Sediment fluxes and sinks for Magela Creek, Northern Territory, Australia

2018 ◽  
Vol 69 (7) ◽  
pp. 1018 ◽  
Author(s):  
Wayne D. Erskine ◽  
M. J. Saynor ◽  
J. M. Boyden ◽  
K. G. Evans
Keyword(s):  
Suspended Sediment ◽  
Sediment Load ◽  
Northern Territory ◽  
Bed Load ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Erosion Rates ◽  
Dry Tropics ◽  
The World ◽  
Total Sediment

Sediment fluxes and sinks based on total sediment load for Magela Creek in the Australian wet–dry tropics have been constructed from detailed measurements of stream suspended sediment (turbidity and suspended sand) and bed load for the 10-year period, 2001–2002 to 2010–2011. This work shows that the sediment trap efficiency of the vegetated wetlands on lower Magela is high at ~89.5%. Sediment fluxes are the lowest in the world because of low soil erosion rates and because upstream floodplains and downstream wetlands trap and store sediment. Bedload yields are less than suspended sediment yields, but the amount of silt and clay is much less than the amount of sand (suspended sand and bedload). All sand is stored upstream of the East Alligator River. Downstream connectivity of sediment movement does not occur. Therefore, sediment moves discontinuously from the upper to the lower catchment.

scholarly journals Combining caesium-137 measurements and suspended sediment load data to investigate the sediment response of a small catchment in southern Italy

2015 ◽  
Vol 367 ◽  
pp. 220-227
Author(s):  
P. Porto ◽  
D. E. Walling ◽  
C. La Spada ◽  
N. Mallimo
Keyword(s):  
Suspended Sediment ◽  
Sediment Yield ◽  
Soil Loss ◽  
Sediment Load ◽  
Southern Italy ◽  
Medium Term ◽  
Sediment Yields ◽  
Erosion Rates ◽  
Long Term Measurement

Abstract. A long-term measurement programme was operated in southern Italy during the 1960s and 1970s, to provide information on the suspended sediment yields from the main river basins. Information obtained for the rivers of Calabria suggests that suspended sediment yields in this area are relatively low. However, there is evidence that the intensity of land degradation within the upstream catchments is substantially higher than suggested by the values of specific sediment yield and there is a need to explore the relationship between on-site soil loss and downstream sediment yield more closely. Monitoring time-integrated erosion rates over large areas has traditionally required extensive long-term measurement programmes employing experimental plots. The fallout radionuclide caesium-137 (137Cs) offers an alternative means of documenting medium-term rates of soil loss. This paper describes the use of 137Cs measurements and the available sediment load data to explore the links between soil erosion, sediment redistribution and storage, and sediment output for a medium-scale (41.3 km2) catchment in Calabria. Data available from a sediment load monitoring programme undertaken at the catchment outlet during 1962–1977 have been used to estimate the longer-term catchment sediment yield. This estimate has been combined with information provided by the 137Cs measurements, to establish a medium-term sediment budget for the catchment. The results provided by the 137Cs measurements indicate that the catchment is subject to much higher rates of soil loss and land degradation than suggested by its specific sediment yield. These findings are consistent with the results obtained for other catchments in Calabria for which both 137Cs derived erosion rates and measured sediment yields are available.

scholarly journals Do suspended sediment and bedload move progressively from the summit to the sea along Magela Creek, northern Australia?

2015 ◽  
Vol 367 ◽  
pp. 283-290
Author(s):  
W. D. Erskine ◽  
M. J. Saynor ◽  
K. Turner ◽  
T. Whiteside ◽  
J. Boyden ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Suspended Sediment ◽  
Waste Rock ◽  
Uranium Mine ◽  
Northern Australia ◽  
Sediment Yields ◽  
Flood Plains ◽  
Erosion Rates ◽  
Base Level ◽  
Soil Erosion Rates

