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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Degradation of Triton X‐100 in Water Falling Film Dielectric Barrier Discharge Reactor          下载免费PDF全文

Munera M. Aonyas  Jelena Nešić  Milica Jović  Marijana Marković  Biljana Dojčinović  Bratislav Obradović  Goran M. Roglić 《洁净——土壤、空气、水》2016,44(4):422-429

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黑河上游山区典型站的水热过程模拟研究   总被引：8，自引：7，他引：1  

陈浩  南卓铜  王书功  赵林 《冰川冻土》2013,35(1):126-137

Noah LSM陆面过程模型在国际上被广泛应用于陆面的水热过程模拟, 但在高寒山区的适用性研究并不充分, 目前还没有在黑河上游高寒山区应用的案例. 利用Noah和黑河上游两个典型站(大冬树山垭口站和阿柔站)2008-2009年的观测数据, 对两站的水热过程进行了模拟. 通过比较模拟结果和实测的地温和液态水含量, 表明Noah能够较真实地反映该地区的水热过程. Noah对观测站的地温模拟较好, 但冬季存在一定偏差; 液态水含量的模拟总体偏低, 表层液态水含量在春季土壤融化期的模拟偏差较大. 以上现象与该地区土壤异质性较大、 春季融化期土壤冻融过程中土壤含冰量判定存在偏差、 冬季降水量观测不准等有关. 此外, 结合模拟结果, 讨论了观测数据的质量问题.  相似文献   

Near-term priorities for the science, policy and practice of Coastal and Marine Spatial Planning (CMSP)     

Benjamin S. Halpern  Jordan Diamond  Sarah Lester 《Marine Policy》2012,36(1):198-205

There is currently a rare opportunity to inform emerging efforts to implement coastal and marine spatial planning (CMSP) in the United States, Europe and elsewhere around the world. In particular, the newly formed US National Ocean Council is developing a strategic action plan for CMSP over the next 18-24 months. In order to identify priority needs for significantly advancing CMSP, a group of experts in the science, policy and practice of CMSP developed recommendations for (1) process development, (2) communication and engagement efforts, (3) tradeoff and valuation analyses, and (4) decision support. Some of these priorities are supported by existing activities in the United States and elsewhere. Others have yet to be addressed and merit immediate attention.  相似文献   

Hydrogeomorphic processes and vegetation: disturbance,process histories,dependencies and interactions   总被引：1，自引：0，他引：1  

Markus Stoffel  David J. Wilford 《地球表面变化过程与地形》2012,37(1):9-22

Riparian vegetation and hydrogeomorphic processes are intimately connected parts of upland catchment and fan environments. Trees, shrubs and grasses and hydrogeomorphic processes interact and depend on each other in complex ways on the hillslopes, channels and cone‐shaped fans of torrential watersheds. While the presence and density of vegetation have a profound influence on hydrogeomorphic processes, the occurrence of the latter will also exert control on the presence, vitality, species, and age distribution of vegetation. This contribution aims at providing a review of foundational and more recent work on the dependencies and interactions between hydrogeomorphic processes and vegetation. In particular, we address the role of vegetation in the initiation of hydrogeomorphic processes and its impact on stream morphology as well as immediate and long‐term effects of hydrogeomorphic disturbance on vegetation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献