Suspended Sediment Data Research Articles

Yangtze River-derived sediments in the southwestern South Yellow Sea: Provenance discrimination and seasonal transport mechanisms

The southwestern South Yellow Sea (SYS) is influenced by tremendous sediment loads derived from the Yellow River (Huanghe) and the Yangtze River (Changjiang). However, the influence of Yangtze River sediments and their transport mechanism in this area remain unresolved. In this study, we present the grain size, clay minerals, and elemental compositions of surface sediments from the southwestern SYS, together with an analysis of field observation seawater salinity and suspended sediment data, to investigate the provenance and transport mechanism of the sediments. Discrimination diagrams of clay minerals, Cr/Th vs. Sc/Al, and rare earth elements (REEs) indicate that the southwestern SYS sediments are mainly derived from the old Yellow River subaqueous delta and the Yangtze River. Interestingly, Yangtze sediments enter the SYS in ways that differ seasonally. In summer, Yangtze sediments may be transported into the central SYS by the dispersion of Changjiang Diluted Water (CDW) and may also be transported northwestward by the Subei Coastal Current (SCC) to the area off the Jiangsu coast. In winter, the Yangtze-derived sediments deposited off the Jiangsu coast in summer are transported into the central and/or even north SYS under the combined effects of the SCC, Yellow Sea Coastal Current (YSCC), and Yellow Sea Warm Current (YSWC). Throughout the transport processes, there is an alternation between a source and sink of Yangtze sediments off the Jiangsu coast; the coast serves as a sink of Yangtze sediments in summer but as a source of SYS sedimentation in winter. The depositional and transport mechanisms of Yangtze-derived sediments are closely associated with seasonal variations in the circulation system of the SYS.

Pembuatan Model Kendali Mutu Data Sedimen

Special treatment for watershed management was needed due to severe of watershed condition in most regions in Indonesia. The treatment should be directed to comprehensive changes of management paradigm for all aspects in it. Those were indicated by the increasing of disasters around the watershed, such as floods, droughts, landslides, erosion and increased of sediment transported by the river basin. The increasing of sedimentation which occurs in the river flow will disrupt the performance of existing hydraulic structure in the river. The event could be monitored by hydrological data, especially with the continuously and accurately of discharge and sediment data. In order to solve the problem, sediment data quality control model was needed. The purpose of this research is to determined suspended sediment data quality control model, in order to have continuous and quality guaranteed of sediment transport data. The scopes of this sediment data quality control were making criteria and sub, determining rank priority between criteria and sub, arranging scoring form, trial and error, finalization. The model consists of three main stages, there are measurement of discharge and taking sediment sample (QC1), drawing of sediment rating curve (QC2), and conversion of discharge data to sediment transport (QC3).

Sediment yield at southwest Ethiopia's forest frontier

AbstractDeforestation is one of the major factors affecting soil erosion in tropical regions but to what extent does the crop growth in deforested areas protect the land from erosion? We evaluated the effect of deforestation on suspended sediment yield at the scale of zero‐order catchments by contrasting five paired small forest and cropland catchments at Ethiopia's southwestern forest frontier. Suspended sediment samples were collected from nine San Dimas flumes and one V‐notch weir installed in catchments draining the natural forest and cropland, at different altitudes. The suspended sediment data were collected from June 8 to October 30, 2013 and 2014. The suspended sediment yield of both land‐use types was strongly correlated with the corresponding runoff discharge. The results show that the average seasonal suspended sediment yield from cropland (17.0 ± 7.6 Mg ha−1) is four times higher than from the paired forests (4.0 ± 1.9 Mg ha−1). High sediment yields from forests are related to livestock grazing, but forests still have an important role in the protection of the surface soil from erosion at southwest Ethiopia's forest frontier. Land management in southwestern Ethiopia's highlands will need a strong change in paradigm, in which the overall belief in the recently imported mahrasha ard plough is abandoned, oxen and other cattle decreased in number and kept in homesteads, the forests being protected from human and livestock interferences and the open farmlands turned into agroforestry. Such an approach is still possible as all required elements are available in the landscape.

