Abstract
The ecological environment of the Yellow River Delta is fragile, and the soil degradation in the region is serious. Therefore it is important to discern the status of the soil degradation in a timely manner for soil conservation and utilization. The study area of this study was Kenli County in the Yellow River Delta of China. First, physical and chemical data of the soil were obtained by field investigations and soil sample analyses, and the hyper-spectra of air-dried soil samples were obtained via spectrometer. Then, the soil degradation index (SDI) was constructed by the key indicators of soil degradation, including pH, SSC, OM, AN, AP, AK, and soil texture. Next, according to a cluster analysis, soil degradation was divided into the following three grades: light degradation, moderate degradation, and heavy degradation. Moreover, the spectral characteristics of soil degradation were analyzed, and an estimation model of SDI was established by multiple stepwise regression. The results showed that the overall level of reflectance spectra increased with increased degree of soil degradation, that both derivative transformation and waveband reorganization could enhance the spectral information of soil degradation, and that the correlation between SDI and the spectral parameter of (Rλ2+Rλ1)/(Rλ2-Rλ1) was the highest among all the spectral parameters studied. On this basis, the optimum estimation model of SDI was established with the correlation coefficient of 0.811. This study fully embodies the potential of hyper-spectral technology in the study of soil degradation and provides a technical reference for the rapid extraction of information from soil degradation. Additionally, the study area is typical and representative, and thus can indirectly reflect the soil degradation situation of the whole Yellow River Delta.
Highlights
Due to the large Chinese population and the increasingly smaller appropriation of per capita land resources, natural resources have been used unreasonably for a long time
Supposing that there are k evaluation indexes and that each index has n values representing n soil samples, Yij represents the ith value of the jth evaluation index, R = (Yij)n×k (i = 1,2,. . .n; j = 1,2,. . .k) is the normalized matrix after dimensionless treatment, Pij represents the proportion of Yij to the sum of all the index values, Ej represents the information entropy of the jth index, and Wj represents the weight of the index
Salinization was the main factor in the soil degradation in Kenli County, and the vegetation cover types of the soil degradation grades from heavy to light were as follows: seepweed, reed, cogongrass, rice and cotton, and wheat, respectively
Summary
Due to the large Chinese population and the increasingly smaller appropriation of per capita land resources, natural resources have been used unreasonably for a long time. Unreasonable use of land resources has caused serious damage to regional ecological. Hyper-spectral response and estimation model of soil degradation environments, causing an increase of the severity of soil degradation [1, 2]. The Yellow River Delta, located on the west coast of the Bohai Sea, is an important land resource reserve in China. It has a fragile ecological environment and serious salinization degradation under the impact of the dynamic systems of rivers, land, ocean, and other environmental factors [3,4,5].
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