Abstract:

To explore the law of water and salt transportation under different improvement modes of saline-alkali land in the Yellow River Delta, this study innovatively adopted a combination of continuous dynamic monitoring ( June-November 2024 ) and multi-factor ( soil-groundwater-drain ) comprehensive analysis. Taking Kenli District of Dongying City as the research area, the response mechanism of water and soil environment in the process of saline-alkali land improvement was systematically studied through field fixed-point sampling. The results showed as follows. (1) Under the condition of subsurface pipe drainage, the soil total salt content in the rice-improved area decreased by 82.81%-91.73% at the end of the growth period, which was significantly higher than that in the rain-fed area (71.79% -81.54%). (2) Following the conversion to rice cultivation, the soil pH increased, and salt leaching led to a pH increase of 6.55%-13.10%, showing a typical 'desalination and alkalization' feature; Notably, except for HCO₃^-, there was a significant correlation observed between other ion indicators, total salinity and soil pH. (3) The total salt content of groundwater was driven by irrigation-precipitation coupling, showing a trend of increasing first and then decreasing. The buried depth from July to September was generally <1.2 m, and the water quality from August to November (total salt content >2g/L) exceeded the standard of farmland irrigation and should not be directly used for farmland irrigation. The results of this study can provide some theoretical and technical support for the regulation and control of soil salinization in the Yellow River Delta.

Key words: soil salinity, soil ions, groundwater quality, drainage ditch water quality, total salt content