought in different regions at different times have different performance characteristics, makes drought index of regional applicability problems inevitably. Therefore, explore the regional adaptability of different meteorological drought index in Gansu province has important theoretical significance and practical value.(1) Five kinds of index has a good corresponding relation with precipitation, but MI index in poor response to precipitation in Hexi area. Five kinds of index of Gansu province recognition ability of drought event in recent 50 years SPEI> CI> SPI, both MI and Pa index recognition ability were poor. Five index is consistent with the actual drought in Hexi eastern and western regions, Pa index self-agreement were highest,82% and 87% respectively; Ganmin, Longzhong anf Longdong region SPEI index self-agreement highest,76%,78% and 86% respectively; Longnan region CI index self-agreement highest, at 82%.(2) Five kinds of index can monitor drought in Gansu province, but has a significant difference at the different periods. Winter CI index in Longdong and Longnan area monitoring better, SPI index in Longdong and Ganmin better; Spring CI index and longnan area in western hexi effect is good, SPI index in Eastern of Hexi and Ganmin monitoring better; Summer SPI index in Hexi monitoring better, Hedong five index were better, but parts of CI and Pa index in monitoring a partial light; Autumn CI index better in Hedong region, SPI index in Eastern Hexi, SPI better in Longnan and Ganmin. MI index in winter and spring monitored lay particular stress on, but the fall in Hexi and parts of Hedong monitoring better. Pa index is suitable for different season of drought monitoring in Hexi area, SPEI index for drought monitoring of Hedong district in different seasons.(3) 1 month time scale of Hexi area monitoring effect in order:Pa> SPI> CI, Hedong region:SPEI> CI> SPI; 3 month time scale in Hexi area a better monitoring index were:Pa> SPI> CI, Hedong region:SPEI> SPI.12 month time scale of Gansu province, in the monitoring effect were:SPI> SPEI>MI> CI> Pa.(4) Drought duration to identify of five index, CI in Longzhong area of drought happened in the process of monitoring better, MI better in Longdong region of the dry process of monitoring, SPI in Ganmin and eastern Hexi region monitoring effect is good, the process of drought Pa monitoring to the drought in Hexi area from start to remove all of the time, Hedong region SPEI of drought process to identify the best effect.(5) CI of five index for month and seasonal drought monitoring, but CI in Ganmin and west of Hexi monitoring effect is poorer, such as in the winter drought monitoring partial light; SPEI and SPI for drought monitoring in different time scales, but the SPI index of drought in western Hexi can not effectively monitor the drought and drought monitoring in partial light, SPEI monitoring error is severe in Hexi region, and the higher temperature in some heavy drought; MI in drought monitoring at different times of the bias and the error is bigger, it is not recommended in Gansu province. Pa in inland arid zone monitoring effect is good, can be an index of Pa further revision, make it more accurate monitoring of drought strength and start and stop time. Integrated five kinds of index in different areas and different time scales of monitoring effect, recommend the use of Pa in Hexi area index, Hedong region suggest using SPEI.(6) Gansu province has obvious seasonal and regional drought characteristics in recent 50 years, drying differences were significant different season, region in Hexi and Hedong region presents the opposite change tendency. Hedong drought mutations in 1995, and after drying in the 1990 s, drought year of mutation was not significant in Hexi area, the 1960 s to 1980 s, the general partial wet, then returns to normal. Hedong are in drying trend in spring, summer and autumn, fall drying trend were the most significant (P= 0.00). Hexi in the spring, autumn and winter all showed a trend of humidification, and winter humidification in the most significant (P= 0.03).(7) Hedong region drought event occurred since the 1970 s, the dividing line were in the 1990 s, extreme and severe drought events by 2.08 times in two hours. Hexi of drought event occurrences, but fell, relatively few times of drought. The number of Hexi area, extreme and severe drought is about 2.46 times of drought. In general, the occurrence of drought frequency on concentrated in spring and summer, drought were severe in west of Hexi, Longzhong, Longnan and Longdong. Autumn and winter drought grade are mainly in the dry, extreme and severe drought event to occur less.