Coupling hysteresis analysis with sediment and hydrological connectivity in three agricultural catchments in Navarre, Spain

Rain storm events mobilise large proportions of fine sediments in catchment systems. Sediments from agricultural catchments are often adsorbed by nutrients, heavy metals and other (in)organic pollutants that may impact downstream environments. To mitigate erosion, sediment transport and associated pollutant transport, it is crucial to know the origin of the sediment that is found in the drainage system, and therefore, it is important to understand catchment sediment dynamics throughout the continuity of runoff events. To assess the impact of the state of a catchment on the transport of fine suspended sediment to catchment outlets, an algorithm has been developed which classifies rain storm events into simple (clockwise, counter-clockwise) and compound (figure-of-eight; complex) events. This algorithm is the first tool that uses all available discharge and suspended sediment data and analyses these data automatically. A total of 797 runoff events from three experimental watersheds in Navarre (Spain) were analysed with the help of long-term, high-resolution discharge and sediment data that was collected between 2000 and 2014. Morphological complexity and in-stream vegetation structures acted as disconnecting landscape features which caused storage of sediment along the transport cascade. The occurrence of sediment storage along transport paths was therefore responsible for clockwise hysteresis due to the availability of in-stream sediment which could cause the “first flush” affect. Conversely, the catchment with steeper channel gradients and a lower stream density showed much more counter-clockwise hysteresis due to better downstream and lateral surface hydrological connectivity. In this research, hydrological connectivity is defined as the actual and potential transfer paths in a catchment. The classification of event SSC-Q hysteresis provided a seasonal benchmark value to which catchment managers can compare runoff events in order to understand the origin and locations of suspended sediment in the catchment. A new algorithm uses all available discharge and suspended sediment data to assess catchment sediment dynamics. From these analyses, the catchment connectivity can be assessed which is useful to develop catchment land management.

Impact of an Extreme Typhoon Event on Subsequent Sediment Discharges and Rainfall-Driven Landslides in Affected Mountainous Regions of Taiwan

Fluctuations in the sediment yielding rate within mountainous areas are found after extreme precipitations. These changes are associated with rainfall-driven landslides and can be evaluated through observations of sediment transported in river water. In this study, we assess the differential impact level and duration of an extreme rainfall event caused by the 2009 Typhoon Morakot in Taiwan. Using a time series of suspended sediment data and landslide inventories within three affected catchments, our results found that the proportion of the typhoon-generated sediment discharges reached 58% of the 2009 annual sediment discharges, and the annual sediment discharges could be 15-fold higher than the average annual sediment discharges prior to the typhoon. The impact of the typhoon on suspended sediment discharge lasted for around four months. It is further revealed that a significant increase in the number of landslides was attributed to the impact of the extreme typhoon event, and the critical rainfall condition triggering landslides, based on the relationship between rainfall and landslide number and the rainfall intensity-duration thresholds, declined for 4–5 years.

Estimation of Sediment Deposition at Nausehri Reservoir by Using Multiple Linear Regression and Assessment of its Effect on Hydropower Generation Capacity

This article presents investigation of the inflow of sediments depending upon the stream flow, density and kinematic viscosity of water. The process involves Multiple Linear Regression (MLR) technique for estimation of sediment load and volume, by using UNISTAT software (Version 5.6). A general equation is developed for a specific flow rate while considering density and kinematic viscosity of water as other parameters. The developed equation can be applied in future for determining the sediment concentration when the flow rate is known. The daily stream flow and suspended sediment data belonging to the station Nausehri operated by the Water and Power Development Authority, Pakistan is used as case study. The results indicate that the dam site experiences a mean annual sediment load of 3.74mst. With this much incoming sediment load the reservoir life comes out to be 45 years when no flushing is done. The impact of this sediment deposition on hydro-electric energy generation is also determined, which shows a decrease of 113MW (12%) in the production capacity of the power plant over the life of the reservoir.

Dinamika Proses Sedimentasi di Perairan Muara Sungai Riko, Teluk Balikpapan

<strong>Dynamics of Sedimentation Process at Riko River Estuary, Balikpapan Bay.</strong> Development of the marine facilities (i.e. port, workshops, laboratories, etc) for Indonesian Research Vessels and National Center for Marine Research in the proposed National Science Technopark (NSTP) Maritime Region at District of Penajam Paser Utara, East Kalimantan Province, needs to understanding the dynamic of waters physical environment. Due to the NSTP-Maritime region located at Riko River as part of Balikpapan Bay waters, it needs an ocean interaction study between open sea (Balikpapan Bay) and Riko River waters. This study used a 2D-Hydrodynamic Model for Riko River and Balikpapan Bay waters and adjacent sea. The model simulated the hydrodynamic conditions on the waters and furthermore predicted the mud transport in September - November 2016 using the river flow and total suspended sediment data collected in November 2016. The model results showed that the average of sediment load movement due to the dynamic of waters at the estuary is ± 4,25 x10-3 kg per second or ± 367,7 kg per day. This preliminary study hopefully can explain the shallowing processes in mouth of Riko River.

