蒸发和环流因素对湖泊演化的影响——河西走廊猪野泽不同位置全新世沉积物古环境意义探讨

湖泊不同位置沉积物重建的古环境变化过程往往具有差异,而这种差异可能揭示了不同的古环境信息.本文以河西走廊石羊河流域终端湖泊猪野泽为例,探讨湖泊不同位置沉积物所代表的古环境意义.位于湖盆边缘的三角城剖面可能反映了石羊河上游地区的降水及其古径流量的变化,这种变化在千年尺度上对应了北大西洋Bond事件,显示该区域通过季风环流系统与全球气候系统的联系.位于湖泊中部的QTH01、QTH02、QTL-03剖面反映了湖泊演化的信息,显示中全新世期间(约7.0-约3.5 cal ka BP)湖泊水位较高的特征,但是这种特征并不能和该流域的古径流相联系,说明该区域湖泊演化除了受千年尺度大气环流特征的影响外,湖泊表面蒸发可能也起了重要作用.该研究为中亚地区普遍存在的中全新世高湖面问题提供了研究思路.     

Long‐term morphological impacts of the opening of a new inlet on a multiple inlet system

In this study, the artificial opening of a new tidal inlet in an existing multiple inlet system is shown to significantly modify the adjacent nearshore and backbarrier morphology, as well as both updrift and downdrift shorelines. The study focuses on the dominant Faro‐Olhão and Armona inlets in the Ria Formosa barrier island system of southern Portugal. The equilibrium state and future evolution of the system are inferred using a range of morphological and hydrodynamic indicators, including the evolution of the inlet cross‐section, changes in tidal prism, and changes in the dimensions (length and area) of barrier islands. The results reveal how the morphology of an interconnected two‐inlet bay system and the adjacent coastlines has evolved following the artificial opening and stabilization of Faro‐Olhão inlet since 1929. A clear relationship between barrier island size, inlet cross‐section/width, and tidal prism is demonstrated. Decadal time‐scale changes in the tidal prism of the two interconnected inlets are shown to be the main mechanism responsible for morphological change, and have resulted in the remobilization of ebb‐tidal delta sediments deposited during previous hydraulic configurations. These changes, in turn, have contributed to a narrowing of Armona inlet and an increase in the size of Culatra Island. The work highlights the importance of ebb‐tidal deltas both as sand reservoirs and as conduits through which sand exchange between estuaries or lagoons and the open coast is regulated. It also shows the pivotal role of ebb‐tidal deltas in trapping longshore‐transported sediment and releasing it again during periods of increased wave activity. The findings have implications regarding the accurate assessment of the stability of multiple inlet systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Holocene evolution of a rock‐bounded barrier‐lagoon system,Cíes Islands,northwest Iberia

Coastal geomorphology results from the combined effects of contemporary dynamics, sea‐level rise and the inherited geological framework, yet the relative importance of these driving mechanisms may change throughout the evolutionary history of coastal deposits. In this contribution, we analyse the depositional history of the Cíes Islands barrier‐lagoon system, based on lithofacies, radiocarbon ages, and pollen analysis. Our results reveal a sedimentary sequence that provides evidence for striking changes in the dynamical functioning of this complex since the mid‐Holocene. The sedimentary sequence commenced about 7700 cal years bp by fresh‐water ponding of an upland depression located about 4 m below present mean sea‐level. Fresh‐water ponds were infilled by aeolian sediments following a gradual lowering of the water‐table 4000 cal years bp . Post‐3600 cal years bp sea‐level rise allowed water oscillations to reach the elevation of the bedrock causing the inundation of fresh‐water ponds and subsequent lagoonal and marine sedimentation. Subsequently, landward and upward migration of a sand‐barrier led to overwash and deposition of sand in the newly formed lagoon. The resultant sedimentary sequence suggests that climatic conditions played an important role controlling the sedimentation regime during the entire history of the basin; changing water‐table levels during early stages of evolution and increasing storminess during more recent times. In addition, background sea‐level rise related to the Holocene transgression was a key factor in controlling the evolution of the system, yet its influence depended to an extent on the relative elevation of the bedrock topography. Copyright © 2009 John Wiley & Sons, Ltd.     

