Landsat Image-Based Spatiotemporal Variation Analysis of Erosion and Deposition off the Qingshuigou of the Yellow River Delta from 1984 to 2021

Owing to climate change and human activity,the Qingshuigou of the Yellow River Delta(YRD)has undergone dynamic changes in erosion and deposition.Therefore,studying these changes is important to ensure ecological protection and sustainable development.In this study,the trend of erosion-deposition evolution in the Qingshuigou was investigated based on 38 coastline phases extracted from Landsat series images of the YRD at one-year intervals from 1984 to 2021.The periodicity of the scouring and deposition evolution was also analyzed using wavelet analysis.Results showed that the total area of the Qingshuigou was affected by deposition and erosion and that the fluctuation first increased and then decreased.The total area reached a maximum in 1993.The depositional area first increased and then decreased,whereas the overall erosion area decreased.Deposition and erosion areas showed periodic changes to some extent;however,the periodic signal intensity decreased.Furthermore,factors including channel morphological evolution and variations in water and sediment discharge affect the spatiotemporal dynamics of erosion and deposition processes.The application of nonconsistency tests finally revealed that deposition area and flushing magnitude exhibited non-stationarities,which are potentially attributed to impacts from climatic change drivers.

The coastal erosion and evolution of the Yellow River Delta abandoned lobe

A statistic analysis predicting coastal change of the Yellow River abandoneddelta lobe formed from 1964 to 1976 using Landsat TM imagery was conducted by calculating thecoastal erosion/accumulation rates obtained from four different classic profiles and plotting thechange curves of coastline with time. The studies showed that the regularity of the evolution of thecoastline was very obvious after the delta lobe was abandoned. The coastal evolution can be dividedinto three different phases: erosion phase, transition phase and cyclical change phase. At present,the coast has evolved to the cyclical change phase. The natural coastline change cycle is 4 yearsbetween the dam and is 5 years to the west of the dam. In the cyclical change phase, thequasi-equilibrium line of the coast was located near the coastline of 1996, the current coast mayrecede 1.79 km to reach the natural equilibrium coastline. Therefore, some measures must be taken toprotect the dam or the dam will be destroyed by the force of nature. The curves also revealed themagnitude of erosion/accumulation rates would decrease gradually with time. The results of the studyoffer guidance for coast protection, and proves that the evolution of silty coast actually was acyclical change process too.

Coastal Erosion Feature and Mechanism at Feiyantan in the Yellow River Delta

Feiyantan was the discharge area of Diaokou River distributary of the Yellow River during the period of 1964 to 1976. The coastal erosion feature and morphological evolution at the Feiyantan coast are studied in the light of the topography and section depth, and the corresponding dynamics of wave and current. Results indicate that the protruding topography left after the Diaokou River distributary was abandoned is the main cause of strong coastal erosion. Further research suggests that waves start up the sediment and the tidal current transports it, and the waves and tidal current are combined to be the dominant dynamic mechanism of coastal erosion, in which the tidal residual current takes and transports the sediment outward, thus causing the sediment to wane in the coast.

Formation of Equilibrium Beach Profile of the Abandoned Yellow River Delta Coast in North Jiangsu

The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B

A flume test on erosion mechanism for an abandoned section of the Huanghe(Yellow)River Delta

The erosion mechanisms of abandoned coastal section are understood detailedly by flume experiment, which play an important role to the offshore engineering facilities. A movable-bed physical model has been used to investigate the coastal erosion of an abandoned section of the Huanghe （Yellow） River Delta. The theory of physical scale models is discussed and a method for constructing the representative seabed section is developed. The results indicate that during the period initially after the abandonment of the delta the entire bed experienced rapid erosion because the seabed was steep and prone to liquefaction that resulted from storm wave action. After this initial period, a balance of erosion and accretion was established, and the beach profllc equilibrated with a point of balance present on the profile. The experimental results indicate that the volume of deposition was about half that of the erosion. Wave action may also induce significant stratal changes through its interaction with the soft seabed. The major morphological features developed in the model delta section were found to be qualitatively comparable with those observed in the prototype. A distorted modeling law that maintains the similarity of the modeled and prototype equilibrium beach profiles is proposed. Experimental results show that the distorted modeling is able to reproduce the beach-face slope in nature, and the model also successfully reproduced three historical evolutionary stages of erosion.

