Study On Yield Estimation Of Winter Wheat By Remote Sensing In Yucheng Based On CASA Model

The food is fundamental to people engaged in various production activities,stability and development in relation to the whole society.Winter wheat is the main crop in Northern China's grain production,and its production is seriously threatened in today's increasingly serious environmental pollution.Therefore,it is very important to monitor the growth of winter wheat growth cycle,analyze of key factors affecting its growth,estimate the yield of winter wheat,and strengthen the supervision to protect the growth of winter wheat.Using remote sensing data,solar radiation data,temperature data,temperature data and land use data,CASA model was used to estimate the NPP of winter wheat in Yucheng in 2015.Moreover,the distribution of NPP of winter wheat and the importance of each factor were analyzed in this paper.Finally,the yield of winter wheat was estimated through the transformation model in Yucheng City,and it was compared with the measured data to verify the accuracy of the model.The main contents are as follows:(1)Estimate the important parameters of CASA model,such as vegetation coverage index,net solar radiation,total solar radiation,and the ratio of vegetation to photosynthetically active radiation.Revise the important parameters in CASA model,the main revision of winter wheat on the vegetation coverage index and maximum light use efficiency,through the data query,combined with the actual situation of Yucheng City,the important parameters in Yucheng City simulation.(2)Through the analysis of the results of NPP,the tempo-spatial distribution of net primary productivity in Yucheng from October 2014 to 2015 was analyzed.The results showed that the NPP of winter wheat showed a decreasing trend from October2014 to January 2015.From January to May 2015,the NPP of winter wheat increasedrapidly,the growth rate increased significantly,and NPP reached the highest value in the year of May.With the maturity and harvest of winter wheat,winter wheat NPP decreased significantly after entering June.NPP showed different growth period of Winter Wheat in Yucheng City.The seedling total NPP reached the maximum value of193.5gc/m2,the total growth period of NPP reached the maximum value of208.66gc/m2,the mature period of total NPP reached the maximum value of582.94gc/m2.In addition,from October 2014 to June 2015 in Yucheng City,the winter wheat total maximum NPP value is 916.84gc/a,the regional average for612.76gc/a.The mean value of NPP of Winter Wheat in 11 towns in Yucheng was not obvious,and the NPP value was higher than 500gc/m2.The average NPP value of winter wheat was higher.The difference between the total NPP and the mean value of NPP in 11 towns of Yucheng is relatively large,and the distribution of the whole NPP is uneven,the highest of which is the temple and the town,which is 39216gc/a,which accounts for more than 30% of the total amount of winter wheat.(3)To construct the yield conversion model,and calculate the yield of Winter Wheat in Yucheng in 2015 with the NPP value.By constructing the yield conversion model,combined with the Yucheng City Winter Wheat NPP estimation results,obtained in Yucheng City 2015 winter wheat yield estimation simulation results,2015 Yucheng winter wheat yield is 6296.4kg/hm2,lower than the winter wheat yield in Yucheng city in 2015(6847.5kg/hm2),winter wheat yield is mainly distributed in4000~8000kg/hm2,and the yield distribution in the area of small 0~4000kg/hm2 and8000~10000kg/hm2.To verify the accuracy and yield estimation model by statistics,the absolute error of 11 townships in Yucheng city with an average of-293.4kg/ hm2,the average relative error is-4.76%,the precision can meet the basic requirements of winter wheat yield estimation.