新疆克里雅河流域绿洲适宜规模   总被引：4，自引：0，他引：4       下载免费PDF全文

凌红波  徐海量  刘新华  张青青  傅荩仪  白元 《水科学进展》2012,23(4):563-568

利用克里雅河流域1957~2009年水文气象资料及2010年遥感影像数据,借助Z指数法及水热平衡模型分析了流域水资源在不同丰枯水平下的绿洲适宜规模。结果表明:克里雅河流域地表径流存在明显的丰枯变化;维持克里雅河流域下游天然绿洲稳定所需要的水资源为1.583亿 m3;现状面积下,克里雅河流域人工绿洲在丰水期处于稳定水平,枯水期与平水期皆为亚稳定水平;克里雅河流域人工绿洲在丰水期、平水期和枯水期的适宜规模分别为1 608~2 413 km2、1 157~1 736 km2和978~1 467 km2,而较高水资源保证度下最为适宜的规模应控制在978~1 736 km2。  相似文献   

南大洋物理过程在全球气候系统中的作用     

马浩  王召民  史久新 《地球科学进展》2012,27(4):398-412

南大洋是全球面积最大的一个大洋。传统观点倾向于认为由于南大洋与北半球相距遥远而与北半球气候系统关系不大,其全球性气候效应也较弱,这主要是由于以往对南大洋的了解不足。随着观测分析、数值模拟与理论研究的加强,以及对南大洋的认识不断加深,南大洋的气候效应日益凸显。从南极底层水、南极绕极流、南大洋海冰、南大洋与热带之间的遥相关、以及南大洋对气候变化的响应等多个角度梳理了南大洋物理过程特别是动力过程在全球气候系统中的作用,较为完整地总结了对南大洋气候效应的已有认识,并结合南大洋研究现状对未来有价值的科学问题和潜在的研究热点进行了探讨,以期强调南大洋在全球气候系统中的重要地位,推动南大洋研究不断走向深入。  相似文献   

碳酸盐与硅质碎屑的混合沉积机理和控制因素探讨   总被引：2，自引：0，他引：2  

赵灿  李旭兵  郇金来  于玉帅 《地质论评》2013,59(4):615-626

混合沉积作用是一类特殊而又有重要研究价值的沉积现象,混合沉积作用的研究虽已经取得了一定的进展,但目前国内对其沉积机理、控制因素等方面的认识仍不够深入,经典的范例较少.本文在国内外研究进展的基础上,结合笔者等近期的研究成果,阐述和总结了混积岩产出的沉积环境,混合沉积的4种类型、4种剖面结构以及与之相对应的沉积机理与控制因素等混合沉积研究的重点和难点问题.并以下刚果盆地Albian阶Sendji组混积岩的研究为例,利用频谱分析的方法求得混积地层较好地保存了米兰科维奇旋回,证实了受米兰科维奇旋回影响的气候因素对混合沉积作用的发生、发展具有极为重要影响,同时混合沉积作用强弱及其旋回性变化也是区域构造活动的响应,构造活动的强弱与混积作用范围、规模密切相关.  相似文献   

Provenance and sediment characteristics of contemporary gravel deposits at Sellicks Beach,eastern shore of Gulf St Vincent,South Australia     

J. H. Cann  C. S. Lower  J. B. Jago 《Australian Journal of Earth Sciences》2013,60(6):819-836

Sellicks Beach, located on the eastern shore of Gulf St Vincent, South Australia, is subject to wave-dominated processes and northward longshore transport. During winter, when wave energy is typically vigorous, gravel deposits are exposed across most of the beach, and three step-like berms are well developed. Sand is restricted to a narrow strip that is exposed only at low tide. In contrast, during summer, when wave energy is generally moderate to low, much of the gravel is covered by a thin veneer of sand and only the high berm, on the landward edge of the beach, remains as an obvious feature. Steeply dipping Neoproterozoic to Cambrian strata that outcrop strongly across Sellicks Hill are the original source rocks for the beach gravel; distinctive sedimentary textures, structures and fossils in the cobble-size clasts can be confidently matched with those of the provenance rocks. Much of the sediment entered the modern beach environment as a consequence of coastal erosion of transitional alluvial fan sediments. The oldest alluvial fan sediments are of late Pliocene to earliest Pleistocene age. Mount Terrible Gully provides a conduit for the input of fluvial sediment at the mouth of Cactus Canyon, where clasts as large as boulders accumulate across the beach. Sellicks Beach gravels are subject to longshore transport northwards. Relatively softer clasts, such as those derived from the Heatherdale Shale, are rare beyond Cactus Canyon. In contrast, quartzite clasts are more abundant towards the north. This lithological differentiation is attributed to preferential survivorship of clasts that are physically harder and chemically less reactive. The change in the shapes of clasts northwards, from predominately shingle-like ‘very platy’ and ‘very bladed’ at Cactus Canyon, to more ‘compact’ towards the boat ramp, is in accord with the more massive fabric of the surviving quartzite clasts. At Sellicks Beach, preservation of uplifted, coarse gravels, with entire and comminuted marine molluscan shells, of last interglacial age, provides evidence of neotectonism. At the landward margin of the beach, imbricated gravels in which pore spaces have been infilled with mud, and which show no evidence of modern coastal erosion, may provide evidence of continuing uplift during the recent Holocene. The geological setting, geomorphic framework and modern sedimentary regime at Sellicks Beach combine to provide an exceptionally useful outdoor laboratory for education in field geology.  相似文献   

Alluvial fans of the Eastern Italian Alps: morphometry and depositional processes     