Dynamics Characteristics and Topographic Profile Shaping Process of Feiyan Shoal at the Yellow River Delta

Feiyan Shoal is a sub Yellow River Delta, which was formed from Jan. 1964 to May 1976, when the Yellow River entered sea via Diaokou Channel. Since the terminal reach shifted to Qingshuigou channel in 1976, Feiyan Shoal has been experiencing severe erosion and retreat. This paper explains the evolutionary characteristics of the typical profile of Feiyan Shoal from the perspective of dynamical force and sediments＇ characteristics. All this is on the basis of the data of topographic profiles observed since the 1970s and the samples of hydrology and sediments collected in situ in Apr. 2004, the analysis of the retreating distance, and the tidal and wave friction velocity distribution. Feiyan Shoal topographical profile has experienced a course of ＂fast erosion and retrogression - slow eroding modulation - fluctuate triggering change＂ in recent 30 years, which is also the gradual disappearing process of the delta front. The different intensity of sediment erosion resistance is the main reason for the erosion speed changes. Due to the hydrodynamic force changes, the water depth range of maximum retreating distance and between erosion and progradation became shallow. It indicates that the storm tide will still be the triggering force of seashore topographic profile evolutions in the future.

Monitoring the Anthropogenic Impact on the Muddy Coast by Means of Topographic and Bathymetric Surveys North of the Yellow River Mouth, China

The effects of the artificial-diversion of the Yellow River Mouth for extensive petroleum exploration beginning in August 1996 on the morphology of the mud flat coast are discussed. Changes in the morphology of the coastal zone were monitored during the period from 1996 to 2000. A Golden Software system was used to calculate the differential surfaces between the surveys in order to investigate the local patterns of accretion and erosion and to determine the volume changes between consecutive surveys. Volumetric studies showed that the net accretion in the study period was about 1.7×10 8 m 3. Between July 1996 and October 1996, a time interval characterized by intense runoff, an accumulation of about 4×10 8 m 3 occurred. In the period from October 1996 to October 1998, a period of diminution in runoff and sediment supply in the upstream, an erosion of 8.9×10 7 m 3 occurred, indicating sediment starvation of the area. Between October 1998 and October 2000, due to an inadequate supply of runoff and sediment, about 1.4×10 8 m 3 of sediments was eroded and transported offshore.

Evolution of Modern Yellow River Delta Coast

This paper deals with the development and evolution of modern Yellow River delta and the erosion or deposition rates of its different sections. In June, 1996, Yellow Rivers terminal course was artificially turned eastwards to empty into the sea and then the 11th lobe of the modern Yellow River delta began to form. This course change may mark the beginning of the 3rd subdelta formation. As a result of that, the Yellow River delta advances towards east by north with the 1st, 2nd and 3rd subdeltas arranged in succession. Coast zone in the deltaic area is divided into 7 different sections according to their different erosion or deposition rates: the relatively stable section from Dakou River to Shunjiang Stream, the weakly retreating section from Shunjiang Stream to the Tiaohe River mouth, the strongly retreating section from the Tiaohe River mouth to the station 106, the artificially stable section due to stone dam protection from the station 106 to Gudong Oilfield, the strong deposition section from Gudong Oilfield to Dawenliu Haipu, the weakly deposition section from Dawenliu Haipu to the Zimai Stream mouth, and the stable section from the Zimai Stream mouth to the Jiaolai River mouth. It is predicted that the erosion and deposition situations of the sections will nearly remain the same in 10 years, but the retreating and silting-up rates will tend to become slower gradually. Human activities have an evident influence on the changes of the coastline.

