Quantitative Determination of the Optimal Scale for the Proportion of Saline-Alkali Patches of Soda Saline-Alkali Land in Northeast China
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING(2024)
摘要
As an important index reflecting the degree of soil salinization and alkalization, the proportion of saline-alkali patches (PSP) is beneficial for identifying the degree of saline-alkali land on a large scale with high spatial heterogeneity. However, determining the optimal scale for observing PSP remains inconclusive. In this article, we considered a typical area of saline-alkali land, which is located in Da'an City in Northeast China, as an example and selected nine sample areas from the sentinel-2A remote sensing images to calculate the salt index. According to the semivariogram function, we obtained the spatial autocorrelation range of the average radius of saline-alkali land. By combining the Nyquist-Shannon sampling theory, we determined the optimal scale for the remote sensing monitoring of saline-alkali land in Da'an City. The PSP index is calculated using this scale. The results were as follows: First, the optimal scale for the remote sensing monitoring of saline-alkali land in Da'an City is 41.2 m, and the calculated PSP index at this scale has the best correlation with the measured pH value data (R-2 = 0.828). Second, Using the PSP index calculated at this scale, we divided the degree of saline-alkali land in Da'an City into three grades. Among them, the slightly, moderately, and severely saline-alkali lands cover areas of 90.52, 111.78, and 959.77 km2, respectively. In this article, we propose a new method for grading the degree of soil salinization and alkalization on land with high spatial heterogeneity, providing technical support for the utilization of saline-alkali land.
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关键词
Grading and mapping,optimal scale,semivario- gram function,soda saline-alkali land in Northeast China,the proportion of saline-alkali patches (PSP)
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