Sediment Transport In Rivers Research Articles

Downstream impacts of dams: shifts in benthic invertivorous fish assemblages

Impoundments alter connectivity, sediment transport and water discharge in rivers and floodplains, affecting recruitment, habitat and resource availability for fish including benthic invertivorous fish, which represent an important link between primary producers and higher trophic levels in tropical aquatic ecosystems. We investigated long-term changes to water regime, water quality, and invertivorous fish assemblages pre and post impoundment in three rivers downstream of Porto Primavera Reservoir in south Brazil: Parana, Baia and Ivinhema rivers. Impacts were distinct in the Parana River, which is fully obstructed by the dam, less evident in the Baia River which is partially obstructed by the dam, but absent in the unimpounded Ivinhema River. Changes in water regime were reflected mainly as changes in water-level fluctuation with little effect on timing. Water transparency increased in the Parana River post impoundment but did not change in the Baia and Ivinhema rivers. Changes in fish assemblages included a decrease in benthic invertivorous fish in the Parana River and a shift in invertivorous fish assemblage structure in the Baia and Parana rivers but not in the unimpounded Ivinhema River. Changes in water regime and water transparency, caused by impoundment, directly or indirectly impacted invertivorous fish assemblages. Alterations of fish assemblages following environmental changes have consequences over the entire ecosystem, including a potential decrease in the diversity of mechanisms for energy flow. We suggest that keeping existing unimpounded tributaries free of dams, engineering artificial floods, and intensive management of fish habitat within the floodplain may preserve native fish assemblages and help maintain functionality and ecosystem services in highly impounded rivers.

Flows and sediment dynamics in the Ganga River under present and future climate scenarios

ABSTRACTIdentification of factors controlling sediment dynamics under natural flow regimes can establish a baseline for quantifying effects of present day hydrological alteration and future climate change on sediment delivery and associated flooding. The process-based INCA-Sediment model was used to simulate Ganga River sediment transport under baseline conditions and to quantify possible future changes using three contrasting climate scenarios. Construction of barrages and canals has significantly altered natural flow regimes, with profound consequences for sediment transport. Projected increases in future monsoonal precipitation will lead to higher peak flows, increasing flood frequency and greater water availability. Increased groundwater recharge during monsoon periods and greater rates of evaporation due to increased temperature complicate projections of water availability in non-monsoon periods. Rainfall and land surface interaction in high-relief areas drive uncertainties in Upper Ganga sediment loads. However, higher monsoonal peak flows will increase erosion and sediment delivery in western and lower reaches.

Environmental and human impacts on sediment transport of the largest Asian rivers of Russia and China

The paper deals with comparative summary of sediment loads and particulate trace metals (V, Cr, Co, Cu, Zn, Cd, Pb) transport in the largest Asian rivers of Russia and China. Environmental conditions and human interventions in the selected catchments (Lena, Ob, Enisey, Selenga, Kolyma, Amur, Yellow, Yangtze, Pearl) are analyzed with respect to the rate and composition of suspended sediment loads. The paper presents calculations of sediment load changes at the downstream sections of the rivers and new database of the chemical composition of suspended matter which involves all recent studies of the last decade for the sediment geochemistry. The results indicate that fluvial system and its human modifications are the most significant drivers of sediment load. Fluvial erosion in the unconfined channels exerts a significant control on the sediment load changes due to observed permafrost melting. We concluded that construction of reservoirs has the most important influence on land–ocean sediment fluxes in the largest rivers of Asia but plays relatively weak role in heavy metal composition in suspended particulate matter (SPM) due to lowest sedimentation rates of the fine clay particles, which are mostly enriched with heavy metals. The paper also presents novel mapping approaches related to cartographic recognition of the fluvial system and its human modification and sediment transfer processes in the largest Asian rivers of Russia and China, linked with a specific legend. Finally, analysis of uncertainties associated with estimating the SPM composition in the rivers was done with respect to spatial and temporal variability. It was shown that the main error occurs due to incorporation of data only from particular hydrological seasons which usually ignore high flood conditions.

