长江徐六泾河段渔业群落结构(2005-2006年)及多样性初探

根据2005-2006年间徐六泾河段进行的渔业资源调查,初步研究了徐六泾河段渔业群落结构和多样性.调查到鱼类48种、虾类3种、蟹类2种,分别隶属于12目20科44属,其中江湖半洄游性渔业生物(青鱼、草鱼等)6种、江海洄游性渔业生物(刀鲚、鳗鲡等)7种、近海河口类渔业生物(斑尾复鰕虎、六带鲹等)9种,淡水定居性渔业生物31种.相对重要指数(IRI)大于1000的种类定为优势种,共有3种:日本沼虾、斑尾复鰕虎、鳊.多样性特征值为:Wilhm改进指数(H″)为3,Margalef指数(R″)为4.66,Pilou指数(E″)为0.76,McNaughton指数(D″)为0.22.利用生态类型、个体生物学特征、多样性指数、相对重要指数等分析了徐六泾河段的渔业群落结构及多样性现状,表明徐六泾河段渔业群落属于河口渔业群落与淡水渔业群落交叉的类型,相比长江其他江段,多样性处于中等水平,但群落结构不稳定,有小型化趋势.     

气候变化对长江流域汉江和赣江径流的影响

近几年来,国家气候中心己经建立了中国主要四大流域气候对水资源影响评估的模式框架.本文拟进一步证明其中之一的两参数分布式月水量平衡水文模式对长江之上汉江和赣江两子流域径流的模拟能力,结果表明该水文模式对目前气候条件下径流模拟效果较好,运行稳定,可用于实时业务运行.在此基础上,利用ECHAM4和HadCM2两GCM(General Circulation Model)未来气候情景模拟结果及目前实测气候情况,对汉江和赣江两子流域的径流对未来气候变化的敏感性进行评估.经检验,两GCM对未来气候,特别是降水情景模拟存在一定差异,因此,造成径流对气候变化的响应不同,这充分反映了全球模式模拟结果不确定性在气候变化影响研究中的重要性.     

长江上游区域蒸发皿蒸发量变化及其对水分循环的影响

利用长江上游最近30年(66个测站)蒸发皿蒸发量和最近50年(90个测站)的7种气象要素,分析了蒸发皿蒸发量的区域变化趋势和影响蒸发皿蒸发量变化的因素;针对7个水文站的年径流量变化,探讨了蒸发皿蒸发量变化后对水分循环的影响.结果表明,长江上游蒸发皿蒸发量的变化可以划分为三个分区,研究区域东西两侧(青藏高原和大巴山一带)为显著减少区,分别命名为RⅠ和RⅡ,中间(云贵高原北部到黄土高原南缘以及由二者包围的四川盆地一带)为显著增大区,命名为RⅢ区.影响区域蒸发皿蒸发量变化的原因各有不同,青藏高原一带(RⅠ区)蒸发皿蒸发量减少的原因可归结于太阳辐射强度和风动力扰动减弱所致.大巴山一带(RⅡ区)减少原因是太阳辐射强度、风动力扰动强度、湿度条件都在显著下降所引起的.云贵高原到四川盆地一带(RⅢ区)蒸发皿蒸发量增加是环境气温强烈升高,导致其上空大气水汽含量显著减少,大气很干燥,引发蒸发过程加强所致.蒸发皿蒸发量发生变化的直接后果就是导致水分循环强弱发生变化,对于RⅠ区,尽管蒸发皿蒸发量减少,由于降水量和径流量增加的作用,这一区域的水分循环有所加强.在RⅡ区,降水量、径流量和蒸发量都在减少,因此RⅡ区水分循环显著减弱.在RⅢ区,降水量和径流量同时减少,而蒸发量增大,水量消耗增大,因此RⅢ区水分循环有减弱趋势.     

