长江中下游阻隔性河段作用机理

阻隔性河段能够阻隔上游河势调整向下游的传递,对稳定河势起到关键性作用。本文以长江中下游34个单一河段为研究对象,在系统总结长江中下游河道演变规律的基础上,归纳出阻隔性河段控制要素包括：单一微弯的河道平面形态、河段中上部无挑流节点;河相系数小于4;河道纵比降大于1.2?;凹岸黏粒含量高于9.5%;床沙中值粒径大于0.158 mm等。从Navier-Stokes方程出发,推导出河湾水流动力轴线弯曲半径的表达式,进而分析了各控制要素对水流动力轴线摆动及阻隔性河段形成的作用。阻隔性河段的判别条件为：不同流量级下水流动力轴线摆动力与河道边界条件约束力的比值始终小于1;阻隔性河段作用机理在于：即便上游河势发生调整,本河段的河道边界始终能约束主流摆动幅度,归顺上游不同河势条件下的主流平面位置,为下游河道提供了相对稳定的入流条件,从而阻隔上游河势调整向下游传递。     

Assessment and exploitation of the waterfront resources in the middle and lower reaches of the Yangtze River

Waterfront resources are important and special kind of natural resources in the marginal area between land and water. The Yangtze River, the longest river in China, is not only rich in waterfront resources, but also has favorable development conditions with great potentiality. Aided by large-scale underwater topographic map, the major factors of the waterfront resources in the middle and lower reaches of the Yangtze River, such as the stability, the water depth and the natural conditions for port construction, are assessed in this paper respectively on the basis of the overall investigations. The results show that: (1) the waterfront resources are abundant in the middle and lower reaches of the Yangtze River, but lack of perfectly combined high grade waterfront; (2) there exists an obvious regional difference in the natural quality of the waterfront along the Yangtze; (3) the fore-bank water depth and waterfront stability are the main natural factors related to the waterfront quality in the middle and lower reaches of the Yangtze River; (4) the waterfronts along the Yangtze are mainly used for port, warehouse and industrial purposes; and (5) the waterfronts near important cities are highly used, especially the high-quality waterfronts. In addition, some suggestions for the development and utilization of the waterfront resources are presented in this paper.     

Summertime temperature variations in the middle and lower reaches of Yangtze River and their related circulation anomalies in the past five decades

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.     

近50年长江中下游地区夏季气温变化与环流异常

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.     

1961-2010年长江中下游地区农业洪涝灾害时空变化

为揭示长江中下游地区农业洪涝灾害的发生、分布及时空演变特征,基于1961-2010年研究区内426个气象站点的逐日降水数据,以湖北省单站洪涝等级标准为初始指标,对该指标临界值在-50~100 mm范围内进行同步增减,结合该区7省（市）的洪涝历史灾情记载和农业洪涝受灾面积,采用逐步剔除的方法筛选指标,构建分省农业洪涝等级指标并验证指标的合理性,分析该区近50年农业洪涝灾害的时空变化。结果表明：① 近50年长江中下游地区的农业洪涝灾害发生总体呈增加的趋势,但不同区域和不同年代际差异明显;② 20世纪60年代至80年代农业洪涝发生次数相对平稳,90年代洪涝明显增多,21世纪初洪涝又相对减少;③ 区域农业洪涝灾害明显呈现出江南多、江北少的分布特征。农业洪涝多发区主要集中在江西中北部、江汉平原、浙江沿海,以及安徽、江西和浙江三省交界地带。     

Study on the extremely cold winter of 1670 over the middle and lower reaches of the Yangtze River

The snow-cover days over the middle and lower reaches of the Yangtze River （MLRYR） in the winter of 1670 were extracted from Chinese historical documents. By these records, the winter temperature anomalies （compared to the mean of 1961-1990） recorded at seven meteorological stations and the regional mean winter temperature were estimated. The results show that： （1） There was an average of about 30 snow-cover days over the MLRYR region in 1670, ranging from 11-20 days in Shanghai and eastern Zhejiang to 5140 days in eastern Hunan Province. The snow-cover days averaged about 40 days in Anqing and Nan- cheng, and ranged from 30 to 40 days in Quzhou, Jingdezhen, and Nanchang; and （2） the regional mean winter temperature in 1670 was estimated to be approximately 4.0 ℃ lower than that of 1961-1990. The maximum negative anomaly of 5.6℃ occurred in Nanchang and the minimum anomaly of-2.8 ℃ was detected in Quzhou. Both of these were lower than that of the coldest winter during the instrumental observation period of 1951-2010. This research could not only provide a method to es- timate historical climate extremes, but also provide a background to understand the recent instrumentally climate extremes.     