Avulsions in a Simulated Large Lowland Braided River

The understanding of the complicated braiding mechanisms in braided rivers is closely related to avulsions. They control the channel generation, migration and disappearance in large lowland braided rivers, and are considered to be the key factor that keeps the river maintaining a dynamic braided pattern. However, their occurring processes and mechanisms are still not well understood due to the lack of detailed measurements with sufficient temporal and spatial data covering multiple bifurcations. In the present study, a numerical model based on the physical process of hydrodynamics and sediment transport is used to simulate the suspended sediment transport and river channel evolution in braided rivers. The model predicted braiding processes are comparable to those observed in nature. Efforts are made to investigate the morphological processes that are key for river braiding. Three types of avulsions observed in natural rivers have been identified in the model predicted river and their evolution processes and controlling factors are examined based on the predicted flow velocity, sediment concentration, bed elevation and sediment size distribution. It was found that, a curving channel bend is the key factor in introducing a constriction avulsion, while the choking avulsion and apex avulsion are controlled by the water surface slope and bed elevation. They are mostly affected by the upstream channel pattern changes.

Variation in flow and suspended sediment transport in a montane river affected by hydropeaking and instream mining

The temporal and spatial variability of water and sediment loads of rivers is controlled by a suite of factors whose individual effects are often difficult to disentangle. While land use changes and localised human activities such as instream mining and hydropeaking alter water and sediment transfer, tributaries naturally contribute to discharge and sediment load of mainstem rivers, and so may help compensate upstream anthropogenic factors. The work presented here aimed to assess water and the sediment transfer in a river reach affected by gravel extraction and hydropeaking, set against a backdrop of changes to the supply of water and sediment from tributaries. Discharge and suspended sediment transport were monitored during two average hydrological years at three cross-sections along a 10-km reach of the upper River Cinca, in the Southern Pyrenees. Water and sediment loads differed substantially between the reaches. The upper reach showed a largely torrential discharge regime, controlled mainly by floods, and had high but variable water and sediment loads. The middle reach was influenced markedly by hydropeaking and tributary inflows, which increased its annual water yield four-fold. Suspended sediment load in this reach increased by only 25% compared to upstream, indicating that dilution predominated. In the lowermost section, while discharge remained largely unaltered, sediment load increased appreciably as a result of changes to sediment availability from instream mining and inputs from tributaries. At the reach scale, snowmelt and summer and autumn thunderstorms were responsible for most of the water yield, while flood flows determined the magnitude and transport of the sediment load. The study highlights that a combination of natural and human factors control the spatial and temporal transfer of water and sediment in river channels and that, depending on their geographic location and effect-size, can result in marked variability even over short downstream distances.

Great expectations: Flow restoration and sediment transport in the Waimea River, Kaua'i

Conventional and novel observations made in the Waimea River basin between 1960 and 1995 permit the total riverine mass flux to be estimated and the influence that flow restoration will have on sediment dynamics in the river's lower reaches to be assessed. Flows between the threshold for sediment transport (~6.0 m3 s−1) and the most effective flow (80.7 m3 s−1) recur annually and transport ~60% of the Waimea River's suspended sediment load. Discharges of this magnitude essentially were unaffected by plantation era agricultural diversions of 2.3 ± 0.7 m3 s−1. The modern-day mass flux from the Waimea River basin is 155 ± 38 t km−2 y−1, and comparison with an independent cosmogenic nuclide-based estimate implies that it has remained at about this level for the past 10 ky. Previous work indicated that: (i) most of the sand the Waimea River transports to the coast is derived from steep, rapidly eroding, sparsely vegetated, bedrock-dominated hillslopes; and (ii) the sediment transport regime of the Waimea River is supply-limited at very high discharges (recurrence interval > 2.5 years). Consequently, major floods tend to remove sand from the estuary. Climate change has caused a statewide decline in heavy rainfall, and a commensurate decline in the magnitude of peak flows in the basin's pristine, undiverted headwaters over the past 97 years. The effect this secular change in climate presently is having on streamflow was foreshadowed in the late 1970s by a naturally occurring, warm Pacific Decadal Oscillation phase reduction in the magnitude of flows with low exceedance probabilities. Additionally, the controlling base level at the river mouth has risen and been displaced seaward. Simple proportionality approximations show that, for a constant sediment supply, aggradation will occur if either the magnitude of flows with a low exceedance probability declines and/or base level rises. Thus, anthropogenic stresses on Waimea River's lower reaches are not derived from the within-basin influence agricultural diversions exert on the flow regime and will not be resolved by restoring flow to the river. These stresses primarily accrue from extrinsic factors that will continue to influence the river's hydrologic and sediment transport regimes until global, offsetting, climate-ameliorating measures are implemented.