Primary study on the diapir in the north of the Yellow River delta

Based on the measuring data of landforms, high-resolution seismic profiles, drilling cores, etc. a diapir body was found in the north of the modem Yellow River delta. The diapir body with a length of 5 km and a width of 1 km is distributed on the middle to low part of the slope of an abandoned delta lobe. Its formation is related to the deformity of the soft stratum which is deposited in the prodelta and covered by the stratum of the mouth bar sediments. Research results show that its formation is very different from the Mississippi River delta’s diapirs but related to the erosion of the seabed and occurs on the location with a large eroded quantity. The soft stratum and its diapir body can result in a great hazard to marine buildings.

近30年黄河陆上三角洲蚀退-淤进对气候变化和人类活动的响应

近30年来,受全球气候变化和流域人类活动加剧的影响,黄河三角洲陆地蚀退-淤进过程对黄河流域水循环系统的响应变得更为显著。基于谷歌地球引擎(Google Earth Engine)和长时间序列的Landsat影像,结合流域内气象水文长期测量数据,定量研究了近30年黄河陆上三角洲蚀退-淤进对气候变化和人类活动的响应。研究发现,1993—2022年间,黄河三角洲陆地面积经历了先增加后减少再波动增加的阶段,现行河口岸段为主要淤积区,陆地面积每年增长约1.67 km^(2),刁口河岸段为主要侵蚀区,陆地面积每年减少约2.15 km^(2);入海水沙与河口面积变化在1993—2001年自然水沙输运时期存在周期为4~5 a的负相位关系;多元回归分析表明,自然水沙输运时期(1993—2001年)气候变化主导了河口蚀退-淤进,人工水沙调控时期(2002—2022年)人类活动的影响远大于气候变化。

入海水沙变化背景下黄河三角洲岸线冲淤研究

受黄河入海流路变迁和入海泥沙锐减的影响,近年来黄河三角洲岸线冲淤变化复杂。本研究基于Landsat遥感影像,提取2000—2020年黄河三角洲的年平均岸线,分析其岸线冲淤变化。结果显示,北部岸段和原清水沟入海水道岸段岸线呈现蚀退作用,现清八汊入海水道岸线呈现淤积作用。

1985年以来黄河三角洲东营港工程变化与海床冲淤演变响应关系

河口三角洲区域地质环境脆弱,对环境变化响应敏感,三角洲港口冲淤演变受工程结构影响较大。黄河三角洲的东营港区域以粉砂质海岸为主,区域内泥沙运移活跃,此类区域港口建设的关键问题在于工程结构导致的海床冲淤变化。通过东营港建港以来实测水深数据构建水下地形数字高程模型(DEM),并结合水动力数值模拟,探讨了东营港冲淤演变过程和工程影响。结果表明,由于波浪和潮流导致的海底地形变化,东营港近岸海域的冲淤演变形势已从单一侵蚀转变到近岸侵蚀、离岸淤积的新情势;工程结构影响局地潮流流速和流向,口门处出现高速横流,最大流速可达0.7 m/s;高流速导致北防波堤的堤头位置出现直径约1 km的冲刷坑;工程结构的遮蔽区有促淤效应,遮蔽区大小与潮流流向、工程结构-岸线夹角有关,但在波浪、余流的作用下,2007-2015年工程结构遮蔽区依旧存在0.5 m以上的侵蚀。持续的侵蚀作用使海域防波堤和海堤的不稳定性加剧,迫切需要加强检测与防护。

