The Evolution Of Cereal Crops Producing Pattern And The Effect Of Water Resources And Productivity In The Hebei Plain

Food security is related to a series of major issues,such as national sovereignty security,social stability and sustainable development of national economy,so food security is regarded as top priority by the nation and has caught the high attention of the nation.At the same time,water consumption of food crop problem is also a focus of the nation.Hebei plain is a important grain production base in China,but long-term irrigation has caused heavy losses of groundwater resource of Hebei plain,so the groundwater level of Hebei plain continues to decline.It is of great significance for protecting food security and water security of Hebei plain and across the nation to provide timely and accurate grain crop production and water consumption condition of relevant information of Hebei plain.The paper took Hebei plain as study area,based on temporal remote sensing data,using Harmonic Analysis of Time Series to reconstruct of MODIS NDVI time-series remote sensing data,then used the CART supervised classification algorithm and support vector machine to extract the planting area of winter wheat-summer maize and quarterly maize of Hebei plain in 2000-2016,discussed temporal-spatial variation characteristics of main food crop of Hebei plain in 2000-2016,analyzed its driving force of variation,using crop model to simulate yield and water consumption under different planting patterns in different areas of Hebei plain from 1986 to 2015,based on the difference of regional precipitation to analyze agricultural production of different areas in different precipitation years.According to the study,get the following main conclusions:(1)By using remote sensing image of 2000-2016 nearly 17 years,the spatial distribution of food crops in Hebei plain was identified.Through the accuracy test,we found that crop classification results was accurate and reliable.The classification results can be used to analyse and research temporal-spatial change of food crops in Hebei plain.(2)On the spatial distribution characteristics,growing areas of winter wheat-summer maize were mainly distributed in the mid-west region,south,northwest and mid-east region of Hebei plain,quarterly maize is mainly distributed in the northeast of Hebei plain.On the temporal-spatial variation of Hebei plain overall,winter wheat-summer maize planting area presented downward trend,mainly for the change of planting structure,economic development and urbanization in the region;Quarterly maize planting area showed a trend of rise and fall,this trend law mainly for the adjustment of agricultural production policy,maize price fluctuation and changes of farming irrigation.(3)By APSIM model to simulate the production and water consumption of a variety of planting patterns,the study showed that,in Hebei plain areas,two crops per year planting pattern had highest annual output,but also had the high water consumption,whose water loss was the most serious;three crops in two years(winter wheat-summer maize-early maize)planting patterns took account of both yield and water consumption,and it had the best comprehensive effect of production and water consumption.In addition,the precipitation resources had important significance for the high production or low production,and the difference of Hebei plain region precipitation was more obvious,so Hebei plain planting pattern of food crops should be changed,the focus of food crop production should be gradually shifted from ? area and ? area to ? area and ? region.