Abstract. Soil erosion rates on plots of waste rock at Ranger uranium mine and basin sediment yields have been measured for over 30 years in Magela Creek in northern Australia. Soil erosion rates on chlorite schist waste rock are higher than for mica schist and weathering is also much faster. Sediment yields are low but are further reduced by sediment trapping effects of flood plains, floodouts, billabongs and extensive wetlands. Suspended sediment yields exceed bedload yields in this deeply weathered, tropical landscape, but the amount of sand transported greatly exceeds that of silt and clay. Nevertheless, sand is totally stored above the topographic base level. Longitudinal continuity of sediment transport is not maintained. As a result, suspended sediment and bedload do not move progressively from the summit to the sea along Magela Creek and lower Magela Creek wetlands trap about 90.5% of the total sediment load input.

scholarly journals Sediment Load and Suspended Sediment Concentration Prediction

2013 ◽  
Vol 1 (No. 1) ◽  
pp. 23-31 ◽  
Author(s):  
Bečvář Martin
Keyword(s):  
Suspended Sediment ◽  
Sediment Yield ◽  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Sediment Concentration ◽  
River Basins ◽  
River Systems ◽  
Sediment Yields ◽  
Suspended Sediment Concentrations ◽  
Annual Sediment

Sediment is a natural component of riverine environments and its presence in river systems is essential. However, in many ways and many places river systems and the landscape have been strongly affected by human activities which have destroyed naturally balanced sediment supply and sediment transport within catchments. As a consequence a number of severe environmental problems and failures have been identified, in particular the link between sediments and chemicals is crucial and has become a subject of major scientific interest. Sediment load and sediment concentration are therefore highly important variables that may play a key role in environment quality assessment and help to evaluate the extent of potential adverse impacts. This paper introduces a methodology to predict sediment loads and suspended sediment concentrations (SSC) in large European river basins. The methodology was developed within an MSc research study that was conducted in order to improve sediment modelling in the GREAT-ER point source pollution river modelling package. Currently GREAT-ER uses suspended sediment concentration of 15 mg/l for all rivers in Europe which is an obvious oversimplification. The basic principle of the methodology to predict sediment concentration is to estimate annual sediment load at the point of interest and the amount of water that transports it. The amount of transported material is then redistributed in that corresponding water volume (using the flow characteristic) which determines sediment concentrations. Across the continent, 44 river basins belonging to major European rivers were investigated. Suspended sediment concentration data were collected from various European basins in order to obtain observed sediment yields. These were then compared against the traditional empiric sediment yield estimators. Three good approaches for sediment yield prediction were introduced based on the comparison. The three approaches were applied to predict annual sediment yields which were consequently translated into suspended sediment concentrations. SSC were predicted at 47 locations widely distributed around Europe. The verification of the methodology was carried out using data from the Czech Republic. Observed SSC were compared against the predicted ones which validated the methodology for SSC prediction.

scholarly journals Anthropogenic Reservoirs of Various Sizes Trap Most of the Sediment in the Mediterranean Maghreb Basin

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 927 ◽  
Author(s):  
Mahrez Sadaoui ◽  
Wolfgang Ludwig ◽  
François Bourrin ◽  
Yves Bissonnais ◽  
Estela Romero
Keyword(s):  
Arid Zones ◽  
Anthropogenic Pressure ◽  
Sediment Retention ◽  
Natural Sediment ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Erosion Rates ◽  
Riverine Sediment ◽  
The Mediterranean ◽  
The Impact

The purpose of this study is to obtain a spatially explicit assessment of the impact of reservoirs on natural river sediment fluxes to the sea in the Mediterranean Maghreb Basin (MMB), a region where both mechanical erosion rates and the anthropogenic pressure on surface water resources are high. We combined modeling of riverine sediment yields (sediment fluxes divided by the drainage basin area) and water drainage intensities in a 5’ × 5’ grid point resolution (~10 km × 10 km) with a compilation of existing reservoirs in the area, and calculated sediment trapping based on average water residence time in these reservoirs. A total number of 670 reservoirs could be assembled from various sources (including digitization from Google maps), comprising large-scale, small-scale and hillside reservoirs. 450 of them could be implemented in our modeling approach. Our results confirm that natural sediment yields are clearly above the world average, with the greatest values for Morocco (506 t km−2 year−1), followed by Algeria (328 t km−2 year−1) and by Tunisia (250 t km−2 year−1). Including dams in the downstream routing of suspended sediments to the sea reduces the natural sediment flux in the entire MMB to the sea from 96 to 36 Mt km−1 year−1, which corresponds to an average sediment retention of 62%. Trapping rates are highest in the Tunisian basin part, with about 72%, followed by the Algerian (63%) and the Moroccan basin parts (55%). Small reservoirs and hillside reservoirs are quantitatively important in the interception of these sediments compared to large reservoirs. If we only considered the dams included in the widely used Global Reservoir and Dam (GRanD) database which comprises mainly large reservoirs sediment retention behind dams would account for 36% of the natural suspended particulate matter (SPM) flux to the Mediterranean Sea. Our data reveal negative correlation between sediment retention and natural erosion rates among the three Maghreb countries, which can be explained by the greater difficulties to build dams in steep terrains where natural sediment yields are high. Although the lowest sediment retention rates are found in the Moroccan part of the MMB, it is probably here where riverine sediment starvation has the greatest impacts on coastline dynamics. Understanding the impact of dams and related water infrastructures on riverine sediment dynamics is key in arid zones such as the MMB, where global warming is predicted to cause important changes in the climatic conditions and the water availability.

