Soil water content(SWC)is a crucial parameter in ecology,agriculture,hydrology,and engineering studies.Research on non-invasive monitoring of SWC has been a long-lasting topic in these fields.Ground penetrating radar(...Soil water content(SWC)is a crucial parameter in ecology,agriculture,hydrology,and engineering studies.Research on non-invasive monitoring of SWC has been a long-lasting topic in these fields.Ground penetrating radar(GPR),a non-destructive geophysical technique,has the advantages of high resolution,deep detection depth,and high efficiency in SWC measurements at medium scale.It has been successfully applied in field investigations.This paper summarizes the recent progress in developing GPR-based SWC measurement methods,including reflected wave,ground wave,surface reflection,borehole GPR,full waveform inversion,average envelope amplitude,and frequency shift methods.The principles,advantages,limitations,and applications of these methods are described in detail.A comprehensive technical framework,which comprises the seven methods,is proposed to understand their principles and applicability.Two key procedures,namely,data acquisition and data processing,are emphasized as crucial to method applications.The suitable methods that will satisfy diverse application demands and field conditions are recommended.Future development,potential applications,and advances in hardware and data processing techniques are also highlighted.展开更多
Shrub encroachment into arid and semi-arid grasslands has elicited extensive research attention worldwide under the background of climate change and increasing anthropogenic activities.Shrub encroachment may considera...Shrub encroachment into arid and semi-arid grasslands has elicited extensive research attention worldwide under the background of climate change and increasing anthropogenic activities.Shrub encroachment may considerably impact local ecosystems and economies,including the conversion of the structure and function of ecosystems,the shift in ambient conditions,and the weakness of local stock farming capacity.This article reviews recent research progresses on the shrub encroachment process and mechanism,shrub identification and dynamic monitoring using remote sensing,and modeling and simulation of the shrub encroachment process and dynamics.These studies can help to evaluate the ecological effect of shrub encroachment,and thus,practically manage and recover the ecological environment of degraded areas.However,the lack of effective measures and data for monitoring shrub encroachment at a large spatial scale severely limits research on the mechanism,modeling,and simulation of shrub encroachment,and the shrub encroachment stages can hardly be quantitatively defined,resulting in insufficient analysis and simulation of shrub encroachment for different spatiotemporal scales and stages shift.Improvement in remote sensingbased shrub encroachment dynamic monitoring might be crucial for analyzing and understanding the process and mechanism of shrub encroachment,and multi-disciplinary and multi-partnerships are required in the shrub encroachment studies.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41571404)on project of State Key Laboratory of Earth Surface Processes and Resource Ecology.
文摘Soil water content(SWC)is a crucial parameter in ecology,agriculture,hydrology,and engineering studies.Research on non-invasive monitoring of SWC has been a long-lasting topic in these fields.Ground penetrating radar(GPR),a non-destructive geophysical technique,has the advantages of high resolution,deep detection depth,and high efficiency in SWC measurements at medium scale.It has been successfully applied in field investigations.This paper summarizes the recent progress in developing GPR-based SWC measurement methods,including reflected wave,ground wave,surface reflection,borehole GPR,full waveform inversion,average envelope amplitude,and frequency shift methods.The principles,advantages,limitations,and applications of these methods are described in detail.A comprehensive technical framework,which comprises the seven methods,is proposed to understand their principles and applicability.Two key procedures,namely,data acquisition and data processing,are emphasized as crucial to method applications.The suitable methods that will satisfy diverse application demands and field conditions are recommended.Future development,potential applications,and advances in hardware and data processing techniques are also highlighted.
基金supported by the National Natural Science Foundation of China[grant number 41571406]the Fund for Creative Research Groups of National Natural Science Foundation of China[grant number 41621061]the State Key Laboratory of Earth Surface Processes and Resource Ecology at Beijing Normal University[grant number 2015-ZDTD-011].
文摘Shrub encroachment into arid and semi-arid grasslands has elicited extensive research attention worldwide under the background of climate change and increasing anthropogenic activities.Shrub encroachment may considerably impact local ecosystems and economies,including the conversion of the structure and function of ecosystems,the shift in ambient conditions,and the weakness of local stock farming capacity.This article reviews recent research progresses on the shrub encroachment process and mechanism,shrub identification and dynamic monitoring using remote sensing,and modeling and simulation of the shrub encroachment process and dynamics.These studies can help to evaluate the ecological effect of shrub encroachment,and thus,practically manage and recover the ecological environment of degraded areas.However,the lack of effective measures and data for monitoring shrub encroachment at a large spatial scale severely limits research on the mechanism,modeling,and simulation of shrub encroachment,and the shrub encroachment stages can hardly be quantitatively defined,resulting in insufficient analysis and simulation of shrub encroachment for different spatiotemporal scales and stages shift.Improvement in remote sensingbased shrub encroachment dynamic monitoring might be crucial for analyzing and understanding the process and mechanism of shrub encroachment,and multi-disciplinary and multi-partnerships are required in the shrub encroachment studies.