Floodplain evolution in a small,tectonically active basin of northern California

Sediment cores were collected along ?oodplains in the Navarro River basin of coastal northern California to examine the controls on ?oodplain evolution in a tectonically active setting. Sedimentary strata were subsampled for organic content, bulk density, and grain size measurements. Organic samples were analysed for ¹⁴C age, which yielded net‐averaged sedimentation rates for all cores. Overbank deposition rates decreased at all study sites through time and declined in the downstream direction. The ability of intermediary‐order streams to store sediment in ?oodplains decreased the ability of highest‐order streams to record sediment‐pulse events. The effects of anthropogenic disturbance, primarily logging, on long‐term overbank deposition rates were minimal. Climatic variability, by affecting sediment loading in the channel network, is the principal control on ?oodplain evolution through the Holocene. A hypothetical model is proposed to explain overbank deposition rates in the Navarro basin, which may be extrapolated to the northern‐coastal California region during the late Pleistocene and Holocene. The complexities observed in sediment storage and routing in this study imply that caution should be made when extrapolating sediment‐yield measurements obtained at river mouths or coastal shelves to geomorphic events within small, tectonically active basins. Copyright © 2003 John Wiley & Sons, Ltd.     

全新世以来洞庭湖的演变

本文根据全新世沉积物的岩性、岩相特征和文化遗址的时空分布,结合孢粉资料与历史文献记载,揭示了全新世以来洞庭湖演变的六个阶段:(1)晚更新世末至全新世初为河湖切割平原;(2)中全新世早、中期(8000—5000a B.P.)是湖泊扩展时期;(3)中全新世晚期(5000—3000 a B.P.)四水复合三角洲发育,湖沼洼地零星分布;(4)商周至秦汉(3000—1700 a B.P.)四水分流间洼地湖泊和沼泽广布,汛期河湖水体相连;(5)魏晋至19世纪中叶,洞庭湖逐渐发展至鼎盛阶段;(6)19世纪中叶至今,三角洲迅速推进,湖泊逐渐萎缩。研究认为这种发育演化过程与区域性气候变化、人类活动直接相关。     

Morphological response of a barrier island system on a catastrophic event: the AD 1634 North Sea storm

The AD 1634 North Sea storm is one of the most catastrophic storms along the Wadden Sea coast of Denmark. In this study we show how pre‐1634 storm morphology exerted a strong control on the resulting post‐storm coastal morphology. Erosional responses associated with the storm were barrier breaching, dune scarping and shoreface erosion and accretionary responses were washover deposition, shoreface healing and barrier‐island formation. Local sediment sources appeared to have a particularly strong influence on post‐storm coastal evolution and allowed a very rapid formation of a barrier shoal which resulted in several kilometres of coastal progradation. Sediment budgets suggest that formation of the barrier shoal was possible, but the sediment transport rates in the decades after the 1634 storm, must have been two to three times higher than present‐day rates. The study demonstrates that catastrophic storms are capable of moving large amounts of sediments over relatively short time‐periods and can create barrier shoals, whereas moderate storms mostly rework the shoal or barrier and create more local erosion and/or landward migration. Catastrophic storms substantially influence long‐term and large‐scale coastal evolution, and storms may positively contribute to the sediment budget and promote coastal progradation in coastal areas with longshore sediment convergence. Copyright © 2015 John Wiley & Sons, Ltd.     

