Sedimentary characteristics of distributive fluvial system in arid area: A case study of the Shule River distributive fluvial system, NW China

Based on detailed investigation of the modern sedimentation of the distributive fluvial system of Shule River and the data of unmanned aerial vehicle(UAV)aerial photography and satellite remote sensing,the sedimentary characteristics and differences of distributive fluvial system in arid areas are analyzed.By comparing the changes in slope,river morphology and sedimentary characteristics in different sections from the apex to the toe,the distributive fluvial system of Shule River can be divided into three facies belts:"proximal","middle"and"distal".The proximal belt has the largest slope and strongest hydrodynamic condition,mainly appears as large-scale braided river deposits;the fluvial bars in this belt are mainly composed of gravels,the gravels have good roundness and certain directionality,and are medium-large boulders,with low sand content;the main microfacies in this belt are braided channel and flood plain.The middle belt with slope smaller than the proximal belt,is mainly composed of braided bifurcating river deposits.Due to branching and infiltration,this belt has weaker hydrodynamic conditions,so some of the distributive rivers dry up,appearing as ephemeral rivers.This belt has small lenticular sandbodies,fine to medium gravels,higher sand content,and mainly braided channel,flood plain and aeolian dune microfacies.The distal belt has the smallest slope and flat terrain,where the river begins to transform from braided river to meandering river,the sediment is mainly sand.Due to the influence of slope,this belt has weaker erosion toward source and stronger lateral erosion,and point bars developing around the edge of the active lobes.In this belt,the river is completely meandering,and the main microfacies are braided channel,meandering channel,flood plain,aeolian dune,lake and swamp.

Wandering gravel-bed rivers and high-constructive stable channel sandy fluvial systems in the Ross River area,Yukon Territory,Canada

Mid-Cretaceous strata within the Tintina Trench, 3 km west of the community of Ross River, contain evidence of deposition in two distinct, alternating, fluvial settings. Coal-bearing, mud-dominated strata are commonly associated with high-constructive sandy channel systems, with extensive overbank, levee and splay deposits. Channels are between 3 and 30 m wide and 0.4-7 m thick. They show repetitive development of side and in-channel bar-forms, as well as up-channel widening of the rivers by selective erosion of associated overbank and levee deposits. Levees extended for several hundred metres away from the channels. In this setting low-angle inclined stratification and epsilon cross stratification may reflect lateral migration of crevasse channels or small streams. The paucity of exposure prevents recognition of the channels as products of multiple channel anastomosed systems or single channel high-constructive systems. Gravel-dominated strata, inter-bedded with, and overlying coal-bearing units, are interpreted as deposits of wandering gravel-bed rivers, with sinuosity approaching 1.4. In most exposures they appear to be dominated by massive and thin planar-bedded granule to small pebble conglomerates, which would traditionally be interpreted as sheet-flood or longitudinal bar deposits of a high-gradient braided stream or alluvial fan. Architectural analysis of exposures in an open-pit shows that the predominance of flat bedding is an artefact of the geometry of the roadside exposures. In the pit the conglomerates are dominated by large scale cross stratification on a scale of 1-5.5 m. These appear to have developed as downstream and lateral accretion elements on side-bars and on in-channel bars in water depths of 2-12 m. Stacking of strata on domed 3rd order surfaces suggests development of longitudinal in-channel bar complexes similar to those observed in parts of the modern Rhone River system. Mudstone preserved in some of the channels reflects intervals of channel abandonment or avulsion. Minimum channel width is from 70 to 450 m.

Analysis of the Sedimentary Characteristics of a Modern Distributive Fluvial System:A Case Study of the Great Halten River in the Sugan Lake Basin,Qinghai,China

Understanding controls on river planform changes can help to build predictive models for distributive fluvial systems,and then guide the oil and gas exploration.To do this we have undertaken a detailed investigation of the modern Great Halten River distributive fluvial system from the Sugan Lake Basin,Qinghai,China.Unmanned aerial vehicle(UAV) photography,satellite remote sensing data and elemental analysis were used to determine differences in the sedimentary characteristics of the distributive fluvial system.From the apex to the toe,the changes in the slope,river morphology,sedimentary characteristics and element content in different regions were determined and three facies belts:“proximal”,“medial” and “distal” were identified.We found that the sedimentary structure and elemental content characteristics of each facies differ greatly.We compare the large-scale evolution of rivers from braided to meandering rivers,and the fine description of sedimentary characteristics in combination with each observation,we strengthen our overall understanding of the modern DFS from macro to micro scale.At the same time,we summarize the sedimentation model of the Great Halten River DFS,and our study provides a reference for establishing the sedimentary model in continental petroliferous basins.

