荒漠湿地小流域土壤储水量季节变化特征研究

Study on seasonal variation characteristics of soil water in small basin of desert wetlands

【目的】借助SWAT模型模拟长时间序列优势分析荒漠湿地小流域土壤储水量的时空格局变化,为小流域生态植被建设提供科学依据。【方法】通过构建适用于荒漠湿地小流域的SWAT模型,模拟南海子小流域0~2.5 m土层的土壤储水量变化趋势,揭示不同植被类型和不同土壤类型土壤储水量时空变化特征。【结果】流域土壤储水量2020—2022年年内变化均呈现先上升而后下降趋势,月均土壤储水量范围为25.95~103.66 mm之间;各月份波动较大,与降水呈现明显的正相关;流域土壤储水量具有明显空间异质性,不同植被类型土壤储水量值总体表现为灌木>乔木>草本。【结论】结果表明:降水波动是引起土壤储水量变化的首要因素,土壤储水量具有随降水波动的明显季节性变化;流域土壤储水量在空间上呈现自西北向东南增加的趋势,草地对降水响应最敏感,林地对降雨的响应最为平稳;草甸土、风沙土、黄绵土、灰钙土4种土壤类型由于降雨的季节性波动均呈现相应的季节变化过程,但不同土壤类型对降水的响应存在差异。通过分析南海子荒漠湿地小流域土壤储水量变化特征,为荒漠地区区域水资源合理配置和指导干旱半干旱区开展科学的植被恢复工作提供理论依据。

[Objective]Aiming at providing a scientific basis for the construction of ecological vegetation in small watersheds,the spatial and temporal patterns of soil water storage in desert wetland small basin were analyzed with the advantage of simulating long time series by SWAT model.[Methods]By constructing the SWAT model applicable to the desert wetland sub-basin,the change trend of soil water storage in the 0-2.5 m soil layer of Nanhai small basin was simulated to reveal the spatial and temporal change characteristics of soil water storage of different vegetation types and different soil types.[Results]Soil water storage in the watershed showed an upward and then downward trend from 2020 to 2022,and the monthly average soil water storage ranged from 25.95 to 103.66 mm.It fluctuated greatly in each month and showed an obvious positive correlation with precipitation.Soil water storage in the watershed had obvious spatial heterogeneity,and the overall soil water storage values of different vegetation types showed the overall soil water storage values of different vegetation types were shrubs>trees>herbs.[Conclusion]The result indicate that:Precipitation fluctuation is the primary factor causing soil water storage changes,and soil water storage has obvious seasonal changes with precipitation fluctuation.Soil water storage in the watershed shows a spatial trend of increasing from northwest to southeast,with grassland being the most sensitive to precipitation and woodland being the most stable to rainfall.The four soil types of meadow soil,wind-sand soil,yellow cotton soil and gray calcium soil show corresponding seasonal changes due to seasonal fluctuation of rainfall.However,the response of different soil types to precipitation varies.By analyzing the characteristics of soil water storage changes in Nanhaizi desert wetland small basin,we can provide theoretical basis for the rational allocation of regional water resources in desert areas and guide the scientific vegetation restoration work in arid and semi-arid areas.