Study On Distribution Characteristics Of Soil Water Content In Xilingol Grassland

Soil moisture content refers to the amount of water contained in the soil,which is divided into mass moisture content and volume moisture content.The dry and wet conditions of the soil are closely related to the physical and chemical properties of the soil.Monitoring of ecological environmental changes,environmental recocery,water resources dynamics,and agricultural production are all closely related to soil moisture content.Therefore,monitoring of soil moisture content is of great significance to the environment,agriculture,and water resources management.The acquisition of soil moisture content includes field measurement and model simulation.There is no doubt the measured data is relatively accurate,but it can only measure the point data,and it is limited in time and space,and cannot meet the needs of large-scale real-time monitoring;Remote sensing method has a unique advantage in space and time because of its long-term and large scale monitoring.It overcomes the shortage of field measurement methods,but the results of remote sensing inversion inevitably have certain deviations..Therefore,using measured data to correct and verify the results of remote sensing inversion,combining them is a scientific and effective monitoring method.This method can be used for reference and reference for further study of soil moisture content and related research..This paper uses the soil moisture meter TZS-1K to measure the soil moisture in the Xilin Gol League from May to September 2017.the surface water content index SWCI is used to measure the soil moisture content of the Xilin Gol League in 2000-2017 based on MODIS data,.The remote sensing inversion was carried out and corrected with historical measured data.The inversion results of remote sensing were also verified with the actual measured data in 2017,which shows that the method was feasible.The conclusions of this paper are as follows:(1)Through field analysis of field measurements in 2017,it was shown that the change in soil water content in the same layer of soil water content was basically that of desert grassland <typical grassland <meadow grassland;the soil moisture content of each type of grassland in the vegetation growing season.0-30 cm changes greatly,there is no fixed rule to be found,and the change is slow in 30-50 cm.The ratio of accumulated precipitation and average temperature(P/T)is positively correlated between soil moisture and P/T in each layer.The 0-10 cm of the surface layer has the greatest correlation and the maximum correlation coefficient is reached 9 days before the date of the measurement point.The soil layer above 30 cm is affected by the precipitation and temperature in a certain period of time,but the soil layer under 30 cm is not affected by prolonged precipitation and temperature.The deep soil moisture of 40-50 cm is only significantly related to the change of weather conditions in a short time.(2)In this paper,remote sensing models were used to invert soil moisture in the growing season(April-September)in 2000,2003,2007,2012,2015,and 2016,and in July of each year in 2000-2017.The results showed that regardless of the year,the soil moisture distribution in the Xilin Gol League has gradually increased from the southwest to the northeast.The soil moisture in desert grassland is generally low,ranging from 3% to 9.5%;the soil moisture content in typical grasslands is moderate,most areas are between 9.5% and 12%,and a small part is above 12%;Taipusi Banner in the south Duolun County and Duolun County belong to the farming-pastoral ecotone,agricultural irrigation water supply,water content is more,and Duolun County has abundant water resources and forest resources,resulting in high soil moisture content.The moisture content of meadow grassland is generally above 12%,and the soil moisture content in the upper reaches of Dongwuzhumuqin Banner,Xiwuzhumuqin Banner and Xilin River Basin is generally higher than other regions.In the years with abundant rainfall,the areas with high soil moisture content increased significantly;In the year of lack of precipitation,the areas with high soil moisture content are significantly reduced,and the year of flat water is middle.In the Midwest of East Ujimqin Banner,west of West Ujumqin Banner,Xilinhot,northern Abaga Banner and Taipusi Banner,the soil water content changes in different years are significantly higher than in other regions.By analyzing the correlation of soil moisture content with temperature and precipitation,it was found that the correlation between soil moisture content and precipitation was 0.58(P<0.05),and the correlation with air temperature was-0.68(P<0.01),both showing significant correlation,indicating that the temperature Precipitation largely affects the change in soil moisture content.