scholarly journals Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)

2016 ◽  
Vol 20 (4) ◽  
pp. 1355-1372 ◽  
Author(s):  
Mohammed Achite ◽  
Sylvain Ouillon
Keyword(s):  
Sediment Yield ◽  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Rating Curve ◽  
Cascading Effects ◽  
Suspended Particulate ◽  
Hysteresis Phenomena ◽  
Hydrological Regimes

Abstract. Here we investigate the changes of temperature, precipitation, river runoff and sediment transport in the Wadi Abd in northwest Algeria over a time series of 40 hydrological years (1970–2010). Temperature increased and precipitation decreased with the reduction in rainfall being relatively higher during the rainy season. A shift towards an earlier onset of first rains during summer was also found with cascading effects on hydrology (hydrological regimes, vegetation, etc.) and thus on erosion and sediment yield. During the 1980s, the flow regime shifted from perennial to intermittent with an amplification of the variations of discharge and a modification of the sediment regime with higher and more irregular suspended particulate flux. Sediment flux was shown to almost double every decade from the 1970s to the 2000s. The sediment regime shifted from two equivalent seasons of sediment yield (spring and fall) to a single major season regime. In the 2000s, autumn produced over 4 times more sediment than spring. The enhanced scatter of the C–Q pairs denotes an increase of hysteresis phenomena in the Wadi Abd that is probably related to the change in the hydrologic regime. At the end of the period, due to irregularity of the discharge, the ability of a rating curve to derive suspended sediment concentration from river discharge was poor.

scholarly journals Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)

2015 ◽  
Vol 12 (10) ◽  
pp. 10457-10513
Author(s):  
M. Achite ◽  
S. Ouillon
Keyword(s):  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Rating Curve ◽  
Sediment Delivery ◽  
Cascading Effects ◽  
Suspended Particulate ◽  
Rating Curves ◽  
Hysteresis Phenomena

Abstract. Here we investigate the changes of temperature, precipitation, river runoff and sediment transport in the Wadi Abd in NW Algeria over a time series of 40 hydrological years (1970–2010). Temperature increased and precipitation decreased with the reduction in rainfall being relatively higher during the rainy season. A shift towards an earlier onset of first rains during summer was also found with cascading effects on hydrology (hydrological regimes, vegetation etc) and thus on erosion and sediment yield. During the 1980s, the flow regime shifted from perennial to intermittent with an amplification of the variations of discharge and a modification of the sediment regime with higher and more irregular suspended particulate flux. Sediment flux was shown to almost double every decade from 1970s to 2000s. The sediment regime shifted from two equivalent seasons of sediment delivery (spring and autumn) to a single major season regime. In 2000s, autumn produced over 4 times more sediment than spring. The enhanced scatter denotes an increase of hysteresis phenomena in the Wadi Abd that is probably related to the change in the hydrologic regime. The increased erosion of the watershed is accompanied by a decrease in the coefficient b of its rating curves and a decrease in the erosive power of the river. At the end of the period, due to the irregularity of the discharge, the ability of a rating curve to derive suspended sediment concentration from river discharge was poor.

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 Development and Interpretation of New Sediment Rating Curve Considering the Effect of Vegetation Cover for Asian Basins

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Jie Wang ◽  
Hiroshi Ishidaira ◽  
Wenchao Sun ◽  
Shaowei Ning
Keyword(s):  
Suspended Sediment ◽  
Sediment Yield ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Suspended Sediment Concentration ◽  
Hydrological Cycle ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Rating Curve ◽  
Sediment Rating Curve

Suspended sediment concentration of a river can provide very important perspective on erosion or soil loss of one river basin ecosystem. The changes of land use and land cover, such as deforestation or afforestation, affect sediment yield process of a catchment through changing the hydrological cycle of the area. A sediment rating curve can describe the average relation between discharge and suspended sediment concentration for a certain location. However, the sediment load of a river is likely to be undersimulated from water discharge using least squares regression of log-transformed variables and the sediment rating curve does not consider temporal changes of vegetation cover. The Normalized Difference Vegetation Index (NDVI) can well be used to analyze the status of the vegetation cover well. Thus long time monthly NDVI data was used to detect vegetation change in the past 19 years in this study. Then monthly suspended sediment concentration and discharge from 1988 to 2006 in Laichau station were used to develop one new sediment rating curve and were validated in other Asian basins. The new sediment model can describe the relationship among sediment yield, streamflow, and vegetation cover, which can be the basis for soil conservation and sustainable ecosystem management.

scholarly journals Insights on the Impacts of Hydroclimatic Extremes and Anthropogenic Activities on Sediment Yield of a River Basin