Application of remote sensing in the description of fluvial system in dryland:A case study of Golmud distributive fluvial system,Qaidam Basin,NW China

Distributive fluvial systems(DFS)are widespread in drylands in the northwestern China.Analyzing differences in fluvial morphology in drylands is beneficial for studying ancient rock records and the extraterrestrial surface environment.The remote sensing image,characterized by real-time and possibility of repeated observations,is a vital tool for recording and comparing fluvial systems in drylands.Satellite remote sensing technology is a method of investigating fluvial morphologies.Due to the limited accuracy of satellite imagery,there are few reports on the detailed description of the fluvial system in drylands of NW China.We analyze the pattern of fluvial morphology changes in the Golmud distributive fluvial system(DFS)in the Qaidam Basin,northwestern China,using satellite remote sensing and unmanned aerial vehicles(UAV).Firstly,we use Google Earth real-time image data,historical image data,and radar digital elevation data to extract geomorphological information;then the UAV remote sensing image data were used to interpret fluvial network information;finally,we use the gray-scale differential vector method to describe the fluvial morphologies.Three zones have been identified in the Golmud DFS:the proximal,the medial,and the distal,by comparing the differences in topographic and geomorphic characteristics,fluvial morphologies,and sedimentary characteristics of the Golmud DFS.The proximal slope is higher than the other two zones,and the geomorphic features are mainly gravel gobi.The proximal fluvial morphologies are mainly large braided rivers,and sediments are more gravelly and less sandy.The medial slope is relatively small,and the geomorphic features are mostly oasis plains.The medial fluvial morphologies are mainly meandering rivers associating with braided rivers,and sediments are more sandy and less gravelly.The distal slope is the lowest,and the geomorphic features are mostly oasis plains,lakes,and marsh plains.The distal fluvial morphologies are mainly meandering rivers,and sediments are sandy and muddy.Comparison of the DFS from proximal to medial to distal in Golmud confirmed the potential of remote sensing image technology in identifying the fluvial morphologies and sedimentary facies distribution in dryland.

Coupling within Fluvial Geomorphic Systems:Spatial and Temporal Implications

Coupling within fluvial systems relates to the connectivity between the various components of the system. It can be viewed at several scales from local scales of hillslopetochannel and reachtoreach coupling, to larger scales of zonal coupling between the major functional zones of the fluvial system, and to the scale of regional coupling. Coupling influences how the system responds to environmental change and how the effects of environmental change are propagated through the system. This paper provides a review, based largely on previously published work, of the coupling concept, and how the effective temporal scales vary with the spatial scale of coupling. Local scale coupling is considered through the hillslope to channel coupling in the Howgill Fells, northwest England, observed over a 30year monitoring period, together with examples from badlands in Spain, and reachtoreach coupling on the River Dane, northwest England. At the zonal scale the relative influence of climatic and baselevel change on coupling through dryregion alluvial fans is considered on fan systems in Spain, Nevada, and UAE/Oman. For large scale regional coupling, the response of the Tabernas basin, southeast Spain to tectonic uplift, is examined. The factors influencing coupling mechanisms vary with temporal and spatial scales. At the hillslopetochannel scale the significant factors are the magnitude and frequency characteristics of sediment generation and removal mechanisms within the context of progressive morphological change. Effective timescales range from the individual event to decadal timescales. At the zonal scale, that of alluvial fans, the significant factors are climatic change, and particularly in the appropriate morphological setting, baselevel change. Effective timescales are of the order of hundreds to thousands of years. At the regional scale, the response to tectonic uplift may take >100 ka to be transmitted through the drainage basin.

