Identification Of Sediment Sources Research Articles

Suspended sediment characterization and tracing using a magnetic fingerprinting technique: Bassenthwaite Lake, Cumbria, UK

Robust identification of catchment suspended sediment sources is a prerequisite both for understanding sediment delivery processes and targeting of effective mitigation measures. Fine sediment delivery can pose universal management problems, especially with regard to nutrient run-off and lake siltation. Here, 19 suspended sediment samplers were located within the three main tributary inflows to Lake Bassenthwaite, a key but vulnerable site of special scientific interest, with water quality problems linked to accelerated delivery of fine sediment. Magnetic properties of contemporary suspended sediments, collected on a monthly basis, were measured on a particle size-specific basis and compared with the lake sediment core-tops. Ferrimagnetic grain size and magnetic `hardness' vary significantly between the suspended sediments collected from the different tributaries, with the 8—31 µm and 31—63 µm clastic grain fractions displaying greatest magnetic contrasts. Postdepositional formation of bacterial magnetosomes is evident in the 2—8 µm and < 2 µm fractions of the lake sediments. Thus, for comparison with the potential source suspended sediments, we use only the detrital, clastic fractions, 8—31 µm and 31—63 µm. The lake sediment magnetic properties show little spatial variation, indicating through-lake transport of sediment (no evidence was found of postdepositional diagenetic sulphide formation). Magnetic comparisons between the potential sources and the lake surface sediments indicate that Newlands Beck, providing only ~ 10% of the lake's hydraulic load, is the main contributor of sediment to the deep basin of the lake. Sediments from the River Derwent subcatchment, contributing ~ 80% of the hydraulic load, are possibly stored either on the floodplain or in shallower areas of the lake.

Combining a spatial model with geochemical tracers and river station data to construct a catchment sediment budget

Information about diffuse pollutant sources in river catchments and the processes responsible for their generation is often obtained using geochemical tracing, in‐stream monitoring, or process based modeling. Yet these methods are rarely combined. In this study, we combine these three methods to produce a catchment sediment budget for the Lake Burragorang catchment in Australia. The physically based process model SedNet was modified using local catchment data to constrain predicted hillslope erosion rates in forested areas, the rate and texture of sediment supply from gully erosion, and the predicted floodplain deposition rates. The model's capacity to match the geochemical tracer (both spatial source and erosion process) data and gauging station load data improved markedly. Hillslope erosion, primarily in the steeper, mainly forested areas near the reservoir, is identified by the model as the main source of sediment delivered to Lake Burragorang. The contribution from gully and river bank erosion is comparatively small, though gully erosion can be locally dominant. This result is consistent with the tracer data. Utilizing multiple independent data sets allows for a more rigorous evaluation of model performance and, it is argued, increases the likelihood that the model is correctly representing the main components of the catchment's sediment budget. The identification of diffuse sediment sources in other catchments can clearly benefit from combining a range of observational data with a structured model evaluation process.

Fitzroy River Basin, Queensland, Australia. IV. Identification of flood sediment sources in the Fitzroy River

Environmental context. During flood events, the Fitzroy River is a major contributor to the loads of suspended sediment and nutrients to the southern Great Barrier Reef. The present geochemical and modelling study provides for the first time a quantitative estimate of the temporal variation in sediment sources over an entire flood hydrograph. Basaltic soils are substantially enriched in this flood event relative to their catchment abundance. Abstract. Suspended sediment collected over a complete flood hydrograph in the Fitzroy River provided an insight into the origin and transport of sediment in this system. Strong temporal trends are evident in the proportions of catchment soil types estimated using a Bayesian mixing model in the fine (<10 μm) fraction of the suspended sediment. These temporal trends were also manifested in changes in mineralogy, major and trace element and Nd–Sr and C–N isotope geochemistry. Tertiary Basaltic soils were the most abundant catchment soil type transported in the flood event studied here, constituting 39% of the <10-μm sediment fraction, but varied between an estimated 20 and 50% of the suspended solids over the course of the flood event. The techniques used here allow quantification and comparison between flow and suspended sediment sources and are widely applicable to other river systems.