Evaluation of neuro-fuzzy and Bayesian techniques in estimating suspended sediment loads

Sediment is considered the largest surface water pollutant by volume, which is crucial for surface water planning and management. Different management scenario evaluations require multiple in-stream suspended sediment forecasts and estimations. Physically-based models are considered to be good modeling techniques for suspended sediment estimation; nevertheless, they require a large number of parameters and intensive calculations. This study aims to enhance suspended sediment predicting techniques using efficient fusion modeling that can be used for evaluations by watershed managers and stakeholders. Adaptive neuro-fuzzy inference system (ANFIS) and Bayesian regression models were tested to find the best alternative to a calibrated and validated Soil and Water Assessment Tool (SWAT) model to predict suspended sediment loads in the Saginaw River watershed. For both methods, four different method-types were tested, namely General, Temporal, Spatial and Spatiotemporal. Results of the study showed that both methods can be used as good alternatives to the SWAT model at the global level for watershed estimations. The best suspended sediment replicating models, the Bayesian Spatiotemporal and ANFIS Spatial, produced results with Nash–Sutcliffe model efficiency values of 0.95 and 0.94, respectively. For the subbasin level, Bayesian and ANFIS techniques showed satisfactory results for 84 and 77 subbasins, respectively, out of 155 subbasins in the watershed. Box-Cox transformation of suspended sediment load values, made the use of the Bayesian model feasible and improved the prediction of the ANFIS models. However, suspended sediment data exhibited a bimodal distribution after transformation, making the modeling process challenging and complex.

Derivation of suspended sediment data for Al-Adhiam watershed-Iraq using artificial neural network model

The mean part of river sediments is suspended sediment load, its prediction and simulation has important significance to manage the water resources and environments. In Iraq, most researchers avoid to fighting in sediment researches when related with hydrological models spatially with that need enough observed sediment data for calibration and validation because the sediment data very limitation or scars. The aim of this study is employing the Artificial Neural Network (ANN) model to estimate the suspended sediment load of Al-Adhaim watershed in Iraq from available measured sediment data, identify the suitable pattern of input and target data sampling and obtaining the best nonlinear equation between the river discharge and suspended sediment load. To this end, the ANN model was training and tested with the available sediment data, which was for water year (1983-1984). Two modes were applied for input and target data sampling each mode has two cases, where in the first mode the time series data sampling was used with flow as an input for case one while flow and average precipitation in case two with used suspended sediment as a target variable. For second mode the supervise data sampling was used with the same input and target division in first mode. The performance of the model was evaluated by using Coefficient of determination (R2) and the Nash- Sutcliffe efficiency (NS) and standardization of root mean square error (RSR), the statistical analysis model testing for Al-Adhiam watershed showed satisfactory agreement between observed and estimated daily values for Mode2- Case2. R2, NS and RSR of the testing period were 0.99 and 0.8and 0.2 respectively. The result shows that the conducted ANN model can be used with the best net as a predictor for sediment yield in this watershed. The model was used to predict daily sediment load data for period from 1Oct. 1984 to 31Spt 1985. The predicted daily sediment data was plotted against daily measured flow. The correlation between predicted sediment and measured flow was in good agreement with R2 =0.89 and the best relation was polynomial equation from second degree.

Study on Sediment Regime Changes in Downstream of the Ba River, Vietnam under the Impact of Reservoirs System

Reservoirs system in upstream of Ba River has been affecting to the hydrology and sediment regime at the downstream. Sediment imbalance causes consequences such as erosion at river bank, lack of sediment supply to downstream areas and deposition/erosion in estuaries. This study focused on a quantitative assessment of the impact of Ba Ha reservoir and Song Hinh reservoir on sediment regime at the Cung Son hydrological station (12 km downstream of Ba Ha reservoir and 45 km from the mouth of the Da Dien river). Research used analytical and statistical methods with flow and suspended sediment data measured at the Cung Son hydrological station from 1977 to 2016. The results show that the system of these two reservoirs has a huge impact to the sedimentation regime, especially after the operation of Ba Ha reservoir. The average amount of sediment in the period before and after 2008 significantly reduced from about 2.5 million to about 1 million tons per year.