L. Marchi  P.R. Tecca 《Geodinamica Acta》2013,26(1):20-27

Abstract

Alluvial fans are abundant in many valleys of the Alps, consisting of important sites for human settlements. Relationships between alluvial fan morphometry and drainage basin characteristics have been investigated in six valleys of the Eastern Italian Alps, displaying different geological and morphological conditions. Both debris flow fans and fluvial fans are present in the studied region, the latest occurring only in quite large basins. Expansion of alluvial fans is greatly determined by the topographic characteristics of receiving valleys. Fan gradient is mainly affected by basin ruggedness conditioning depositional processes, by debris size, and, in some cases, by post-depositional reworking of fan surfaces.  相似文献   

Using chlorofluorocarbons (CFCs) and tritium to improve conceptual model of groundwater flow in the South Coast Aquifers of Laizhou Bay,China   总被引：1，自引：0，他引：1  

D. M. Han  X. F. Song  Matthew J. Currell  Maki Tsujimura 《水文研究》2012,26(23):3614-3629

The southern coastal plain of Laizhou Bay, which is the area most seriously affected by salt water intrusion in north China, is a large alluvial depression, which represents one of the most important hydrogeological units in the coastal region of northern China. Chlorofluorocarbons (CFCs, including CFC‐11, CFC‐12 and CFC‐113) and tritium were used together for dating groundwater up to 50 years old in the study area. There are two cones of depression, caused by intensive over‐exploitation of fresh groundwater in the south and brine water in the north. The assigned CFC apparent ages for shallow groundwater range from 8 a to >50 a. A binary mixing model based on CFC‐113 and CFC‐12 concentrations in groundwater was used to estimate fractions of young and pre‐modern water in shallow aquifers and to identify groundwater mixing processes during saltwater intrusion. Discordance between concentrations of different CFC compounds indicate that shallow groundwater around the Changyi cone of depression is vulnerable to contamination. Pumping activities, CFC contamination, mixing and/or a large unsaturated zone thickness (e.g. >20 m) may be reasons for some groundwater containing CFCs without tritium. Saline intrusion mainly occurs because of large head gradients between fresh groundwater in the south and saline water bodies in the north, forming a wedge of saline water below/within fresh aquifer layers. Both CFC and tritium dates indicate that the majority of the saline water is from >50 a, with little or no modern seawater component. Based on the distribution of CFC apparent ages, tritium contents plus chemical and physical data, a conceptual model of groundwater flow along the investigated Changyi‐Xiaying transect has been developed to describe the hydrogeological processes. Three regimes are identified from south to north: (i) fresh groundwater zone, with a mixing fraction of 0.80–0.65 ‘young’ water calculated with the CFC binary mixing model (groundwater ages <34 a) and 1.9–7.8TU of tritium; (ii) mixing zone characterized by a mixing fraction of 0.05–0.65 young groundwater (ages of 23–44 a), accompanied by local vertical recharge and upward leakage of older groundwater; and (iii) salt water zone, mostly comprising waters with ages beyond the dating range of both CFCs and tritium. Some shallow groundwater in the north of the Changyi groundwater depression belongs to the >50a water group (iii), indicating slow velocity of groundwater circulation and possible drawing in of saline or deep groundwater that is tracer‐free. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

基于CoupModel的青藏高原多年冻土区土壤水热过程模拟   总被引：6，自引：5，他引：1  

张伟  王根绪  周剑  刘光生  王一博 《冰川冻土》2012,34(5):1099-1109

近年来, 青藏高原多年冻土区生态环境呈现出逐年恶化趋势, 从而对多年冻土活动层水热过程造成显著影响. 此外, 如何构建更加有效、 针对寒区的陆面过程模式成为寒区研究的重点、 热点之一. 作为一种有效的参数估计方法, Bayes参数估计算法具有准确估计陆面过程模式参数的能力. 因此, 基于2005-2008年观测数据, 利用CoupModel模型对青藏高原风火山流域土壤水热运移过程进行模拟; 同时, 利用Bayes参数估计方法估计部分水热运移参数. 结果显示: 模型对土壤温度(ST)的模拟效果较好, NSE系数均在0.90以上; 也能够较好模拟浅层(0~40 cm)土壤水分, NSE值均达到0.80以上, 而对40 cm以下土壤水分的模拟结果较差. 模型也能够较准确模拟活动层土壤的冻结-融化过程. 模型对温度水分极值和40 cm深度以下水分的模拟存在一些偏差. 值得一提的是, 基于重要性采样MCMC方案的Bayes参数估计算法能够有效估计水热运移参数, 模型模拟结果得到极大的改进. Bayes算法能够广泛解决陆面过程模式参数估计问题.  相似文献   

Degradation of Linear Alkyl Benzene Using an Immobilized Nano TiO2 Photocatalytic Reactor: Process Analysis and Modeling          下载免费PDF全文

Hadis Zangeneh  Ali Akbar Lorestani Zinatizadeh  Mostafa Feyzi 《洁净——土壤、空气、水》2016,44(1):78-88

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Biodegradation Pathway of Acid Red 27 by White‐Rot Fungus Armillaria sp. F022 and Phytotoxicity Evaluation          下载免费PDF全文

Tony Hadibarata  Abdull Rahim Mohd Yusoff 《洁净——土壤、空气、水》2016,44(3):239-246

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Operational and Environmental Conditions for Efficient Biological Nutrient Removal in an Urban Wastewater Treatment Plant          下载免费PDF全文

Javier Bayo  Joaquín López‐Castellanos  Julio Puerta 《洁净——土壤、空气、水》2016,44(9):1123-1130

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