长江上游区域蒸发皿蒸发量变化及其对水分循环的影响

利用长江上游最近30年(66个测站)蒸发皿蒸发量和最近50年(90个测站)的7种气象要素,分析了蒸发皿蒸发量的区域变化趋势和影响蒸发皿蒸发量变化的因素;针对7个水文站的年径流量变化,探讨了蒸发皿蒸发量变化后对水分循环的影响.结果表明,长江上游蒸发皿蒸发量的变化可以划分为三个分区,研究区域东西两侧(青藏高原和大巴山一带)为显著减少区,分别命名为RⅠ和RⅡ,中间(云贵高原北部到黄土高原南缘以及由二者包围的四川盆地一带)为显著增大区,命名为RⅢ区.影响区域蒸发皿蒸发量变化的原因各有不同,青藏高原一带(RⅠ区)蒸发皿蒸发量减少的原因可归结于太阳辐射强度和风动力扰动减弱所致.大巴山一带(RⅡ区)减少原因是太阳辐射强度、风动力扰动强度、湿度条件都在显著下降所引起的.云贵高原到四川盆地一带(RⅢ区)蒸发皿蒸发量增加是环境气温强烈升高,导致其上空大气水汽含量显著减少,大气很干燥,引发蒸发过程加强所致.蒸发皿蒸发量发生变化的直接后果就是导致水分循环强弱发生变化,对于RⅠ区,尽管蒸发皿蒸发量减少,由于降水量和径流量增加的作用,这一区域的水分循环有所加强.在RⅡ区,降水量、径流量和蒸发量都在减少,因此RⅡ区水分循环显著减弱.在RⅢ区,降水量和径流量同时减少,而蒸发量增大,水量消耗增大,因此RⅢ区水分循环有减弱趋势.     

Impact of climate change on hydrological extremes in the Yangtze River Basin,China

The recent (1970–1999) and future (2070–2099) climates under the SRES A1B scenario, simulated by the regional climate model RegCM4.0 driven with lateral boundary conditions from the ECHAM5 general circulation model, are utilized to force a large-scale hydrological model for assessing the hydrological response to climate changes in the Yangtze River Basin, China. The variable infiltration capacity model (VIC) is utilized to simulate various hydrological components for examining the changes in streamflow at various locations throughout the Yangtze River Basin. In the end of the twenty-first century, most of the Yangtze River Basin stands out as “hotspots” of climate change in China, with an annual temperature increase of approximately 3.5 °C, an increase of annual precipitation in North and a decrease in South. Runoff in the upper reach of Yangtze River is projected to increase throughout the year in the future, especially in spring when the increase will be approximately 30 %. Runoff from the catchments in the northern part of Yangtze River will increase by approximately 10 %, whereas that in the southern part will decrease, especially in the dry season, following precipitation changes. The frequency of extreme floods at three mainstream stations (Cuntan, Yichang, and Datong) is projected to increase significantly. The original extreme floods with return periods of 50, 20, and 10 years will change into floods with return periods of no more than 20, 10, and 5 years. The projected increase in extreme floods will have significant impacts on water resources management and flood control systems in the Yangtze River Basin.     

Spatio-temporal variation of net anthropogenic nitrogen inputs in the upper Yangtze River basin from 1990 to 2012

The net anthropogenic nitrogen input(NANI) is an important nutrient source that causes eutrophication in water bodies. Understanding the spatio-temporal variation of NANI is important for regional environment assessment and management.This paper calculated NANI in the upper Yangtze River basin(YRB), upstream of the Three Gorges Dam(TGD), from1990 to 2012, and analyzed its spatio-temporal characteristics. Over the past 23 years of the study, the average annual NANI increased from 3200 kg N km~(-2) to 4931 kg N km~(-2). The major components were fertilizer N application, atmospheric N deposition,and net food and feed N import. In the northwest high mountainous region with a sparse population, the main component was atmospheric N deposition. Fertilizer N application and net food and feed N import were concentrated in the Chengdu Plain because of the high population density and large areas of farmland. This research found that NANI increased with rapid urbanization and increasing population. The Pearson correlation results illustrated that the spatial distributions of NANI and its major components were affected by land cover/use, agricultural GDP and total population. Increasing NANI has been the major cause of the degrading stream water quality over the past 20 years and is becoming a major threat to the water quality of the TGD reservoir.     