scholarly journals Sub-daily variability of suspended sediment fluxes in small mountainous catchments – implications for community-based river monitoring

2010 ◽  
Vol 7 (5) ◽  
pp. 8233-8263
Author(s):  
C. Duvert ◽  
N. Gratiot ◽  
J. Némery ◽  
A. Burgos ◽  
O. Navratil
Keyword(s):  
Suspended Sediment ◽  
Rural Areas ◽  
Temporal Variability ◽  
Fine Sediment ◽  
Community Based ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Monitoring Strategies ◽  
Mountainous Catchments ◽  
Daily Variability

Abstract. Accurate estimates of suspended sediment yields depend on effective monitoring strategies. In mountainous environments undergoing intense seasonal precipitation, the implementation of such monitoring programs relies primarily on a rigorous study of the temporal variability of fine sediment transport. This investigation focuses on seasonal and short-term sediment variability in a subhumid region of the Mexican Volcanic Belt. Intensive hydrosedimentary monitoring was conducted during one year on four contrasting catchments (3 to 630 km2). Analyses revealed significant temporal variability in suspended sediment export over various time scales, with between 63 and 97% of the annual load exported in as little as 2% of the time. Statistical techniques were used to evaluate the sampling frequency required to get reliable annual sediment yield estimates at the four sites. A bi-daily sampling would be required at the outlet of the 630-km2 catchment, whereas in the three smaller catchments (3–12 km2), the achievement of accurate estimates would inevitably require hourly monitoring. At the larger catchment scale, analysis of the sub-daily variability of fine sediment fluxes showed that the frequency of sampling could be lowered by up to 100% (i.e. from bi-daily to daily) if considering a specific and regular sampling time in the day. In contrast, conducting a similar sampling strategy at the three smaller catchments could lead to serious misinterpretation (i.e. up to 1000% error). Our findings emphasise the importance of an analysis of the sub-daily variability of sediment fluxes in mountainous catchments. Characterising this variability may offer useful insights for improving the effectiveness of community-based monitoring strategies in rural areas of developing countries. In regions where historical records based on discrete sampling are available, it may also help assessing the quality of past flux estimates. Finally, the study confirms the global necessity of acquiring more high frequency data in small mountainous catchments, especially in poorly gauged areas.

scholarly journals Suspended sediment and discharge dynamics in a glacierized alpine environment: Identifying crucial areas and time periods on several spatial and temporal scales in the Ötztal, Austria

2022 ◽  
Author(s):  
Lena Katharina Schmidt ◽  
Till Francke ◽  
Erwin Rottler ◽  
Theresa Blume ◽  
Johannes Schöber ◽  
...  
Keyword(s):  
Snow Cover ◽  
Suspended Sediment ◽  
Sediment Dynamics ◽  
Recent Sediment ◽  
Mass Balances ◽  
Temporal Scales ◽  
Spatial And Temporal Scales ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Precipitation Events

