The Research Based On The MODIS Data Of Soil Moisture In Yulin

Soil moisture is an important index for monitoring land degradation. Compared with the soil moist area and soil dry area, the wind erosion and soil desertification degree is more serious in the soil moist area. Using remote sensing technology we can quickly and accurately get the soil moisture condition. This research is based on previous researches. Though comparing the characteristics of the regional and the modelm, we believe that the vegetation coverage of Yullin is low in the dry season and can use the Apparent thermal inertia(ATI).In this paper, we take the day and night MODIS-L1 B of Yulin in 2014.4.25,2013.10.25、11.28 as the basic data, Using the ENVI software, with apparent thermal inertia model for quantitative inversion basis, and we can get three ATI image. Based on the images, we analysis soil moisture conditions of Yulin area from two aspects of time and space, and dra conclusions as follows:In time, after the summer rainfall, the soil moisture condition of Yulin is good. But as passage of time, the water in the soil goes, which is closely related to rainfall.On the space, the soil moisture of Yulin present the trend from southeast to northwest, which is closely related to the local soil texture、climate、geological landforms. Southeast area is mainly yellow spongy soils and water retention is good. Northwest area is mainly sand soil and water retention is poor. The transition region of southeast and northwest continuous sand, water retention ability in general; In terms of climate, southeast of Yulin influenced by southeast monsoon faint, and the influence degree along the northwest is reducing; In terms of geological features, the northwest area is sand meadow, with high and flat topography, which is vulnerable to northwest wind erosion. Southeast is the loess hilly-gully region with low altitude, which is hard to wind erosion. Just the reason, in space, Yulin soil moisture declines from southeast to northwest. But in combination with land use types, we find that the sandy area covered with trees compared with the continuous sand area without trees, the soil moisture condition is same. Thus it can be seen that afforestation is good for sand-fixation and keeping soil moisture.