| The accurate analysis of spatiotemporal patterns of temperature,precipitation and agro-meteorological droughts,play a crucial role in the sustainable management of water resources.Various types of methodologies based on climatic trends statistics,drought indices and future forecasting approaches have been used in this study for the analysis of historical and future meteorological changes and drought anomalies with the aim to provide a comprehensive study for the researchers and policy makers for the given region.The study has been conducted at the thirty-six meteorological stations of Heilongjiang Province,China.Firstly,meteorological drought has been identified for comparative analysis by considering four well known drought indices named as Reconnaissance Drought Index(RDI),Standardized Precipitation Evaporative Drought Index(SPEI),Effective Drought Index(EDI)and most commonly used Standardized Precipitation Index(SPI),at various time-step by using historical data.Moreover,Mann-Kendall trend test at 5% significant level was applied for assessing droughts trend in the basin.Drought outcomes showed that 12-month series for Songhua River basin is appropriate for the assessment of drying conditions and comparison of drought indices.The Pearson's correlation analysis of meteorological variables and drought indices discovered that SPI is a well performance index for the assessment of regional drought(r = 0.99).The climatic conditions were severe and extremely dry in the study region during the years of 1990 and 2001.Furthermore,drought indices that compute the drought events by their drought initiation,termination time and statistical properties such as frequency,severity,intensity and duration are practically stratagems for the estimating and monitoring the impact of drought events on the region.This study also investigated the agricultural drought trends and their characteristics by using the Standardized Soil Moisture Index(SSI).Additionally,Multivariate Standardized Drought Index(MSDI)was also used for the assessment of the composite effect of both agricultural and meteorological droughts.The results showed that 2004-05 was the extreme and remarkable drought year.The spatiotemporal analysis indicated that Annual Drought Frequency(ADF)value changes from 1.20 to 2.70,Mean Drought Duration(MDD)found from 5 to 11 month,Mean Drought Severity(MDS,-0.30 to-0.90)and Mean Drought Intensity(MDI,-0.20 to-0.70)were found in the study area during the study period.The results also indicated that MSDI identified the drought onset earlier as compared to SSI.Overall,the finding justified the suitability of MSDI as an alternative tool for the evaluation and monitoring of agricultural and meteorological drought events and provides an insight to choose the suitable time-step and drought index for a specific region to identify the severities of drought.secondly,for agricultural drought monitoring we develop an composite drought index naming integrated weighted drought index(IWDI)by using numerous data i.e.climatic variables such as temperature & precipitation,PET,ET,GPP and also take numerous drought index in to consideration that have diverse backgrounds like PDSI,SPEI,VCI,SPI and NDVI.IWDI also takes soil moisture into consideration because of its importance for agriculture drought.The evaluation of IWDI specified that it can be significantly used for monitoring the monitoring of agriculture drought in Heilongjiang and maybe in similar climatic conditions area of the globe.IWDI significantly correlated with well-known drought indexes,climate variability and captured more drought.In our study during growing season duration most area faces moderate or light drought,whereas moderate,severe and extreme droughts detected on large areas of the study region in 2003(91%),2007(70%),2011-12(66%),2001(60%),2002(50%),during growing season of rice.Furthermore,we found that 2013-2016 was almost wet except Suihua where 8th to 10 th months drought detected.In addition,IWDI and rice yield regression results predicted that the drought influence on yield were 17% to 78% in different cities / stations.It was also noted that rice yield influenced by the drought intensity,drought duration and its timing.For example,short but high intensity drought detected at Suihua during 2015 & 2016 but in the month of September which was harvesting month therefore drought did not affect the yield.Thirdly,future forecasting analysis of meteorological droughts have been assessed by using the statistical downscaled meteorological data of Climate Model Intercomparison Project(CMIP)approach naming CMIP5.CMIP3 uses an emission scenario from the Intergovernmental Panel on Climate Change while Representative Concentration Pathways(RCP)was used in CMIP5.CMIP5 used three Representative Concentration Pathways namely RCP2.6,RCP4.5 and RCP8.5.Investigating drought index(RDI),precipitation decile(PD)and standardized precipitation index(SPI)were used for precisely prediction about the future drought events in the study area.The drought indices were calculated from the meteorological data which were generated by CMIP5 climatic model.Furthermore,the future climatic and drought trends in the study area were evaluated by the Marksim GCM's with three Representative Concentration Pathways(RCP).The results of CMIP5 showed that RCP8.5 and RCP 4.5 predicted a greater number of years are expected under severe droughts conditions while RCP4.5 outcomes showed that a greater number of years are projected under mild and moderate droughts condition in the study area.Conclusively,the evaluation and quantification of the present study provides a scheme for the policy makers in order to moderate the impact of extreme climatic and agro-meteorological drought conditions so that the local water resources management may improve in the region. |
PDF Full Text Request