| Drought is a global natural disaster that affects industry,agricultural production and the ecological environment when the drought is severe.There are many reasons for the drought,mostly related to less precipitation and higher temperature.The drought in the Jinghui Canal Irrigation District is frequent,and the drought in the irrigation area will directly affect the grain yield.Grain yield is the core of agricultural production and one of the basic problems of human survival and social economic development.Therefore,it is of great significance to study the relationship between the change of agricultural drought and the yield of grain per mu in the irrigation area of the Jinghui Canal Irrigation District.At present,in the study of agricultural drought using a single index or a comprehensive index,groundwater parameters are rarely considered,and changes in groundwater level are greatly affected by human activities.The groundwater over-exploitation in the Jinghui Canal Irrigation District is serious,which makes the drought-resistance capacity of the irrigation area decrease.Therefore,it is necessary to add groundwater parameters when constructing the comprehensive agricultural drought index.In this study,the calculated Standardized Precipitation Evapotranspiration Index(SPEI),the Normalized Difference Vegetation Index(NDVI),the Standardized Soil Moisture Index(SSI),and the Standardized Groundwater Index(SGI)were used as input variables,using principal component analysis and The CRITIC objective weighting method can construct two comprehensive agricultural drought indices(CADI).The applicability of two comprehensive agricultural drought indices was evaluated based on the correlation between two comprehensive agricultural drought indices and self-calibrating Palmer drought index(so-PDSI),The applicability evaluation results were verified by the existing drought research results in the irrigation area.Use the comprehensive agricultural drought index to analyze the characteristics of agricultural drought change in the Jinghui Canal Irrigation District,including trend analysis and mutation test,and changes during the year(inter-month and inter-season)and inter-annual changes.Finally,the correlation between the comprehensive agricultural drought index and the grain yield per mu data of the irrigation area was analyzed,and the relationship between the comprehensive agricultural drought and the grain yield per mu was determined.The conclusions of this study are as follows:(1)The comprehensive agricultural drought index constructed by CRITIC objective weighting method is more suiTab.for the Jinghui Canal irrigation area than the comprehensive agricultural drought index constructed by principal component analysis.The former has a strong correlation with the self-calibrating Palmer Drought Index(ski-PDSI),and the Pearson correlation coefficient is 0.73.(2)The comprehensive agricultural drought index of the Jinghui Canal Irrigation District was compared with four single indexes such as SPEI,NDVI,SSI and SGI.Since the comprehensive agricultural drought index is considered taking into account many factors such as precipitation,evapotranspiration,vegetation status,soil relative humidity and groundwater depth,it is considered that the comprehensive agricultural drought index can reflect the actual agricultural drought situation in the Jinghui Canal Irrigation District than the single index.The results of the analysis were verified by the actual drought data.The results showed that the situation reflected by the comprehensive agricultural drought index was consistent with the actual drought and the applicability was strong in the study area.(3)The characteristics of agricultural drought change in the Jinghui Canal Irrigation District were analyzed by using the comprehensive agricultural drought index.The trend analysis shows that the index fluctuated at a rate of 0.032/year,indicating that the drought in the Jinghui Canal Irrigation District has a tendency to alleviate.The results of mutation analysis indicated that the mutation time was July 2011.The annual variation of the comprehensive agricultural drought index in the Jinghui Canal Irrigation District was analyzed,the results show that the monthly average comprehensive agricultural drought index is the smallest in November,and also small in March,April,June and October,that is,the frequency of drought in these areas is higher in the Jinghui Canal Irrigation District.The average monthly agricultural drought index in February,August and September was relatively large,that is,the Jinghui Canal irrigation area was relatively humid in these months.The analysis of the comprehensive agricultural drought index in the Jinghui Canal Irrigation District during the season shows that: The comprehensive agricultural drought index in the four seasons showed a volatility,and the growth rate was: Spring > Summer > Autumn > Winter.The inter-annual analysis of the comprehensive agricultural drought index in the Jinghui Canal Irrigation District shows that: There was no serious drought in the irrigation districts in 2004,2011,2012 and 2013.In 2002,the comprehensive agricultural drought index was small,and the irrigation area experienced a continuous drought.(4)Correlation analysis was carried out between the grain yield per mu in the Jinghui Canal Irrigation District and the comprehensive agricultural drought index.The results showed that: The comprehensive agricultural drought index in July of last year was the highest correlation with the winter wheat yield per year,and the Pearson correlation coefficient was 0.554;The comprehensive agricultural drought index in May is the highest correlation with the summer maize yield per mu,and the Pearson correlation coefficient is 0.648.Finally,the relationship between the comprehensive agricultural drought index and the grain yield per mu in the Jinghui Canal Irrigation District was quantitatively analyzed,and the relationship between the comprehensive agricultural drought index and the yield per mu of winter wheat and summer maize was obtained. |
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