长江中下游流域自然保护地空间分布及其与人类活动强度关系研究

以2015年土地利用类型数据为基础,计算长江中下游流域人类活动强度,采用最邻近指数、地理集中指数和不均衡指数分析研究区自然保护区、风景名胜区等六类国家级自然保护地分布特征,并定量揭示保护地空间分布与人类活动强度的关系,旨在为长江中下游流域建立基于人类活动强度的各类自然保护地管控策略提供科学依据。结果表明：1）人类活动高、较高、中、较低和低强度带在研究区的占比分别为3.74%、9.83%、14.98%、30.81%和40.63%;高等级强度带主要分布在长江三角洲平原、江汉平原等平原区,低等级强度带主要分布在秦岭山区、武陵山区等山地丘陵区。2）湿地公园、森林公园、风景名胜区和地质公园的空间分布类型为均匀型,水利风景区和自然保护区为凝聚型;六类保护地在各人类活动强度带空间分布不均衡。3）湿地公园、森林公园、水利风景区、自然保护区、风景名胜区和地质公园分别在中、较高、高、低、较低和低强度带密度最大;在高等级强度带“人地”矛盾更突出,应加强对自然保护地的保护力度和人类活动管控,尤其针对湿地公园、森林公园和水利风景区。     

Characteristics of dry-wet abrupt alternation events in the middle and lower reaches of the Yangtze River Basin and the relationship with ENSO

During recent decades, more frequent flood-drought alternations have been seen in China as a result of global climate change and intensive human activities, which have significant implications on water and food security. To better identify the characteristics of flood-drought alternations, we proposed a modified dry-wet abrupt alternation index (DWAAI) and applied the new method in the middle and lower reaches of the Yangtze River Basin (YRB-ML) to analyze the long-term spatio-temporal characteristics of dry-wet abrupt alternation (DWAA) events based on the daily precipitation observations at 75 rainfall stations in summer from 1960 to 2015. We found that the DWAA events have been spreading in the study area with higher frequency and intensity since 1960. In particular, the DWAA events mainly occurred in May and June in the northwest of the YRB-ML, including Hanjiang River Basin, the middle reaches of the YRB, north of Dongting Lake and northwest of Poyang Lake. In addition, we also analyzed the impact of El Niño Southern Oscillation (ENSO) on DWAA events in the YRB-ML. The results showed that around 41.04% of DWAA events occurred during the declining stages of La Niña or within the subsequent 8 months after La Niña, which implies that La Niña events could be predictive signals of DWAA events. Besides, significant negative correlations have been found between the modified DWAAI values of all the rainfall stations and the sea surface temperature anomalies in the Nino3.4 region within the 6 months prior to the DWAA events, particularly for the Poyang Lake watershed and the middle reaches of the YRB. This study has significant implications on the flood and drought control and water resources management in the YRB-ML under the challenge of future climate change.     

