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1.
1990年以来黄河第一湾齐哈玛河段砾质网状河的演变特征   总被引:1,自引:0,他引:1  
高超  王随继 《地理学报》2018,73(7):1352-1364
黄河第一湾的网状河型因其砾石质的河床质而与砂床质网状河明显不同,但是其具体的冲淤特性、河道与河间地的稳定性等是否与砂质网状河具有相似之处,尚待揭示。以齐哈玛乡主河道长约为12 km的砾石质网状河段为研究对象,利用1990年、2001年、2013年和2016年共4期Landsat遥感影像数据和2011年与2013年两期Google Earth高分辨率图像数据,结合野外采样观测分析其1990-2016年间的平面形态变化与沉积特征。结果表明:砾石质网状河整体具有很高的稳定性,众多分支河道与河间地无明显冲淤现象。网状带面积仅增加2.43%,陆地与水体面积比例接近1∶1;网状带部分小型河间湿地及河间岛屿呈现碎片化现象,导致河间湿地个数逐渐增加,最大增加率为62.16%。河道主流线长期左右迁移交替变化,且变化率相对稳定,受主流线迁移的影响,主河道内部河间岛屿形态变化较大,其河岸变化率为5 m/a。网状河众多支河道非常稳定,平均河宽变化率仅为1 m/a左右。河岸沉积物以细砂或粉砂为主,黏土含量较高,粒度分布曲线呈现多峰,这与砂质网状河流河岸以泥质沉积物为主略有不同,但河岸及河间湿地茂密的植被保护了众多分支河道免受侵蚀、维持了河道的稳定性,这也是砾石质网状河流体系具有高稳定性的重要原因。  相似文献   

2.
Both interchannel wetlands and multi-channels are crucial geomorphologic units in an anastomosing river system. Planform characteristics and development of interchannel wetlands and multi-channels control the characteristics of anastomosing rivers. To understand the role that interchannel wetlands play in the development of anastomosing rivers, a study was conducted on the Maqu Reach of the Upper Yellow River(MRUYR), a gravel-bed anastomosing river characterized by highly developed interchannel wetlands and anabranches. Geomorphologic units in the studied reach were extracted from high resolution satellite imagery in Google Earth. The size distributions of interchannel wetlands and interchannel wetland clusters(IWCs), a special combination of interchannel wetlands and anabranches, were investigated. Geomorphologic parameters, including the ratio of interchannel wetland area to IWC area(P), shoreline density(D_l), and node density(D_n) were used to analyze planform characteristics of IWCs and the development of multi-channels in the studied reach. The results suggest that small or middle sized interchannel wetlands and large or mega sized IWCs are more common at the study site. The area of IWC(S_u) is highly correlated with other geomorphologic parameters. P increases with increasing S_u, and the upper limit is about 80%, which indicates that the development of interchannel wetlands and anabranches in the IWC is in the equilibrium stage. In contrast, D_l and D_n show a tendency to decrease with increasing S u due to diverse evolution processes in IWCs with different sizes. There are three main reasons leading to the formation of IWCs: varying stream power due to the meandering principal channel; development of the river corridor due to the weakening of geologic structure control; and high stability of interchannel wetlands due to conservation by shoreline vegetation.  相似文献   

3.
Extreme weather is an important noise factor in affecting dynamic access to river morphology information.The response characteristics of river channel on climate disturbances draw us to develop a method to investigate the dynamic evolution of bankfull channel geometries(including the hydraulic geometry variables and bankfull discharges)with stochastic differential equations in this study.Three different forms of random inputs,including single Gaussian white noise and compound Gaussian/Fractional white noise plus Poisson noise,are explored respectively on the basis of the classical deterministic models.The model parameters are consistently estimated by applying a composite nonparametric maximum likelihood estimation(MLE)method.Results of the model application in the Lower Yellow River reveal the potential responses of bankfull channel geometries to climate disturbances in a probabilistic way,and,the calculated average trends mainly run to synchronize with the measured values.Comparisons among the three models confirm the advantage of Fractional jump-diffusion model,and through further discussion,stream power based on such a model is concluded as a better systematic measure of river dynamics.The proposed method helps to offer an effective tool for analyzing fluvial relationships and improves the ability of crisis management of river system under varying environment conditions.  相似文献   

