Study On The Influence Of Cover Types And Groundwater Depth On Soil Water Transport In The Southeast Margin Of Maowusu

Soil water movement,as one of the key processes in the terrestrial water cycle,is an important link connecting atmospheric water,groundwater,and soil water.The southeastern edge of Maowusu is located in the northwest arid region,and soil water is an important limiting factor for local ecological restoration and protection.It exhibits significant spatiotemporal differences due to the impact of precipitation intensity and frequency,vegetation coverage type,and groundwater depth.Its content changes are the foundation for the stability of the local ecosystem.Therefore,conducting research on the spatiotemporal variability and transport patterns of soil moisture under different groundwater depths and cover types can help deepen the scientific understanding of soil moisture movement patterns and land use optimization management in sandy areas,and provide a basis for scientific regulation of local soil and water resources and reasonable planting and water conservation.This article conducted in situ experiments on the Mu Us sandy land,selecting April 9,2022 to August 31,2022 as the research period.The study samples were bare land,grassland,and salix fields in deep and shallow underground burial areas.Field sampling,positioning monitoring,and numerical simulation techniques were combined to analyze the spatiotemporal dynamic characteristics of soil moisture in the sample plots;Through the dynamic process of precipitation soil water vegetation water consumption groundwater system,the impact of different cover types and groundwater burial conditions on soil water transport was clarified.The main research results are as follows:(1)By collecting monitoring data and analyzing,it can be concluded that the precipitation during the study period was 455.7mm,which is in a wet year.The variability of soil moisture in different surface layers is strong due to the influence of precipitation and evapotranspiration,while deep soil moisture is relatively stable;During the research period,the moisture content of bare land in deep groundwater burial areas showed an upward trend with increasing depth,while the moisture content in vegetation covered areas showed a bimodal characteristic;The overall soil moisture in various shallow burial areas shows an upward trend with increasing depth.The water content of various plots in deep burial areas is lower than that in shallow burial areas,indicating that groundwater level can significantly affect the distribution of soil water content profiles.(2)Based on a dynamic model,the differences in evapotranspiration and water balance of the sample plots under different cover types were quantified.The evapotranspiration of bare land,grassland,and salix land in the deep burial area are 284.1 mm,427.2 mm,and 395.2 mm,respectively.The water storage capacity of the soil is as follows: bare land(65.7 mm)>salix land(57.0 mm)>grassland(22.8 mm);The evapotranspiration of the three plots in the shallow burial area were 363.5 mm,616.9 mm,and 589.9 mm,respectively.The water storage capacity of the grassland remained basically unchanged,while the bare land and salix land increased by16.2 mm and 14.3 mm,respectively.The evapotranspiration and water consumption of each cover type under shallow burial depth are significantly higher than those in the burial depth area,and grassland evapotranspiration is the highest.Vegetation coverage in deep buried areas can intercept precipitation infiltration into deep soil,and vegetation coverage in shallow buried areas can help Groundwater recharge recharge soil water.At the same time,when the precipitation increases from 0.5 times to 1.5 times,the variation of soil leakage in various deep layers is as follows: bare land>sandy willow land>grassland,and in shallow buried areas,it is generally greater than deep buried areas.It indicates that vegetation can increase transpiration and hinder deep soil water leakage under heavy rainfall conditions,while it can accelerate the consumption of deep soil water or groundwater under light rainfall conditions..(3)Based on the dryness index,the soil water deficit status of different cover types of sample plots was evaluated.It was found that the average dryness index of bare land,grassland,and salix land in the groundwater depth burial area was 21.8%,34.15%,and 28.65%,respectively.The water deficit status of various plots was severe,and water deficit was evident at soil depths of 0-150 cm.Precipitation could only briefly reduce the degree of surface deficit;The drying index of various lands in the shallow burial area is-1.43%,11.82%,and-3.94%,respectively.Only 0-100 cm of soil has water deficit,which can be effectively alleviated under natural rainfall conditions.In addition,redundancy analysis shows that in deep groundwater areas,precipitation(18.4%),daily evaporation(17.47%),and temperature(12.87%)are key factors affecting the difference in soil moisture content;In shallow burial areas,precipitation(15.9%),air humidity(12.1%),and daily evaporation(10.13%)are key factors affecting soil moisture content.Groundwater burial depth and cover type can both affect the contribution of meteorological factors to changes in soil moisture content.