Investigating the extrapolation performance of neural network models in suspended sediment data

ABSTRACTSuspended sediment modelling is a quite significant issue in hydrology. The prediction of suspended sediment has taken the attention of several scientists in water resources. With extrapolation, the forecasting ability of the employed forecasting model beyond the calibration range is investigated. In the present study, different smoothing parameters are used to differentiate the kurtosis of the local critical points (local minima and maxima). The two models used are an artificial neural network (ANN) model and a multiple linear regression (MLR) model for prediction in order to examine the model extrapolation ability. The ANN model provides closer estimations to the observed peaks, being higher than the corresponding MLR ones. For the local minima, the ANN predictions are higher than the MLR predictions. As there are limited local points, all the remaining ANN predictions are lower than the MLR ones except for one point.

A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme

The Madeira River is the second largest tributary of the Amazon River. It contributes approximately 13% of the Amazon River flow and it may contribute up to 50% of its sediment discharge to the Atlantic Ocean. Until now, the suspended sediment load of the Madeira River was not well known and was estimated in a broad range from 240 to 715Mtyr−1. Since 2002, the HYBAM international network developed a new monitoring programme specially designed to provide more reliable data than in previous intents. It is based on the continuous monitoring of a set of 11 gauging stations in the Madeira River watershed from the Andes piedmont to the confluence with the Amazon River, and discrete sampling of the suspended sediment concentration every 7 or 10days. This paper presents the results of the suspended sediment data obtained in the Madeira drainage basin during 2002–2011. The Madeira River suspended sediment load is estimated at 430Mtyr−1 near its confluence with the Amazon River. The average production of the Madeira River Andean catchment is estimated at 640Mtyr−1 (±30%), the corresponding sediment yield for the Andes is estimated at 3000tkm−2yr−1 (±30%), and the average denudation rate is estimated at 1.20mmyr−1 (±30%). Contrary to previous results that had mentioned high sedimentation rates in the Beni River floodplain, we detected no measurable sedimentation process in this part of the basin. On the Mamoré River basin, we observed heavy sediment deposition of approximately 210Mtyr−1 that seem to confirm previous studies. But while these studies mentioned heavy sedimentation in the floodplain, we showed that sediment deposition occurred mainly in the Andean piedmont and immediate foreland in rivers (Parapeti, Grande, Pirai, Yapacani, Chimoré, Chaparé, Secure, Maniqui) with discharges that are not sufficiently large to transport their sediment load downstream in the lowlands.

Spatio-temporal monitoring of suspended sediments in the Solimões River (2000–2014)

The Amazon River sediment discharge has been estimated at between 600 and 1200Mt/year, of which more than 50% comes from the Solimões River. Because of the area's inaccessibility, few studies have examined the sediment discharge spatial and temporal pattern in the upper Solimões region. In this study, we use MODIS satellite images to retrieve and understand the spatial and temporal behaviour of suspended sediments in the Solimões River from Peru to Brazil. Six virtual suspended sediment gauging stations were created along the Solimões River on a 2050-km-long transect. At each station, field-derived river discharge estimates were available and field-sampling trips were conducted for validation of remote-sensing estimates during different periods of the annual hydrological cycle between 2007 and 2014. At two stations, 10-day surface suspended sediment data were available from the SO-HYBAM monitoring program (881 field SSS samples). MODIS-derived sediment discharge closely matched the field observations, showing a relative RMSE value of 27.3% (0.48Mtday) overall. Satellite-retrieved annual sediment discharge at the Tamshiyacu (Peru) and Manacapuru (Brazil) stations is estimated at 521 and 825Mt/year, respectively. While upstream the river presents one main sediment discharge peak during the hydrological cycle, a secondary sediment discharge peak is detected downstream during the declining water levels, which is induced by sediment resuspension from the floodplain, causing a 72% increase on average from June to September.

Reintroduced large wood modifies fine sediment transport and storage in a lowland river channel