4.
The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole(Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10~8 m~3, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient 0.007 kg·s·m~(–6) and a flow discharge 700 m~3·s~(–1). The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m~3·s~(–1) and a comprehensive incoming sediment coefficient 0.005 kg·s·m~(–6). The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10~8 t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most.  相似文献   

5.
Quantitative studies on river channel lateral erosion/accretion area changes over time can reveal the characteristics of channel evolution. Taking the 213-km-long Linhe reach braided channel of the Yellow River as an example, area changes in channel bank erosion/accretion in four sub-reaches(S1, S2, S3 and S4) over 19 different periods were evaluated on the basis of remote sensing images captured since 1977. Mean channel shrinkage rate for the whole river reach was also obtained. Results show that the left and right banks of the Linhe reach were dominated by lateral net accretion between 1977 and 2014. The channel area of this section of the Yellow River was characterized by reduction between 1977 and 2001, while periods of alternate erosion and accretion occurred subsequent to 2001. Mean channel shrinkage rate in the Linhe reach braided channel was 6.15 km~2/yr between 1977 and 2014, while the most remarkable changes in channel planform occurred in the 1990 s. Compared to 1995, channel length and sinuosity increased by 5.8% and 6.6% by 2000, while channel area and mean width decreased by 39.4% and 42.8%, respectively. Significant changes in channel planform and shrinkage of the Linhe reach occurred in the 1990 s, mainly as a result of the joint-operation of the Longyangxia and Liujiaxia reservoirs since 1986, which caused substantial reductions in runoff and sediment flux during the annual flooding season. In addition, bank erosion/accretion in the four sub-reaches was affected by the physical properties of local banks, engineering emplaced to protect channel banks, and hydrodynamic differences. However, since the implementation of integrated river management measures from 2000 onwards, these changes have been significantly mitigated and the health of the Linhe reach braided channel of the Yellow River has been restored.  相似文献   

6.
李鹤  张平宇 《干旱区地理》2012,35(5):829-837
工业结构优化升级是振兴东北老工业基地的一项核心任务。基于对区域工业行业结构、所有制结构、企业规模结构动态变化的定量分析,总结了1990年以来东北地区工业结构演变特征与存在的问题,分析了区域工业结构演变的主要驱动因素,并探讨了区域工业结构优化升级的发展方向。研究表明:1990年以来东北地区工业结构调整在解决体制性矛盾、发挥存量优势方面成效明显,在政府支持、外资驱动、市场需求拉动以及资源环境压力等因素的影响下,东北地区工业结构高加工度化发展趋势初步显现,重工业比重持续上升的态势得到遏制,工业所有制结构调整阶段性效果显著,所有制结构单一的现象得到改善,企业规模分化现象近年来表现出下降趋势,大型工业企业主导工业发展态势的局面正在逐步改变。但偏重的工业结构未发生实质性改变,优势工业行业构成变动不明显,多数新兴工业行业规模较小,高技术产业发展滞缓,推动区域工业结构优化升级的内生性动力不足,工业结构优化升级与拉动就业之间的矛盾开始凸显。  相似文献   

