Exploring Regional Ecological Cultures in the Upper Reaches of the Yellow River in the Ming and Qing Dynasties from the Perspective of "Top Eight Views"

By studying typical "Top Eight Views" in cities like Xining,Lanzhou and Yinchuan in the upper reaches of the Yellow River,mountain and water landscapes in the study area were analyzed in terms of natural ecology;bridges,canals,ferries,pavilions,mansions,towers,temples,historical sites,production and living landscapes were analyzed in terms of humanistic ecology.On this basis,"Top Eight Views" in the upper reaches of the Yellow River were compared and the following conclusions obtained:mountain landscapes were distributed in the whole region,waterscapes unevenly valued in different cities,bridges,canals and ferries mostly located in Ningxia,temples commonly found in all cities,garden arts introduced into cities,traditional cultures carried forward by historical relics.Then the relationship between "Top Eight Views" and regional eco-cultures was analyzed,and it was proposed that humanistic and cultural connotations of these "Top Eight Views" contributed a lot to beautifying urban environment,satisfying needs of the locals' spiritual life,carrying forward local history and culture,enriching urban cultural connotations,expanding living spaces of local residents and improving integrated functions of cities."Top Eight Views" culture complied with the construction gist of urban ecological cultures,and was of great referential value for the construction of urban ecological cultures in the upper reaches of the Yellow River,and also the healthy,scientific and sustainable development of local cities.

Landslide Developmental Characteristics and Response to Climate Change since the Last Glacial in the Upper Reaches of the Yellow River, NE Tibetan Plateau

The upper reaches of the Yellow River in northeastern Tibetan Plateau are geohazards areas.The evolution of the Yellow River,chronology of some landslides,and spatiotemporal distribution characteristics of super large scale and giant landslides within the region are summarized using paleoclimate evidence,and the relationship between the intensive landslide period and climatic changes since the Last Glacial period is analyzed.It is concluded that （1） Super large scale and giant landslides are distributed widely within the region,particularly in the Qunke-Jianzha basin.（2） The chronological sequence of landslides is established by dating the slip zones of landslides and analyzing the relations between landslides and their overlying or underlying loess formations.Five landslide development periods are determined：53-49 ka BP,33-24 ka BP,10-8 ka BP,5-3.5 ka BP,and the present.（3） These correspond closely to warm and wet periods during the last 100,000 years,i.e.,two weak paleosol development stages of Malan loess deposited during the last Glacial period in the Chinese loess Plateau,L1-4 and L1-2 that belong to the marine oxygen isotope stage 3,the last deglaeial period,the Holocene Optimum,and the modern global warming period.（4） Landslide triggers may be closely linked to warm and wet periods related to rapid climatic transitions.

Precipitation cycles in the middle and lower reaches of the Yellow River （1736-2000）

Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.

Impact of vegetation restoration on hydrological processes in the middle reaches of the Yellow River,China

Sediment discharge from the Yellow River originates mainly from the drainage area between Hekouzhen and Longmen, i.e., the Helong area. Spatial-temporal variations of the vegetation cover in this area during the 1981-2007 period have been investigated using GIMMS and SPOT VGT NDVI data. We have also analyzed the interannual variations in vegetation cover and changes in annual runoff and sediment discharge, the consequences from precipitation change and the Grain for Green Project （GGP）. The results show that vegetation cover of the Helong area has increased during the 1981-2007 period. The northwestern part the Helong area, where the flat sandy lands are covered by grass, has experienced the largest increase. The region where the vegetation cover has declined is largely found in the southern and southeastern Helong area, which is a gullied hilly area or forested. Although precipitation was relatively low during the 1999-2007 period, the vegetation cover showed a significant increase in the Helong area, due to the implementation of the GGP. During this period, the most significant improvement in the vegetation cover occurred mainly in the gullied hilly areas of the Loess Plateau, such as the drainage basins of the Kuyehe and Tuweihe rivers and the middle and lower reaches of the Wudinghe and Yanhe rivers. A comparison of the average annual maximum NDVI between the earlier （1998-2002） stage and the next five years （2003-2007） of the GGP indicates that the areas with increases of 10% and 20% in NDVI account for 72.5% and 36.4% of the total area, respectively. Interannual variation of annual runoff and sediment discharge shows a declining trend, especially since the 1980s, when the decrease became very obvious. Compared with the 1950-1969 period, the average runoff during the 1980-2007 period was reduced by 34.8 × 10^8 m3 and the sediment discharge by 6.4 ×10^8 t, accounting for 49.4% and 64.9% of that in the 1950-1969 period, respectively. There is a positive correlation between the annual maximum NDVI and annual runoff and sediment discharge. This correlation was reversed since the implementation of the GGP in 1999 and vegetation cover in the He- long area has increased, associated with the decrease in runoff and sediment discharge. Less precipitation has been an important fac- tor driving the decrease in runoff and sediment discharge during 1999 2007. However, restoration and improvement of the vegetation cover may also have played a significant role in accelerating the decrease in annual runoff and sediment discharge by enhancing evapotranspiration and alleviating soil erosion.

