Human Modification of the Geomorphically Unstable Salt River in Metropolitan Phoenix

In‐stream gravel mining, massive bridge piers, and channelization have all contributed to the geomorphic instability of the Lower Salt River channel in Arizona. Dam closure, changing dam operating rules, and the frequent modification of the channel bed have decreased our ability to predict the Salt River hydrology. Engineering practice has adapted to this situation and to a public that is increasingly intolerant of service disruptions by constructing larger bridges and extending levees. Building these larger structures may be counterproductive; future construction should not constrict the channel and should re‐establish a braided river to decrease the energy available to the system.     

Stream Temperature Spatial Variability Reflects Geomorphology,Hydrology, and Microclimate: Navarro River Watershed,California

Stream temperatures are critical to coldwater fish and vary with microclimate, geomorphology, and hydrology, including influx of groundwater. Spatial variability of stream temperatures was examined at reach and watershed scales within the 816 km² Navarro River watershed in California. Field monitoring and numerical modeling illustrate that stream temperatures were highest at sites with high solar incidence (low shading and wide streams), long travel times, and low discharge. Microclimate helps explain deviation from the general pattern of streams warming with increasing drainage area. Reach-scale field observations of channel width and groundwater influx explain variation in stream temperatures not captured by watershed-scale models.     

River Classification as a Geographic Tool in the Age of Big Data and Global Change

Spatial classification is a well‐defined analysis method in geography, which involves defining regions of the Earth based on shared characteristics. An analogy can be made between classification in geography and taxonomy in biology, because both are used to reduce complexity. Just as modern evolutionary theory and genetics technologies have transformed biological taxonomy from the sometimes arbitrary classification of living things based on superficial similarities and differences into a system that reflects the history of life and relationships among organisms, modern advances in conceptual understanding and development of technology have similarly revolutionized classification in geography as a powerful method for describing and quantifying processes. Here, I describe the history and current trends of geographic classifications relevant to river systems. Overall, there is significant emerging potential in classification as a tool for understanding river processes     

The Hydrologic Importance of Small- and Medium-Sized Dams: Examples from Texas

Studies of the effects of dams have emphasized large and very large dams; less well understood are the impacts caused by smaller dams. Using Texas as an example area, this article highlights the role of small- and medium-sized dams in affecting the surface hydrology of river systems. Analysis of data from the National Inventory of Dams (NID) in a geographic information system showed that small and medium dams comprise about 97 percent of the dams registered in Texas. A small-or medium-sized dam is found approximately every 100 km² of area and about 120 km of river length. Different from large dams, which affect water storage the most, the major impact of these smaller dams is fragmentation of river landscapes. Analysis of data for dams extracted from digital orthoquads and for water bodies from the National Hydrography Dataset indicates that the extent of river fragmentation is likely greater than that suggested by data from the NID, because the NID underrepresents the smaller dams. Such extent of river fragmentation can degrade stream habitats and pose barriers to the migration of aquatic species and transport of sediment. Because small and medium dams are largely built for fire protection and stock ponds, mitigating the impacts associated with these dams likely involves working with the private individuals who own them.     

近20年辽河三角洲地貌演化

运用钻探和浅地层探测等最新调查成果,对近20年的辽河三角洲潮流沉积进行了研究.根据不同时期水深地形和卫星影像资料对比分析了现代辽河三角洲潮流地貌变化.现代辽河三角洲的沉积主体位于双台子河口.研究区10 m深度内的地层主要包括:潮滩相、潮道相和浅海相沉积,其下为古三角洲相.潮滩相沉积物以砂和粉砂为主,分选中等,跳跃和悬浮组分各占50%左右:浅海相和潮道相沉积物主要为软弱的粘土质粉砂和粉砂质粘土,以悬浮组分为主.全新世以来至1896年,研究区为古辽河、古大凌河和绕阳河之间的小海湾.1896年,双台子河被人工开挖为分洪河道以来,口门外形成盖州滩等潮滩,并快速发育.1958年,双台子河建闸后,人海径流量和输沙量减小.目前.双台子河口整体处于淤积状态,潮滩面积不断增加,整体向南、西、北3个方向扩展.潮滩最大淤进速率为87～683 m/a,平均淤积速率为0.189 m/a.潮滩东侧局部发生侵蚀,平均侵蚀速率为0.122 m/a.潮道面积缩小,具有向西、向北迁移的趋势,最大迁移速率为48～200m/a.双台子河口地貌发育受径流、海洋动力和人类活动的影响,沉积物的主要来源由双台子河河流输沙演变为潮流和沿岸流输沙.     