长江中下游流域旱涝急转事件特征分析及其与ENSO的关系

基于长江中下游流域75个雨量站1960-2015年的日降水资料,通过对原有的旱涝急转指数加以改进,定义了日尺度旱涝急转指数（Dry-Wet Abrupt Alternation Index, DWAAI）,全面分析长江中下游流域夏季（5-8月）旱涝急转事件的时空演变特征,并讨论了旱涝急转事件与事件发生前太平洋海表温度的关系。结果表明：① 改进的DWAAI综合考虑了事件前后期旱涝差异与急转快慢程度,筛选事件更加全面。② 总体来说,自20世纪60年以来,流域内发生旱涝急转事件的区域范围越来越广,事件频率和强度均具有逐年增长趋势。旱涝急转事件主要发生在5月和6月,且汉江水系、中游干流区间、洞庭湖水系北部和鄱阳湖水系西北部地区为事件高发区。③ 旱涝急转事件与事件发生前Nino 3.4区域海温持续异常偏低存在一定关系。在发生时间上,La Ni?a现象具有一定的先兆作用,41.04%的事件发生在La Ni?a现象衰亡期或现象结束后8个月内;在事件强度上,流域内站点的DWAAI与事件发生前第1~6个月的Nino 3.4区域海温异常值存在显著的负相关性,尤其是在鄱阳湖水系和中游干流区间,二者负相关性最强。研究结果可以为长江中下游流域防洪抗旱工作提供一定的依据。     

长江中下游岸线资源的特征及其评价利用

Waterfront resources are important and special kind of natural resources in the marginal area between land and water.The Yangtze River,the longest river in China,is not only rich in waterfront resources,but also has favorable development conditions with great potentiality.Aided by large-scale underwater topographic map,the major factors of the waterfront resources in the middle and lower reaches of the Yangtze River,such as the stability,the water depth and the natural conditions for port construction,are assessed in this paper rspectively on the basis of the overall investigations.The results show that:(1)the waterfront resources are abundant in the middle and lower reaches of the Yangtze River,but lack of perfectly combined high grade waterfront;(2)there exists and obvious regional difference in the natural quality of the waterfront along the Yangtze;(3)the fore-bank water depth and waterfront stability are the main natural factors related to the waterfront auality in the middle and lower reaches of the Yangtze River;(4)the waterfronts along the Yangtze are mainly used for port,warehouse and industrial pruposes; and (5)the waterfronts near important cities are highly used,especially the high-quality waterfronts.In addition,some suggestions for the development and utilization of the waterfront resources are presented in this paper.     

长江中游新石器时代遗址规模的分布特征

运用ArcGIS软件建立了长江中游地区9.0~4.0 ka BP文化遗址的空间数据库,采用叠加分析和统计学方法,对文化遗址的规模、海拔分布、坡度、距河流远近等特征进行了系统分析。结果表明：① 由新石器时代早期到晚期,遗址的数量、规模和分布范围等均呈现增长或扩大趋势,叠置型遗址个数增加;② 遗址一般具有低海拔、平缓地形和距河流较近的选址倾向,晚期的文化遗址大体保持该倾向,但对海拔、坡度及距河流远近等的选择开始出现分化。③ 新石器时代晚期不同规模的文化遗址在选址上存在一定分异。小型遗址多分布在坡度为6°~15°的缓坡地,中型及以上规模的遗址更倾向于坡度为2°~6°平缓地;中小型至大型遗址的海拔分布均以30~50 m为主,特大型遗址的海拔分布以50~100 m为主;特大型遗址在距河流1000 m以内的分布比例高于其他规模遗址;④ 新石器文化在早中期受气候、水源、地形等自然环境因素影响较大,晚期文化的适应能力有所增强。     

都市区视角下长江中游城市群发展的思考

本文首先对都市区、城市群概念、标准进行界定,并将城市群建立在都市区基础上,从而为城市群的认定划分提供了具体的指标依据;进而用近两次人口普查和2011年区域经济统计年鉴数据,对社会经济意义上的长江中游地区湖北、湖南、江西、安徽四省进行实证研究。结果表明,2010年长江中游地区共有都市区22个,比2000年新增2个;长江中游城市群由四省内部相对独立的四个小城市群,沿东北-西南和西北-东南十字形轴向组合而成。最后根据长江中游城市群大分散、小集中的特点和区位价值的提升等提出四点发展建议。     