Abstract. Climatic changes are expected to fundamentally alter discharge and sediment dynamics in glaciated high alpine areas, e.g. through glacier retreat, prolonged snow-free periods and more frequent intense rainfall events in summer. However, how exactly these hydrological changes will affect sediment dynamics is not yet known. In the present study, we aim to pinpoint areas and processes most relevant to recent sediment and discharge dynamics on different spatial and temporal scales in the Ötztal Alpine Region in Tyrol, Austria. Therefore, we analyze observed discharge and relatively long suspended sediment time series of up to 15 years from three gauges in a nested catchment setup. The catchments range from 100 to almost 800 km2 in size with 10 to 30 % glacier cover and span an elevation range of 930 to 3772 m a.s.l.. The investigation of satellite-based snow cover maps, glacier inventories, mass balances and precipitation data complement the analysis. Our results indicate that mean annual specific discharge and suspended sediment fluxes are highest in the most glaciated sub-catchment and both fluxes correlate significantly with annual glacier mass balances. Furthermore, both discharge and suspended sediment loads show a distinct seasonality with low values during winter and high values during summer. However, the spring onset of sediment transport is almost synchronous at the three gauges, contrary to the spring rise in discharge, which occurs earlier further downstream. A spatio-temporal analysis of snow cover evolution indicates that the spring increase in sediment fluxes at all gauges coincides with the onset of snow melt above 2500 m elevation. Zones above this elevation include glacier tongues and recently deglaciated areas, which seem to be crucial for the sediment dynamics in the catchment. Precipitation events in summer were associated with peak sediment concentrations and fluxes, but on average accounted for only 21 % of the annual sediment yields of the years 2011 to 2020. We conclude that glaciers and the areas above 2500 m elevation play a dominant role for discharge and sediment dynamics in the Ötztal area, while precipitation events play a secondary role. Our study extends the scientific knowledge on current hydro-sedimentological changes in glaciated high alpine areas and provides a baseline for investigations on projected future changes in hydro-sedimentological system dynamics.

Estimation of suspended sediment loads in a seasonal stream in the wet-dry tropics, Northern Territory, Australia

2004 ◽  
Vol 18 (3) ◽  
pp. 531-544 ◽  
Author(s):  
D. R. Moliere ◽  
K. G. Evans ◽  
M. J. Saynor ◽  
W. D. Erskine
Keyword(s):  
Suspended Sediment ◽  
Northern Territory ◽  
Dry Tropics ◽  
Sediment Loads

scholarly journals Water and sediment fluxes in Mediterranean mountainous regions: comprehensive dataset for hydro-sedimentological analyses and modelling in a mesoscale catchment (River Isábena, NE Spain)

2018 ◽  
Vol 10 (2) ◽  
pp. 1063-1075 ◽  
Author(s):  
Till Francke ◽  
Saskia Foerster ◽  
Arlena Brosinsky ◽  
Erik Sommerer ◽  
Jose A. Lopez-Tarazon ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Meteorological Data ◽  
Sediment Source ◽  
Discharge Data ◽  
Sediment Yields ◽  
Sediment Fluxes ◽  
Mountainous Regions ◽  
Water And Sediment ◽  
Ne Spain ◽  
River Isábena

Abstract. A comprehensive hydro-sedimentological dataset for the Isábena catchment, northeastern (NE) Spain, for the period 2010–2018 is presented to analyse water and sediment fluxes in a Mediterranean mesoscale catchment. The dataset includes rainfall data from 12 rain gauges distributed within the study area complemented by meteorological data of 12 official meteo-stations. It comprises discharge data derived from water stage measurements as well as suspended sediment concentrations (SSCs) at six gauging stations of the River Isábena and its sub-catchments. Soil spectroscopic data from 351 suspended sediment samples and 152 soil samples were collected to characterize sediment source regions and sediment properties via fingerprinting analyses. The Isábena catchment (445 km2) is located in the southern central Pyrenees ranging from 450 m to 2720 m a.s.l.; together with a pronounced topography, this leads to distinct temperature and precipitation gradients. The River Isábena shows marked discharge variations and high sediment yields causing severe siltation problems in the downstream Barasona Reservoir. The main sediment source is badland areas located on Eocene marls that are well connected to the river network. The dataset features a comprehensive set of variables in a high spatial and temporal resolution suitable for the advanced process understanding of water and sediment fluxes, their origin and connectivity and sediment budgeting and for the evaluation and further development of hydro-sedimentological models in Mediterranean mesoscale mountainous catchments. The dataset is available at http://doi.org/10.5880/fidgeo.2018.011.

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