黄河流域产水产沙、输移和沉积系统的划分

根据Schumm提出的河流系统的理论对黄河流域地貌系统进行了划分。结果表明 ,整个黄河流域地貌系统可以很明确地分为产水产沙系统、输移系统和沉积系统 ,其模式与Schumm的理想流域模式非常吻合 ,同时又表现出其特殊性。以河口镇为界 ,黄河流域上游和中下游两部分分别具有对应的产水系统、产沙系统和河道输移系统 ,各子系统处于动态变化过程中 ,存在一种强耦合关系 ,这种特点主要是由黄河流域的历史发育过程决定的。     

Water discharge changes of the Changjiang River downstream Datong during dry season

Based on hydrometric data and extensive investigations on water-extracting projects, this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during dry season. The natural hydrological processes and human factors that influence the water discharge are analyzed with the help of GIS method. The investigations indicate that the water-extracting projects downstream from Datong to Xuliujing had amounted to 64 in number by the end of 2000, with a water-extracting capacity up to 4,626 m3/s averaged in a tidal cycle. The water extraction from the Changjiang River has become the most important factor influencing the water discharge downstream Datong during dry season. The potential magnitude in water discharge changes are estimated based on historical records of water extraction and a water balance model. The computational results were calibrated with the actual data. The future trend in changes of water discharge into the sea during dry season was discussed by taking into consideration of newly built hydro-engineering projects. The water extraction downstream Datong in dry season before 2000 had a great influence on discharges into the sea in the extremely dry year like 1978-1979. It produced a net decrease of more than 490 m3/s in monthly mean discharges from the Changjiang into the sea. It is expected that the water extraction will continually increase in the coming decades, especially in dry years, when the net decrease in monthly mean water discharge will increase to more than 1000 m3/s and will give a far-reaching effect on the changes of water discharge from the Changjiang into the sea.     

地貌过程研究回顾与展望

地貌学是现代地理科学的一个重要分支学科。本文对中国科学院地理科学与资源研究所建所以来在地貌研究领域的主要研究成果进行了综述,包括河流地貌、黄土高原与坡地地貌、青藏高原及南极地貌与第四纪、喀斯特与旅游地貌、地貌实验与模拟、地貌制图共六个方面,对地理资源所地貌研究团队目前的研究方向进行了介绍,并就提高地理资源所地貌研究在学科发展和服务国家建设中的作用提出了建议。     

长江大通-河口段枯季的径流量变化

Based on hydrometric data and extensive investigations on water-extracting projects, this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during dry season. The natural hydrological processes and human factors that influence the water discharge are analyzed with the help of GIS method. The investigations indicate that the water-extracting projects downstream from Datong to Xuliujing had amounted to 64 in number by the end of 2000,with a water-extracting capacity up to 4,626 m3/s averaged in a tidal cycle. The water extraction from the Changjiang River has become the most important factor influencing the water discharge downstream Datong during dry season. The potential magnitude in water discharge changes are estimated based on historical records of water extraction and a water balance model. The computational results were calibrated with the actual data. The future trend in changes of water discharge into the sea during dry season was discussed by taking into consideration of newly built hydro-engineering projects. The water extraction downstream Datong in dry season before 2000 had a great influence on discharges into the sea in the extremely dry year like 1978-1979. It produced a net decrease of more than 490 m^3/s in monthly mean discharges from the Changjiang into the sea. It is expected that the water extraction will continually increase in the coming decades, especially in dry years, when the net decrease in monthly mean water discharge will increase to more than 1000 m^3/s and will give a far-reaching effect on the changes of water discharge from the Changjiang into the sea.     

金沙江巧家—蒙姑段的阶地发育与河谷地貌演化

金沙江水系演化与河谷发育问题长期以来是地质地貌学界关注的重大问题,目前仍存在较大争议。河流阶地及其相关沉积是河谷发育过程的产物,可以提供河谷发育的时代与形式等诸多信息。金沙江在巧家—蒙姑段河谷中,葫芦口附近发育和保存了8级基座阶地,结合光释光和电子自旋共振测年方法,依据古气候资料,推断T6~T1的下切时间分别对应于深海氧同位素（MIS）的36/35、34/33、24/23、20/19、14/13和4/3阶段,即气候由冷至暖的转型期。青岗坝附近则发育了5级由堰塞湖相沉积组成的堆积型阶地,指示了中更新世以来该段河谷在下切过程中经历了频繁的滑坡堵江堰塞,发育形式以“下切—滑坡—堰塞—堆积—下切”过程为主。此外,河流的平均下切速率自0.82 Ma以来由此前的0.56 mm/a下降至0.19 mm/a,表明中更新世以来频繁发生的堵江堰塞事件严重抑制了该段河谷的下切作用。综合流域内河流阶地序列及相关沉积的研究,金沙江下游段现代河谷的形成时代不晚于早更新世。     