AbstractThis paper explores changes in suspended sediment transport and fine sediment storage at the reach and patch scale associated with the reintroduction of partial large wood (LW) jams in an artificially over‐widened lowland river. The field site incorporates two adjacent reaches: a downstream section where LW jams were reintroduced in 2010 and a reach immediately upstream where no LW was introduced. LW pieces were organized into ‘partial’ jams incorporating several ‘key pieces’ which were later colonized by substantial stands of aquatic and wetland plants. Reach‐scale suspended sediment transport was investigated using arrays of time‐integrated suspended sediment samplers. Patch‐scale suspended sediment transport was explored experimentally using turbidity sensors to track the magnitude and velocity of artificially generated sediment plumes. Fine sediment storage was quantified at both reach and patch scales by repeat surveys of fine sediment depth. The results show that partial LW jams influence fine sediment dynamics at both the patch and reach scale. At the patch‐scale, introduction of LW led to a reduction in the concentration and increase in the time lag of released sediment plumes within the LW, indicating increased diffusion of plumes. This contrasted with higher concentrations and lower time lags in areas adjacent to the LW; indicating more effective advection processes. This led to increased fine sediment storage within the LW compared with areas adjacent to the LW. At the reach‐scale there was a greater increase in fine sediment storage through time within the restored reach relative to the unrestored reach, although the changes in sediment transport responsible for this were not evident from time‐integrated suspended sediment data. The results of the study have been used to develop a conceptual model which may inform restoration design. Copyright © 2017 John Wiley & Sons, Ltd.

Analysis of Wave and Current in Anmok Coastal Waters

In this study, waves and currents observed by acoustic AWAC, VECTOR and Aquadopp Profiler in Anmok coastal waters were analysed to account for the variability of wave and current and to understand the mechanism of sediment transport generated by wave-induced current in the surf-zone. The monthly variation of wave and residual currents were analysed and processed with long-term observed AWAC data at station W1, located at the water depth of about 18m measured during from February 2015 to September 2016. Wave-induced currents were also analysed with intensive field measurements such as wave, current, suspended sediment, and bathymetry data observed at the surf-zone during in winter and summer. The statistical result of wave data shows that high waves coming from NNE and NE in winter (DEC-FEB) are dominant due to strong winds from NE. But in the other season waves coming from NE and ENE are prevalent due to the seasonal winds from E and SE. The residual currents with southeastern direction parallel to the shoreline are dominant throughout a year except in winter showing in opposite direction. The speed of ebb-dominant southeastern residual currents decreasing from surface to the bottom is strong in summer and fall but weak in winter and spring. By analysing wave-induced current, we found that cross-shore current were generated by swell waves mainly in winter with incoming wave direction about 45° normal to the shoreline. Depending on the direction of incoming waves, longshore currents in the surf-zone were separated to southeastern and northwestern flows in winter and summer respectively. The variation of observed currents near crescentic bars in the surf-zone shows different direction of longshore and cross-shore currents depending on incoming waves implying to the reason of beach erosion generating the beach cusp and sandbar migration during high waves at Anmok.

A New Approach for Modeling Sediment-Discharge Relationship: Local Weighted Linear Regression

Accurate estimation of suspended sediment is important for water resources projects. The accuracy of local weighted linear regression (LWLR) technique is investigated in this study for modeling streamflow-suspended sediment relationship. Daily data from two stations on the Eel River in California were used in the applications. In the first part of the study, the LWLR results were compared with those of the least square support vector machine (LSSVM), artificial neural networks (ANNs) and sediment rating curve (SRC) for modeling sediment data of upstream and downstream stations, separately. Root mean square errors (RMSE), mean absolute errors (MAE) and determination coefficient (R2) statistics were used for comparison of the applied models Comparison results indicated that the LWLR model performed better than the LSSVM, ANN and SRC models. Accuracies of the sediment modeling increased by the LWLR model compared with the LSSVM model: 14 % (60 %) and 33 % (42 %) decrease in the RMSE (MAE) values for the upstream and downstream stations, respectively. The second part of the study focused on the comparison of the models in estimating downstream suspended sediment data by using data from both stations. LWLR was found to be better than the LSSVM, ANN and SRC models. The RMSE accuracy of the LSSVM model was increased by 39 % using the LWLR model.

Reducing Sediment Connectivity Through man‐Made and Natural Sediment Sinks in the Minizr Catchment, Northwest Ethiopia