7.
Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions. Numerous studies have been carried out on the fluvial processes of downstream reservoirs. However, only a few of them have focused on the relationship between runoff-sediment conditions and channel pattern indicators. Also, the impacts of river training works on fluvial processes are seldom dealt with. In this paper, the evolutionary processes of three sections in the Lower Yellow River, including Tiexie-Yiluo River mouth reach, Huayuankou-Heigangkou reach and Jiahetan-Gaocun reach, were analyzed for variations in the channel boundary line and the mainstream between 1960 and 2015. Channel pattern indicators such as sinuosity, mainstream wandering range and width/depth ratio were analyzed based on field measurements obtained by the Hydrological Department of the Yellow River Conservancy Commission. The effects of river training works on the channel evolution are then described. Since 1960, numerous medium- and large-sized reservoirs have been built on the Yellow River, including Longyangxia Reservoir, Liujiaxia Reservoir and Xiaolangdi Reservoir. These reservoirs impound the runoff from upstream and retain the sediment, which changes the runoff and sediment conditions in the downstream reach. As a consequence, annual runoff and the frequency and peak of flooding have all decreased. As a result, the flow dynamics and their action on the river channel are also reduced, which changes the dynamic state of the river course. The discrimination results obtained using the single parameter discrimination rule and the discrimination equation show that the degree of wandering is weakened in the reaches studied. The variations in the channel pattern indicators show that the sinuosity increases and the wandering range decreases with a reduction in the total annual volume of water. However, the degree of wandering has little relationship to the sediment concentration. In addition, river training works play an important role in controlling the river course. Due to improvements in the river training works, the river course has become more stable under the same runoff and sediment conditions. A new discrimination rule that takes into account the impacts of the river training works is proposed. The discrimination results were found to fit well with the actual river pattern, which shows that the discrimination rule is applicable to the Lower Yellow River. The results show that the runoff and sediment conditions are the most important factors in the evolution of the river course. The river training works have at the same time limited the wandering range of the mainstream and played an important role in the fluvial processes. Both factors combined lead to the stabilization of the river.  相似文献   

8.
Air temperature(AT) is a subsystem of a complex climate.Long-range correlation(LRC) is an important feature of complexity.Our research attempt to evaluate AT’s complexity differences in different land-use types in the Heihe River Basin(HRB) based on the stability and LRC.The results show the following:(1) AT’s stability presents differences in different land-use types.In agricultural land,there is no obvious variation in the trend throughout the year.Whereas in a desert,the variation in the trend is obvious: the AT is more stable in summer than it is in winter,with Ta ranges of [8,20]°C and SD of the AT residual ranges of [0.2,0.7],respectively.Additionally,in mountainous areas,when the altitude is beyond a certain value,AT’s stability changes.(2) AT’s LRC presents differences in different land-use types.In agricultural land,the long-range correlation of AT is the most persistent throughout the year,showing the smallest difference between summer and winter,with the Hs range of [0.8,1].Vegetation could be an important factor.In a desert,the long-range correlation of AT is less persistent,showing the greatest difference between summer and winter,with the Hs range of [0.54,0.96].Solar insolation could be a dominant factor.In an alpine meadow,the long-range correlation of AT is the least persistent throughout the year,presenting a smaller difference between summer and winter,with the Hs range of [0.6,0.85].Altitude could be an important factor.(3) Usually,LRC is a combination of the Ta and SD of the AT residuals.A larger Ta and smaller SD of the AT residual would be conducive to a more persistent LRC,whereas a smaller Ta and larger SD of the AT residual would limit the persistence of LRC.A larger Ta and SD of the AT residual would create persistence to a degree between those of the first two cases,as would a smaller Ta and SD of the AT residual.In addition,the last two cases might show the same LRC.  相似文献   

9.
Agro-meteorological disasters(AMD) have become more frequent with climate warming. In this study, the temporal and spatial changes in the occurrence frequency of major meteorological disasters on wheat production were firstly explored by analyzing the observed records at national agro-meteorological stations(AMS) of China from 1991 to 2009. Furthermore, impact of climate change on AMD was discussed by comparing the warmer decade(2000–2009) with another decade(1991–2000). It was found that drought was the most frequent disaster during the last two decades, with a highest proportion of 79%. And the frequency of AMD increased significantly with climate change. Specifically, the main disasters occurred more frequently in the reproductive period than in the vegetative period. Besides, the spatial changes in the AMD frequency were characterized by region-specific. For example, the wheat cultivation areas located on the Loess Plateau and the middle-lower reaches of the Yellow River suffered mainly from drought. All these results were strongly linked to climate change in China. Therefore, sound adaptation options should be taken based on the latest changes of AMD under global warming to reduce agricultural damages.  相似文献   