长江中游沙质河段床沙级配调整过程计算

三峡工程运用后,长江中游荆江河段持续冲刷,床沙与推移质、悬移质泥沙不断交换,从而造成该河段床沙发生不同程度的调整,对长江中下游河床演变及非平衡输沙机理的研究具有重要影响.在新水沙条件下,总结分析了沙波运动特性及床沙交换方式,引入Markov三态转移概率及非均匀沙隐暴系数,得到基于状态转移概率的沙质河段床沙级配调整的计算模型.研究结果表明:(1)20092014年,沙市站年内床沙中值粒径有先增大后减小的趋势,而监利站年内床沙中值粒径则先减小后增大,且荆江河段年际床沙中值粒径总体呈上升趋势,粗化程度约为6.9%~9.3%;(2)20092014年,沙市站床沙组成中粒径d<0.062 mm的泥沙所占比重不变,0.062 mm≤d<0.25 mm的泥沙所占比重逐年减少(累计减少11.4%),d≥0.25 mm的泥沙所占比重逐年增加(累计增加11.4%),而监利站床沙组成均存在波动性变化;(3)荆江河段床沙转换为推移质的概率随着泥沙粒径的增大而增大,床沙转换为悬移质的概率随着泥沙粒径的增大而减小,而推移质和悬移质转换为床沙的概率均随着泥沙粒径的增大而增大,河床发生冲刷粗化时泥沙输移的主要形式为悬移质(概率为81%~87%),而淤积细化时床沙补给主要来源于推移质(概率为8%~12%).通过验证,本文概率模型的计算结果与实测资料符合较好,能够应用于长江中游沙质河段年际床沙粗化及年内床沙级配调整过程预报,为进一步开展三峡工程下游非均匀悬移质泥沙沿程恢复机理的研究提供理论基础.     

Impact assessment of urbanization on flood risk in the Yangtze River Delta

The Yangtze River Delta region is the region with highest urbanization speed in China. In this study, 6 typical urbanization areas in Yangtze River Delta were selected as the objectives of study. Flood risk assessment index system was established based on the flood disaster formation mechanism, and analytic hierarchy process was utilized to define the weight of indices. The flood hazard, the exposure of disaster bearing body, the vulnerability of disaster bearing body and the comprehensive flood risk corresponding to three typical years in different urbanization stages, 1991, 2001 and 2006 were assessed. The results show that the flood hazard and the exposure of disaster bearing body in the 6 areas are all with an increasing trend in the process of urbanization, among which, the increasing trend of the exposure of disaster bearing body is especially obvious. Though the vulnerabilities of disaster bearing body in the 6 areas are all with decreasing trend owe to the enhancement of flood control and disaster mitigation capability, the comprehensive flood risks in the 6 areas increased as a whole, which would pose a serious threat to urban sustainable development. Finally, effective countermeasures for flood risk management of urbanization areas in Yangtze River Delta were put forward based on the assessment results.     

Morphological responses in a meandering and island-braided reach of the Middle Yangtze River to the Three Gorges Reservoir impoundment

Lateral migration is an important form of morphological changes on the Middle Yangtze River (MYR), particularly for the lower Jingjiang reach. The Three Gorges Reservoir (TGR) has substantially reduced sediment supply to the downstream river channels since its impoundment in June 2003. The scientific understanding of how decrease of sediment influences the processes of bank erosion and channel adjustments is complex and limited. In the present paper, the morphological responses in a typical meandering and island-braided river segment of the MYR to the filling of the TGR were investigated by a 3-D morphodynamic model. The potential of the 3-D model has been demonstrated by the observed data. The morphological evolutions in the Shishou bend during the first 12 years of the TGR impound-ment were predicted. The effects of the TGR operation on the planform evolutions in the study reach were analyzed based on the simulated results. Sediment load is decreased by 75%due to the early filling of the TGR. The magnitude of bed degradation with less sediment load due to the TGR operation is increased compared with the pre-dam situation. Qualitatively, the overall planform evolution trends in the Shishou bend after the TGR operation are similar to that without the TGR operation. The magnitude of lateral migration has been increased in some part of the channel bend, where the morphological response of the TGR operation exhibits more lateral migration rather than vertical degradation. Scouring at the bank toe enhances bank failure. Decrease of sediment load and weak bank anti-scour ability as well as the significant helical flow can be responsible for intensified bank erosion in the channel bend.     