Identification of sediment sources to Lake Wivenhoe, south-east Queensland, Australia

Effective management of sediment fluxes in aquatic systems involves, in part, the identification of catchment sediment sources. Lake Wivenhoe (LW), the largest water storage in south-east Queensland, serves two important roles: it supplies 80% of the drinking water to the region and acts as a major flood mitigation feature for the city of Brisbane. Highly developed subcatchments in LW have resulted in declining waterway health, with sediment movement from the catchment to LW of major concern. Although there is considerable hydrological information, only limited data exist on sediment and nutrient fluxes. A detailed lake sediment (128 samples) and reconnaissance catchment soil sampling program (89 samples) was undertaken. Geochemical, Nd–Sr isotopic and statistical analyses were used to identify major sources of sediment to LW. A purpose-built Bayesian mixing model was then used to quantitatively estimate the proportion of sediment from major catchment sources. Approximately 36% of the LW catchment delivers the majority of sediment; enrichment factors for the three major sediment sources (dam to catchment ratio) range from ~2 to 5. The Esk Formation is the major sediment source comprising ~10% of catchment area but contributing 50% of the sediment and 33% of the total phosphorus delivered to LW.

Fitzroy River Basin, Queensland, Australia. I. Identification of Sediment Sources in Impoundments and Flood Events

Environmental Context. The Fitzroy River Basin is a major contributor to the loads of suspended sediment and nutrients reaching coastal areas in the southern Great Barrier Reef. Cost-effective investment in improved land, vegetation, and water management to lower these loads requires an understanding of the sources and movement of sediments within the basin. This multidisciplinary geochemical and modelling study provides for the first time a quantitative estimate of sediment sources and spatial and hydrology-related variation within the Fitzroy River Basin. Abstract. An integrated geochemical, modelling, and reconnaissance soil sampling approach has been used to identify the sources of sediment in the Fitzroy River Basin (FRB). The composition of sediment in weirs and dams within the FRB indicate that in the southern and central FRB the Dawson River contributes only a small basaltic component and the inputs are dominated by soils from the Surat and Bowen Basins. Rivers from the central FRB carry variable amounts of basaltic soils. In contrast, basaltic soils constitute the majority of sediment transported during flood events. Surat Basin soils form a minor component of flood events with little contribution from soils of the Bowen Basin despite it constituting the majority of the area of the central FRB. Soils from the Thomson Fold Belt constitute a substantial proportion of the sediment transported by, and retained in, impoundments in the central FRB and also dominate sediment delivered from the western FRB. This study will inform cost-effective investment by government to target remedial actions to reduce sediment and nutrient loads within the FRB that may be ultimately transported via the Fitzroy River Estuary to the southern Great Barrier Reef.

Sediment source identification by using137Cs and210Pb radionuclides in a small catchment of the Hilly Sichuan Basin, China

Double radionuclide tracers of137Cs and210Pb were used to investigate sediment sources in the Wujia Gully, a small catchment in the Hilly Sichuam Basin in 2002. Average137Cs and210Pb concentrations in the source soils of the steep forest slopes, gentle cultivated terraces and bare slopes were 7.15 ±0.40 and 162.01 ±3.86 Bq·kg-1, 4.01 ±0.31 and 70.96 ±2.65 Bq · kg-1, and 0 and 15.12 ±1.22 Bq · kg-1, respectively, while those concentrations in the recently deposited sediments in the reservoir were 3.06 ±0.23 and 72.66 ±1.61 Bq · kg-1, respectively. By using the mixing model, the relative sediment contributions from steep forest slopes, gentle cultivated terraces and bare slopes (including channel banks) were estimated to be 18%, 46% and 36%, respectively. Cultivated terraces and bare slopes (including channel banks) were the first and the second important sediment sources in catchment. Specific sediment yield in the catchment was 642 t · km-2 · a-1 from the deposited sediment volume in the reservoir since 1956. Soil erosion rates for the forest slopes and cultivated terraces, which accounted for 2/3 and 1/3 of the drainage area in the catchment, were estimated to be 173 and 886 t · km-2 · a-1, respectively.

Development and Application of a Methodology for Sediment Source Identification. I: Modified Unit Sedimentograph Approach

Identification of sediment source areas within a watershed is useful for designing appropriate management alternatives that reduce sediment losses. In most watersheds, data collection programs are present at the stream gauging station, and sediment source identification must be treated as an inverse problem. A physically based watershed-scale surface flow and erosion model, KINEROS was utilized as the modeling tool in this study. A modified unit sedimentograph approach was used for source identification based on hydrograph and sedimentograph data collected at the watershed outlet. Data from several events were examined over two small water- sheds, and a statistical procedure was employed to assess the erosion vulnerability of different regions in the two watersheds. These results were presented in the form of maps to obtain a spatial picture of potential sediment generating areas. A statistical analysis was also utilized to determine if erosion potentials of different regions of a watershed were significantly different. It appears that identification of source areas is possible when a limited number of regions are contributing sediments.