Formation Mechanisms and Geomorphic Evolution of the Erlian Mudflow Fans, Eastern Guide Basin of the Upper Reaches of Yellow River

Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.

Community Structure of the Phytoplankton and Its Relationship with Environmental Factor in Lower Reaches of the Yellow River

[ Objective] The research aimed to study community structure of the phytoplankton and its relationship with environmental factor in lower reaches of the Yellow River. [ Method] From April to June in 2011, phytoplankton was conducted qualitative and quantitative researches in Lijin in lower reaches of the Yellow River. By combining population characteristics of the phytoplankton, its＇relationship with environmental factor was dis- cussed. [ Result] 114 species and 5 phylum of phytoplankton were observed in the whole river section. The abundance of phytoplankton was 0.90 ×104 -303.35×104 ind/m3, and mean was 27.20 ×104 ind/m3. The biomass of phytoplankton was 0.008-5.890 mg/m3, and mean was 0.641 mg/m3. Shannon-Weaver diversity index, Pielou evenness index and Simpson＇s diversity index were respectively 1.59, 0.36 and 0.55. SPSS data analysis indicated that transparency was the uppermost environmental factor affected phytoplankton abundance. Phytoplankton abundance had posi- tive correlation with transparency, and the regression equation was y= -393.8 ＋115.5×-11 .lx2 ＋0.35x3（n=18, R2 =0.952, F=92.665, P〈0.01 ）. [ Conclusion] The community structure of phytoplankton was unstable, and transparency was the uppermost environmental factor affected phyto- plankton abundance in lower reaches of the Yellow River.

Spatial Variation and Risk Assessment of Arsenic and Heavy Metals in Surface Water and Suspended Particulate Matter in Tail Reaches of the Yellow River, China

To determine the pollution levels and potential toxic risks of arsenic(As) and heavy metals(Cr, Ni, Cu, Zn, Pb and Cd) in water and suspended particulate matter(SPM) in tail reaches(including freshwater reach and low-salinity reach) of the Yellow River as the Flow-Sediment Regulation Project(FSRP) has been carried out for approximately 15 yr, the surface water and SPM were sampled at pre-flood(April) and post-flood seasons(October). Results showed that similar changes of As and metal levels in water and SPM were observed along the tail reaches at pre-flood or post-flood season. Compared to pre-flood season, the levels of As, Cu, Cr and Ni in freshwater reach and the concentrations of Cr and Ni in low-salinity reach rose greatly at post-flood season. The levels of As and metals in SPM of freshwater reach or low-salinity reach at pre-flood season were significantly higher than those at post-flood season(P < 0.01).The pollutions of As and metals in surface water of tail reaches at pre-flood or post-flood season were not serious. The SPM in freshwater reach at pre-flood season were polluted by Cd, As, Cr, Cu and Ni while those in low-salinity reach were polluted by Cd and Cr. The SPM in freshwater reach at post-flood season were polluted by Cd and Pb while those in low-salinity reach were polluted by Cd and Cr.Cd was identified as heavy metal of primary concern at both pre-flood and post-flood seasons. Combined with the existed data reported in present research, this study found that the toxic risk of As and metals in SPM of tail reaches at pre-flood season was higher than that at post-flood season, implying that the implementation of FSRP during flooding season, to a great extent, reduced the toxic risk of these elements. With the long-term implementation of FSRP, the pollution levels of As and metals(particularly for Cd) in SPM of tail reaches might be elevated and the potential toxic risk primarily produced by Cr, Ni and As might be increased if effective measures were not taken in future.