Channel sedimentation and erosion of the Jiangsu reach of the Yangtze River during the last 44 years

River channel sedimentation in the lower reaches of the Yangtze River can be affected by both changes in sea level and changes in solid discharge from the upper river. To evaluate dynamic changes of sedimentation and erosion in the Jiangsu reach of the Yangtze River (about 330 km in length) from 1959 to 2003, databases were designed and constructed using a digital elevation model (DEM) of channel topography based on the Jiangsu River Relief Map for 1959, 1970, 1985, 1992, and 2003. The results indicated that the main course of the Yangtze River in Jiangsu Province had experienced an obvious switch from sedimentation to erosion status around 1985 because of the decreasing amount of solid load from the upper parts of the river channel after that year. The sedimentation process in the main course of the Jiangsu reach of the Yangtze River demonstrated the propulsive process of ‘downstream‐ward aggradations.’ Between 1985 and 2003, the erosion rate of the lower segment was greater than those of the middle and upper segments; this is probably because both channel flow and tide current had influenced the lower segment. When channel flow combines with tide current in the same direction, channel erosion can be intensified, especially if there is a solid load shortage in the channel. Copyright © 2009 John Wiley & Sons, Ltd.     

Assessing the impacts of anthropogenic and hydro-climatic drivers on estrogen legacies and trajectories

Intensification of concentrated animal feeding operations combined with the use of tile drains in agricultural fields has resulted in land-applied manure being a significant source of hormones to the environment. Currently, no model exists to simulate hormone fluxes from tile drains under field conditions. Therefore, we developed the Hormone Export and Recovery Dynamics (HERD) model, which incorporates hydro-climatic, biogeochemical, and anthropogenic drivers that affect hormone fate and transport. We validated HERD using known input (rainfall; lagoon effluent irrigation) and response data (tile drain flow; 17β-estradiol and estrone fluxes) from the 2009 growing season, 18 years after land-application activities began at a tile-drained field in Indiana. We used HERD to better understand the: (1) decision-making process underlying effluent irrigation activities; (2) contribution of macropore flow to estrogen transport; (3) potential for long-term applications to result in the development of legacy estrogen sources within the soil profile; and (4) potential recovery trajectory of estrogen transport following the cessation of animal waste applications. HERD adequately predicted irrigation events based on lagoon storage limits. Simple threshold exceedance logic for macropore flow activation accounted for ∼87% of the observed estrogen loads. Application history was found to be important, as not accounting for 18 years of application led to a severe underestimation of the observed estrogen loads; however, accounting for application history led to a much closer match between modeled and observed fluxes. Simulated trajectories after cessation of applications indicated that estrogens may continue to leach for several decades, which has important implications for mitigating hormone concentrations in receiving water bodies.     

三峡水库影响下长江中下游水文干旱演变及对气象干旱的响应

利用1960-2016年长江流域183个气象站逐月气温和降水数据以及干流3个水文站逐月径流资料,采用标准化降水蒸散指数(SPEI)和标准化径流指数(SRI)分析三峡水库蓄水运行前后长江中下游宜昌、汉口和大通站水文干旱的多时间尺度演变以及对气象干旱的响应特征.结果表明:(1)三峡水库运行后下游各站冬春季旱情明显趋缓,而秋季干旱状况略有加重;水库蓄水后各站中旱和重旱发生频率均呈减少趋势,其中中旱减幅明显,而特旱发生频率则总体表现为增加趋势;(2)三峡水库蓄水后3个站平均干旱历时的变幅相对较小,而干旱烈度和烈度峰值的均值增幅较大;同时,各站短时间尺度(1和3个月)干旱特征变量的变幅总体呈现沿程递增趋势,而长时间尺度(6和12个月)干旱特征变量的变幅整体表现为沿程递减趋势;(3)水库蓄水后各站短时间尺度SRI与SPEI的相关性减小,但相关性随时间尺度增加而迅速增强,12个月时间尺度的相关系数达到最大并略高于蓄水前;在年内相关性上,蓄水后各站短时间尺度SRI与SPEI的相关系数明显减小,冬季表现尤为突出,而长时间尺度的相关系数则略有增加;(4)水库影响下不同时间尺度宜昌站水文干旱滞后于气象干旱平...     

