干旱区生态学研究中若干问题的思考   总被引：1，自引：1，他引：0  

贾宝全 《干旱区地理》2007,30(1):1-6

在分析目前干旱区生态学研究存在的主要问题的基础上,对未来干旱区生态学研究的核心、尺度和研究手段选择等问题进行了探讨,最后就干旱区生态学研究几个值得关注的研究领域进行了阐述。作者认为,干旱区生态学研究的核心应该是绿洲,从管理实践的角度,干旱区的生态学研究尺度应该是湖泊流域,而非以前被广泛采纳的河流流域。在干旱区生态学研究的手段上,随着高清晰度商业化遥感卫星的应用,结合过去的传统方法,与GIS和RS相结合的遥感手段应该是今后生态学研究所依赖的主要手段。而早春短命植物层片与短命动物研究、干旱区的城市森林建设、干旱区民族生态学与人地关系研究、生态用水的深化研究、绿洲景观生态过程及其规划实践研究等,应该是在不偏废过去研究工作的基础上,值得在未来关注的研究领域。  相似文献   

层次分析法在下垫面因子影响沙尘暴危险度研究中的应用     

杜子璇  李宁  刘忠阳  申占营  付祥建 《干旱区地理》2007,30(2):184-188

沙尘暴是一种危害严重的气象灾害,其形成依赖于大气环流和沙质地表两种不同密度的物理介质的相互作用,风力条件和下垫面的性质是影响沙尘暴强度和危害程度的两个重要因素。减轻沙尘暴危害的有效方法就是改善沙尘暴源地的下垫面状况,但这需要评估下垫面各因子在不同天气、气候背景条件下对沙尘暴发生的影响程度。从下垫面的角度出发,以内蒙古中西部地区为例,利用气象资料和实测数据,应用AHP方法对下垫面定性与定量因子进行综合分析,得出不同地区下垫面因子对沙尘暴发生作用的权重,为从下垫面角度研究沙尘暴危险度奠定基础。  相似文献   

向海湿地自然保护区鸟类多样性评价方法的比较研究   总被引：2，自引：1，他引：1  

何春光  崔丽娟  盛连喜  赵俊  邹丽芳 《干旱区地理》2007,30(6):858-864

鸟类多样性是评价湿地生态环境质量极其敏感的指标。向海湿地自然保护区地处半干旱区,受气候和人为影响,生态环境变化极为剧烈,因此,寻求一种行之有效且简单易行的鸟类多样性评价手段,对于及时了解湿地生态环境质量的动态变化信息,提出湿地和鸟类多样性的管理和保护对策至关重要。稀疏标准化法是一种建立在物种-面积关系上的生物多样性评价方法,主要用于区域尺度上的生物多样性评估。运用改进的稀疏标准化程序,利用多年调查和收集的鸟类数据,来评价和分析向海自然保护区鸟类多样性及其变化,结合香农-威纳多样性指数和均匀度指数,分析了两种方法获取结果的相关性。评估结果表明:稀疏标准化法获取的鸟类多样性和均匀度信息与传统的香农-威纳多样性指数和Pielou均匀度指数间具有显著的相关关系,可以用于鸟类的多样性和均匀度评价,且具有科学、直观、运算简捷、快速等优势。  相似文献   

大兴安岭地区成矿地质特征及找矿前景分析   总被引：9，自引：5，他引：4  

邵积东  王守光  赵文涛  贾和义  王新亮  张梅  任亦萍 《地质与资源》2007,16(4):252-256,262

大兴安岭地区是古生代古亚洲成矿域与中生代滨太平洋成矿域相互叠置的重要成矿区带,具有潜在的找矿前景.本文根据该地区的这一特殊的成矿地质环境,对矿床（点）分布、矿床类型、物化探异常特征及成矿地质背景进行了详细研究,总结了各成矿区带的成矿地质特征、成矿作用及成矿规律,进行了找矿前景分析,提出了以找大矿、富矿和找隐伏矿、半隐伏矿为主的找矿思路,并指出了本区找矿重点和找矿方向,提出了矿产工作的部署建议.  相似文献   