疏勒河中下游土地荒漠化敏感性评估

土地荒漠化是疏勒河流域面临的关键环境问题,加强该区域的荒漠化敏感性评估对有效控制荒漠化至关重要。通过集成多源GIS与遥感数据,构建土壤、植被、气候和管理定量评估指标,利用地中海荒漠化与土地利用模型（MEDALUS）计算环境敏感性指数,识别荒漠化敏感区,在此基础上分析荒漠化敏感性的成因,并引入变异系数法确定荒漠化敏感性的主要影响因素。结果表明：目前疏勒河中下游荒漠化态势严峻,17.70%的区域属于极高敏感区,54.34%属于较高敏感区。荒漠化敏感性的空间格局是中部高、北部低,主要由与人类活动有关的管理质量指数决定。从绿洲内至绿洲外荒漠化敏感性逐渐升高,大致呈层状分布,表明人类活动对荒漠化影响显著,建议加强和巩固绿洲外围的防护体系建设。     

基于Google Earth和MODIS陆地数据的农林地转换对地表温度的影响——以长江中下游及毗邻地区为例

揭示耕地与林地转换对地表温度的影响对于认识人类活动的气候与环境效应具有重要意义。基于卫星遥感数据的统计分析是揭示土地利用/覆盖变化对地表温度影响的重要手段。但是,在景观破碎度较高地区,混合像元问题成为使用这一技术手段的主要限制性因素,中国南方长江流域尤为典型。为突破这一限制,论文基于Google Earth高清影像,在1 km尺度上辨识了200对耕地与林地纯像元,进而利用MODIS陆地数据产品,对比分析了耕地与林地的地表温度(LST)、叶面积指数(LAI)、地表反照率(Albedo)之差。结果表明：耕地的LST高于林地,白天和夜间温度分别约偏高2.75 ℃和1.15 ℃,并且温差因季节而异,白昼温差呈双峰(分别是5月和10月,温差约3.18 ℃和3.33 ℃),夜间温差为单峰(7月,约2.46 ℃)。同时,温差因地而异,总体表现为西高东低,陕甘交界处的白昼温差最大,年平均约为3.83 ℃;安徽中南部温差最小,约为1.1 ℃。耕地与林地的LST之差主要由蒸散发的差异所致。林地的LAI较大,蒸散发较强,地表向大气的潜热通量较大,用于直接加热地表的感热相对偏少,因而LST相对偏低。上述结果表明近年来长江流域及毗邻地区的耕地转为林地通过增加蒸发产生了一定的致冷效应。     

长江中下游浅水湖泊表层沉积物潜在可交换性磷研究

利用无限稀释外推法 (IDE法 )和Hieltjes与Lijklema提出的H-L法对长江中下游浅水湖泊表层沉积物中可交换性磷进行测定,研究了IDE法测定的潜在可交换性磷 (IDE-P )与H-L法使用NH₄Cl测定的氯化铵磷 (NH₄Cl-P )在不同污染程度沉积物中的分布规律及二者关系,并对IDE-P和NH₄Cl-P与沉积物土壤测试磷 (STP)、磷吸附饱和度 (DPS)、总磷 (TP)和有机质关系进行讨论。结果表明,沉积物IDE-P和NH₄Cl-P分布遵循重污染沉积物>污染较轻沉积物的规律,IDE-P含量高于NH₄Cl-P含量;不同沉积物的(NH₄Cl-P/IDE-P)%变化较大;IDE-P和NH₄Cl-P与STP、DPS、总磷和有机质的相关性较好。     

长江中下游河道岸线的整治与开发利用

通过分析长江中下游河道的各段的整治措施，提出长江中下游河道整治的关键是：（1）控制河势，治理河岸崩塌，增强河床与河岸的稳定性；（2）充分重视三峡工程建成后对河道变化产生的影响；（3）科学合理地控制好长江采砂。并分析了长江岸线开发利用现状及存在问题，提出了岸线利用的原则。在长江中下游河道岸线利用过程中，还存在：河势不稳定，布局不合理，深水浅用浪费岸线资源和水污染严重等问题，提出遵照河道演变规律开发岸线，保护河岸工程的安全，根据河岸水质污污染与河床特点合理布置引水口和排污口，提高引水质量。     

Evolution characteristics and drivers of the water level at an identical discharge in the Jingjiang reaches of the Yangtze River