欧洲洪水影响评价技术在长江流域的运用及其若干修正

本文回顾了欧洲洪水影响评价技术.突出的问题是怎样处理洪灾及如何使洪灾损失降到最低.很明显在长江流域开展洪水风险和潜在的损失评价非常有意义.而现有的欧洲洪水影响评价技术难以在长江流域直接运用.我们对其进行了若干修正,并引入了基于GIS/RS的综合水文水动力和最小损失评价模型,该模型己经较好地运用于长江流域洪水影响评价的研究项目.     

Seasonal water storage change of the Yangtze River basin detected by GRACE

1 Introduction Large-scale mass redistribution, or temporal varia- tion of mass within the Earth system, the driving force of interactions between solid Earth and geophysical fluids envelope (i.e., atmosphere, ocean, and hydro- sphere), is an important geophysical process critical to human life. Most of the interactions between solid Earth and the atmosphere/oceans happen at seasonal and inter-annual time scales. One important contribu- tor of mass redistribution at seasonal and inter-annual …     

长江中下游成矿带中段岩石圈电性结构研究

长江中下游成矿带位于大别造山带、长江中下游凹陷、江南隆起带等大地构造单元结合部位,通过在研究区内布设两条首尾相接共计150 km长的大地电磁剖面,获得了50 km以浅岩石圈尺度的电性分布.长江中下游地区中段地下电性结构显示出在地下10 km和30 km处分别存在明显的圈层结构,以此认为现今横向稳定的"电莫霍"反映了研究区经历燕山期陆内构造-岩浆活动后已基本上完成壳幔重新平衡;而分隔大地构造单元的郯庐断裂带、长江断裂带以及江南断裂带在电性上具有特征的梯度显现,在印支造山期后的引张背景下,断裂带成为强伸展活动带与控制了燕山期大范围的陆内岩浆活动;高导地幔的局域性存在以及从北向南地幔导电性的变化反映了在经受深部动力学过程中处于不同大地构造部位的地幔所遭受的不同类型的改造以及地幔深部的构造极性.     

Influence of anthropogenic land‐use change on hillslope erosion in the Waipaoa River Basin,New Zealand

European settlement of the Poverty Bay Region resulted in deforestation and conversion of > 90% of the landscape to pastureland. The resulting loss of vegetation triggered a rapid increase in hillslope erosion as widespread landslide complexes and gully systems developed on weak lithologic units in the Waipaoa Basin. To quantify the rate and volume of historic hillslope degradation, we used a 1956–2010 sequence of aerial photographs for a ~16 km² catchment to map temporal changes in the spatial extent of active landslides. Then we created a ‘turf index’ based on the extent and style of pastoral ground disruption, which correlates with downslope velocity. Based on the movement of trees and other features, we assigned average velocities to the turf classes as follows: (1) minimal disrupted ground: 0.6 m/yr, (2) a mix of disrupted ground and intact blocks: 3.4 m/yr, and (3) no intact blocks or vegetation: > 6 m/yr. We then calculated the average annual sediment flux using these turf‐derived velocities, the width of the landslide‐channel intersection, and an average toe depth of 4.4 ± 1.3 m (mean ± standard deviation [SD]) from 37 field measurements. The resulting catchment averaged erosion rates are (mean ± SD): 29.9 ± 12.9 mm/yr (1956), 28.8 ± 13.7 mm/yr (1969), 13.4 ± 4.9 mm/yr (1979), 17.0 ± 6.2 mm/yr (1988), and 9.9 ± 3.6 mm/yr (2010). Compared with long‐term (post‐18 ka) erosion rates (1.6 mm/yr) and the long‐term uplift rate (~1 mm/yr) for this site, the 50‐year anthropogenically‐driven rate is an order of magnitude larger (~20 mm/yr). Previously, we measured an increase in erosion over the past 3.4 kyr (2.2 mm/yr), and here, we demonstrate this increase could be primarily due to human land‐use change – showing that a century of rapid erosion superimposed on the background geologic rate can profoundly skew the interpretation of erosion rates. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of projected climate change on the hydrological regime of the Yangtze River Basin,China

