Guan'gai paishui xuebao (Jan 2023)
Evaluating the Efficacy of Channel Lining in Ameliorating Soil Salinization in Hetao Irrigation District Using Satellite Imageries
Abstract
【Objective】 Most channels in Hetao irrigation district have been linned in attempts to reduce seepage and ameliorate soil salinization, but there is lack of understanding of its efficacy at district scales. This paper is to fill this knowledge gap using remote sensing technologies. 【Method】 The analysis was based on Landsat8 multispectral satellite imageries, and saline-alkali soils in the irrigation district were automatically extracted using the ISODATA clustering method. A buffer zone wide d on both sides of each channel was identified using a spatial analysis method, saline-alkali area and the salinization index (φ) in which were statistically analyzed. 【Result】 Saline-alkali soil area decreased significantly on both sides of the channel after the lining, and spatial distribution of the saline-alkali soils is in a trapezoid-shape. From 2013-2016, the salt-alkali soils within the 500m proximal to the channels had reduced from 49.63% to 86.81%, depending on locations, while within the 1 000 m and 1 500 m adjacent to the channels, they had reduced from 47.95% to 95.06%, and from 54.56% and 95.68%, respectively. Soil texture will affect the change of saline-alkali land area, and the area of saline-alkali land decreases faster in the region with low soil clay. 【Conclusion】 ① Satellite remote sensing technology is feasible to evaluate the salt control effect of large-scale channel projects. ② The spatial distribution pattern of saline-alkali land changed from uniform distribution to aggregation distribution after canal lining. ③ The channel lining project effectively inhibited the soil salinization process on both sides of the saline-alkali land. ④ Soil texture indirectly affects the treatment effect of lining engineering. The treatment effect of lining engineering is more obvious in the area with lower soil clay.
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