Abstract
Abstract Groundwater is the key factor of determining the growth of vegetation. Identifying the characteristics of groundwater is an important basis to formulate a management plan for water resources and develop the technology of controlling desertification in arid areas scientifically. It is also important to the environmental protection in China. Ground penetrating radar (GPR) signals produce a special response to the changes in water content during propagation, thus it is essential to study the propagation of electromagnetic pulse in aeolian sand with different water content. The GPR tests of aeolian sand samples with different water content were conducted by a GPR system, dielectric constant meter, and conductivity meter. The temporal and frequency spectral characteristics of electromagnetic signals measured from aeolian sand samples were analyzed. The results show that the dielectric constant and conductivity of aeolian sand increase nonlinearly as the water content increases, and the attenuation coefficient of electromagnetic pulses increases parabolically. Meanwhile, the temporal waveform fluctuates significantly at the boundary of different media, and its two-way travel time increases nonlinearly as the water content increases, the pulse velocity decreases nonlinearly. Furthermore, the peak frequency of the spectrum for a signal propagating through aeolian sand decreases as the water content increases. The peak frequency is concentrated in the 1000 to 1400 MHz range, but the shape and bandwidth of the spectrum are less affected by water content. The above-mentioned correlations can provide a water content estimation of aeolian sand with direct value to the local authorities which are involved in the decision-making process for effective water management in arid and semi-arid area.
Highlights
As an important component of an ecosystem, water plays a crucial role in agricultural filed, in the prevention of soil erosion and desertification, and in protecting of functional ecosystems, especially in the arid and semi-arid areas
Ground penetrating radar (GPR) signals produce a special response to the changes in water content during propagation, it is essential to study the propagation of electromagnetic pulse in aeolian sand with different water content
The results show that the dielectric constant and conductivity of aeolian sand increase nonlinearly as the water content increases, and the attenuation coefficient of electromagnetic pulses increases parabolically
Summary
As an important component of an ecosystem, water plays a crucial role in agricultural filed (e.g., vegetation growth, nutrient absorption, irrigation practices, optimizing crop yields), in the prevention of soil erosion and desertification, and in protecting of functional ecosystems, especially in the arid and semi-arid areas. To achieve efficient water management over large area, varying information about water content in cultivated and desertified region is much necessary, among which rapid assessment and monitoring of groundwater are receiving greater attention. As stated by several authors [3], the main problems of all these methods are the disturbance-destruction of water flow paths and occurrence space in soil mass, the inability of providing rapid data collection in large soil volume while most of the collecting ways are usually limited to point scale measures, except the approach of surface ground penetrating radar(GPR) and remote sensing. Considering the work principles and data quality, the GPR has apparent advan-
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