Monitoring the seasonal dynamics of soil salinization in the Yellow River delta of China using Landsat data

• Main Authors: H. Chen, G. Zhao, Y. Li, D. Wang, Y. Ma
• Format: Article
• Language: English
• Published: Copernicus Publications 2019-07-01
• Series: Natural Hazards and Earth System Sciences
• Online Access: https://www.nat-hazards-earth-syst-sci.net/19/1499/2019/nhess-19-1499-2019.pdf
• ISSN: 1561-8633; 1684-9981

<p>In regions with distinct seasons, soil salinity usually varies greatly by season. Thus, the seasonal dynamics of soil salinization must be monitored to prevent and control soil salinity hazards and to reduce ecological risk. This article took the Kenli District in the Yellow River delta (YRD) of China as the experimental area. Based on Landsat data from spring and autumn, improved vegetation indices (IVIs) were created and then applied to inversion modeling of the soil salinity content (SSC) by employing stepwise multiple linear regression, back propagation neural network and support vector machine methods. Finally, the optimal SSC model in each season was extracted, and the spatial distributions and seasonal dynamics of SSC within a year were analyzed. The results indicated that the SSC varied by season in the YRD, and the support vector machine method offered the best SSC inversion models for the precision of the calibration set (<span class="inline-formula"><i>R</i>²&gt;0.72</span>, RMSE&thinsp;<span class="inline-formula">&lt;</span>&thinsp;6.34&thinsp;g&thinsp;kg<span class="inline-formula">⁻¹</span>) and the validation set (<span class="inline-formula"><i>R</i>²&gt;0.71</span>, RMSE&thinsp;<span class="inline-formula">&lt;</span>&thinsp;6.00&thinsp;g&thinsp;kg<span class="inline-formula">⁻¹</span> and RPD&thinsp;<span class="inline-formula">&gt;</span>&thinsp;1.66). The best SSC inversion model for spring could be applied to the SSC inversion in winter (<span class="inline-formula"><i>R</i>²</span> of 0.66), and the best model for autumn could be applied to the SSC inversion in summer (<span class="inline-formula"><i>R</i>²</span> of 0.65). The SSC exhibited a gradual increasing trend from the southwest to northeast in the Kenli District. The SSC also underwent the following seasonal dynamics: soil salinity accumulated in spring, decreased in summer, increased in autumn and reached its peak at the end of winter. This work provides data support for the control of soil salinity hazards and utilization of saline–alkali soil in the YRD.</p>