Multiple‐station neural network for modelling tidal currents across Shinnecock inlet,USA

This paper presents the development of a multiple‐station neural network for predicting tidal currents across a coastal inlet. Unlike traditional hydrodynamic models, the neural network model does not need inputs of coastal topography and bathymetry, grids, surface and bottom frictions, and turbulent eddy viscosity. Without solving hydrodynamic equations, the neural network model applies an interconnected neural network to correlate the inputs of boundary forcing of water levels at a remote station to the outputs of tidal currents at multiple stations across a local coastal inlet. Coefficients in the neural network model are trained using a continuous dataset consisting of inputs of water levels at a remote station and outputs of tidal currents at the inlet, and verified using another independent input and output dataset. Once the neural network model has been satisfactorily trained and verified, it can be used to predict tidal currents at a coastal inlet from the inputs of water levels at a remote station. For the case study at Shinnecock Inlet in the southern shore of New York, tidal currents at nine stations across the inlet were predicted by the neural network model using water level data located from a station about 70 km away from the inlet. A continuous dataset in May 2000 was used for the training, and another dataset in July 2000 was used for the verification of the neural network model. Comparing model predictions and observations indicates correlation coefficients range from 0·95 to 0·98, and the root‐mean‐square error ranges from 0·04 to 0·08 m s^?1 at the nine current locations across the inlet. Copyright © 2007 John Wiley & Sons, Ltd.     

Beach Morphodynamics influenced by an ebb‐tidal delta on the north Florida Atlantic coast

Tidal inlets interrupt longshore sediment transport, thereby exerting an influence on adjacent beach morphology. To investigate the details and spatial extent of an inlet's influence, we examine beach topographic change along a 1.5 km coastal reach adjacent to Matanzas Inlet, on the Florida Atlantic coast. Analyses of beach morphology reveal a behavioral change between 0.64 and 0.86 km from the inlet channel centerline, interpreted to represent the spatial extent of inlet influence. Beyond this boundary, the beach is narrow, exhibits a statistically significant inverse correlation of shoreline position with offshore wave conditions, and has a uniform alongshore pattern in temporal behavior, as determined from empirical orthogonal function (EOF) analysis. On the inlet side of the boundary, the beach experiences monotonic widening (with proximity to the inlet), lacks spatial consistency in correlation between shoreline position and wave conditions, and exhibits an irregular pattern in spatial EOF modes. We augment the field observations with numerical modeling that provides calculations of wave setup and nearshore current patterns near the inlet, highlighting the effects of the ebb‐tidal delta on the assailing waves. The modeling results are verified by a natural experiment that occurred during May 2009, when a storm‐produced sedimentary mass accreted to the lower beach, then subsequently split into two oppositely directed waves of sediment that migrated away from the initial accretion site in the subsequent months. Our results suggest that the ebb‐tidal delta produces a pattern of wave setup that creates a pressure gradient driving an alongshore flow that opposes the longshore currents derived from breaking of obliquely oriented incident waves. The resulting recirculation pattern on the margin of the ebb‐tidal delta provides a mechanism through which the inlet influences adjacent barrier island beach morphology. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of offshore waves and vegetation on the sediment budget in the Virginia Coast Reserve (VA)

The potential for rapid coastline modification in the face of sea-level rise or other stressors is alarming, since coasts are often densely populated and support valuable infrastructure. In addition to coastal submergence, nutrient-related water pollution is a growing concern for coastal wetlands. Previous studies found that the Suspended Sediment Concentration (SSC) of coastal wetlands acts as a first-order control of their sustainability, but SSC dynamics are poorly understood. Our study focuses on the Virginia Coast Reserve (VCR) Long Term Ecological Research (LTER) site, a shallow multiple tidal inlet system in the USA. We apply numerical modelling (Delft3D-SWAN) and subsequent analyses to determine SSC dynamics within the VCR. In particular, we consider two important controls on SSC in the system: vegetation (seagrass and salt marsh) and offshore waves. Our results show that vegetation colonies and increased wave energy lengthen water residence time. The reduction in the tidal prism decreases SSC export from the bay via tidal inlets, leading to increased sediment retention in the bay. We found that alongshore currents can enhance lagoon SSC by importing fine sediments from an adjacent inlet along the coastline. Our numerical experiments on vegetation seasonality can improve the understanding of wave climate impact on coastal bay sediment budget. Offshore waves increase sediment export from coastal bays, particularly during winter seasons with low vegetation density. Therefore, our study can help managers and stakeholders to understand how to implement restoration strategies for the VCR. © 2020 John Wiley & Sons, Ltd.     