Slope-gully erosion relationship in small catchments of the middle reaches of the Yellow River

The slope-gully erosion relationship in small catchments of the middle reaches of the Yellow River has long been a topic concerned by relevant departments in China Slope-gully relationship in typical small catchment is determined determined on the concept of net increase of sediment yield by using analytical method of sediment formation at different positions in the catchment The result shows that sediments in a small catchment in the middle reaches of the Yellow River mainly come from slopes. ms paper indicated that the sediment sources from slopes are roughly 55, 60, 78 and 85 % of the total sediment yield of a small catchment in Yangdaogou. Wangjiagou. Jiuyuangou and Nanxiaohegou, respectively, due to impacts of varying degress from slope runoff.

CRITICAL ENVIRONMENTAL SITUATION IN THE MIDDLE REACHES OF THE YELLOW RIVER IN CHINA

This paper researches and analyses the critical envirormental situation in the Middle Reaches of the Yellow River and compiles the map of critical environmental situation of this area (1:2,000,000). Five types of environmental situation (ES) are divided, namely, conflict ES, critical ES, crisis ES, disastrous ES and accidental ES and 7 groups of main factors are used to identify and classify the critical environmental situation after considering the speciality of this region and the law of guiding factors. They are pollution, endemic disease, soil erosion, drought and water-shortage, forest degeration, wind-erosion and desertification, and soil salinization. Based on mapping and analysis, the paper also concludes the regional distribution law of critical environmental situation of this region and divides it into 8 small districts through combining the critical envirormental situation, regional distribution law and guiding factors. This can provide scientific basis and reference for preserving and renovating the environments with different fragile types and fragile levels.

RS-based research on the relationship between vegetation development and groundwater in upper-middle reaches region of the Yellow River basin

The relationship between the groundwater and the surface eco-environment in arid area is very close. In this paper, the authors extracted normalized difference vegetation index （NDVI） and vegetation conditional ratio （VCR） from MODIS images, and analyzed the relationships among NDVI, VCR and the measured data of groundwater of the same location in the research region. Based on this, the depth of groundwater suitable for vegetation growth in the upper-middle reaches of the Yellow River basin has been calculated. The results show that the depth of groundwater suitable for vegetation growth in the research region ranges from 0.8 to 4.5m, and the optimal groundwater depth is 1.2m. The method developed in this study is applicable to research the relationship between the groundwater and land surface vegetation environment on large-scale in arid area.

Natural Disasters of the Lower Reaches of Yellow River during the Longshan Period——The Natural Background of Dayu's Flood Control

It is very important to study the archaeological culture and origin of civilization in ancient China.The changes of the channels in the lower reaches of the Yellow River in the prehistoric period are part of the natural environmental background of the development of the ancient civilization in that area to be explored.This paper presents a series of legends,indications,scientific evidence,and macroscopic geographical background information of the evolution in the lower reaches of the Yellow River during the Longshan period.At first the river flowed from Northern Henan and Hebei to southwestern Shandong Province and Northern Anhui–Jiangsu provinces,and the mainstream of the Yellow River changed from the southeast to return to the north and flowed into the Bohai Sea in the late Longshan Period.During this period,floods were frequent.Various ethnic groups in the northern China plains suffered natural disasters and made great migrations which also contributed to the ethnic exchanges and integration.The people of the Central Plains made more dynamic adjustments in the relationship between mankind and the land by primitively escaping from the water and self–defensively controlling the rivers then to maintaining the local ecological environment by large–scale flood control measures,which promoted the settlement of Shandong,Henan,Jiangsu and Anhui provinces,the urban cultural development,and social evolution.Based on these events,the culture symbol of Dayu's Flood Control could be formed.