Passive acoustic measurement of bedload grain size distribution using self-generated noise

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

A simplification of the Einstein equation for the calculation of suspended sediment transport in rivers

A simplification of the Einstein equation for the calculation of suspended sediment transport in rivers

A Simplification of the Einstein Equation for the Calculation of Suspended Sediment Transport in Rivers

In this study, a simplified equation for estimating suspended sediment load is proposed, based on regression analysis and the concept presented by Einstein, Ackers and White, and Shields. Field data for 11 rivers located at different parts of the world were used for the calibration and validation of the proposed equation. The results show that the equation gives a good performance compared with Einstein's and Bagnold's equations when tested using field data for the Atchafalaya, Red, South American, Rio Grande and Al-Garraf rivers. The minimum and maximum values of mean absolute error (MAE) and root mean square error (RMSE) between the output of the proposed equation and field records were 0.005 to 0.007 and 0.09 to 0.289, respectively. For the above rivers, graphical comparisons show that the predicted values of suspended sediment load had a range of D50 0.2 gave a good prediction compared with the measured sediment load. The main advantages of the proposed equation are that it is easy to apply and the results obtained from its application have reasonable accuracy.

Methodology for Volumetric Measuring Transport of River Sand, in a Laboratory Channel with Mobile Bottom

Most public universities in Latin America and Mexico lack laboratories for measuring sediment transport or to do academic activities. The Research Center of the engineering faculty of Chiapas state university (UNACH by its acronym in Spanish) designed a portable prismatic channel for teaching and researching the sediment transportation in rivers. This paper presents the method to measure river sand transportation in a laboratory channel with a mobile bottom and presents the results of twenty-seven experiments done in the portable channel, using nine different slope inclinations and 27 flow and water speed values. The three main results are the following: 1) The construction of the channel with variable slopes, to experiment and measure sediment transportation. 2) A method developed for measuring the volume of sediment in a laboratory. 3) In a channel with a bottom slope of 0.071, a water flow of 2 l/s and a water speed of 1.77 m/s, the volume of transported sediment was 0.015 m3; in a channel with a bottom slope of 0.44, a water flow of 2 l/s and a water speed of 0.788 m/s, the volume of transported sediment was 0.006 m3; in a channel with the bottom slope of 0.024, a water flow of 2 l/s and a water speed of 0.62 m/s, the transported sediment was 0 m3.

Bedload transport and hydro-abrasive erosion at steep bedrock rivers and hydraulic structures

Sediment transport in glacier basins and rivers, and hence reservoir sedimentation tend to increase under the impact of climate change. The raise of bedload transport rates results in an increase of hydro-abrasive erosion leading to bedrock incision in rivers and wear at hydraulic structures. Mechanistic abrasion models are a helpful tool for both river and landscape evolution and hydroabrasion of hydraulic structures. Therefore, knowledge of the physical processes of turbulent flow characteristics, bedload particle motion, and hydroabrasion and their interrelations is needed. Ongoing research at VAW of ETH Zurich aims at improving the required knowledge to address hydroabrasion issues by means of laboratory and prototype experiments in supercritical flows over fixed smooth and transitionally rough beds. A physical model investigation revealed that particle trajectories on fixed planar beds are rather symmetric, flat and long compared to alluvial beds. By applying newly developed particle motion equations, an existing mechanistic abrasion model was adapted and calibrated for concrete and natural rock by means of prototype data. This advances abrasion prediction modelling and contributes to a better understanding of river bed and landscape evolution and to a sustainable design and operation of hydraulic structures facing severe hydro-abrasive erosion.

