宁夏典型灌区土壤盐渍化和地下水埋深时空变化特征及其关系研究OA

Characterizing the spatiotemporal variations of soil salinization and groundwater depth is crucial for controlling salinization and optimizing water use in irrigation districts.This study investigated a typical irrigation district in Ningxia—the lower Qingtongxia Irrigation District-using a combination of geostatistics and GIS to analyze the spatiotemporal changes and relationships between soil salinization in the 0~20 cm layer(2017 and 2024)and groundwater depth(2016-2023).Results showed that in 2017,salinized soil in the 0~20 cm layer accounted for 97.34%of the study area,with moderate and severe salinization covering 70.45%,exhibiting a continuous distribution from southwest to northeast.By 2024,the proportion of mildly or non-salinized soil increased from 31.55%to 68.51%,while moderate and severe salinization decreased from 70.45%to 31.56%.In 2024,soil salinity was highly concentrated at the surface(0~10 cm layer),primarily in the form of chlorides and sulfates,with carbonate ions being the main contributor to alkalization.From 2016 to 2023,the annual average groundwater depth showed an increasing trend,reaching 2.82 m in 2023-an increase of 0.34 m compared to 2016.Intra-annual monthly variations in groundwater depth consistently reflected irrigation patterns.Spatially,shallow groundwater depth increased over the years,decreasing from southwest to northeast and increasing from southeast to northwest within the study area.Statistical analysis identified that the critical groundwater depth thresholds for the occurrence of moderate and mild salinization were 2.16 m and 2.64 m,respectively.These findings provide a scientific basis for the graded and targeted control of soil salinization and the determination of appropriate groundwater depth thresholds in the lower Qingtongxia Irrigation District.