黄河三角洲飞雁滩海岸的侵蚀及机理

飞雁滩海域是1964—1976年黄河刁口河流路入海区域。根据地形和断面水深监测资料,阐述了该岸段流路废弃后的岸滩侵蚀特征和地貌变化。研究结果表明,刁口河流路废弃后飞雁滩海岸向海凸出的地形特征,是造成该岸段强烈侵蚀的重要原因。进一步结合波、流动力的对应分析认为,波浪以掀沙为主,潮流以输沙为主,波浪和潮流的联合作用是飞雁滩海岸侵蚀的主要动力机制,其中潮流主要通过余流携沙外输,造成近岸泥沙亏损。

黄河三角洲废弃叶瓣海岸侵蚀与岸线演化

利用Landsat TM卫星遥感图像,对黄河1964～1976年间形成的三角洲叶瓣自1976年废弃以后的岸线进行了识别,选取了四个典型剖面,绘制了它们的岸线蚀退或淤进平均速率曲线.结果显示,不同剖面处天然岸线的蚀退或淤进速率很有规律.根据曲线特征将其分为蚀退期,转换过渡期和周期性波动期.现废弃叶瓣已进入周期性波动期.由于受大坝影响,不同位置岸线波动周期不同,两大坝之间约为4年,大坝西侧约为5年,岸线变化准平衡线位于1996年的海岸线附近.岸线变化速率波动幅值将随着时间的延长而减小.

现代黄河三角洲滨浅海区的灾害地质

利用卫星遥感、测深、浅地层剖面及钻孔资料研究了黄河三角洲海岸及近海海洋灾害地质,编制了黄河三角洲海洋灾害地质图。黄河三角洲海岸灾害地质以海岸侵蚀为主,根据1976—2001年海岸的变化速率,可将海岸分为快速侵蚀海岸、中等程度侵蚀海岸、稳定海岸和淤积海岸四类,快速侵蚀海岸和中等程度侵蚀海岸长期以来遭受侵蚀。灾害地质因素有浅层气、灾害地貌、活动断层、海底滑坡、底辟、隆起脊、埋藏冲沟-古河道。浅层气主要分布在老黄河口附近渤海海底,近岸少见。浅层灾害地貌主要分布在三角洲前缘斜坡上的扰动区。扰动区位置在整个三角洲上变动明显,有向岸移动的趋势,斜坡坡度减小,扰动强度减弱。底辟除了发生在废弃三角洲侵蚀区外,还发生在三角洲外的渤海海底下部。隆起脊位于黄河口东部渤海海底,沿NE—SW方向发育,顺隆起脊发育活动断层。

现代黄河三角洲海岸演化研究

通过不同年代海图或地形图对比、不同年代的卫片对比、野外地质调查、不同年代潮滩剖面测量及对比等，研究了现代黄河三角洲海岸带不同时期的冲淤速率及其发展演化趋势。黄河尾闾 1996 年 6 月进行人工改道向东流入海，开始堆积现代黄河三角洲的第11 个叶瓣，推测这次改道可能是第 3 个亚三角洲形成的开始，使黄河三角洲的发展呈第一、第二、第三亚三角洲逐次向东偏北方向推进之势。现代黄河三角洲及莱州湾海岸带可分成 7 个冲淤状态不同的岸段：大口河至顺江沟岸段为相对稳定海岸段；顺江沟至挑河口岸段为弱蚀退岸段；挑河口至 106 站岸段为强蚀退岸段；106 站至孤东油田段为石堤护岸强制稳定海岸段；孤东油田至大汶流海堡岸段为强淤进岸段；大汶流海堡至淄脉沟岸段为弱淤进海岸段；淄脉沟口至胶莱河口岸段为稳定海岸段。预测 10 a 内，各海岸段的冲淤状态基本保持不变，但各海岸段的蚀退或淤进速率有逐渐减缓之趋势。人类活动对岸线的变迁有明显影响。

