Архив метки: satellite imagery

METHODOLOGICAL APPROACHES TO ASSESSING THE STATE OF IRRIGATED LANDS IN THE DRY STEPPE ZONE OF THE VOLGOGRAD REGION USING SATELLITE IMAGES

Ecology and dynamics Опубликовано автором

Gorokhova I.N., Pankova E.I. Methodological Approaches to Assessing the State of Irrigated Land in the Dry Steppe Zone of the Volgograd Region Using Satellite Images // Ecosystems: ecology and dynamics. No 1. 2023. P. 38-65. | Abstract | PDF | Reference

 

In this article we present the materials of studies that were carried out in the Volgograd Region. They can be used as the basis for methodological recommendations to map and determine the area and condition of irrigated lands using satellite images. They were obtained during the long-term researches in the irrigated lands in the Volgograd Region that took place on solonetz complexes in the dry steppe. Satellite imagery will help to map and determine 1) the areas of irrigated lands, 2) the areas and age of fallow lands in irrigated territories, 3) the state of irrigated soils and factors that limit their fertility. Crops growing in different hydrogeological conditions react differently to those limiting factors. Therefore, to compile a map it is recommended to adhere to such stages as identifying fields with different crops and fallow lands; highlighting patches in the images with sparse or absent crops; on the basis of field researches and analyzed soil samples, establishing the cause of the patchiness; selecting an algorithm for processing satellite images based on the results of field researches. The patchiness of irrigated fields, reflected in the images, can have a different origin, so their interpretation requires a mandatory study of the characteristics of the chosen area. Patchiness associated with secondary and residual salinization of soils is determined by the state of vegetation; therefore, the pictures should be taken during the period of high vegetative activity of plants. Among other things, it is necessary to obtain data on the level of groundwater, because its critical level is the main cause of secondary salinization. For deeply saline soils, it is necessary to build a salt map using interpolation of point data that was obtained in the field and laboratory. Patchiness associated with the carbonate content in the surface horizon does not depend on the level of groundwater and is best seen on the images showing an open soil surface. The accuracy of the map is checked by comparing it with maps of a larger scale and field observations, as well as by evaluating the accuracy of the classification of the image by determining the verification indexes. The materials presented in our article are intended for a wide range of specialists who use space information in their work, as well as for soil scientists, agronomists and chemists who work in agriculture in the southern regions of Russia.

Keywords: dry steppe zone, irrigated lands, saline soils, satellite imagery, mapping of irrigated soils.

Funding. This work was carried out for the State Assignment No. 0439-2022-0009 “To Study the Transformation, Evolution and Degradation of the Soil Cover of Agricultural Landscapes at Different Organizational Levels, Including Intra-field Heterogeneity Using a Combination of Ground Surveys and Digital Technologies”.

DOI: 10.24412/2542-2006-2023-1-38-65

EDN: BLIRXH

SATELLITEDATA TO HELP DISTINGUISHCALCAREOUSSOILS IN THE VOLGA-DON IRRIGATION SYSTEM, VOLGOGRAD REGION

Ecology and dynamics Опубликовано автором

Gorokhova I.N., Chursin I.N., Khitrov N.B., Kruglyakova N.K. Satellite Data to Help Distinguish Calcareous Soils in the Volga-Don Irrigation System, Volgograd Region // Ecosystems: ecology and dynamics. No 1. 2023. P. 92-114. | Abstract | PDF | Reference

 

In this study we substantiate the importance of identification of the areas with calcareous soils on the key plot of the “Oroshayemaya” experimental station that belongs to the Volga-Don irrigation system, Volgograd Region, using high-resolution satellite data (Pleiades). Carbonates in soils have both a positive and a negative impact; therefore, it is important to identify such soils. We identified calcareous areas on the satellite images, judging by the spots of various degrees of soil effervescence on the surface, caused by HC1 solution, which, in its turn, was detected via the contact method in the cultivated fields. After that we determined a relationship between the spectral brightness of soil effervescence in different channels of the satellite image and its degree. In order to do this, we took a sample of pixels from the images that corresponded to the patches of surface effervescence in the terrain that was previously used in the Random Forest algorithm to select classes in the image. The results showed that identification of the areas with surface layer of calcareous soils (soil effervescence), using satellite data, will be the most optimal if the field research and the survey data took place during the dry season of the year, i.e. from May to July.

For image processing the images of open fields should be used, while the undeveloped ones should be ignored. It is also necessary to exclude patches of meadow and meadow-chestnut soils from the sample, since they are usually located in depressions and can interfere with calculations due to the carbonates that flow in from the side. It is best to allocate the areas of calcareous soils within a single field or within a group of fields with similar brightness level; different brightness levels indicate different types of land use, such as dry farming and irrigated fields. Such a differentiated approach allows the precision of soils classification on the satellite image reach 0.75-0.90, based on the degree of their effervescence (no effervescence, weak, average, strong). However, when the entire key plot is processed, only the soils with “strong effervescence” or “no effervescence” can be identified with the precision of 0.7. The novelty of our work results lies in the substantiation of the possibility to reliably identify (while following all the requirements) calcareous soils on the ground surface by using high-resolution satellite data together with field survey data.

Keywords: calcareous soils, soil effervescence, degree of soil effervescence, open surface, satellite imagery, spectral brightness, classification precision, Volgograd Region.

Funding. This work was carried out for the state assignments No. 0439-2022-0009 “To Study the Transformation, Evolution and Degradation of the Soil Cover in the Agricultural Landscapes at Different Levels of Organization, Including the Heterogeneity of Their Fields and Using Ground Surveys along with Digital Technologies”.

DOI: 10.24412/2542-2006-2023-1-92-114

EDN: CXMSUO