Sediment Variation Characteristics of Major Rivers in the Middle Reaches of the Yellow River

The sediment sequence analysis of Mann-Kendall method based on major rivers of 10 hydrological station in the middle reaches of the Yellow River*[1]*t,.The results show that:The main rivers in the middle reaches of the Yellow River hydrologic station sediment overall showed a trend of decreased significantly.Sediment discharge of all stations except Gao Jiachuan station have reached the maximum in 1956-1969s[2_3].Among various hydrologic station sediment discharge of inter-generational are generally shows the tendency of reducing year by year.Calculate the sediment transport of major river basin of Yellow River,which average is 0.63.

STUDIES ON TERRACES AND RIVER SYSTEM CHANGES OF THE UPPER YELLOW RIVER

There are seven steps of terrace both in the Guide basin and Gonghe basin along the Yellow River. More close to the source, less the steps of terrace. Three ancient terraces are found in Gonghe basin. The upper reaches of the Yellow River was joined up by a series of stream captures at different periods of time, the ancient Yellow River linked up the Gonghe basin and Guide basin at the end of the middle Pleistocene, the Longyangxia gorge developed around 60 Ka.B.P., and the gorge between Maqu and Tangnag developed around 20 Ka.B.P.

Comparison of River Terraces in the Middle Reach Valleys of the Yellow River and Analysis on the Multi-Gradational Features of Tectonism in the Formation of Terrace Series

Where the Yellow River flows through the Haiyuan-Tongxin arc-form tectonic region on the northeastern side of the Qinghai-Xizang (Tibet) Plateau, as many as 10～21 basis and erosion terraces have been produced, among which the biggest altitude above river level is 401m and the formation age of the highest terrace is 1.57 Ma B.P. Based on comparative analysis of the Yellow River terraces located separately in the Mijiashan mountain, the Chemuxia gorge, the Heishanxia gorge and the other river terraces in the vast extent of the northern part of China, it has been found that the tectonic processes resulting in the formation of the terrace series is one of multi-gradational features, i.e., a terrace series can include the various terraces produced by tectonic uplifts of different scopes or scales and different ranks. The Yellow River terrace series in the study region can be divided into three grades. Among them, in the first grade there are 6 terraces which were formed separately at the same time in the vast extent of the northern part of China and represent the number and magnitude of uplift of the Qinghai-Xizang Plateau since 1.6 Ma B. P.; in the second grade there are 5 terraces which were separately and simultaneously developed within the Haiyuan-Tianjingshan tectonic region and represent the number and magnitude of uplift of this tectonic region itself since 1.6Ma B.P.; in the third grade there are 10 terraces which developed on the eastern slope of the Mijiashan mountain and represent the number and amplitude of uplift of the Haiyuan tectonic belt itself since 1.6Ma B.P. Comparison of the terrace ages with loess-paleosoil sequence has also showed that the first grade terraces reflecting the vast scope uplifts of the Qinghai-Xizang Plateau are very comparable with climatic changes and their formation ages all correspond to the interglacial epochs during which paleosoils were formed. This implies that the vast extent tectonic uplifts resulting in river down-cutting are closely related to the warm-humid climatic periods which can also result in river downward erosion after strong dry and cold climatic periods, and they have jointly formed the tectonic-climatic cycles. There exists no unanimous and specific relationship between the formation ages of the second and third grade terraces and climatic changes and it is shown that the formation of those terraces was most mainly controlled by tectonic uplifts of the Tianjingshan block and the Haiyuan belt. The river terraces in the study region, therefore, may belong to 2 kinds of formation cause. One is a tectonic-climatic cyclical terrace produced jointly by vast extent tectonic uplifts and climatic changes, and the terraces of this kind are extensively distributed and can be well compared with each other among regions. Another is a pulse-tectonic cyclical terrace produced by local tectonic uplifts as dominant elements, and their distribution is restricted within an active belt and can not be compared with among regions.