AbstractMan‐made and natural sediment sinks provide a practical means for reducing downstream reservoir sedimentation by decreasing soil erosion and enhancing the rate of sedimentation within a catchment. The Minizr catchment (20 km2) in the northwest Ethiopian highlands contains numerous man‐made soil and water conservation (SWC) structures such as soil bunds (Erken), fanya juu ridge (Cab) and micro‐trenches and natural sediment sinks such as wetlands, floodplains and grassed waterways. These sediment sinks reduce downstream sedimentation into the Koga reservoir, located at the catchment outlet, however, a large quantity of sediment is still reaching the reservoir. This study evaluates the function and effectiveness of both man‐made SWC structures and natural sediment sinks in reducing sediment export from the Minizr catchment. SWC structures and natural sediment sinks were digitized using Google Earth Imagery. Sediment pins and vertical sampling through the deposit were used to quantify the amount of deposited sediment. In addition, inflow and outflow of suspended sediment data were used to calculate the sediment‐trapping efficacies (STE) of man‐made SWC structures (soil bunds and fanya juu ridges) and natural sediment sinks. Results reveal that 144 km soil bunds and fanya juu ridges trapped 7,920 Mg y−1 (55 kg m−1 y−1) and micro‐trenches trapped 13·26 Mg y−1, each micro‐trench on average trapped 23 kg y−1. The 17 ha floodplain located in the centre of the catchment trapped 9,970 Mg y−1 (59 kg m−2 y−1), while a wetland with a surface area of 24 ha, located near the outlet of the catchment, trapped 8,715 Mg y−1 (36 kg m−2 y−1). The STEs of soil bunds and fanya juu ridges, wetlands and floodplains were 54%, 85% and 77%, respectively. Substantial differences were observed between the STE of grassed and un‐grassed waterways at 75% and 21%, respectively. Existing man‐made and natural sediment sinks played an important role in trapping sediment, with 38% (26,600 Mg y−1) of transported sediment being trapped, while 62% (43,000 Mg y−1) is exported from the catchment and thus enters the Koga reservoir. Therefore, additional catchment treatment measures are required as an integrated catchment scale sediment trapping approach to help reduce sediment loads entering Koga reservoir. Moreover, to maximize the effectiveness of sediment trapping measures, avoid structural failure and ensure their sustainability, regular maintenance is needed. Copyright © 2016 John Wiley & Sons, Ltd.

Reduced fine sediment flux and channel change in response to the managed diversion of an upland river channel

Abstract. This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment (< 2 mm) in Glaisdale Beck, a small, predominantly upland catchment in the UK. Hydro-meteorological and suspended sediment data sets are collected over a 2-year period spanning pre- and post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterized by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L−1 prior to mitigation, to 74.36 mg L−1 following the diversion. A Mann–Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median suspended sediment concentrations (SSCs). Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Loga and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilizes. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in headwater streams but the full value of this may take many years to achieve whilst the fluvial system slowly readjusts.

Monitoring stream sediment loads in response to agriculture in Prince Edward Island, Canada.

Increased agricultural land use leads to accelerated erosion and deposition of fine sediment in surface water. Monitoring of suspended sediment yields has proven challenging due to the spatial and temporal variability of sediment loading. Reliable sediment yield calculations depend on accurate monitoring of these highly episodic sediment loading events. This study aims to quantify precipitation-induced loading of suspended sediments on Prince Edward Island, Canada. Turbidity is considered to be a reasonably accurate proxy for suspended sediment data. In this study, turbidity was used to monitor suspended sediment concentration (SSC) and was measured for 2years (December 2012-2014) in three subwatersheds with varying degrees of agricultural land use ranging from 10 to 69%. Comparison of three turbidity meter calibration methods, two using suspended streambed sediment and one using automated sampling during rainfall events, revealed that the use of SSC samples constructed from streambed sediment was not an accurate replacement for water column sampling during rainfall events for calibration. Different particle size distributions in the three rivers produced significant impacts on the calibration methods demonstrating the need for river-specific calibration. Rainfall-induced sediment loading was significantly greater in the most agriculturally impacted site only when the load per rainfall event was corrected for runoff volume (total flow minus baseflow), flow increase intensity (the slope between the start of a runoff event and the peak of the hydrograph), and season. Monitoring turbidity, in combination with sediment modeling, may offer the best option for management purposes.

Qualities and Limitations of Fluvial Suspended Sediment Data Published by the United States Geological Survey

ABSTRACT Sommerfield, C.K., 2016. Qualities and limitations of fluvial suspended sediment data published by the United States Geological Survey. Fluvial suspended sediment concentration (SSC) data published by the United States Geological Survey (USGS) are frequently used to address questions of sediment delivery to estuaries and coasts. Despite the availability of USGS reports detailing methods of sample collection and data processing, many end users remain misinformed about the characteristics and limitations of these data. Two types of USGS-SSC data are available for stream gauging stations: (1) discrete samples and (2) daily record. Discrete samples are laboratory measurements of SSC from water collected at a stream gauging station. In contrast, daily-record data are interpolations of SSC from a smaller number of discrete samples available for a station. A potential source of confusion arises because both types of USGS-SSC data are given the identical description (suspended sediment concentration, mg/...