Geomorphic evolution of small river–lake‐systems in northeast Germany during the Late Quaternary

This study investigates the post‐glacial development of four small river–lake systems in the Weichselian belt of northern central Europe. The valleys investigated are part of an immature drainage system characterized by frequent and abrupt changes in flow direction and the presence of numerous stagnant‐ice depressions in the valley course. The depressions contain thick sedimentary sequences which provide excellent archives for the reconstruction of the post‐glacial valley development. Study results indicate that the valleys reuse segments of former subglacial meltwater channels. During the Late Pleniglacial these channels carried meltwater streams. Stagnant‐ice melting occurred in stages from the Oldest Dryas to the early Holocene and was often followed by the formation of lakes in the valley course. Flow reversals occurred during the Late‐glacial–Holocene transition and were in response to general base‐level lowering caused by stagnant‐ice melting, headwater erosion and lake overspills. Lacustrine deposition typically started during the early Late‐glacial comprising mainly silicate gyttjas, whereas organic gyttjas and peats accumulated during the Allerød. The Younger Dryas is associated with a marked increase in fluvial and aeolian sedimentation, and lake‐level high stands. This was followed by early Holocene lake‐level low stands and a subsequent stabilization phase with decreasing silicate input and increasing organic lacustrine deposition. In general, dramatic changes in Late Pleniglacial to early Holocene sedimentation suggest that small‐scale catastrophic events played a more important role in triggering geomorphic changes then previously recognized. Infilling continued until peat accumulation and terrestrialization of lake basins became widespread during the mid‐ to late Holocene. Beginning in the late Holocene anthropogenic influences become important mainly involving an increase in sediment supply due to forest clearing and land use, followed by mill stowage, river course correction and anthropogenic lake‐level manipulations. Copyright © 2007 John Wiley & Sons, Ltd.     

Downdrift coarsening of beach foreshore sediments at tidal inlets: An example from the coast of New Jersey

Analysis of grain size statistics of upper foreshore sediments on sand beaches at two tidal inlets in New Jersey, U.S.A. reveals that sediments are coarser at beaches flanking the inlets than updrift, although sediments become finer downdrift at the broad, regional scale. The local reversal of the regional trend in size grading is attributed to: (1) the offshore diversion of the finer sands along the surf zone on the ebb tidal delta, and (2) the removal of the finer sands from the inlet flank beach caused by low wave energy conditions at low stages of the tide and by deflation. Sediments thus become coarser at inlet beaches as a result of alterations in the interaction of waves with the beach and as a result of aeolian processes, not solely as a result of increased tidal current velocities as previously reported. The distance along the New Jersey barrier islands over which inlet processes are likely to affect changes in sediment size updrift averages less than 1100 m, but the impacts of inlets on the sedimentary record can be extended greater distances as a result of inlet migration.     

Morphology of the Itapeva to Tramandai transgressive dunefield barrier system and mid‐ to late Holocene sea level change

The surface morphology of the transgressive dunefield barrier extending from Itapeva to Tramandai along the northern littoral of Rio Grande do Sul, is examined and an attempt is presented to link morphological changes across the barrier to Holocene sea level changes. The 4·5 km wide Holocene barrier displays two typical morphologies: an inner part dominated by large‐scale, continuous alongshore, overlapping dunefield phases comprising sand sheets, dunes, deflation plains and precipitation ridges; and an outer part dominated by discontinuous, medium‐ to small‐scale, triangular to lobate transgressive dunefield phases, cut by both active and relict (palaeo‐) creeks or washouts. Holocene sea level in the region rose to c. +1 to +3 m above present reaching a maximum around 5100 years bp and then progressively fell to the present level. We argue that the effect on barrier development was to suppress the development of a drainage system during the rising and maximum stages, and encourage the development of an organized drainage system in the form of regularly spaced washouts during the falling period, and that this change in sea level from rising to falling therefore produced the large‐scale differences in barrier morphology. Copyright © 2006 John Wiley & Sons, Ltd.     

