Variation of environmental factors plays an important roll in the process of desertification. In this paper, taking Shule River as an example, the variation and correlation coefficient was calculated to evaluate the main environmental factors’ changes and its relation to the state of desertification. The results obtained indicate that the variations of factors including meteorological factors and human active factors are obvious. Since 80’s the annual precipitation and annual number of sandstorm days have been declining in a fluctuating state. The population and the area of cultivated land have been increasing. The correlation analysis shows that there exist positive correlations between desertification and population and area of cultivated land. The correlation between area of desertification and annual wind speed, annual number of sandstorm days is significant. In Shule River area, desertification state has more obvious relation with human active factor, comparing with meteorological factors.
Desertification taking place in arid area is often related with vegetation deterioration in lower reaches of interior river. In the cause of it, the soil characteristics changed regularly due to less surface water and ground water lowing, which cause soil drying and salinizing. Through the analysis and comparison of soil characteristics in different sites with different desertification degree revealed the trend of soil water content, soil salinity, organic matter, soil texture, as well as changing trend from bog soil, meadow soil to adobe soil, halomorphic soil. These changes were accelerated as the vegetation ruined and lead to land desertification. The process of changing from autochthonous soil to adobe soil can be divided into different stages which differ in changing speed, i.e., the formation of climax soil will last long time. But, once its loss the stability, desertification will develop rapidly. Studying the possibility for the converse changes of
climax soil is significant to vegetation restoration and should become a research direction in the future.
The Tarim River Watershed consists of the headstream and trunk-stream zone, and the water consumed by the human and ecosystem in the trunk-stream zone is basically controlled by the hydrological process in the headstream. This process is random. Because the serial of hydrological observation data is short, it is necessary to analyze the uncertainty of hydrological system in order to obtain integrated hydrological information. The probability statistics is a method which frequently used to deal with this problem. But P-III Frequency Curve in common use is not perfect. And the multiplication frequency curve type III, based on the multiplication theorem of probability and the attribute of median, have such qualities as fitting the calculation of non-instantaneous value( for annual runoff quantum), no J-shaped & Z-shaped distribution and resistibility and robust. Using the X-III2 multiplication frequency curve, the 5 long data serials (n=14800) are simulated with the observed data through 35 years of 5 hydrological stations in headstream zone. The statistic analyses of these analog serials are made. The analytical results show that the hydrologic and water resource system in headstream zone is stable. This conclusion will help the exploitation and utilization of water resource in the basin.
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