An Information Entropy-Based Methodology to Construct the Avulsion Threshold in the Tail Reach of the Estuarine Alluvial Plain

Channel avulsion is a natural phenomenon that occurs abruptly on alluvial river deltas,which can affect the channel stability.The causes for avulsion could be generally categorized as topography-and flood-driven factors.However,previous studies on avulsion thresholds usually focused on topography-driven factors due to the centurial or millennial avulsion timescales of the world’s most deltas,but neglected the impacts of flood-driven factors.In the current study,a novel demarcation equation including the two driven factors was proposed,with the decadal timescale of avulsion being considered in the Yellow River Estuary(YRE).In order to quantify the contributions of different factors in each category,an entropy-based methodology was used to calculate the contributing weights of these factors.The factor with the highest weight in each category was then used to construct the demarcation equation,based on avulsion datasets associated with the YRE.An avulsion threshold was deduced according to the demarcation equation.This avulsion threshold was then applied to conduct the risk assessment of avulsion in the YRE.The results show that:two dominant factors cover respectively geomorphic coefficient representing the topography-driven factor and fluvial erosion intensity representing the flood-driven factor,which were thus employed to define a two dimensional mathematical space in which the demarcation equation can be obtained;the avulsion threshold derived from the equation was also applied in the risk assessment of avulsion;and the avulsion threshold proposed in this study is more accurate,as compared with the existing thresholds.

Neutron activation analysis (NAA) and geochemical studies of 38 elements in surface sediments from lower reach and estuary of Huanghe (Yellow) River

Using a neutron activation analysis technique, which involves gamma-spectrometry with a Ge(Li) detector coupled to a S40 multichannel analyzer and interfaced to a PDP-11 computer, we determined thirty-eight elements in sediments from the lower reach (downstream from Jinan) and estuary of Huanghe. The results are discussed in this paper.From inter-elemental correlations, it ts found that a large number of metals (Mn.As, Co, Cr.Cs, Rb, Sc, Ti, Ta, V and Zn) correlate positively with Fe. Ba and Ca correlate positively with Al. Whereas some elements (e. g. , Ti and lanthanides) show no correlation with either Fe or Al. On the other hand, Hf and Zr show a negative correlation with Fe. Elements which tend to be scavenged by Fe and Al colloids or suspended particles are enriched in sediments at the Huanghe Estuary relative to its lower reach. On the other hand, the contents of some elements (e. g. , Zr,Hf,U, Ba, etc. )are higher in sediments from the lower reach of Huanghe than in the estuarine sediments,which may be related to the sorting during deposition of source materials. On the basis of their chemical property and geochemical behavior, the 38 elements we studied are classified into seven groups. (1) weathering-prone elements,group A:K,Rb, Cs and Na; (2) weathering-prone elements, group B:Mg, Ca, Ba and Al; (3) transition elements:Fe, Co.Ni, Zn, As, Sb, Mn, Cr, W,Mo,V, Ta and Sc; (4) rare elements:group A (Zr and Hf) and group B (Ti); (5) rare earth elements:the lanthanides; (6) halogens: Cl and Br; amd (7) natural radioactive elements:U and Th. The basis for this classification is discussed and we emphasize that geochemical associations of elements in the natural environment are not necessarily in accord with their chemical properties as dictated by position at the periodic table.

Ecological risk assessment and ecological security pattern optimization in the middle reaches of the Yellow River based on ERI+MCR model

