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Deposition of sandstorms in a vegetation-covered sand dune in ejin oasis and its characteristics

Journal of Geographical Sciences 2006年第4期16卷 502-508页

作者： WENXiaohao LI Baosheng WANG Wei LI Sen OU Xianjiao ZHENG Yanming Sehool of Geography South China Normal University Guangzhou 510631 China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment CAS Xi＇an 710075 China Department of Tourism Resourees and Environment Foshan University Foshan 528000 China

＂ejin Section＂ found in a typical vegetation-covered sand dune in ejin oasis was investigated. In this study, 263 samples were taken from the section for grain-size analysis, 25 for chemical analysis, 11 for ^14C dating and 6 for scanning electron microscope （SEM）. The results of the study indicate that 3 types of the sediments in the section can be identified, YS, LS and ST. YS, homogeneous yellow-brown dune sands, is equal to those of inland deserts, LS, loess-like sandy soils, is the same as the sandy loess in the middle Yellow River and modem falling dusts, and ST, sandy sediments interbeded with the deadwood and defoliation of Tamarix spp, represents the depositional process of the section interrupted by abrupt changes in climate. The ejin Section has recorded the repeated dust-storms or sandstorms since 2500 yr BP and the peak periods of the dust-storms or sandstorms revealed by the section are consistent with the records of ＂dust rains＂ in historical literatures, indicating that the change of climate is a key factor to increase sandstorms or dust-storms, whereas, ＂artificial＂ factor may only be an accelerating one for desertification.

关键词： ejin oasis vegetation-covered sand dune dust storm sandstorm grain size major chemical element

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Using the concept of ecological groundwater level to evaluate shallow groundwater resources in hyperarid desert regions

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Journal of Arid Land 2012年第4期4卷 378-389页

作者： Qi FENG JiaZhong PENG JianGuo LI HaiYang XI JianHua SI Alashan Desert Eco-hydrology Experimental Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou 730000China Department of Geography Shaanxi Normal UniversityXi’an 710062China Gansu Hydrology and Water Resources Engineering Center Lanzhou 730000China

This paper, based on the analysis and calculation of the groundwater resources in an arid region from 1980 to 2001, put forward the concept of ecological groundwater level threshold for either salinity control or the determination of ecological warning. The surveys suggest that soil moisture and soil salinity are the most important environmental factors in determining the distribution and changes in vegetation. The groundwater level threshold of ecological warning can be determined by using a network of groundwater depth observation sites that monitor the environmental moisture gradient as reflected by plant physiological characteristics. According to long-term field observations within the ejin oases, the groundwater level threshold for salinity control varied between 0.5 m and 1.5 m, and the ecological warning threshold varied between 3.5 m and 4.0 m. The quantity of groundwater re- sources （renewable water resources, ecological water resources, and exploitable water resources） in arid areas can be calculated from regional groundwater level information, without localized hydrogeological data. The concept of groundwater level threshold of ecological warning was established according to water development and water re- sources supply, and available groundwater resources were calculated. The concept not only enriches and broadens the content of groundwater studies, but also helps in predicting the prospects for water resources development.

关键词： evaluation water resources ejin oasis ecological groundwater level groundwater level threshold of ecologicalwarning

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