黄河三角洲沉积物的自然固结压实过程及其影响

对黄河三角洲及下伏沉积物的压实量和压实过程及其引起的地面沉降进行了分析研究。分析认为 ,在厚度为 15m的新淤积的黄河三角洲沉积重压下 ,前三角洲粘土和下伏海相粘土总固结量可达约 1.3 5m ,海湾或烂泥湾及前三角洲和海相粘土总压缩量为 1.48m。这些粘土层在亚三角洲建设时期就开始受压固结 ,但是在亚三角洲废弃后 ,仍要经过几十年自然固结才会基本完成。除去前 10年的固结量 ,前三角洲粘土与下伏海相粘土叠加形成的 14m厚粘土在随后的 2 7年内可能会压缩 5 0cm ;而海湾或烂泥湾及前三角洲和海相粘土叠加成的 2 0m厚粘土在 5 0年内可能会压缩 86cm ,两者的年平均压缩速率都超过 17mm/a。固结量和速率与上负沉积物重量成正比 ,而亚三角洲沉积厚度从沉积中心向外围逐渐减少 ,所以下伏粘土固结量和速率也向周围逐渐降低。但从亚三角洲沉积厚度分布情况看 ,在大范围内 ,下伏粘土固结引起的地面沉降在几十年内都将比较明显 ,从而可能加重三角洲地区风暴潮和海岸侵蚀灾害 。

黄河三角洲海岸强侵蚀机理及治理对策

黄河三角洲从挑河湾到孤东临海堤北端是黄河刁口河和神仙沟行水期间发育形成的年轻海岸,为强蚀型岸段。经初步计算,1976～1988年,每公里年均泥沙侵蚀率为320万t,现已建有桩西海堤和孤东海堤进行防护,但侵蚀仍在继续。本文分析了侵蚀的主要原因:一是流路停行初期,波状岸滩地形在涨落潮流往复作用下侵蚀;二是波浪能对底沙起作用的水深区位于强潮流区,波、流结合加剧了侵蚀作用。为此,单一的海岸防护工程,不能消除该岸段的泥沙流失,应同时通过调沙措施使其达到动态稳定。建议采用"二级分汊、多汊并存、人工控制、按需排放"的治理对策,避免海岸侵蚀,同时消除陆域洪灾。

现代黄河三角洲潮滩原状沉积物冲刷试验

在海岸防护工程决策中，沉积物的抗冲能力成为需要考虑的重要因素之一。以2004年4月在黄河三角洲北部海岸高潮滩取得的一个30m沉积物柱状样为例，在测定沉积物的结构、颗粒组成、密度、含水率等基础上，进行了分层沉积物的冲刷试验。结果表明，沉积物临界起动切应力与含水率、中值粒径成一定的负相关关系，与粘士含量呈显著正相关关系，同一类型沉积物的临界起动切应力与密度成一定的正相关关系。同时，近表层沉积物抗冲性最差，9．1～13．5m深度存在抗冲性较强的沉积层。沉积物的颗粒组成、结构、密度、含水率等决定了冲刷率与剪应力的变化关系。

黄河三角洲整体冲淤平衡及其地质意义

海岸侵蚀、三角洲面积减小已成为世界上关注的热点问题。三角洲造陆的趋势及速度制约着三角洲地区经济的持续发展和生态环境的演变。本文以 1976、1986、1992、1996～ 1998年黄河三角洲卫星遥感照片及海区水深等实测资料为依据 ,通过其高潮线的对比分析 ,研究整个黄河三角洲面积变化的趋势。结果表明 ,黄河三角洲在整体淤进的同时伴随着蚀退 ,三角洲的造陆面积呈逐渐减小的趋势。通过对 195 0～ 1998年黄河利津站实测来水来沙资料的分析 ,发现近年来水沙呈递减趋势 ,这可能是三角洲造陆面积减小的重要原因。研究了黄河三角洲造陆面积与流域来水来沙的关系 ,从而得出当来沙量为 2 .45亿 t/ a时 ,三角洲面积整体趋于不冲不淤的平衡。若来水来沙量继续减少 ,黄河三角洲将走向全面蚀退 。