10.
Landforms are an important factor determining the spatial pattern of cropland through allocation of surface water and heat. Therefore, it is of great importance to study the change in cropland distribution from the perspective of geomorphologic divisions. Based on China's multi-year land cover data(1990, 1995, 2000, 2005, 2010 and 2015) and geomorphologic regionalization data, we analyzed the change in cropland area and its distribution pattern in six geomorphologic regions of China over the period of 1990-2015 with the aid of GIS techniques. Our results showed that the total cropland area increased from 177.1 to 178.5 million ha with an average increase rate of 0.03%. Cropland area decreased in southern China and increased in northern China. Region I(Eastern hilly plains) had the highest cropland increase rate, while the cropland dynamic degree of Region IV(Northwestern middle and high mountains, basins and plateaus) was significantly higher than that of other regions. The barycenter of China's cropland shifted from northern China to the northwest over the 25-year period. Regions IV and I were the two regions with the greatest increase of cropland. Region II(Southeastern low and middle mountains) and Region V(Southwestern middle and low mountains, plateaus and basins) were the main decreasing cropland regions. The area of cropland remained almost unchanged in Region III(Northern China and Inner Mongolia eastern-central mountains and plateaus) and Region VI(Tibetan Plateau). The loss of cropland occurred mostly in Regions I and II as a result of growing industrialization and urbanization, while the increase of cropland occurred mainly in Region IV because of reclamation of grassland and other wasteland. These analyzing results would provide fundamental information for further studies of urban planning, ecosystem management, and natural resourcesconservation in China.  相似文献   

11.
The 270 km long section of the Upper Yellow River at the First Great Bend is comprised of single channel and multiple channel systems that alternate among anastomosing, anabranching, meandering and braided reaches. The sequence of downstream pattern changes is characterized as: anastomosing-anabranching, anabranching-meandering, meandering-braided and braided-meandering. Remote sensing images, DEM data and field investigations are used to assess ahd interpret controls on these reach transitions. Channel slope and bed sediment size are key determinants of transitions in channel planform. Anas- tomosing reaches have a relatively high bed slope (0.86‰) and coarser sediment bed material (d50 = 3.5 mm). In contrast, meandering reaches have a low slope (0.30‰) and fine sediment bed material (d50 = 0.036 mm). The transition from a meandering to braided pattern is characterized by an increase in channel width-depth ratio, indicating the important role of bank strength (i.e. cohesive versus non-cohesive versus channel boundaries). Interestingly, the braided-meandering and meandering-braided transitions are coincident with variable flow inputs from tributary rivers (Baihe and Heihe rivers respectively). Theoretical analysis of the meandering-braided transition highlights the key control of channel width-depth ratio as a determinant of channel planform.  相似文献   

12.
Both interchannel wetlands and multi-channels are crucial geomorphologic units in an anastomosing river system. Planform characteristics and development of interchannel wetlands and multi-channels control the characteristics of anastomosing rivers. To understand the role that interchannel wetlands play in the development of anastomosing rivers, a study was conducted on the Maqu Reach of the Upper Yellow River (MRUYR), a gravel-bed anastomosing river characterized by highly developed interchannel wetlands and anabranches. Geomorphologic units in the studied reach were extracted from high resolution satellite imagery in Google Earth. The size distributions of interchannel wetlands and interchannel wetland clusters (IWCs), a special combination of interchannel wetlands and anabranches, were investigated. Geomorphologic parameters, including the ratio of interchannel wetland area to IWC area (P), shoreline density (Dl), and node density (Dn) were used to analyze planform characteristics of IWCs and the development of multi-channels in the studied reach. The results suggest that small or middle sized interchannel wetlands and large or mega sized IWCs are more common at the study site. The area of IWC (Su) is highly correlated with other geomorphologic parameters. P increases with increasing Su, and the upper limit is about 80%, which indicates that the development of interchannel wetlands and anabranches in the IWC is in the equilibrium stage. In contrast, Dl and Dn show a tendency to decrease with increasing Su due to diverse evolution processes in IWCs with different sizes. There are three main reasons leading to the formation of IWCs: varying stream power due to the meandering principal channel; development of the river corridor due to the weakening of geologic structure control; and high stability of interchannel wetlands due to conservation by shoreline vegetation.  相似文献   