Application of an impact plate – Bedload transport measuring system for high-speed flows

To achieve the sustainable use of dams, the development of methods for sediment management in reservoirs is required. One such method includes the use of Sediment Bypass Tunnels (SBTs) to divert sediment around a dam, thereby preventing sedimentation in the reservoir. However, SBTs are prone to severe invert abrasion caused by the high sediment flux. Therefore, it is necessary to establish a measurement system of the sediment transport rate in these tunnels. One system to measure sediment transport in rivers is the Swiss plate geophone, which can register plate vibrations caused by particle impact. In Japan, the Japanese pipe microphone is used, and sediment transport is measured based on the sound emitted by the particle impact. In this study an attempt was made to optimize the advantages of both systems by fixing a microphone and an acceleration sensor to a steel plate. The results of calibration experiments with this new system are presented and compared with the existing methods. It was found that the acceleration sensor can detect sediment particles larger than 2mm in diameter. Moreover, a new parameter, referred to as the detection rate, was introduced to describe the correlation between the actual amount of sediment and the registered output. Finally, two parameters - the saturation rate and hit rate - are introduced and exhibit strong correlation with the detection rate.

Transport Time Scales in Soil Erosion Modeling

Core Ideas Erosion timescales inherent in the Hairsine–Rose soil erosion are exposed. Both fast and slow timescales are isolated and can be estimated a priori. The maximum sediment settling rate controls the possible range of timescales. In practice, the full range of erosion timescales are not seen in flume experiments. Unlike sediment transport in rivers, erosion of agricultural soil must overcome its cohesive strength to move soil particles into suspension. Soil particle size variability also leads to fall velocities covering many orders of magnitude, and hence to different suspended travel distances in overland flow. Consequently, there is a large range of inherent timescales involved in transport of eroded soil. For conditions where there is a constant rainfall rate and detachment is the dominant erosion mechanism, we use the Hairsine–Rose (HR) model to analyze these timescales, to determine their magnitude (bounds) and to provide simple approximations for them. We show that each particle size produces both fast and slow timescales. The fast timescale controls the rapid adjustment away from experimental initial conditions—this happens so quickly that it cannot be measured in practice. The slow timescales control the subsequent transition to steady state and are so large that true steady state is rarely achieved in laboratory experiments. Both the fastest and slowest timescales are governed by the largest particle size class. Physically, these correspond to the rate of vertical movement between suspension and the soil bed and the time to achieve steady state, respectively. For typical distributions of size classes, we also find that there is often a single dominant timescale that governs the growth in the total mass of sediment in the non‐cohesive deposited layer. This finding allows a considerable simplification of the HR model, leading to analytical expressions for the evolution of suspended and deposited layer concentrations.

Sediment Transport Time Scales and Trapping Efficiency in a Tidal River

AbstractObservations and a numerical model are used to characterize sediment transport in the tidal Hudson River. A sediment budget over 11 years including major discharge events indicates the tidal fresh region traps about 40% of the sediment input from the watershed. Sediment input scales with the river discharge cubed, while seaward transport in the tidal river scales linearly, so the tidal river accumulates sediment during the highest discharge events. Sediment pulses associated with discharge events dissipate moving seaward and lag the advection speed of the river by a factor of 1.5 to 3. Idealized model simulations with a range of discharge and settling velocity were used to evaluate the trapping efficiency, transport rate, and mean age of sediment input from the watershed. The seaward transport of suspended sediment scales linearly with discharge but lags the river velocity by a factor that is linear with settling velocity. The lag factor is 30–40 times the settling velocity (mm s−1), so transport speeds vary by orders of magnitude from clay (0.01 mm s−1) to coarse silt (1 mm s−1). Deposition along the tidal river depends strongly on settling velocity, and a simple advection‐reaction equation represents the loss due to settling on depositional shoals. The long‐term discharge record is used to represent statistically the distribution of transport times, and time scales for settling velocities of 0.1 mm s−1 and 1 mm s−1 range from several months to several years for transport through the tidal river and several years to several decades through the estuary.

