Construction Of Southwest Drought Input-Output Model Based On Hyperbolic Tangent Function

Drought refers to the long-term without precipitation or abnormal in the climate background,due to the imbalance of water or supply and demand imbalance in the formation of water shortage phenomenon.Drought is a major natural disaster that endangers China's agricultural production,and it is also the most extensive meteorological disaster in China.In recent years,frequent drought events have brought huge economic losses to our country.Firstly,this paper analyzes the characteristics of drought in china.Based on the monthly precipitation of 613 meteorological stations in China during 1961-2010,the standardized precipitation index(SPI)was caculated,firstly.Then,the drought events were selected by using the run length theory,and the probability distribution fucnctions of drought intensity and drought duriation were tested by using K-S test.And on this basis that the joint probability distribution function of dought intensity and drought duriation was established by using the Compula function,and the influence of the revised and unrevised drought duration distribution function on different types dry joint probability and recurrence peroid was contrastively analyzed.The results show that the drought intensity variable conformed to Gamma disttibution,while the drought duriation didn't completely accord with the exponential function.Therefore,it was necessary to revise the drought duration distribution function so as to pass the K-S test.Under the revised drought duration distribution function condition,the joint probability of most drought types decreased,while that of a few increased,and the joint return peroid of different types drought increased.The difference of the maximum and minimum joint return peroid wasn't obvious as the intensity of drought increased under the same drought duration,but that obviously enlarged as the drought duration increased under the same drought intensity.In this study,by analyzing the characteristics of the drought disaster losses curve,we established a drought disaster losses assessment model based on a hyperbolic tangent function,and we also clarified the method for calculating the parameters in the model and their physical significance.The 6-month standardized precipitation index(SPI)index(6-month SPI)and direct economic losses(excluding inflation)were imported into the model as the independent variable and dependent variable,respectively,to build a drought disaster losses assessment model for southwest China.The initial values of the model parameters were determined according to the scatter diagram of the original data.The maximum correction coefficient and minimum residual summed squares were taken as the optimal fitting judgment criteria to obtain the optimal disaster losses assessment model.The direct drought disaster economic loss return value for southwest China during 2004-2013 was tested using the optimal disaster losses assessment model,where the correlation coefficient between the return value and the actual statistical value was 0.9,and the root mean squared error between the return value and the actual value was 57.74,thereby indicating that the difference from the return value was reasonable.Furthermore,the direct economic losses due to drought disasters in southwest China were estimated for 2014 and the estimated value was also very similar to the actual economic losses.Thus,the regional drought disaster damage assessment model established in this study is feasible and the drought disaster losses assessment model established for southwest China is reliable.Finally,this paper analyzes the indirect economic impact of agricultural drought on other industries in 2007 in southwest China by the input-output model in economics.Drought has a direct impact on the socio economy,and there is an indirect effect,while the quantitative effect of indirect effects is rarely studied.In this paper,the drought-sensitive and highly vulnerable agricultural economy was selected as the research object.The drought factor was added to the input-output model.The drought as a factor affecting the socioeconomic to study its economic impact on the southwest region.The results show that agricultural drought has some influence on other industries,and the more serious the agricultural losses,the greater the impact on other industries.The strong correlation between the industrial and agricultural production has a great impact,such as chemical industry,food manufacturing and tobacco processing,wholesale and retail;associated with agricultural production is not strong industry less affected,such as:social management and social organization,handicraft and manufacturing industry,postal industry.Industrial structure in various regions of Southwest China are different,Guizhou and Yunnan chemical industry the impact is greater than that of other industries,Sichuan and Chongqing and other industries affected by the relatively balanced.This also reflects from the side of the Sichuan and Chongqing industrial structure and the relevance of agriculture,in the same circumstances,the indirect economic losses caused by larger.