13.
刘博一  王随继 《地理学报》2017,72(7):1195-1206
河间湿地是网状河流体系中与多河道系统同等重要的地貌单元,其特征和发育程度与河道系统共同决定着网状河流的特性。本文以黄河玛曲网状河段作为研究对象,利用高分辨率Google Earth影像对研究河段河道与河间湿地等微地貌单元进行提取,利用湿地面积与湿地数对河间湿地的组成进行了分析,利用河间湿地面积占比、岸线密度、分汊点密度3个地貌参数,对河间湿地群体(河间湿地与分支河道特定组合体)的平面形态及多河道发育程度进行了研究。结果表明,河间湿地个体以中小型的为主,河间湿地群体则以大型和巨型的为主。河间湿地群体的发育程度与河间湿地群体面积(Su)明显相关,河间湿地面积占比(P)随Su的增大而增大,P值70%是河间湿地发育成熟的指标,而P值80%基本是河间湿地发育的上限值,此时河间湿地与分支河道基本达到动态平衡态。岸线密度、分汊点密度随Su的增加呈减小趋势,这种变化主要是由于不同大小河间湿地群体中河道发育过程差异导致。黄河玛曲段河间湿地群体的形成在于弯曲主河道的主导作用、地形限制因素削弱导致的河道带的发育,以及植被维护的河岸使得河间湿地群体得以较长时间保存。  相似文献   

14.
黄河流域河型转化现象初探   总被引:9,自引:0,他引:9  
黄河以其高含沙水流以及下游河道的高沉积速率而著称于世。迄今的研究, 主要针对黄河中下游流域的 侵蚀、水文泥沙和河床演变方面的研究, 而对黄河流域主支流发生河型转化的现象关注不够。在黄河的不同河段, 河型的变化频繁, 类型多样, 现象复杂, 是研究者不可回避的科学问题。本文选取黄河上游第一弯的玛曲河段、黄河 上游末段托克托附近河段及黄河下游高村上下河段来研究河型转化的形式及影响因素。玛曲河段沿流向发生网状 河型→弯曲河型→辫状河型的转化现象, 该系列转化呈现出由极稳定河型向极不稳定河型的转化, 这与世界上通 常可以观察到的沿流向不稳定河型向稳定河型转化的情况完全相反。这主要受到地壳的抬升、上下峡谷卡口、水动 力特征、边界沉积物特征及植被的区域分布等因素的控制。托克托附近沿流向发生了弯曲河型→顺直河型转化的 现象, 这是较稳定河型向极稳定河型的转化, 主要受到边界沉积物、水动力等因素的控制。高村上下河段沿流向发 生的辫状河型→弯曲河型转化的现象, 是由极不稳定河型向较稳定河型转化的现象, 河道边界沉积物及水动力是 其主要控制因素, 人工大堤只是限制了河道摆动的最大幅度, 对河型的性质影响不大, 但其上游河段修筑的水库导 致下泻的水流在辫状河段的侵蚀能力增强而使其边界沉积物粗化, 并将泥质物大量沉积在弯曲河段, 客观上促进 了河型的转化。  相似文献   