Development and Application of a Methodology for Sediment Source Identification. II: Optimization Approach

In this paper, we re-examine the question of identification of source areas using optimization methods for two Iowa water- sheds. The question of nonuniqueness is addressed first, with the result that only eight sediment contributing regions are allowed to be active simultaneously as in the companion study. Tukey's procedure is utilized to examine if the differences in erodibility of the different regions are statistically significant. Results were presented in the form of maps to obtain a spatial picture of the potential of sediment generating areas. Comparisons with physical characteristics of the watersheds showed good agreement between erosion potential and properties associated with erosion.

Sediment source identification by using 137Cs and 210Pb radionuclides in a small catchment of the Hilly�Sichuan Basin, China

Sediment source identification by using 137Cs and 210Pb radionuclides in a small catchment of the Hilly�Sichuan Basin, China

A review on the provenance discrimination of sediments in the Yellow Sea

The Yellow Sea has been extensively studied for the understanding of dispersal patterns and limits of sediments from neighboring countries including China and Korea. Although sedimentological, mineralogical, and geochemical approaches have been tried to solve the problems, especially including the identification of sediment sources in and around the Yellow Sea, the published results are not enough for understanding them. Suggestions on sediment origins, budgets, sediment accumulation rates, mineralogical, and geochemical compositions are not coincident to each other and sometimes even controversial; for example, conflicts on the distribution patterns of smectite and calcium carbonate, the provenance of the southeastern Yellow Sea mud and sedimentation rates in there, the ratios of V/Al and Mn/Al in Korea and China river sediments, the origin of Ba and Pb in sandy sediments of the northeastern Yellow Sea, and so on. Various geochemical indicators from the literature for the provenance discrimination in the Yellow Sea are reviewed here in depth, and corresponding discussions are described separately. Research topics for the future study, also, are suggested for the proper access to the understanding of the origin and dispersal patterns of the Yellow Sea sediments, especially focusing on the geochemical approaches.

Quantitative approach to sediment source identification by using magnetic diagnosis model

A sequential quantitative approach to sediment source ascription is presented based on mineral magnetic measurements. Rhode River catchment (USA) and Isabel Ⅱ reservoir catchment (Spain) were taken as the examples for developing the magnetic diagnosis model. The multi-parameter cluster analysis was used to classify the sediment source with respect to their magnetic properties, multi-variable mixing model to link magnetic measurement of mixtures with their source component proportions, and linear programming to determine the sediment source components. It has been shown by these two experiments that the magnetic diagnosis model is successful for the quantitative sediment source ascription. The results correspond well with the relative environmental change proxy.

Biological Effects of Fine Sediment in the Lotic Environment

/ Although sedimentation is a naturally occurring phenomenon inrivers, land-use changes have resulted in an increase in anthropogenicallyinduced fine sediment deposition. Poorly managed agricultural practices,mineral extraction, and construction can result in an increase in suspendedsolids and sedimentation in rivers and streams, leading to a decline inhabitat quality. The nature and origins of fine sediments in the loticenvironment are reviewed in relation to channel and nonchannel sources andthe impact of human activity. Fine sediment transport and deposition areoutlined in relation to variations in streamflow and particle sizecharacteristics. A holistic approach to the problems associated with finesediment is outlined to aid in the identification of sediment sources,transport, and deposition processes in the river catchment. The multiplecauses and deleterious impacts associated with fine sediments on riverinehabitats, primary producers, macroinvertebrates, and fisheries are identifiedand reviewed to provide river managers with a guide to source material. Therestoration of rivers with fine sediment problems are discussed in relationto a holistic management framework to aid in the planning and undertaking ofmitigation measures within both the river channel and surrounding catchmentarea.KEY WORDS: Sedimentation; Fine sediment; Holistic approach; Ecologicalimpact; River restoration

Identification of sediment sources by large-scale aerial photography taken from a monitoring blimp

Sediment sources in semi-arid subtropical environments cannot sufficiently be documented by conventional methods of remote sensing. Spatial resolution of satellite sensors as well as of conventional aerial photography does not correspond to the scale of geomorphodynamic processes. With a specially designed hot air blimp as a sensor platform, large scale aerial photographs can be obtained specifically aimed at the scientific demands (geometric and temporal resolution, normal colour or infrared small format film). The pictures are subsequently being transferred into digital format by electronic scanners in order to enable further processing by digital image processing systems. In a semi-arid region of the Ebro Basin, key processes of desertification are being investigated. Areas affected by sheet wash, rill erosion and stone pavements as well as patterns of vegetation distribution are differentiated using imagery acquired by this new method. The combination of these information levels provides insight into interactions of geomorphodynamics and vegetation succession on abandoned fields. Reduced infiltration capacity due to crusts leads to increased run-off and sheet erosion followed by the formation of rills and gullies which are the most important sources of suspended sediment.

