| Cite this article: | 张晓春,刘海若,严忆辉,等.结合物候特征的农田土壤表层含水率遥感反演[J].灌溉排水学报,0,():-. |
| zhang xiaochun,liu hairuo,yan yihui,et al.结合物候特征的农田土壤表层含水率遥感反演[J].灌溉排水学报,0,():-. |
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| DOI： |
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| Remote Sensing Retrieval of Soil Surface Moisture Content in Farmland Combined with Phenological Characteristics |
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zhang xiaochun1, liu hairuo1, yan yihui1, tang rong1, zhang yu2
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1.State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University;2.Spatial Information Technology Application Research Department, Changjiang River Scientific Research Institute
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| Abstract: |
| 【Objective】Soil moisture is a necessary condition for crop growth. Soil moisture can not only affect various nutrients of soil dissolution, transfer and microbial activities, but also reflect local climate, vegetation, topography, soil texture and other natural conditions. The research of soil moisture content is widely used in many fields, such as ecological environment assessment, irrigation system compilation, waterlogging disaster monitoring and precision agriculture, etc. In meteorological standards, soil moisture content is the key parameter for monitoring soil moisture and analyzing the degree of crop waterlogging damage. At the same time, monitoring soil water content based on remote sensing images has the advantages of large monitoring time and space, fast analysis speed, economy and high efficiency. Therefore, the inversion of soil moisture content is of great significance for monitoring soil moisture content, reducing crop waterlogging damage and increasing crop yield. 【Method】A remote sensing retrieval method of farmland soil surface water content combined with crop phenological characteristics was adopted. Firstly, the incident angle data and the total backscattering coefficient under VV polarization are obtained based on the preprocessed Sentinel-1 SAR image, and the normalized difference vegetation index (NDVI) of crops at the corresponding date was extracted from the environmental satellite image. Then, based on the incident angle, backscattering coefficient and NDVI, the backscattering coefficient after removing the influence of vegetation was obtained through the water cloud model. According to the phenological characteristics of crops in the study area, the relationship between backscattering coefficient and soil relative volume moisture content was established in different growth stages, and an inversion model suitable for studying the phenological characteristics of crops in the study area was established. 【Result】According to the phenological characteristics of winter wheat and summer maize, the two rotation crops can be divided into four time period functions, which are sowing-tillering stage, overwintering stage, turning green stage-mature stage of winter wheat, and the whole growth period of summer maize. Then, the empirical equation of the relationship between soil moisture content and backscattering coefficient in each time period was obtained by calculating the data of soil moisture at some measured points in different growth stages, and the linear correlation coefficients were 0.40, 0.80, 0.91 and 0.79 respectively. By extracting the crop planting structure of Guzhen and Lixin, and combining with empirical equation inversion, the distribution map of surface water content of farmland soil in the study area was obtained. The inversion model was verified based on the remaining measured soil water content data, and the results showed that the total complex correlation coefficient of winter wheat during the whole growth period was 0.73, and that of summer maize during the whole growth period was 0.82. 【Conclusion】By establishing the function according to the phenological characteristics in different growth stages, it provides a fast and accurate method for inversion of soil surface water content in crop planting areas, and the results have good simulation accuracy in general rainfall years. From the results, this method is effective. |
| Key words: Soil moisture; Remote sensing inversion; Backscattering coefficient; Phenological characteristics; Crop region |
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