FUNDAMENTAL CHARACTERISTICS OF THE ANASTOMOSING FLUVIAL SYSTEM ON COMPLEX DELTAIC PLAIN

The anastomosing fluvial system was considered as the same term of the braided fluvial system. Smith and others have recognized the difference between them. They described the anastomosing fluvial system as 'a low energy complex of several interconnected channels of variable sinuosity crossing a wetland and forming many elongate vegetated islands', and established a depositional model of anastomosing fluvial system based on their

Tectonic and climatic controls for fluvial terraces of the Yellow River over the past 2.6 Ma at Northeast Tibetan Plateau and Ordos Block

The Yellow River is usually assumed to record tectonic activities and climatic changes;however,a systematic study was lack in the sedimentology,stratigraphy,geomorphology and geochronology for the entire Yellow River though various geologic scholars have conducted numerous works in individual basins.This review focused on well-preserved fluvial terrace sequences that formed along this river on northeastern(NE)Tibetan Plateau and Ordos Block over the past 2.6 Ma.After comparing numerous initial incision ages at different segments along the Yellow River,we found out that the youngest initial incision may occur at ca.150 ka at the Longyang Gorge.The Yellow River may transit from multiple separated endorheic drainages to an entire external drainage after 150 ka,which may cause differentiations in the apparent incision rates before and after 150 ka;thus apparent net incision rates were calculated respectively for the Yellow River before 150 ka and the drainage network post 150 ka.Apparent net incision rates prior to 0.15 Ma were calculated as 0.15,0.29,0.10,0.12 and 0.03 mm/a respectively in Tongde-Xunhua,Lanzhou-Linxia basins,Heishan,Jinshan and Fenwei-Sanmen Gorges in this review,which mainly reflected Kunhuang-Gonghe Tectonic Event,generated by the Indo-Asian collision and diminishing as the NE Tibetan Plateau eastward extruding at ca.1.8-0.15 Ma.Apparent net incision rates post 0.15 Ma were calculated respectively for NE Tibetan Plateau and Ordos Block,considering their different base level.On NE Tibetan Plateau,four fluvial degradational phases were identified between ca.105~70,53~40,25~16 and 12~6 ka associated with terrace levels respectively,at average elevations of 96,40,20 and 10.5 meters above the current river level(m arl)within a range of 5~96 m arl;and four broad periods in the last 150 ka on Ordos Block:possibly marine oxygen isotope stage(MIS)5,ca.118 to 72 ka,most of MIS 3,ca.44~28 ka,transition from LGM to last deglacial ca.20 to 16 ka,and 4~3 ka at average elevations of 67.5,26,19 and 11.5 m arl.These degradational phases post 0.15 Ma were associated with multiple processes including enhanced fluvial discharge with an increase in monsoonal precipitation and/or melt water in deglaciation.

Postglacial sea-level changes and development stages of fluvial-estuarine system

-On the basis of the data obtained from the investigations on some rivers in China and Australia, the author discusses the spatial and temporal changes of various portions of fluvial-estuarine system during postglacial sea-level rising in present coastal and deltaic areas. The evolution of a fluvial-estuarine system can be divided into four development stages: early transgression, late transgression, stationary and regression. Early transgression brought about filling-in of the paleo-valley formed in low stand of sea level. In response to late transgression the estuaries were created, during the stationary stage the big swamp was developed. The regression led to estuaries to be filled with sediments and then became deltas. At the same locality the fluvial-estuarine system changed with time. In the transgressive period the lower reach of a river changed into an estuary, and then became nearshore area. In the regressive period the nearshore area changed into an estuary , and then became delta.