The Spatial Structure of Land Use from 1970–2000 in the Phoenix,Arizona, Metropolitan Area

This article explores the dimensions of rapid urbanization in the Phoenix Standard Metropolitan Statistical Area (SMSA) over the past thirty years with respect to land use change. We devote primary attention to developing an understanding of what land transformations took place, the extent to which they occurred, and where they occurred. Our findings indicate that 32 percent of the Phoenix SMSA changed between 1970 and 2000. More than half of the overall change was from agriculture to some form of urban land use, and although a large percentage of the region remains open desert the parcels of desert are increasingly fragmented. This has significant implications for urban ecology and biodiversity. The growth indicates that rather than a pattern that reflects the agglomeration effects of a polycentric metropolis, the central business district of the City of Phoenix dominates the region. This has implications with respect to employment patterns, traffic congestion, and urban air quality and climate.     

A Sediment Budget of The Lower Yellow River, China, Over The Period from 1855 to 1968

This study investigates the sediment fluxes through the Yellow River sediment routing system, which are among the largest in the world, by constructing a sediment budget of the system over the period from 1855 to 1968. The framework of the sediment budget includes four functional units with the upper and middle reaches of the river as the sediment source and its lower reaches, its delta, and the deep sea as the sediment sinks. Sediment yield from the source and amounts of deposition in the lower Yellow River and the modern Yellow River delta were estimated for completing the sediment budget. The sediment budget produced for the period from 1855 to 1968 was characterized by a sediment input of 1.837 × 10¹¹ tonnes and a distribution of the sediment between the lower Yellow River, the delta, and the deep sea of 64%, 33%, and 3%, respectively. The details of the sediment budget show that the importance of sedimentation in the lower Yellow River changed greatly with variations in the condition of the dykes and other human activities. A comparison of the sediment budgets of the delta for different timescales shows that the proportion of sediment dispersed to the deep sea decreases as the timescale over which the sediment fluxes are investigated increases.     

黄河三角洲岸线及现行河口区水下地形演变

根据实测的岸线和水深数据,利用Surfer 和Mapinfo 等软件进行数据处理,结合不同阶段利津站输沙量,分析了黄河三角洲岸线及现行河口区水下地形演变。结果表明:1953-2000年,68%左右的入海泥沙淤积在口门和滨海区。由于入海流路变迁,不同岸段的岸线变化具有各自的特征。刁口河流路以西岸线基本稳定;刁口河流路以东—孤东油田以北岸线经历先淤后冲,属于强侵蚀岸段,但在防潮大堤的保护下得到人为控制下的稳定;清水沟流路形成的岸线整体向海淤进,但清8 出汊后,清水沟老河口沙嘴南侧出现侵蚀。1976-1996 年,现行河口(清水沟流路) 水下地形总体上表现为淤积,顶坡段变缓,前坡段变陡。1996-2005 年,清水沟老河口水下地形顶坡段和前坡段发生侵蚀,底坡段呈现淤积;出汊新河口水下地形继续淤积,但程度和范围都比1976-1996 年的小。孤东油田近岸侵蚀加剧。     

雅鲁藏布江大拐弯入口地区流水地貌特征及其对构造运动的响应

研究雅鲁藏布江大拐弯入口地区流水地貌对构造运动的响应过程和响应方式。在ArcGIS平台利用新近的SRTM-DEM数据对区内的流水地貌进行分析。结果显示,该区水系为平行状格局,上游和下游河谷分别出现宽谷和峡谷(嶂谷),鲁霞村与龙白村之间的10条支流长度从西南向北东方向逐渐变短,其纵剖面逐渐变陡,鲁霞村与丹娘村两地的支流在平面上出现转折点。根据前人对该区构造演化的研究,该区主要经历了60 Ma以来两大陆碰撞2、3 Ma以来持续挤压和7 Ma以来以南迦巴瓦峰为中心的正断垮塌的构造演化过程,各阶段在地质上分别产生了褶皱、走滑和正断垮塌等构造变形,并控制了水系的发育,形成了上述流水地貌。     