Should Bouchet's hypothesis be taken into account in rainfall‐runoff modelling? An assessment over 308 catchments     

Ludovic Oudin  Claude Michel  Vazken Andrassian  Franois Anctil  Ccile Loumagne 《水文研究》2005,19(20):4093-4106

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A comparison of frameworks for separating the impacts of human activities and climate change on river flow in existing records and different near-future scenarios     

Soghra Andaryani  Vahid Nourani  James Ball  Saeed Jahanbakhsh Asl  Hamidreza Keshtkar  Dennis Trolle 《水文研究》2021,35(7):e14301

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Numerical analysis of the effect of natural microcracks on the supercritical CO2 fracturing crack network of shale rock based on bonded particle models          下载免费PDF全文

Peihuo Peng  Yang Ju  Yongliang Wang  Shaoqin Wang  Feng Gao 《国际地质力学数值与分析法杂志》2017,41(18):1992-2013

The problem of predicting the geometric structure of induced fractures is highly complex and significant in the fracturing stimulation of rock reservoirs. In the traditional continuous fracturing models, the mechanical properties of reservoir rock are input as macroscopic quantities. These models neglect the microcracks and discontinuous characteristics of rock, which are important factors influencing the geometric structure of the induced fractures. In this paper, we simulate supercritical CO₂ fracturing based on the bonded particle model to investigate the effect of original natural microcracks on the induced‐fracture network distribution. The microcracks are simulated explicitly as broken bonds that form and coalesce into macroscopic fractures in the supercritical CO₂ fracturing process. A calculation method for the distribution uniformity index (DUI) is proposed. The influence of the total number and DUI of initial microcracks on the mechanical properties of the rock sample is studied. The DUI of the induced fractures of supercritical CO₂ fracturing and hydraulic fracturing for different DUIs of initial microcracks are compared, holding other conditions constant. The sensitivity of the DUI of the induced fractures to that of initial natural microcracks under different horizontal stress ratios is also probed. The numerical results indicate that the distribution of induced fractures of supercritical CO₂ fracturing is more uniform than that of common hydraulic fracturing when the horizontal stress ratio is small.  相似文献   

Preliminary 3–D geological model of the Kalgoorlie region,Yilgarn Craton,Western Australia,based on deep seismic‐reflection and potential‐field data     

B. R. Goleby  R. J. Korsch  T. Fomin  B. Bell  M. G. Nicoll  B. J. Drummond 《Australian Journal of Earth Sciences》2013,60(6):917-933

The granite‐greenstone terranes of the Eastern Goldfields Province, Yilgarn Craton, Western Australia, are a major Australian and world gold and nickel source. The Kalgoorlie region, in particular, hosts several world‐class gold deposits. To attempt to understand why these deposits occur where they do, it is important to understand the crustal architecture in the region and how the major mineral systems operate in this architecture. One way to understand these relationships is to develop a detailed 3–D geological model for the region. The best method to map the 3–D geometry of major geological structures is by acquisition and interpretation of seismic‐reflection profiles. To contribute to this aim, a grid of deep seismic‐reflection traverses was acquired in 1999 to examine the 3–D geometry of the region in an area including the Kalgoorlie mineral region and mineral fields to the north and west. This grid was tied to the 1991 regional deep seismic traverse and 1997 high‐resolution seismic profiles in the same region. The grid covers an area measuring approximately 50 km wide by 50 km long and extended to a depth of approximately 50 km (below the base of the crust in this region). The resulting 3–D geological model was further constrained by both surface geological data and geophysical interpretations, with the seismic interpretations themselves also constrained by gravity and magnetic modelling. The 3–D model was used to investigate the geometric relationships between the major faults and shear zones in the area, the relationship between the granite‐greenstone succession and the basement, and the spatial relationships between the greenstones and the granites. Interpretation of the grid of seismic lines and construction of the 3–D geological model confirmed the existence of the detachment surface and led to the recognition that the granite‐greenstone contact usually occurs at a much shallower level than the detachment. Also, west‐dipping faults in the vicinity of the Golden Mile, including the Abattoir Shear through to Boulder‐Lefroy Fault, appear to be more important than previously thought in controlling the structure of that area. An antiformal thrust stack occurs beneath a triangle zone centred on the Golden Mile. The Black Flag Group was deposited in a probable extensional setting, and late extension was also probably more important than previously thought. The granite‐gneiss domes were uplifted by the formation of antiformal thrust stacks at depth beneath them.  相似文献   