Fluvial reservoir characterization through channel belt dimension and petrophysical analysis

The dimensions and connectivity of fluvial reservoirs vary greatly, making it challenging to characterize them using conventional approaches. In this study integrated channel belt dimension analysis from seismic geomorphology and empirical equations, well log facies, and petrophysical analysis were performed to characterize the fluvial reservoirs. The study interval consists of fluvial deposits and is divided into three reservoir zones, which are defined by four key regional markers (B, D, K, O). In these intervals, six (6) fluvial facies have been identified. Based on the log facies proportions and their stacking relationships, it is interpreted that the reservoirs in zone 1 (B to D) were deposited in a proximal reach of a meandering system, zone 2 (D to K) in a marginal marine setting, and zone 3 (K) in a distal reach of a meandering system. The dimensions of fluvial channels and channel belts were determined using empirical equations. The results were compared with the observed dimensions of fluvial channels and channel belts from the seismic horizon and stratal slices of the same intervals. Zones 1 and 3 are characterized by broad meander belts (1000–4000 m) compared to zone 2 (600–1300 m). Petrophysical analysis showed zones 1 and 3 have the better petrophysical properties compared to zone 2. Though zone 3 has the most well-developed sand bodies, the best reservoir interval is zone 1 because of its higher porosity. Although channel belt dimensions have a significant influence on reservoir connectivity, they do not seem to have control on reservoir properties. The channel belt dimensions obtained from the empirical equations and interpreted from the seismic geomorphology analysis were found to be strikingly similar. Since three-dimensional seismic data is not available everywhere and seismic imaging quality decreases with depth, empirical equations can be used to analyze fluvial reservoir parameters and their connectivity at greater depths.

分支河流体系沉积学工作框架与流程

基于现有的研究成果和存在的问题,探讨了分支河流体系(DFS)研究中的关键科学问题、主要研究内容、研究方法和工作流程。研究结果表明:①DFS研究中最关键的3个科学问题是明确河网结构和河型演变规律、构建沉积标志和沉积模式、分析其形成和分布的控制因素。②DFS研究的主要内容包括建设形态沉积学数据库、现代沉积机理研究、分类研究、建立沉积模式、储层建模与储层预测等5个方面。③DFS研究中的关键技术包括基于遥感图像的形态数据采集、形成机理的水槽和模拟实验、河网重构、顶点位置预测与河道分汊点自动生成方法、储层建模知识库平台等。④DFS研究的基本工作流程是先建立形态沉积学数据库,搭建数据库软件平台,在此基础上选择具有代表性的DFS进行现代沉积解剖,然后综合现代沉积调查、露头解剖和模拟实验成果,形成分类体系,总结各类DFS的识别标志和沉积模式,分层次建立储层预测模型,形成沉积结构储层预测模型的建模软件平台,从而预测沉积体系中有利储层的分布。

基于地球河流扇预测模型的火星地表水径流量预测

【目的】火星表面的水活动地质历史一直是科学界关心的热点,直接影响着火星探测的研究方向。【方法】根据火星和地球的可对比性,建立了融合345个地球现代河流扇沉积的数据集并形成了高精度扇体面积预测模型,从而识别火星上的河流扇沉积,预测火星河流扇发育期的地表水径流量。【结果】结果表示,在火星南部高地霍尔顿陨石坑附近识别出一个面积约84.35 km^(2)的典型河流扇沉积,并反向预测出该扇体形成需要的年平均地表水径流量为1.8828×10^(6)m^(3),推测出该区域径流量不是由单一降水构成,为雪山(冰川)融水和降水多种来源。【结论】该成果是河流扇研究在行星沉积学中的应用,为进一步深入研究火星和其他天体地表水活动提供了新的方法。

分支河流体系河网形态演变规律——以格尔木河流扇为例

为了探索分支河流体系河网分布规律,为创建储层建模训练图像提供知识库信息。利用Google Earth、Global Mapper、91卫图助手等现代地理信息软件,系统测量了现代格尔木河流扇表面河道分叉特征,应用Horton定律和分形方法建立了河流扇的河网形态模型。结果表明:①格尔木河流扇从顶点到入湖段共识别出26级河道,882个节点和2162个河道段,泉线上、下的河道表现出不同的河网形态;②泉线上部共发育64个节点,每级河道数目增长是上一级河道的R_(B)=1.8900倍,每级河道平均长度是下一级河道的R_(L)=1.0095倍,即河网形态特征参数R_(B)=1.8900和R_(L)=1.0095;泉线下部共发育818个节点,每级河道数目增长是上一级河道的R_(B)=1.0279倍,每级河道平均长度是下一级河道的R_(L)=0.9899倍,即河网形态特征参数是R_(B)=1.0279和R_(L)=0.9899;③河网形态特征参数受坡度影响变化较大,坡度较大则河网形态特征参数较大,坡度较小则河网形态特征参数较小。河网形态特征参数定量表征促进了分支河流体系沉积学发展,为开展陆相盆地储层建模和砂体预测提供了新的知识库信息.