The hydrological response to the potential future climate change in Yangtze River Basin (YRB), China, was assessed by using an ensemble of 54 climate change simulations. The Coupled Model Intercomparison Project 5 simulations under two new Representative Concentration Pathways (RCP) 4.5 and 8.5 emission scenarios were downscaled and used to drive the Variable Infiltration Capacity hydrological model. This study found that the range of temperature changes is homogeneous for almost the entire region, with an average annual increase of more than 2 °C under RCP4.5 and even more than 4 °C under RCP8.5 in the end of the twenty first century. The warmest period (June–July–August) of the year would experience lower changes than the colder ones (December–January–February). Overall, mean precipitation was projected to increase slightly in YRB, with large dispersion among different global climate models, especially during the dry season months. These phenomena lead to changes in future streamflow for three mainstream hydrological stations (Cuntan, Yichang, and Datong), with slightly increasing annual average streamflows, especially at the end of twenty first century. Compared with the percentage change of mean flow, the high flow shows (90th percentile on the probability of no exceedance) a higher increasing trend and the low flow (10th percentile) shows a decreasing trend or lower increasing trend. The maximum daily discharges with 5, 10, 15, and 30-year return periods show an increasing trend in most sub-basins in the future. Therefore, extreme hydrological events (e.g., floods and droughts) will increase significantly, although the annual mean streamflow shows insignificant change. The findings of this study would provide scientific supports to implement the integrated adaptive water resource management for climate change at regional scales in the YRB.     

Gravel excavation and geomorphic evolution of the mining affected river in the upstream reach of the Yangtze River,China

As economic development upstream in the Yangtze River basin has progressed in recent decades,the demand for sediment has rapidly increased and contributed to an expansion in sediment excavation that may affect the river’s stability and navigation safety.In the current study,the distribution of gravel mining in the upstream reach of the Yangtze River was investigated using field measurements obtained from2008 to 2017.An experimental investigation was then done to analyze the bed load behavior in ...     

Impact of land-use change on hydrological processes in the Maying River basin, China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of China. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest China, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.     

Impact of reach geometry on stream channel sensitivity to extreme floods

Predicting spatial and temporal variations in bank erosion due to extreme floods presents a long‐standing challenge in geomorphology. We develop two methodologies for rapid, regional‐scale assessments of stream reaches susceptible to channel widening. The first proposes that channel widening occurs when unit stream power exceeds a critical threshold (300 W/m²). The second is motivated by the observation that widening often occurs at channel bends. We introduce a new metric, the bend stress parameter, which is proportional to the centripetal force exerted on a concave bank. We propose that high centripetal forces generate locally high bank shear forces and enhance channel bank erosion. We test both metrics using the geomorphic signature of Tropical Storm Irene (2011) on the White and the Saxtons Rivers, Vermont. Specifically, we test if reaches where significant channel widening occurred during Irene required one or both metrics to exceed threshold values. We observe two distinct styles of channel widening. Where unit stream power and bend stress parameter are high, widening is usually due to bank retreat. Elsewhere widening is usually due to the stripping of the upstream end of mid‐channel islands. Excluding widening associated with the stripping of the heads of mid‐channel islands, almost all the widening (> 98%) occurred along reaches identified as susceptible to widening. The combined metrics identify up to one‐quarter of the reaches lacking susceptibility to channel widening. Copyright © 2014 John Wiley & Sons, Ltd.