Tide circulation patterns in a coastal lagoon under sea-level rise

This study evaluates the patterns and effects of relative sea-level rise on the tidal circulation of the basin of the Ria Formosa coastal lagoon using a process-based model that is solved on an unstructured mesh. To predict the changes in the lagoon tidal circulation in the year 2100, the model is forced by tides and a static sea level. The bathymetry and the basin geometry are updated in response to sea-level rise for three morphological response scenarios: no bed updating, barrier island rollover, and basin infilling. Model results indicate that sea-level rise (SLR) will change the baseline current velocity patterns inside the lagoon over the ~100-year study period, due to a strong reduction in the area of the intertidal basin. The basin infilling scenario is associated with the most important adjustments of the tidal circulation (i.e., increases in the flood velocities and delays in the ebb tide), together with an increase in the cumulative discharges of the tidal inlets. Under sea-level rise and in the basin infilling scenario, the salt marshes and tidal flats experience increases in the tidal range and current asymmetry. Basin infilling changes the sediment flushing capacity of the lagoon, leading to the attenuation of the flood dominance in the main inlet and the strengthening of the flood dominance in the two secondary inlets. The predictions resulting from these scenarios provide very useful information on the long-term evolution of similar coastal lagoons that experience varying degrees of SLR. This study highlights the need for research focusing on the quantification of the physical and socio-economic impacts of SLR on lagoon systems, thus enabling the development of effective adaptation strategies.     

Controls on surface water chemistry in two lake‐watersheds in the Adirondack region of New York: differences in nitrogen solute sources and sinks

The southwestern Adirondack region of New York receives among the highest rates of atmospheric nitrogen (N) deposition in the USA. Atmospheric N deposition to sensitive ecosystems, like the Adirondacks, may increase the acidification of soils through losses of exchangeable nutrient cations, and the acidification of surface waters associated with enhanced mobility of nitrate (NO₃^?). However, watershed attributes, including surficial terrestrial characteristics, in‐lake processing, and geological settings, have been found to complicate the relationships between atmospheric N deposition and N drainage losses. We studied two lake‐watersheds in the southwestern Adirondacks, Grass Pond and Constable Pond, which are located in close proximity (～26 km) and receive similarly high N deposition, but have contrasting watershed attributes (e.g. wetland area, geological settings). Since the difference in the influence of N deposition was minimal, we were able to examine both within‐ and between‐watershed influences of land cover, the contribution of glacial till groundwater inputs, and in‐lake processes on surface water chemistry with particular emphasis on N solutes and dissolved organic carbon (DOC). Monthly samples at seven inlets and one outlet of each lake were collected from May to October in 1999 and 2000. The concentrations of NO₃^? were high at the Grass Pond inlets, especially at two inlets, and NO₃^? was the major N solute at the Grass Pond inlets. The concentrations of likely weathering products (i.e. dissolved Si, Ca²⁺, Mg²⁺, Na⁺) as well as acid neutralizing capacity and pH values, were also particularly high at those two Grass Pond inlets, suggesting a large contribution of groundwater inputs. Dissolved organic N (DON) was the major N solute at the Constable Pond inlets. The higher concentrations of DON and DOC at the Constable Pond inlets were attributed to a large wetland area in the watershed. The DOC/DON ratios were also higher at the Constable Pond inlets, possibly due to a larger proportion of coniferous forest area. Although DON and DOC were strongly related, the stronger relationship of the proportion of wetland area with DOC suggests that additional factors regulate DON. The aggregated representation of watershed physical features (i.e. elevation, watershed area, mean topographic index, hypsometric‐analysis index) was not clearly related to the lake N and DOC chemistry. Despite distinctive differences in inlet N chemistry, NO₃^? and DON concentrations at the outlets of the two lakes were similar. The lower DOC/DON ratios at the lake outlets and at the inlets having upstream ponds suggest the importance of N processing and organic N sources within the lakes. Although an inverse relationship between NO₃^? and DOC/DON has been suggested to be indicative of a N deposition gradient, the existence of this relationship for sites that receive similar atmospheric N deposition suggest that the relationship between NO₃^? and the DOC/DON ratio is derived from environmental and physical factors. Our results suggest that, despite similar wet N deposition at the two watershed sites, N solutes entering lakes were strongly affected by hydrology associated with groundwater contribution and the presence of wetlands, whereas N solutes leaving lakes were strongly influenced by in‐lake processing. Copyright © 2006 John Wiley & Sons, Ltd.     