试论河流地貌学的新进展和趋势

河流地貌学研究河流动力的侵蚀-搬运-堆积过程(源-汇系统)、河流地貌的时空演化,及其与地球内部构造活动和地球表层气候和环境之间的相互关系。介绍了河流地貌学与表层地球系统科学的关系、研究内容和发展趋势、前沿问题和研究机遇。河流侵蚀、搬运和堆积在构造-气候相互作用中起着重要的媒介作用,是地球内部和外部相互作用的重要纽带。随着高精度数字地形模型定量分析、地表侵蚀速率的定量测定、沉积物测年以及地貌演化数值模拟等新技术和新方法的应用,促进了不同时间和空间尺度流域地形、水系发育、河流地貌动力过程、河流地貌空间分布特征及其对构造、气候和人类活动等的响应和反馈的研究。未来除了更深入地理解流域尺度物质和形态的变化规律和机制外,加强河流地貌过程的定量表达,将流域地貌研究与表层地球系统的热点科学问题相联系,进一步开展学科交叉,服务于国家战略,才能提高河流地貌学、乃至地貌学科的竞争力。

成都平原河流阶地的发育及其对古气候和新构造运动的指示

为了研究第四纪以来成都平原古气候变化规律和新构造运动特征,对成都平原岷江水系河流阶地序列,年代格架,不同地质时期的孢粉组合特征和T4剖面上网纹红土的地球化学特征等进行了深入研究。通过收集大量存量资料,辅以少量野外查证工作,结合地质、地貌和年代学资料,厘定了成都平原岷江水系5级河流阶地,T5至T1拔河分别为98~127 m、59~79 m、36~52 m、4~10 m、2~5 m,形成时代分别为925±92 ka、722±77 ka、462±46 ka、30.13±2.86 ka、9.0 ka,其中T5、T4、T3、T2为基座阶地,发育受构造运动和气候变化共同驱动,可作为第四纪以来成都平原东缘龙泉山背斜南段隆升的地貌标志,T1为堆积阶地,发育主要受气候变化驱动;孢粉组合特征反映第四纪以来成都平原以森林草原植被为主,气候整体具由偏暖偏湿向温干变化的趋势;阶地资料揭示第四纪以来龙泉山背斜南段经历了四次间歇性隆升,隆升高度达127 m,早更新世中期龙泉山背斜南段隆升速率为0.089~0.335 mm/a,早更新世晚期隆升速率急剧下降至0.027~0.165 mm/a,然后呈现出逐渐升高的趋势,到晚更新世—全新世隆升速率上升到0.133~0.322 mm/a;龙泉山背斜南北段存在差异隆升,北段的隆升速率和隆升幅度明显大于南段,在现代地貌上表现为龙泉山北段以低山为主,南段向低山丘陵过渡。

A Paleogeographic and Depositional Model for the Neogene Fluvial Succession, Pishin Belt, Northwest Pakistan: Effect of Post Collisional Tectonics on Sedimentation in a Peripheral Foreland Setting

Detailed facies analysis of the Neogene successions of the Pishin Belt （Katawaz Basin） has enabled documentation of successive depositional systems and paleogeographic settings of the basin formed by the collision of the northwestern continental margin of the Indian Plate and the Afghan Block. During the Early Miocene, subaerial sedimentation started after the final closure of the Katawaz Remnant Ocean. Based on detailed field data, twelve facies were recognized in Neogene successions exposed in the Pishin Belt. These facies were further organized into four facies associations i.e. channels, crevasse splay, natural levee and floodplain facies associations. Facies associations and variations provided ample evidence to recognize a number of fluvial architectural components in the succession e.g., low-sinuosity sandy braided river, mixed-load meandering, high-sinuosity meandering channels, single-story sandstone and/or conglomerate channels, lateral accretion surfaces （point bars） and alluvial fans. Neogene sedimentation in the Pishin Belt was mainly controlled by active tectonism and thrusting in response to the oblique collision of the Indian Plate with the Afghan Block of the Eurasian Plate along the Chaman-Nushki Fault. Post Miocene deformation of these formations successively caused them to contribute as an additional source terrain for the younger formations.