Observations of Coherent Flow Structures Over Subaqueous High‐ and Low‐ Angle Dunes

AbstractLarge‐scale coherent flow structures (CFSs) above dunes are the dominant source of flow resistance and constitute the principal mechanism for sediment transport and mixing in sand bed river and estuarine systems. Based on laboratory observations, CFS formation has been previously linked to flow separation downstream of high‐angle dunes with lee slopes of ~30°. How CFSs form in natural, deep rivers and estuaries where dunes exhibit lower lee slopes and intermittent flow separation is not well understood. Here we present particle image velocimetry measurements from an experiment where dune lee slope was systematically varied (30°, 20°, and 10°), while other geometric and hydraulic parameters were held constant. We show that CFSs form downstream of all three dune geometries from shear layer vortices in the dune lee. The mode of CFS formation undergoes a low‐frequency oscillation with periods of intense vortex shedding interspersed with periods of rare vortex shedding. Streamwise alignment of several vortices during periods of intense shedding results in wedge‐shaped CFSs that are advected above the dune stoss side. Streamwise length scales of wedge‐shaped CFS correspond to large‐scale motions (LSMs). We hypothesize that the advection of LSM over the dune crest triggers the periods of intense shedding in the dune lee. LSMs are weaker and smaller above low‐angle dunes; however, the low‐frequency oscillation in CFS formation periods persists. The formation of smaller and weaker CFS results in a reduction of flow resistance over low‐angle dunes.

Monitoring bedload sediment transport in a pre-Alpine river: an experimental method

Sediment transport in Alpine and pre-Alpine zones is an essential part of the broad field encompassing hydro-geological instabilities, with particular significance during high intensity rainfall events. This study describes an experimental method for the characterization of the dynamics of this phenomenon at a small spatial and temporal resolution. A set of Radio Frequency IDentificator (RFID) equipped pebbles has been tracked for a period of 6 months and their propagation along the stream has been recorded after each rainfall event. A descriptive database has been devised in order to explore the mobility of the single grains with respect to their geometrical characteristics, their mass as well as the influence of the precipitation intensity on the monitored river reach. Preliminary results indicate the strong correlation of sediment mobility to river discharge and suggest the influence of initial position in terms of morphological characteristics on the sediment mobility.

Re-evaluating black carbon in the Himalayas and the Tibetan Plateau: concentrations and deposition

Abstract. Black carbon (BC) is the second most important warming component in the atmosphere after CO2. The BC in the Himalayas and the Tibetan Plateau (HTP) has influenced the Indian monsoon and accelerated the retreat of glaciers, resulting in serious consequences for billions of Asian residents. Although a number of related studies have been conducted in this region, the BC concentrations and deposition rates remain poorly constrained. Because of the presence of arid environments and the potential influence of carbonates in mineral dust (MD), the reported BC concentrations in the HTP are overestimated. In addition, large discrepancies have been reported among the BC deposition derived from lake cores, ice cores, snow pits and models. Therefore, the actual BC concentration and deposition values in this sensitive region must be determined. A comparison between the BC concentrations in acid (HCl)-treated and untreated total suspected particle samples from the HTP showed that the BC concentrations previously reported for the Nam Co station (central part of the HTP) and the Everest station (northern slope of the central Himalayas) were overestimated by approximately 52 ± 35 and 39 ± 24 %, respectively, because of the influence of carbonates in MD. Additionally, the organic carbon (OC) levels were overestimated by approximately 22 ± 10 and 22 ± 12 % for the same reason. Based on previously reported values from the study region, we propose that the actual BC concentrations at the Nam Co and Everest stations are 61 and 154 ng m−3, respectively. Furthermore, a comprehensive comparison of the BC deposition rates obtained via different methods indicated that the deposition of BC in HTP lake cores was mainly related to river sediment transport from the lake basin as a result of climate change (e.g., increases in temperature and precipitation) and that relatively little BC deposition occurred via atmospheric deposition. Therefore, previously reported BC deposition rates from lake cores overestimated the atmospheric deposition of BC in the HTP. Correspondingly, BC deposition derived from snow pits and ice cores agreed well with that derived from models, implying that the BC depositions of these two methods reflect the actual values in the HTP. Therefore, based on reported values from snow pits and ice cores, we propose that the BC deposition in the HTP is 17. 9 ± 5. 3 mg m−2 a−1, with higher and lower values appearing along the fringes and central areas of the HTP, respectively. These adjusted BC concentrations and deposition values in the HTP are critical for performing accurate evaluations of other BC factors, such as atmospheric distribution, radiative forcing and chemical transport in the HTP.