Overwash-dominated stratigraphy of barriers with intermittent inlets

The morphodynamics and structure of barriers with persistent tidal inlets have been well studied. In contrast the stratigraphy and functioning of barrier systems with ephemeral inlets is poorly understood. This article examines the barrier-inlet systems of two intermittently closed open lagoons or temporarily open closed estuaries on the east coast of South Africa. Multiple geophysical surveys using ground-penetrating radar (GPR) were correlated with exposed sections of the barrier where inlet formation revealed the internal stratigraphy. Stratigraphic observations were placed in the context of the contemporary wave dynamics and mesoscale geomorphic evolution. The integrated databases reveal an absence of migrating channel features. Instead the stratigraphy is dominated by landward dipping sheets of alternating high- and low-amplitude reflectors. These correlate with gravel, shell debris and heavy mineral-lined beds formed by overwash processes. Where ephemeral inlet structures are preserved in the stratigraphy, their fills comprise aggrading, high-amplitude reflectors, linked to washover infilling of the inlet mouth. Multiple small channels in the more distal portions of the barrier in georadar stratigraphy are related to channelized washover flow. These barriers often breach during high swell and are subsequently sealed during fairweather wave conditions. Time series analysis of waves and satellite imagery shows a link between storms from the south and breach events. This is consistent with the truncations in subsurface images and inferred barrier lowering by overwash channelling. These barriers experience quasi-stable oscillations in their landward and seaward shore position, punctuated by periods of barrier rollover associated with the most intense storms. As overwash is responsible in part for both the constructive and destructive phases of the barrier, these barriers have low preservation potential. Persistent rollover driven by overwashing will terminate once accommodation space is eliminated and the barriers are eroded by storm activity. © 2019 John Wiley & Sons, Ltd.     

大布苏湖地貌——沉积类型与湖泊演化

大布苏湖地处松嫩平原南部,是一个封闭的构造断湖,湖区山貌类型复杂,沉积环境独具特色,根据地形面的分层和特征,结合^14C测年,确定大布苏湖形成于晚更新世晚期,湖泊形成的早期,曾经历了深湖的发育阶段,全新世以来,湖面波动式下降,并有两次规模较大的扩张和收缩时期,形成了两个完整的湖进、湖退沉积旋回、晚全新世以来,气候干燥,风力作用活跃,湖面明显萎缩,形成我国东部地区极为罕见的盐湖。     

Evaluation of sewage source and fate on southeast Florida coastal reefs

Water, sponge and coral samples were collected from stations impacted by a variety of pollution sources and screened for human enteric viruses as conservative markers for human sewage. While human enteroviruses and adenoviruses were not detected, noroviruses (NoV; human genogroups I and II) were detected in 31% of samples (especially in sponge tissue). Stations near inlets were the only ones to show multiple sample types positive for NoV. Fecal indicator bacteria and enteric viruses were further evaluated at multiple inlet stations on an outgoing tide. Greatest indicator concentrations and highest prevalence of viruses were found at the mouth of the inlet and offshore in the inlet plume. Results suggest that inlets moving large volumes of water into the coastal zone with tides may be an important source of fecal contaminants. Efforts to reduce run-off or unintended release of water into the Intracoastal Waterway may lower contaminants entering sensitive coastal areas.     