The operation of large-scale reservoirs have modified water and sediment transport processes, resulting in adjustments to the river topography and water levels. The polynomial fitting method was applied to analyze the variation characteristics of water levels under different water discharge values in the Jingjiang reach of the Yangtze River from 1991–2016. The segregation variable method was used to estimate the contributions of the varied riverbed evaluation, the downstream-controlled water level, and the comprehensive roughness on the altered water level at an identical flow. We find that low water levels in the Jingjiang reach of the Yangtze River from 1991–2016 are characterized by a significant downward trend, which has intensified since 2009. Riverbed scouring has been the dominate factor causing the reduced low water level while increased roughness alleviated this reduction. From 1991–2016, there was first a decrease followed by an increase in the high water level. The variation characteristic in terms of the "high flood discharge at a high water level" before 2003 transformed into a "middle flood discharge at a high water level" since 2009. The increased comprehensive roughness was the main reason for the increased high water level, where river scouring alleviated this rise. For navigation conditions and flood control, intensified riverbed scouring of the sandy reaches downstream from dams enhanced the effects that the downstream water level has on the upstream water level. This has led to an insufficient water depth in the reaches below the dams, which should receive immediate attention. The alteredvariation characteristics of the high water level have also increased the flood pressure in the middle reaches of the Yangtze River.     

渭河中下游干流洪水资源化效益分析与测算

渭河流域中下游不仅水资源总量紧缺,而且配置型、工程型、水质型缺水问题突出,实施洪水资源利用在河道减淤和流域防洪等方面具有显著的经济和环境效益。通过分析河道冲淤特性、确定洪灾损失标准、统计堤防建设和使用现状,结合研究区经济发展现状和土地利用特征,采用效益分摊系数法,计算渭河中下游干流洪水资源化综合效益。主要结论：（1）洪...     

长江中游城市群创新平台空间分布及其影响因素分析

创新是引领发展的第一动力。创新平台作为区域创新体系的重要组成部分和集聚创新资源的核心支撑载体,是推动创新驱动发展的主要抓手。论文以长江中游城市群为研究区域,运用最邻近指数、核密度估计、Ripley's K函数、地理探测器等方法,探究2017年长江中游城市群省级以上创新平台的空间分布特征及其影响因素。结果表明：① 长江中游城市群创新平台整体呈现出集聚分布特征,以武汉、长沙和南昌为核心呈“品字形”的分布格局;② 基于不同等级和不同功能类型划分的各类创新平台均呈现出显著集聚的特征,但集聚强度和集聚状态存在一定差异;③ 创新平台总体和不同类型创新平台的空间集聚存在尺度效应,随地理距离的变化空间集聚趋势先增强后减弱;④ 创新平台的空间分异是多因素综合作用的结果,金融实力、信息化程度、利用外资水平、人力资本条件的影响最为显著,其次为交通可达性、城镇化水平、经济基础和创新氛围。     

长江中游城市群要素集聚能力的时空演变

随着城市化和工业化的快速推进,对资源要素的需求量大增,城市和区域间对要素的争夺不断加剧,强化自身要素集聚能力成为各城市和区域面临的紧迫挑战。以长江中游城市群为研究对象,对1995-2014年20年间长江中游城市群要素集聚能力的时空演变特征进行研究。结果表明：① 1995-2014年,长江中游城市群要素综合集聚能力在波动中保持增长,在全国处于第四极地位;城市群内城际要素集聚能力差异在波动中保持平衡;科技创新、金融、对外开放等要素更趋向于集聚分布。② 1995-2014年,长江中游城市群要素集聚格局形成了以武汉、长沙、南昌等核心城市为主导的多中心“核心—边缘”结构,空间格局变化较小;其要素集聚格局仍处于初级的中心城市极化发展阶段,一体化的要素集聚组合体尚未形成。③ 长江中游城市群要素集聚格局较为分散,首位城市武汉在整个城市群的要素集聚首位度较低;要素集聚重心跃迁路径沿“西北—东南”整体走向进行往复迁徙;各类要素集聚格局演化分异显著,大部分要素集聚格局呈中心城市指向特征。