15.
王随继  李玲 《地理学报》2014,69(3):399-408
研究选取黄河银川平原全长196 km的河段,以1975 年、1990 年、2010 年和2011 年四个年份的卫星影像数据绘制的左右河岸线,与设立的平均间隔为1.3 km的153 个河道固定横断面的交点位置的变化,估算了1975-1990 年、1990-2010 年和2010-2011 年三个时期的河岸平均摆动速率。结果表明,该河段左岸以向右摆动为主,在上述时期左岸总的平均摆动速率分别为36.5 m/a、27.8 m/a 和61.5 m/a;右岸在1975-1990 年以向右摆动为主,此后则以向左摆动为主,其摆动速率分别为31.7 m/a、23.1 m/a 和50.8 m/a。在1975-2011 全部36 年间,左右河岸的年均摆动速率分别为22.3 m/a 和14.8 m/a。河岸摆动速率在A、B、C三个河段相差悬殊,在1975-2011 的36 年间,左岸向左和向右的平均摆动速率之比分别为1:7.6:4.6 和1:1.7:3.8;右岸向左和向右的平均摆动速率之比为1:1.8:1.2 和1:5.6:17.7。显然,无论左岸右岸,它们在A段的摆动速率最小,向左摆动速率最大的出现在B段,而向右摆动速率最大的则是C段。河岸摆动速率在时序上的增大现象主要受制于人类筑坝蓄水等引起汛期流量的逐渐减小,而空间变化主要受制于河岸物质组成的区域差异。  相似文献   

16.
黄河中游悬移质泥沙粒径与流域环境的关系   总被引:4,自引:0,他引:4  
刘爱霞  卢金发 《地理学报》2002,57(2):232-237
以黄河中游多沙粗沙区为研究区,在流域泥沙粒径、降雨、地面物质组成、地面形态、植被和高含沙水流等资料采集的基础上,采用“环境要素法”和多元回归分析来阐明泥沙粒径空间分异的机理。研究表明,随降雨不均匀系数的减小,断面最大含沙量的减小,流域内黄土覆盖面积的增大,以及植被盖度的增大和沟谷密度的减小,悬移质泥沙粒径趋于变细,反之,趋于变粗。其中,流域地面物质对泥沙粒径组成起最重要的控制作用,其次是植被,高含沙水流、沟谷密度和降雨影响作用相对较小。  相似文献   

17.
黄河内蒙河段河床冲淤演变特征及原因   总被引:4,自引:0,他引:4  
利用黄河内蒙段1962-2000年间4期大断面观测资料,计算了各期河床冲淤和河槽形态指标。发现从1962-2000年间前20年、中间9年及后9年,内蒙河段河槽500m2过水面积下河底高程发生了降低-升高-再升高的过程;河槽漫滩过水面积经历了升高-降低-再降低的过程,2000年只有1982年的大约一半;滩地经历了持续淤积过程,平均抬升0.25m;河槽宽深比值经历了变化不显著-增加-减小的过程。分析结果表明:气候变化、引水、水库拦沙和重点产沙支流来沙变化在河床冲淤和河床形态调整中作用较大;水库对径流的年内调节对1982年后河槽淤积贡献较大;来水来沙变化下河流多要素自动调整是造成河槽形态变化过程复杂的原因。  相似文献   

18.
高超  王随继 《地理科学》2018,38(4):618-627
以黄河青藏高原阿万仓和采日玛两段主河道50 km与65 km长的网状河段为研究对象,利用2013年3期遥感影像绘制了不同流量下(176 m3/s,978 m3/s,1 610 m3/s)网状河段活动河道的分布变化图,结合DEM数据分析了现有河道在流量增加过程中的空间分布格局和潜在定量关系。研究结果表明:根据流量大小划分出的3类活动河道,其分布规律基本是后者位于前者的两侧,据此可以推断,网状河分支河道基本是从主河道向两侧逐渐发展的。对于阿万仓河段,在河谷和河间地相对宽阔处,每个河道断面上3类活动河道数的比值为1:1.67:2.25;而在河谷较窄的地方,该比值为1:1.22:1.33。在采日玛河段,该比值分别为1:1.3:1.4和1:0.95:1.16。在宽阔的草原湿地河段,当网状河的主河道发生弯曲时,弯道内侧的活动河道数要大于弯道外侧的活动河道数。在平坦开阔的河谷地带,断面上的活动河道线密度与河谷宽度之间呈现出极好的线性负相关关系;而峡谷地带由于两侧高地形的限制,河谷宽窄不一,活动河道的线密度相对较大、且差别也较大。  相似文献   

19.
黄河三角洲岸线及现行河口区水下地形演变   总被引:2,自引:0,他引:2  
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。  相似文献   

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