Distribution And Spatial-temporal Variation Of Winter Wheat Based On Integrating Of Remote Sensing And Statistical Data

With the gradual deepening of quantitative research on a series of issues such as the effects of resource and environment,climate change,ecology,and disasters on the country’s or regional grain production systems,the accuracy of large-scale,long-term,and high-precision crop spatial distribution of basic agricultural scientific data Obtaining research on such issues as resources,environment,ecology,climate change and national food security has important practical and scientific significance.This study aimed at the weak points such as poor dexterity and low degree of automation in the threshold setting of the traditional thresholding method which was used to identify the crop identification.Taking the Jingxian County of Hengshui City,Hebei Province,the main grain-producing region of China as a typical experimental area,to carry out the research of using global optimization algorithm to improve the innovation of crop distribution mapping based on threshold detection.In this research,the winter wheat was taken as the research object,and the domestic high-resolution GF-1 was used as the main remote sensing data source.Under the support of the Shuffled Complex Evolution-University of Arizona(SCE-UA)and the hybrid evolutionary algorithm optimized for total control data and global parameters with crop area statistics,this paper proposes a winter wheat spatial distribution mapping method that uses threshold NDVI data to automatically optimize the threshold parameters of the threshold model.Finally,the optimal parameters of the winter wheat threshold model in the experimental area were obtained,and the spatial distribution of winter wheat was extracted using the optimized threshold parameters.Afterwards,the spatial distribution of winter wheat was extracted by using this research method in Huanghuaihai region which is the largest plain area in China.Through the use of MODIS NDVI remote sensing data covering the entire growing season of winter wheat in the region in 2001,2004,2007,2010 and 2013 and winter wheat planting area statistics for the municipal level and based on the total control global optimization threshold method,the spatial distribution of winter wheat in the 5th Huanghuaihai region was extracted,and accuracy was verified as well.Based on the spatial distribution of winter wheat in the Huanghuaihai area from 2001 to 2013 years,which is accurate to the pixel-scale,the changes of the planting area in each administrative scale,the latitudinal and latitudinal direction change characteristics,and the gravity center migration characteristics are analyzed.The main conclusions of the paper are as follows:(1)The ground verification of the identification results of winter wheat in the experimental area shows that the threshold parameter model optimization method of this study has a good total control effect on the classification results of winter wheat,and the classification accuracy reaches a high level.The overall accuracy is 97.03% and the Kappa coefficient is 0.94,both reaching a high level.Among them,winter wheat and other types of mapping accuracy were 97.48% and 96.00%,respectively,and user accuracy was 98.25% and 94.30%,respectively.Compared with the traditional thresholding method,maximum likelihood and support vector machine classification methods,this study has raised the overall winter wheat crop classification accuracy and Kappa coefficient by using the thresholdmodel optimization method.Among them,the overall accuracy increased by 4.55%,2.43%,and 0.15%,respectively,and the Kappa coefficient increased by 0.12,0.06,and 0.01,respectively.This proves that the global optimization algorithm based on total control of crop area statistics supports the optimization of the threshold model parameters under this study.The availability and feasibility of the crop distribution mapping method can obtain high precision winter wheat crop spatial distribution mapping results.(2)Using the method of spatial distribution extraction of winter wheat based on statistical data total control and global optimization algorithm that is proposed by this paper to optimize the sub-market for each subdivision in the Huanghuaihai region.As a result,a set of optimal threshold parameters for each city in the Huanghuaihai region from 2001 to 2013(3-year intervals)was obtained,and the spatial distribution of winter wheat in the study area was extracted using this parameter.The accuracy verification results show that the overall accuracy of the spatial distribution of winter wheat in the Huanghuaihai region is between 89% and 95%.The Kappa coefficient is between 0.85 and 0.93,and it meets the needs of users.(3)The total planting area of winter wheat in the Huanghuaihai region showed a fluctuating upward trend from 2001-2013,and the winter wheat planting areas in the southern provinces of Huanghuaihai Plain such as Shandong,Henan,Anhui,and Jiangsu increased significantly,while the winter wheat planting areas in Beijing,Tianjin,and Hebei in the northern Huanghuaihai Plain increased.Then the volatility drops.From a longitude point of view,the distribution direction of winter wheat in the Huanghuaihai region was mainly in the range of 114°E-116°E in the central and western parts of the Huanghuaihai region during 2001 to 2013.And the planting area of winter wheat showed a trend of significant undulating growth in core longitude,and other longitudes.Winter wheat planting area grows slowly and fluctuates.Looking from the latitudinal direction,during the period from 2001 to 2013,the core latitude of winter wheat planting in the Huanghuaihai region was 33°N,which mainly corresponds to the Yudong Plain,Wuanbei Plain,and Northern Jiangsu Plain in the southeast of Henan Province.(4)From 2001 to 2010,the core latitude was the winter wheat planting area in the area has increased significantly,with the area of growth exceeding 500,000 hectares.In 2010-2013,the planting area of winter wheat has been reduced.From 2001 to 2013,the geographic focus of winter wheat planting area in the Huanghuaihai Plain area was mainly concentrated in Heze City,Shandong Province,and the center of gravity was generally stable.Compared with 2001,the planting area of winter wheat in2013 shifted to the southwest by 27.73 km with an average moving speed of 2.31km/a.From 2001 to2013,the migration rate of winter wheat planting area gradually slowed down.The rate was fastest in2001-2004,and the longest migration distance.