In
arid and semiarid areas soil
moisture is the most importa nt factor which restricts vegetation growth It is very important
to
research dyna mics of soil moisture in these areas The technology of measuring soil moisture content has made great progress in these years Neutron Probe and Time Domain R eflectometry have been normal meters of measuring soil moisture content There a re some new instruments to be invented recent years and it is trend that new ins truments become more and more accurate and automatic Temporal and spatial varia bility of Soil moisture content is obvious Change of season influences the dyna mical behavior of soil moisture, and as soil depth and spot different, soil mo isture varies Precipitation is the most important factor which influences soil moisture Other meteorological factors such as air temperature, solar irradiati on have some influence to soil moisture, too Furthermore, Environmental attri butes such as vegetation,land use and topography such as aspect, slope gradien t, hillslope position play controlling roles in the distribution of soil moistu re content So the phenomenon of the temporal and spatial variability of Soil mo isture content is the result of influence of all factors Now the emphasis of so il moisture dynamical study should be factors of influencing soil moisture conte nt Dry valley is a special arid region in our country, but research of soil mo isture dynamics needs lucubrate in these areas