Morphological characterization of channel initiation

The system of hillslopes and channels that form a drainage basin and shape its morphology and dynamics is the result of a complex interaction between climate and soil through erosion and sediment transport. The identification of sediment sources and pathways must therefore be carried out taking into account system genesis and dynamics. In this framework, drainage density assumes a major significance: it relates morphology to climate and soil properties and cannot be assumed constant throughout the basin. Empirical evidence and theoretical results are available to describe hydrodynamical and morphological conditions that are expected to hold at the boundary between hillslopes and streams. However, the variance of the physical processes and the low accuracy achievable in the estimation of the local slope value from available elevation data sets are limiting factors in the practical application of such concepts. These limiting factors can be removed by means of a global approach in which drainage density is linked to the relative elevation of the subcatchment draining to the site under consideration. Moreover, this can be viewed as a function of morphology through contributing area, local slope, and the fractal dimension of single rivers. The mathematical form that describes this function is equal, in structure, to that of the equations that describe the hydrodynamical and morphological conditions. This approach leads to a well connected and coherent network which is able to describe the boundary between hillslopes and channels and to reproduce the spatial variation of the drainage density.

Magnetic-properties of two soils during reduction, drying and re-oxidation

As part of a study of the use of magnetic properties to identify sources of sediments in water bodies for erosion studies, changes in the magnetic properties of two soils were determined during extended periods of reduction by saturation and during subsequent drying and oxidation. Mass magnetic properties rose during reduction and declined on re-oxidation. The results showed that a new magnetic compound was formed during reduction and then destroyed upon oxidation. These changes occurred in a soil which did not produce sulfides during reduction and the effects were little affected by amending the soil so that sulfides were formed. It was concluded that the compounds responsible for changes in magnetic properties were complex iron oxides rather than sulfides. Differences between the magnetic properties of wet and air dried samples were considered to be mainly due to physical rather than chemical changes. Therefore, when using magnetic properties as a tool for the identification of sediment sources, diagenesis and the effects of drying need to be taken into account.

Selective erosion and sediment source identification, Baringo District, Kenya

Selective erosion and sediment source identification, Baringo District, Kenya

Discrimination of soil erosion and fluvial sediment areas

A computer model has been used to estimate potential sheet and rill erosion and delivered sediment from field-sized areas of five selected agricultural watersheds. Consideration of these estimates in relation to defined tolerance levels of soil erosion and sediment yield has resulted in the mapping of (1) areas that exhibit erosion problems and serve as sediment sources; (2) areas that exhibit only erosion problems (but do not act as sediment sources); (3) areas that serve only as sediment sources (but do not exhibit erosion problems); and (4) areas that have no significant erosion problems or sediment sources. A simple approach has been developed for the preparation of such maps on the basis of a limited data base involving factors affecting erosion and fluvial sedimentation. This relatively simple yet accurate technique offers agricultural and conservation extension personnel a method for the identification of soil erosion problem areas and (or) sediment sources.

The potential use of pollen in the identification of suspended sediment sources

AbstractPollen and spores form a significant part of the suspended organic load of a New Forest stream. Flood concentrations reach 230 grains ml−1 while baseflow carries under one grain ml−1. Hydrographs from different seasons show differing hysteretic loops for pollen and spore concentrations against discharge and suspended sediment. These variations reflect not only factors of production, but the type and distance of the contributing sources. This investigation suggests that variations in flood pollen and spore concentrations may be used to trace such suspended sediment sources as: eroding bedrock, channel banks, or hillslopes under specific vegetation covers.

Identification of Quaternary sediment sources of the Mid-Atlantic Ridge through geochemical elements of transition and hygromagmaphile elements

Identification of Quaternary sediment sources of the Mid-Atlantic Ridge through geochemical elements of transition and hygromagmaphile elements

Identification of suspended sediment sources by means of magnetic measurements: Some preliminary results

Rapid, nondestructive magnetic measurements of initial low‐field susceptibility x, saturation isothermal remanent magnetization (IRMsat), and coercivity of IRM provide a means of identifying the source of suspended sediments in rivers. Preliminary results derived from the application of these measurements both to suspended sediment and to potential sources within the instrumented catchment of the Jackmoor Brook near Exeter, United Kingdom, demonstrate the value of this approach in an area of Permian sandstone bedrock where the contrast in magnetic properties between parent material and topsoil is easily characterized. High flows are shown to be associated with suspended sediment, the magnetic properties of which are indistinguishable from those of the cultivated soils of the catchment.