Analysis On Variation Of Soil Water Based On TDR

Soil water is the link of surface water, groundwarter, meteoric water and soil moisture, the most important factor in the formation, conversion and comsuption of water resource, and it is also a key factor of the SPAC, which was put forward by the Australian scholar. Soil water is the limiting factorof all the vegetation (including the crop). Research about soil water is the basis of agriculture development and sand fixation.The aim of this paper is to discuss the dynamic of soil water in the oasis and oasis-desert ecotone, and also about the difference of the two ground objects'soil water content and their change law, and the results show that:(1) There is a big difference between the oasis and oasis-desert's soil water content and change law. Affected by the human activity (especially the cultivation and irrigation), the soil water content of the farmland keeps a high level, it always increases drastically when irrigated. However, the soil water content of the oasis-desert has decreased gradually with the increasing evaporation in the hot season.(2) The laws of soil water content and their variation are different from each other of different vegetation coverage. Generally, with higher vegetation coverage, the ability of soil water conservation is stronger, also, the soil water content is high, the variation coefficient and the change rate are low, and that of the low vegetation coverage is opposite.(3) The water content of soil profile changes with soil depth obviously both in farmland and oasis-desert ecotone, however there is a difference between their change law and the change range. The highest water content layer of farmland is the crop root layer, which of the oasis-desert ecotone is the bottom, and the variation coefficient of oasis-desert ecotone is bigger than that of the farmland.(4) The temporal variation of soil water and soil temperature is obvious both in the irritation period and a daytime, and with a particular change law in the crop root layer. There is a signigicant negative relation between the soil water and soil temperature, and the relation equations of different periods have been developed using regression analysis method.(5) The spatial variability of farmland and the oasis-desert ecotone is distinct. With the geostatistics analysis, the spatial variability of soil water can be fitted to the spherical model and gaussian model respectively in early April. The soil water of farmland is better distributed, stronger spatial autocorrelation and bigger separation distance with the cultivation and irrigation, and these characters of oasis-desert ecotone is on the contrary.