The concept, characteristics and significance of fluvial fans

The concept and characteristics of fluvial fan are elucidated through literature review and case analysis.Firstly,the concept and terminology of fluvial fan are introduced.Secondly,the progress and controversy on the formation mechanism,analysis methods and sedimentary models of fluvial fan are elaborated,and fluvial fan is compared with alluvial fan,river and lacustrine delta.Finally,ten identification signs of the fluvial fan are proposed.It is found through the study that development and scale of fluvial fan are affected by external factors such as climate,tectonic,provenance and wind field.The facies and lithofacies association inside the fan are controlled by the activity of the internal channel.It is pointed that fluvial fans are widely distributed in the world not only today but also in the geological history.The occurrence of fluvial fan will change the traditional continental deposition system dominated by alluvial fan-river-lacustrine.Meanwhile,the research of fluvial fan will be of great significance in the fields of sedimentology and oil and gas exploration.

Distribution and Forming Model of Fluvial Terrace in the Huangshui Catchment and its Tectonic Indication

The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping. Three terraces in the Haiyan Basin, four terraces in the Huangyuan Basin, 19 terraces in the Xi＇ning Basin （the four high terraces may belong to another river）, nine terraces in the Ping＇an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized. Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River, which is located at the margin of Tibet, are different from that of the rivers at other regions. The formation process of the terrace is more complicated at the Huang Shui catchment： both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins, indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins. A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper. First, the equilibrium state of the river is broken because of climatic change and/or tectonic movement, and the river incises in all basins in the whole catchment until reaching a new equilibrium state. Then, the downstream basin subsides quickly and the equilibrium state is broken again, and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again. Finally, the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins. The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment. These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin. Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.

Fluvial sediments in the Alagxa Plateau as a dust source: iron mineralogical and geochemical evidence

The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests that the fluvial sediments are the source of a large amount of silty material which could be transported to the CLP. Therefore, we conclude that the fluvial sediment in the Alagxa Plateau is an important source of eolian silt, which is deposited in downwind region, and that this source has been previously underestimated.

New acoustic system for continuous measurement of river discharge and water temperature

In many cases, river discharge is indirectly estimated from water level or streamflow velocity near the water surface. However, these methods have limited applicability. In this study, an innovative system, the fluvial acoustic tomography system （FATS）, was used for continuous discharge measurement. Transducers with a central frequency of 30 kHz were installed diagonally across the river. The system＇s significant functions include accurate measurement of the travel time of the transmission signal using a GPS clock and the attainment of a high signal-to-noise ratio as a result of modulation of the signal by the 10th order M-sequence. In addition, FATS is small and lightweight, and its power consumption is low. Operating in unsteady streamflow, FATS successfully measured the cross-sectional average velocity. The agreement between FATS and acoustic Doppler current profilers （ADCPs） on water discharge was satisfactory. Moreover, the temporal variation of the cross-sectional average temperature deduced from the sound speed of FATS was similar to that measured by a temperature sensor near the bank.

Ecological function regionalization of fluvial corridor landscapes and measures for ecological regeneration in the middle and lower reaches of the Tarim River, Xinjiang of China

The middle and lower reaches of the Tarim River are currently one of the main regions of ecological restoration in the arid areas of western China.Using the principles and method of landscape ecology,this study has chosen the fluvial corridor landscape in the middle and lower reaches of the Tarim River,and discusses the region’s ecologically functional regionalization system and issues related to its practical classification.On this basis the corresponding regionalizing principles and standards were developed which were used to qualitatively divide the three main landscapes as the ecologically functional areas in the drainage basin.The paper has also analyzed the characteristic of the study areas,and has put forward the measures for its ecological restoration.