The middle reaches of the Yellow River represent an important area for the protection and development of the Yellow River Basin.Most of the area of the river basin is within the Loess Plateau,which establishes it as a fragile ecological environment.Firstly,using high-resolution data of land use in the watershed from the past 30 years,landscape ecological risk(LER)sample units are defined and an ecological risk index(ERI)model is constructed.Kriging interpolation is used to display the LER spatial patterns,and the temporal and spatial evolution of risk is examined.Secondly,the spatial evolution of land use landscape change(LULC)is analyzed,and the correlation between land use landscape and ecological risk is discussed.Finally,Based on the LER model,a risk-based minimum cumulative resistance(MCR)model is established,and a comprehensive protection and management network system for the ecological source-corridor-node system designed.The results suggest that in the past 30 years,LER has a high spatial correlation and areas with extremely high ecological risks are concentrated in northwest and southeast areas of the region,of which the northwest area accounts for the highest proportion.Risk intensity is closely related to the spatial pattern of land use landscape.ERI values of forestland,grasslands,and unused land and farmland are low,medium,and high,respectively.The trend of risk evolution is“overall improvement and partial deterioration”.Man-made construction and exploitation is the most direct reason for the increase of local ecological risks.The high ecological-risk areas in the northwest are dominated by deserts which reduce excessive interference by human activities on the natural landscape.Recommendations are:high-quality farmland should be protected;forestland should be restored and rebuilt;repair and adjust the existing ecosystem to assist in landscape regeneration and reconstruction;utilize the overall planning vision of“mountain,water,forest,field,lake,grass,sand”to design a management project at the basin scale;adhere to problem-oriented and precise policy implementation.

甘肃积石山强震诱发同震滑坡-泥流灾害链联动耦合致灾效应

近年来黄土区强震和极端天气诱发的典型滑坡-泥流灾害链事件呈多发态势,链式地质灾害较单一灾害隐蔽性更强、波及范围更大、破坏程度更高、损失更严重,因此链式地质灾害防控研究一直是防灾减灾的热点和难点。2023年12月18日23时59分,甘肃省临夏州积石山县发生Ms 6.2级地震,震源深度10 km,已造成151人死亡。此次强震诱发青海省民和县中川乡草滩村—金田村滑坡-泥流链式灾害,共造成20人死亡,灾害链致死率占地震遇难总人数的13.5%。灾后通过遥感影像处理解译、文献资料整理甄别、无人机摄影航测、野外详细勘查访问、现场采样分析测试等手段方法,对滑坡-泥流链式灾害开展了较全面系统研究,恢复和重现滑坡-泥流灾害链的启动-滑动-流动-堆积过程,探讨提出“滑源区地表冻结阻隔滞水效应、滑源区沟谷整平回填滞水效应、滑源区台地灌溉渗流饱水效应、滑源区振动液化筛选启动效应、滑源区漏斗收口增速启动效应、流通区土体差异流动分选效应、流通区沟岸坍塌补给增流效应、流通区沟底冰封饱水加速效应、堆积区上游渗水补给增程效应”等9大联动耦合致灾效应。该研究可为链式地质灾害的形成机理与防控提供科学参考。

初论黄河下游河道的河槽线

黄河白鹤镇至陶城铺河段两岸堤距宽,历史上河道冲淤变化迅速、河势游荡多变,经多年河道整治,总体上河势得到基本控制,滩槽逐步稳定。在此条件下,为促进黄河的生态保护和滩区发展,提高河道管理水平,将河道粗分为河槽与滩地,首次提出河槽线的概念,明确了河槽线的含义及绘制河槽线的原则,强调绘制河槽线要以防洪安全为前提,给出了河槽线的绘制方法及其现场标示办法,分析了河槽线的作用等。

小浪底水库运行以来对黄河下游河道河床演变特性的影响

小浪底水库自1999年10月下闸蓄水,23年来深刻改变了进入黄河下游河道的径流泥沙过程,进而引起了下游河道的再造床。本研究以1960—2022年长序列水文泥沙、断面地形、遥感影像等多源资料为基础,从径流泥沙、冲淤演变、形态调整三个方面阐明了小浪底水库运行以来对下游河道河床演变特性的影响。结果表明:(1)水库拦沙效果显著,下泄水量在年内分配更加均匀、沙量则向汛期更加集中;大流量和高含沙事件的严重程度和发生频率均有所降低;悬沙调整不明显,床沙粗化显著。(2)扭转了黄河下游河道持续淤积的趋势,冲淤调整主要发生在花园口至高村的游荡性河段;冲刷效率持续下降,主槽过流能力得到显著恢复。(3)游荡性河段横断面形态向窄深发展,二级悬河发育得到有效缓解,整体河势处于相对稳定状态。研究成果丰富了多沙河流修建水库对下游河道影响的科学认识,也可为小浪底水库优化调度提供科技支撑。