Gas generation and expulsion characteristics of Middle–Upper Triassic source rocks,eastern Kuqa Depression,Tarim Basin,China: implications for shale gas resource potential     

P. Wang  X. Chen  J. Li  H. Yang  F. Jiang 《Australian Journal of Earth Sciences》2013,60(7):1001-1013

Frontier exploration in the Kuqa Depression, western China, has identified the continuous tight-sand gas accumulation in the Lower Cretaceous and Lower Jurassic as a major unconventional gas pool. However, assessment of the shale gas resource in the Kuqa Depression is new. The shale succession in the Middle–Upper Triassic comprises the Taliqike Formation (T₃t), the Huangshanjie Formation (T₃h) and the middle–upper Karamay Formation (T_2–3k), with an average accumulated thickness of 260 m. The high-quality shale is dominated by type III kerogen with high maturity and an average original total organic carbon (TOC) of about 2.68 wt%. An improved hydrocarbon generation and expulsion model was applied to this self-contained source–reservoir system to reveal the gas generation and expulsion (intensity, efficiency and volume) characteristics of Middle–Upper Triassic source rocks. The maximum volume of shale gas in the source rocks was obtained by determining the difference between generation and expulsion volumes. The results indicate that source rocks reached the hydrocarbon expulsion threshold of 1.1% VR and the hydrocarbon generation and expulsion reached their peak at 1.0% VR and 1.28% VR, with the maximum rate of 56 mg HC/0.1% TOC and 62.8 mg HC/0.1% TOC, respectively. The volumes of gas generation and expulsion from Middle–Upper Triassic source rocks were 12.02 × 10¹² m³ and 5.98 × 10¹² m³, respectively, with the residual volume of 6.04 × 10¹² m³, giving an average gas expulsion efficiency of 44.38% and retention efficiency of 55.62%. Based on the gas generation and expulsion characteristics, the predicted shale gas potential volume is 6.04 × 10¹² m³, indicating a significant shale gas resource in the Middle–Upper Triassic in the eastern Kuqa Depression.  相似文献   

Fluoride enrichment in aquifers of the Thar Desert: controlling factors and its geochemical modelling     

Chander Kumar Singh  Rina Kumari  Neha Singh  Javed Mallick  Saumitra Mukherjee 《水文研究》2013,27(17):2462-2474

The groundwater is the only source of drinking water in the Jaisalmer district of Rajasthan, India. The study area is a part of the Thar Desert. It has low and scattered population and no industries; hence, the possibility of anthropogenic input of fluoride is almost negligible. Thus, the enrichment of fluoride is only possible due to geochemical processes taking place in the groundwater of the region. A total of 100 groundwater samples, 34 samples from Jaisalmer and 66 samples from the Pokharan administrative blocks, were collected. It was observed that the concentration of fluoride ranged from 0.08 mg/l to 4.56 mg/l in the groundwater of Jaisalmer and from 0.56 mg/l to 6.60 mg/l in the samples of the Pokharan block. The alkaline condition (average pH, 7.7 ± 0.22 and 8.01 ± 0.25 in Jaisalmer and the Pokharan administrative block, respectively) in the region favours fluorite dissolution. Ion exchange, dissolution of calcite, semi‐arid climate, alkaline conditions and weathering are responsible for fluoride enrichment in the groundwater of the study area. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献