Meteorological Drought Research In HeDong Area Of Gansu Province In Recent 30 Years

The Hedong area of Gansu Province is located in the east of Gansu Province in the Yellow River.The climate types are diverse,the terrain is complex,the ecological environment is fragile,and the drought is frequent.It is a sensitive area and a vulnerable area of climate change.With the global warming,the drought problem in Hedong area of Gansu Province has caused widespread concern.Based on the daily maximum temperature,average temperature,minimum temperature,relative humidity,sunshine hours and precipitation observation data of 61 meteorological observatories in Hedong area of Gansu Province from 1988 to 2017,We first calculate the index of Relative Humidity of each site,Precipitation Anomaly Percentage,Standardized Precipitation Index,Comprehensive Meteorological Drought Index,Standardized Precipitation Evapotranspiration Index.Secondly,We quantitatively and qualitatively evaluated the applicability of five drought indices in Hedong region from land-atmosphere interaction and literature comparison,and established a database of five meteorological drought indices to screen for drought in Hedong,Gansu Province.Study the optimal drought index and explore the causes and trends of drought.Finally,we divided the drought risk areas based on the optimal drought index and studied the drought vulnerability.The preliminary results are as follows: 1)Considering the SPEI calculated by wind speed and sunshine hours,the annual scale and seasonal scale can be well correlated with the drought events in the typical years of typical sites,and the soil moisture monitoring data and crop disaster data have Significant correlation can better reflect the severity of drought.The SPEI after mathematical statistics is suitable for the study of dry and wet changes in Hedong area of Gansu Province,but also pay attention to the special hydrothermal status of irrigated agricultural areas and make a reasonable analysis.2)The SPEI of Hedong area showed a significant positive correlation with the relative humidity of 10cm-20 cm soil.The larger the SPEI value,the more humid the climate and the greater the soil moisture.3)At the same time scale,there is a significant positive correlation between SPEI and the area affected by crops in different areas,and the correlation coefficient is spatially different.The rice planting area in southern Anhui has a large interference with the calculation of potential evapotranspiration.SPEI on rice the historical drought identification of the planting area is not sensitive.4)The SPEI calculated in this paper can correspond well with the El Ni?o-induced drought events occurring in the same period of history.The Hedong area reflected by SPEI has a significant arid trend.This study provides data support for the analysis of drought trends and changes in long-term sequences at different time scales in Hedong area of Gansu Province.It can also be used as basic data to explore the impact of drought events on eco-hydrological environment and agricultural production.