近百年来人类活动对鸭绿江口河床演变的影响

本文以鸭绿江口西汊道连续性较好、时间分辨率较高、以海湾性质为主的2 处现代沉积物为样本,对其沉积速率、粒度特征、碎屑矿物、重金属进行了测定和分析。柱状样记录了1920 年以来西汊道上游的沉积过程,平均沉积速率约为0.98 cm/a,粒度参数、指示性碎屑矿物、重金属的垂向分布显示出这里的沉积是以海相河口湾沉积为主,但交替存在河流沉积。通过与前期研究成果的比较,揭示了近百年来人类活动对鸭绿江口河床演变的影响。其中,兴修水利对河床演变的影响集中在早期,并带来了河床地貌的重大改变,西汊道失去了河流主汊道的地位;围垦带来的河床演变出现在中期,对河床地貌的影响也很深刻,表现为陆域面积不断扩大,水域面积不断缩小;航道治理等人类活动对河床演变的影响出现在中后期,河床地貌没有明显的改变;最近的人类活动影响有待观察。     

人类活动对别拉洪河流域水文情势的影响研究

为了研究人类活动对水文情势的影响,以别拉洪河流域1957～2004年水文、气象数据为基础,详细分析了降水量、蒸发量及径流量等要素的变化特征;利用累积滤波法、Kendal秩次相关法、径流量年内分配的不均匀系数和径流量的变差系数对径流量的变化及其趋势进行了分析;利用降水-径流双累积曲线法和Mann-Kendall法对径流量序列进行了突变检验;定量研究了人类活动对径流量的影响。结果表明,1957～2004年别拉洪河流域年径流量显著减少,1966年年径流量发生减少突变;人类活动对年径流量减少总量的影响率大于60％,是导致该流域水文循环要素发生变化的主导因素,其次才是年降水量。     

新疆和田河流域柽柳沙堆的生物地貌发育过程

柽柳沙堆是我国干旱区分布最为广泛的灌丛沙堆类型之一。在实地考察新疆和田河流 域柽柳生态地理特征、测量223 个柽柳沙堆形态, 并在两个野外观测点上实测4 个沙堆的风沙流剖面, 结合室内风洞实验段风速8 m/s 条件下模拟沙堆风流场结构等综合分析方法, 本文探讨了柽柳沙堆的生物地貌学特征及其发育过程。结果表明: 研究区柽柳的生态类型属于以胡杨林与灌木林下土壤为基础的吐加依土生境类型, 这个生境类型可以进一步划分为三个亚生境, 这些亚生境反映了柽柳沙堆不同发育阶段的生态环境特征。由于柽柳灌丛的寿命长、木质化枝干的刚性较强、根株萌发力强耐风蚀沙埋, 可对地面风沙流运行产生强烈扰动, 其风速剖面有别于芦苇沙堆和骆驼刺沙堆, 风流场结构有利于聚集风沙, 因此风沙依托柽柳灌丛堆积发育而成的柽柳沙堆平均坡度较大、沙堆存活与发育的周期也较长     

人类活动对黄河中游高含沙水流的影响

以黄河中游干流和渭河、无定河的资料研究了人类活动对黄土高原河流高含沙水流的发生频率的影响。人类破坏森林植被，大量拦截黄河上游清水来源区的清水基流，使得高含沙水流发生频率增大，大规模水土保持措施的实施则使高含沙水流发生频率迅速减小。近50年来黄河干流和一些支流的高含沙水流随时间的变化可以用一个三阶段模式来概括，即20世纪50-60年代，由于人类破坏植被，使高含水流频率增大；20世纪60年代末至80年代中期，大规模水土保持措施的实施使高含沙水流发生的频率减小；20世纪80年代末期以来，人类大量拦截利用清水资源，使高含沙水流的发生频率又复增大。     

珠江三角洲城镇化转型研究

首先采用灰色关联分析法,选取近30年的人口、产业、社会和经济等数据对珠三角城镇化的动力进行分析,其次利用面板数据模型进一步探讨珠三角城镇化转型的驱动力和演变特征。分析发现珠三角二产、人口与土地仍是其城镇化主要的驱动因素,但城镇化的“要素推动”作用下降明显,“外向型城镇化”模式逐渐减弱,“知识源导向”城镇化模式正在形成,城镇化模式趋向多元化。珠三角城镇化正面临转型,存在传统“要素推动”不可持续,新型“知识推动”发展相对缓慢,城镇化质量不高,制度建设滞后以及内需不足等新问题。珠三角要大力推进城镇化“创新驱动”,实现“动力转型”,通过建设宜居城乡以实现“质量转型”,加快农业转移人口市民化等,促进“制度转型”。