The impact of extreme El Ni\xf1o events on modern sediment transport along the western Peruvian Andes (1968\u20132012)

Climate change is considered as one of the main factors controlling sediment fluxes in mountain belts. However, the effect of El Niño, which represents the primary cause of inter-annual climate variability in the South Pacific, on river erosion and sediment transport in the Western Andes remains unclear. Using an unpublished dataset of Suspended Sediment Yield (SSY) in Peru (1968–2012), we show that the annual SSY increases by 3–60 times during Extreme El Niño Events (EENE) compared to normal years. During EENE, 82% to 97% of the annual SSY occurs from January to April. We explain this effect by a sharp increase in river water discharge due to high precipitation rates and transport capacity during EENE. Indeed, sediments accumulate in the mountain and piedmont areas during dry normal years, and are then rapidly mobilized during EENE years. The effect of EENE on SSY depends on the topography, as it is maximum for catchments located in the North of Peru (3–7°S), exhibiting a concave up hypsometric curve, and minimum for catchments in the South (7–18°S), with a concave down hypsometric curve. These findings highlight how the sediment transport of different topographies can respond in very different ways to large climate variability.

INTEGRATED COASTAL PROCESS MODELING AND IMPACT ASSESSMENT OF FLOATING AND SEDIMENTATION IN COASTS AND ESTUARIES

In this study, an integrated coastal process model was applied to assess impact of coastal flooding and sedimentation in an estuary in Taiwan and to evaluate performance of proposed engineering plans for flood prevention and sedimentation management. This in-situ validated model was used to simulate and predict hydrodynamic processes and morphological changes induced by multiple hydrological forcing such as river flood flows, waves, tides, and storms surges from rivers to the estuary and its adjacent coasts. Simulation results quantified coastal flooding risks, erosions, sedimentation, and channel refilling. Predicted dynamic responses to typhoons and monsoons were utilized for identifying the most effective engineering plan to reshape the geometry of the estuary. After the selected engineering plan was accomplished, this model was applied again to further predict morphological changes in the newly-developed estuary. This paper demonstrates effectiveness of a simulation-based coastal and estuary planning approach to manage flood and sedimentation driven by complex physical processes from river flows, waves, tides, and sediment transport.

Use of reservoir deposits to reconstruct the recent changes in sediment yields from a small granite catchment in the Yimeng Mountain region, China

Information on recent changes in sediment yields from small catchments provides a better understanding of temporal trends in soil loss from certain physical and human-influenced landscapes that have been subjected to recent environmental changes, and will help bridge the current knowledge gap that exists between hillslope erosion and sediment transport in rivers. The Yimeng Mountain region, characterized by alternating granite and limestone, is one of the most susceptible regions to soil erosion in northern China, and has been subjected to intensive anthropogenic activity in recent years. Soil loss from areas underlain by granite is particularly obvious, and is the main sediment source for the Yihe River. In this study, we used reservoir deposits to estimate the changes in sediment yields over the past ~50years from a small catchment underlain by granite, namely the Jiangzhuang catchment in the Yimeng Mountain region. Three cores were collected from the Jiangzhuang Reservoir in the catchment. The activities of 137Cs and 210Pbex at different depths, clay (grain size <5μm) contents, and sedimentary organic carbon (SOC) contents in the cores were analysed with reference to human activity and environmental change in the catchment. The chronologies of the cores were established by 137Cs and 210Pbex dating. The area-specific sediment yield (SSY) for different time periods since dam construction was estimated from each core by referring to the original capacity curve of the reservoir. The results indicate that the depth profiles of 137Cs, 210Pbex, clay, and SOC contents in cores from the Jiangzhuang Reservoir reflect the general history of human disturbances on the catchment over the past ~50years. The estimated SSY value from each core for each period ranged from 7.2±2.7 to 23.7±8.3tha−1y−1, with a mean of 12.5±4.6tha−1y−1. SSY decreased during 1954–1972, and then showed a general tendency to increase. The temporal pattern of the sediment yield largely reflects the history of environmental change influenced by human activity in the catchment.