Influence Of Shallow Groundwater Level Change On Surface Energy Balance

The surface energy balance system includes net radiant flux,sensible heat flux,latent heat flux and soil heat flux.The heat exchange and evapotranspiration process between the surface energy and the atmosphere and its water cycle are closely related.The influence of underlying surface factors on surface energy is particularly important.Shallow groundwater has a greater impact on surface energy balance components through factors such as soil water content,surface temperature and long-wave radiation.The water source of Hatoucaidang is located in the hinterland of the arid and semi-arid Maosuwu Desert,with shallow groundwater level and abundant water.A newly-built water source for water supply in Kangbashi New District of Ordos City.This article conducts research on the impact of groundwater on the surface energy balance,which is helpful to explore the role of groundwater on the regional water cycle from the perspective of energy balance,and provides a scientific basis for the sustainable use of regional water resources and ecological environment protection.This time,the water source of Hatoucaidang was selected as the research area,and remote sensing images of different months of 2018 were selected in the study area,combined with the dynamic monitoring data of the water level of the in-situ test site and the water source of Hatoucaidang,using numerical simulation methods and remote sensing Technology,using the SHAW model to explore the temporal and spatial changes of groundwater level changes on the surface energy balance components on the site scale,and apply the SEBAL model to study the relationship between the surface energy balance components and groundwater on the regional scale.Research indicates:(1)Under typical weather(rainy days)at the test site,the impact of changes in groundwater depth on the various components of the surface energy balance system has seasonal characteristics.The characteristics of surface energy changes are: sensible heat flux is dominated in spring;sensible heat flux and latent heat flux are dominated in summer;latent heat flux is dominated in autumn.(2)Based on the SHAW model,it is found that the vegetation reaches the optimal growth state in the range of 0.5-0.7m groundwater depth,and the energy exchange between the earth and the atmosphere is mainly the latent heat flux.In the aeolian sand soil medium,the influence boundary of groundwater on the energy balance system is 0.2-1.6m.(3)The depth of groundwater is the main influencing factor of net radiant flux and latent heat flux in summer,and the main influencing factor of sensible heat flux in spring.(4)The SEBAL model has obvious seasonal deviations in the estimation results of soil heat flux at the headwaters of Hatoucaidang.The estimated results were better from April to October.In March and November due to the freezing and thawing of the soil,the estimated value was significantly larger than the actual measured value.