| Soil salinization is the process of soluble salts accumulation more than 0.1% in the soil surface, which transport from deep soil or groundwater by the soil capillary water. It is a crucial environmental hazards mainly exist in arid, semi-arid or sub-humid regions.The spatial distribution of soil salinization is affected by the dynamic changes of water and salt in the soil. Because of water and salt transportation occur simultaneously, if only a single study salt or water, the formation mechanism of saline soil can not explain. In the arable area of an oasis, the distribution of soil salinization status directly affects the development of farming. Once the salt content exceeds the level of normal crop farming would cause the degradation of oasis environment, which inhibit the growth of crops, causing soil compaction and vegetation cut or death and so on. Study on spatial and temporal changes in soil moisture and salinity in the arid area of oasis has become a top priority. Soluble salts include Na+、K+、Ga2+、SO42-、Cl-、CO32-、HCO3-. In addition to the carbonate and bicarbonate is alkaline, the other almost all neutral salts. Ugan- Kuqa River Oasis is an oasis of locally quarried relatively earlier, along with the increase of human activities, over-exploitation, unreasonable irrigation water and waste, soil salinization and other issues, finally resulting the deterioration of the ecological environment. In oasis irrigation area. Oasis is the quintessence of the arid region, based on water is not only the survival and development of oasis, oasis agriculture is the blood of the oasis, soil and vegetation spatial pattern of different types of attachment to the distribution of water resources in the state space [1], therefore, to study the variation of soil water and salt in the study area in terms of time and space, can provide a scientific basis for the improvement of soil salinization.Xinjiang is located in the drought, saline soils in the soil resources accounts for a larger proportion. So, salinization is always a block in the sustainable development of agricultural production factors, and to understand the space-time change of soil water and salt and improvement of soil salinization is essential. Wei Gan He- kuqa river oasis as the study area, with 1989, 1999, 2004, 2009, 2009, on the basis of the soil water and salt monitoring data by statistics and geographic information system technology combination of soil water and salt on time scale and space scale transformation characteristics of quantitative study, shows that under the action of natural and human factors common oasis change laws of soil water and salt. The main conclusions of this study are as follows:(1)Soil salinity from soil surface to the underlying presents T type distribution. In the vertical direction, the spatial variation of soil salt and water gradually weakened. In a horizontal direction on the spatial variability of soil salinity is stronger than the variability of soil moisture. Different ways of land use, land and grassland of large amounts of salt concentration in the soil, the T distribution, water the opposite trend. Cultivated land in the salt and water are presented, the lower is low, the trend of the central high. Woodland of salt on the whole to get together and table showing a bottom trend. In the base of salt ions, except HCO3- variability is weak, the rest of the ion is belong to the strong spatial variability. Through the statistical analysis of base ions, found the salinization of soil is mainly controlled by Cl- and Na+, so master the content of Cl- and Na+ and the space distribution state governance and the prevention and control of soil salinization has important reference value. HCO3-, Ca2+, Mg2+, SO42-and K+ influenced by random factors, belongs to the weak spatial correlation. Cland Na+ influenced by both nature and human factors, belong to moderate spatial correlation. From interpolation figure found that soil conductivity, water content, salt content, the spatial distribution of the p H is in the shape and the flake; On the edge of the fan in the study area and southeast, south, east salt content is higher, its spatial distribution is closely related to the micro topography and human factors.(2)Various interpolation effect can reflect the spatial distribution of soil salt content, according to the results of cross validation shows that the best of kriging method of expression, good smoothness, inverse distance weighted interpolation method is easy to appear "bull ’s-eye" shape distribution. Affected by the elevation of kriging interpolation method, general effect. Spline function method is affected by multi-dimensional spatial data, interpolation serrated figure exists. Through 3 d interpolation and trend effect diagram can be obviously found on different cells in the study area, the spatial distribution of soil salt content performance differences between different, present the southeast, northwest low spatial distribution, the rendering distribution trend is consistent. 3 d interpolation figure kriging interpolation of spatial distribution of local area salinization reflect more apparent.( 3) The soil content trend is rising from 1989 to 1999 through analysis different years of the average surface soil salt content. With the technology innovation and the implementation of protection measure,the salt content reduced gradually from 1999 to 2014.The strong spatial variability of surface soil salinity in different years because of the random factors is a dominant factor.The trend of soil moisture content have been greatly rise after reducing from 1989 to 2014.In 1989, 1999 and 2014,the soil moisture show moderate spatial variability while the soil moisture in 2004 and 2009 show a strong spatial variability.Through the remote sensing image classification figure of salinization.We can find that the change of salinization in Wei Ku area is very obvious,which present the trend of increase two and four decreases found from 1989 to 1999.The non-salinization land and water area is increased while the light,medium and severe salinization land and other has decreased. From 1999 to 2004 different categories salinization transfer area shows the tendency of three increase three decreases. Medium and severe salinization and salinization land area increased, among them, the severe salinization in increased significantly in local area and other, less water and mild salinization, light to moderate salinization land salinization land transfer is relatively obvious. From 2004 to 2009, due to salinization prevention and cure measures moderate salt lick plaque reduction is mainly, saline land patches by gradually coalesced into the result of punctate. Mild saline to the salinization land conversion in relatively obvious in local area. From 2009 to 2014, mild salinization to moderate salinization in the study area changes fast, major is closely related to human activities, need to take measures to control salinization. Enough to proved the problem of soil salinization and closely related to the sustainable development of land use. Interpolation figure is through the salt content of known points can be used to predict the salt content of the unknown point, on the whole can reflect the spatial distribution of soil salinization oases in arid areas.(4)Different factors on the spatial distribution of soil water and salt has a certain influence, in order to prevent salinization, need to take certain measures and need to improve, strengthen field management, farmland irrigation and drainage equipment, and select the proper saline vegetation to improve the soil environment, preventing soil secondary salinization. Western human activities in the study area is frequent, cultivation, fertilization, unreasonable irrigation, high intensity of land use will affect the soil properties, thus to improve the preventive measures. Southeast of the study area salinization degree is higher, the underground water level is low, need to strengthen the construction of water conservancy, would improve the utilization rate of water, solve the problem of irrigation and drainage than not harmonious, the prevention and treatment of salinization deteriorating. |
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