Assessment of the decadal morphodynamic evolution of a mixed energy inlet using ocean color remote sensing

A consistent time series of synoptic and high-frequency bathymetric observations is fundamental to improving our understanding and predictive capabilities regarding the morphological behavior of large coastal inlets. Based on satellite observations, an original approach is proposed to characterize the long-term morphological evolution of the Arcachon lagoon inlet and to describe sediment bypassing and breaching mechanisms. The almost 26-year-long remotely sensed data archive used in this study is built from 78 suitable SPOT images (1986–2012) collected in the framework of the KALIDEOS-Littoral program. Bathymetric information is derived from satellite data using a physics-based model. A validation exercise performed on a large bathymetric survey data set (N?=?43,949) demonstrates that the inversion model performs excellently in estimating the depth of mildly to moderately turbid shallow waters. The performance of the model suggests that the minimum requirements are fulfilled to apply the SPOT-derived bathymetry to morphodynamic applications. We demonstrate that high-spatial-resolution multispectral sensors are well adapted to analyzing the morphological evolution of small- (i.e., sand dunes), medium- (i.e., sandbanks and channels), and large- (i.e., the entire inlet-lagoon system) scale sedimentary structures present in coastal inlets. For the first time, the long-term evolution of a flood and ebb-tidal delta is characterized by observations at a seasonal timescale. Finally, migration rates of sedimentary entities are quantified, and fundamental mechanisms driving the sediment transport cross the inlet are confirmed.     

Defining rates of landscape evolution in a south Tibetan graben with in situ‐produced cosmogenic 10Be

The Tangra Yum Co graben is one of the active structures that accommodate the east‐west extension of the southern Tibetan Plateau and hosts one of the largest Tibetan lakes, which experienced lake‐level changes of ~200 m during the Holocene. In this study, cosmogenic ¹⁰Be is employed to: (1) quantify catchment‐wide denudation rates in fault‐bounded mountain ranges adjacent to the Tangra Yum Co graben; (2) date palaeo‐shorelines related to the Holocene lake‐level decline; and (3) determine the age of glacial advances in this region. The fault‐bounded, non‐glaciated mountain range north of Tangra Yum Co – and presumably most other areas around the lake – erode at low rates of 10–70 mm/ka. Owing to the slow erosion of the landscape, the sediments delivered to Tangra Yum Co have high ¹⁰Be concentrations. As a consequence, accurate exposure dating of sediment‐covered terraces and beach ridges is difficult, because the pre‐depositional ¹⁰Be concentration may exceed the post‐depositional ¹⁰Be concentration from which exposure ages are calculated. This difficulty is illustrated by a rather inaccurate ¹⁰Be exposure age of 2.3 ± 1.4 ka (i.e. an error of 60%) for a terrace that is located 67 m above the lake. Nevertheless, the age is consistent with luminescence ages for a series of beach ridges and provides further evidence for the decline of the lake level in the late Holocene. At Tangra Yum Co exposure dating of beach ridges via ¹⁰Be depth profiles is not feasible, because the pre‐depositional ¹⁰Be component in these landforms varies with depth, which violates a basic assumption of this approach. ¹⁰Be ages for boulders from two moraines are much older than the early Holocene lake‐level highstand, indicating that melting of glaciers in the mountain ranges adjacent to Tangra Yum Co has not contributed significantly to the lake‐level highstand in the early Holocene. Copyright © 2015 John Wiley & Sons, Ltd.