Drought Assessment And Prediction In The Yellow River Basin

This article takes the Yellow River Basin(YRB)as the research object,starting from the meteorological drought in the basin,and carries out a series of research work on the concept,quantitative indicators,driving factors,evaluation,prediction and other aspects of meteorological drought.Based on the meteorological factors such as precipitation and temperature in the basin,the spatial and temporal distribution characteristics and intergenerational evolution of drought driving factors in each subarea were analyzed.Based on the assessment of the historical drought conditions of the watershed,the trends,mutations,and cycles of drought evolution in each subarea of the YRB Characteristics,revealing the differences in drought changes in different regions under different climate influences;on the basis of identifying short-term and mid-long-term drought events in various regions of the watershed,a multi-angle feature quantity evaluation framework for drought events is proposed to address the drought events in each region Temporal characteristics,intensity characteristics,and evolution characteristics are analyzed through interdecadal changes.Based on the characteristics of the close connection and co-evolution of the drought time,space,and frequency domains,the temporal and spatial distribution of drought in the YRB is revealed from the perspective of the overall meteorological drought field in the watershed.The evolution of structure.Finally,the SSA-ARMA coupled prediction model is used to predict the future changes of watershed drought.The main results achieved by this research are as follows:(1)The average annual rainfall in the YRB is spatially decreasing from southeast to northwest.The northwestern part of the basin is the area with the highest annual precipitation variability.In each sub-area,only the northwestern part of area A showed a significant increase in annual precipitation,while the annual precipitation in YRB shows a spatially decreasing pattern from east to west.After the turning point of each generation in the 1980s,the temperature in each subarea increased,and the annual average temperature showed a significant increase trend.(2)Based on the research on the trends,mutations and cycle characteristics of drought evolution of the watershed,it is found that the YRB still has a tendency to arid on the intra-annual and inter-annual scales;the sub-regions of the watershed show significant differences in the types of mutations at different levels;There are differences in the time and space scales of the periodicity of the drought changes in various zones under the influence of a variety of different climate systems.(3)Based on the relevant rules of the travel theory,the drought events at various time scales are separated,and the evolution of the short-term,medium-and long-term drought events and the spatial-temporal correlation analysis are carried out for each division of the YRB.The whole process of the beginning,development,peak,decline and end of drought events was clarified,and the spatiotemporal evolution law of drought event characteristics was analyzed.Then,the spatiotemporal evolution analysis of historical drought events was taken as an example,and the spatiotemporal changes of drought events at different time scales were found to be close Correlation is likely to cause a socio-economic drought,which in turn will cause serious socio-economic impacts.(4)Using two statistical analysis methods,EOF and CEOF,from the perspective of the overall drought field of the watershed,to explore the deep-level laws of the spatial and temporal evolution of the drought in the YRB.The study found that:from the perspective of the comprehensive evolution of the time and space domains,the interannual drought field was discovered There are three main types,namely the uniform type of the whole basin,the reverse type of south-north and the reverse type of east-west,and the spatial distribution types represented by them are basically stable.Analyzed from the three evolutionary perspectives of time domain,space domain and frequency domain,it was found that the interannual drought field in the watershed mainly includes the whole basin type,the southeast-northwest inversion type and the east-west inversion type,and the three modes of drought and flood changes Has obvious spatial propagation characteristics.(5)A drought synthetic prediction model based on the sequence intrinsic information and drought prediction using the periodic change law of drought index,namely SSA-ARMA prediction model,was established and applied to the drought zoning prediction and spatial-temporal distribution prediction in the YRB.The application of predictive models found that most of the subareas are in a state of balance between drought;every year in the future will have its own typical distribution of drought.