The groundwater table depth, which is typically shallow in coastal areas, is one of the decisive conditions impacting soil salinization. The influence mechanism of shaollow groundwater table depth change on the evolution of saline‐alkali land is still unclear. In this study, Huanghua City, a coastal city of the Bohai Sea in China, was selected as the research area, and four wells with groundwater table depths ranging from shallow to deep were studied. The groundwater table depth was divided into three levels based on the average groundwater table depth over 30 years, namely shallow, medium, and deep. We analyzed the influence of changes in groundwater table depth in each well on the evolution of saline‐alkali land within a radius of 2 km. The results showed that changes in groundwater table depth did not cause conversion between saline‐alkali land grades in shallow areas, whereas, in medium‐depth areas, changes in groundwater table depth caused conversion among saline‐alkali land grades. In deep areas, changes in groundwater table depth did not affect the conversion of moderate/heavy saline‐alkali land to non‐mild saline‐alkali land. The lower limit and upper limit of the groundwater table depth response threshold of saline‐alkali land were found to be 1.35 and 3.58 m, respectively, in this coastal area. When the groundwater table depth of saline‐alkali land remains lower than 1.35 m for a long period, it will become heavily salinized, one appropriate treatment measure in this instance is to plant saline‐alkali tolerant plants beacause improving saline‐alkali land by reducing the groundwater table depth is a challenge. When the groundwater table depth of saline‐alkali land remains greater than 3.58 m for a long period, changes in groundwater table depth will not influence the gradual reduction of salinization, the saline‐alkali land should be properly irrigated and drained to avoid secondary salinization caused by the groundwater level rising to the upper limit of the response threshold. When the water depth in saline‐alkali land remains between 1.35 and 3.58 m for a long time, the degree of salinization will change with the change in water depth, the underground water depth can be reduced under a subsurface drainage system in order to treat the saline‐alkali land. The research results can provide a scientific basis for improvement of saline‐alkali land.

中文翻译：

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地下水位埋深对沿海盐碱地演化的影响

沿海地区地下水位深度通常较浅，是影响土壤盐渍化的决定性条件之一。浅层地下水埋深变化对盐碱地演化的影响机制尚不清楚。本研究以我国渤海沿岸城市黄骅市为研究区域，对地下水位深度由浅至深的4口井进行了研究。根据30年平均地下水位深度，将地下水位深度分为浅层、中层、深层三个等级。分析了各井地下水位深度变化对半径2 km内盐碱地演化的影响。结果表明，浅层地区地下水位埋深的变化不会引起盐碱地等级的转换，而在中埋深地区，地下水位埋深的变化会引起盐碱地等级的转换。在深层地区，地下水位深度的变化不影响中/重度盐碱地向非弱盐碱地的转变。该沿海地区盐碱地地下水位深度响应阈值下限和上限分别为1.35和3.58 m。当盐碱地地下水位深度长期低于1.35 m时，就会出现严重盐碱化，此时适当的处理措施是种植耐盐碱植物，通过减少盐碱地的水位来改善盐碱地。地下水位深度是一个挑战。当盐碱地地下水位埋深长期保持大于3.58 m时，地下水位埋深的变化不会影响盐碱化的逐步减少，应对盐碱地进行适当的灌溉和排水，避免造成二次盐碱化。地下水位上升至响应阈值上限。当盐碱地水深长期保持在1.35～3.58m之间时，盐化程度会随着水深的变化而变化，可采用地下排水系统减少地下水埋深，以处理盐碱地的盐碱化问题。盐碱地。研究成果可为盐碱地改良提供科学依据。