Drought assessment in a typical rainfed agricultural region of Inner-Mongolia, China

摘要

Agricultural drought is a type of natural disaster that has a serious impact on food security.Because the relationships among short-term rainfall,soil moisture,and crop growth are complex,the accurate identification of a drought situation is difficult.In this study,using a conceptual model based on the relationship between water deficit and yield reduction,we evaluated the drought process in a typical rainfed agricultural region,Hailar County in Inner Mongolia,China.To quantify drought,we used the three precipitation indices(Precipitation Anomaly(PA),Standardized Precipitation Index(SPI),Effective Drought Index(EDI),and the soil moisture–based Crop Moisture Index(CMI)as well as the Normalized Difference Vegetation Index(NDVI).Correlation analysis was conducted to examine the relationships between dekad-scale drought indices during the growing season(May–September)and final yield,using data collected from 2000 to 2010.The results showed that the yield has positive relationships with both EDI and CMI from mid-June to mid-July and with the NDVI anomaly throughout July.Further analysis of the relationship between the drought indices showed that the NDVI anomaly responds to both EDI and CMI with a lag of 1 dekad,particularly in July.To examine the feasibility of employing these indices for monitoring the drought process at a dekad time scale,a detailed drought assessment was carried out for selected drought years.It confirmed that the drought indices in the late vegetative to early reproductive growth stages can be used to detect agricultural drought in the study area.Therefore,the framework of the conceptual model developed for drought monitoring can be employed to support drought mitigation in the rainfed agricultural region of northern China.