Earth ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 32-50
Author(s):  
Rocky Talchabhadel ◽  
Jeeban Panthi ◽  
Sanjib Sharma ◽  
Ganesh R. Ghimire ◽  
Rupesh Baniya ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
River Basin ◽  
Extreme Precipitation ◽  
Suspended Sediment Concentration ◽  
Anthropogenic Activities ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Mountain River ◽  
Ecological Processes ◽  
Precipitation Indices

Streamflow and sediment flux variations in a mountain river basin directly affect the downstream biodiversity and ecological processes. Precipitation is expected to be one of the main drivers of these variations in the Himalayas. However, such relations have not been explored for the mountain river basin, Nepal. This paper explores the variation in streamflow and sediment flux from 2006 to 2019 in central Nepal’s Kali Gandaki River basin and correlates them to precipitation indices computed from 77 stations across the basin. Nine precipitation indices and four other ratio-based indices are used for comparison. Percentage contributions of maximum 1-day, consecutive 3-day, 5-day and 7-day precipitation to the annual precipitation provide information on the severity of precipitation extremeness. We found that maximum suspended sediment concentration had a significant positive correlation with the maximum consecutive 3-day precipitation. In contrast, average suspended sediment concentration had significant positive correlations with all ratio-based precipitation indices. The existing sediment erosion trend, driven by the amount, intensity, and frequency of extreme precipitation, demands urgency in sediment source management on the Nepal Himalaya’s mountain slopes. The increment in extreme sediment transports partially resulted from anthropogenic interventions, especially landslides triggered by poorly-constructed roads, and the changing nature of extreme precipitation driven by climate variability.

Impact of Chelicorophium curvispinum on the concentration-discharge response of suspended sediment in the Rhine River

2021 ◽  
Author(s):  
Marcel van der Perk
Keyword(s):  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sudden Increase ◽  
Rhine River ◽  
Rating Curve ◽  
Independent Evidence ◽  
Sediment Rating Curve ◽  
Suspended Sediment Concentrations

<p>In an ongoing study to the decline in suspended sediment concentrations and loads in the Rhine river since the mid-1950s, the temporal changes in the power-law sediment rating curve parameters were examined. This revealed that the rating exponent of the rating curve increased substantially between the early and late 1980s. Until the early 1980s, the ratings curves were relatively flat with values of the rating exponent b varying around 0.2. In the mid-1980s, the exponent suddenly increased to a value between 0.4 and 0.6 and since then has remained within this range. This change in the rating exponent was mainly caused by a decrease in suspended sediment concentrations during low discharges. During high discharges, the suspended sediment concentration initially increased during the late 1980s, but this increase was nullified soon afterwards due to the declining trend in suspended sediment concentration.</p><p>The sudden increase of the rating exponent coincided with the period that the Ponto-Caspian <em>Chelicorophium curvispinum</em> (Caspian mud shrimp) invaded the Rhine river basin. This suggests that this suspension-feeder species bears the prime responsibility for this increase, although this hypothesis requires further independent evidence. The sudden increase in the rating exponent does however not manifest itself in the long-term gradual trend of declining suspended sediment concentrations and vice versa. Apparently, the sequestration of sediment by <em>Chelicorophium curvispinum</em> is only temporary: the suspended sediment sequestered during periods of relatively low discharges is likely remobilised again during periods of high discharge. This implies that the invasion of <em>Chelicorophium curvispinum</em> has not played a significant role in the decline of suspended sediment concentrations. The precise reasons for the gradual long-term decline in suspended sediment concentration remain yet unknown.</p>

scholarly journals Suspended sediment fluxes in an Indonesian river draining a rainforested basin subject to land cover change

2011 ◽  
Vol 8 (4) ◽  
pp. 7137-7175 ◽  
Author(s):  
F. A. Buschman ◽  
A. J. F. Hoitink ◽  
S. M. de Jong ◽  
P. Hoekstra
Keyword(s):  
Land Cover ◽  
Suspended Sediment ◽  
River Discharge ◽  
Soil Loss ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sediment Flux ◽  
Sediment Fluxes ◽  
Suspended Sediment Flux ◽  
The Impact

Abstract. Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in the tropics. The increasing sediment fluxes pose a threat to coastal marine ecosystems such as coral reefs. This study presents observations of suspended sediment fluxes in the Berau river (Indonesia), which debouches into a coastal ocean that can be considered the preeminent center of coral diversity. The Berau is an example of a small river draining a mountainous, relatively pristine basin that receives abundant rainfall. Flow velocity was measured over a large part of the river width at a station under the influence of tides, using a Horizontal Acoustic Doppler Current Profiler (HADCP). Surrogate measurements of suspended sediment concentration were taken with an Optical Backscatter Sensor (OBS). Tidally averaged suspended sediment concentration increases with river discharge, implying that the tidally averaged suspended sediment flux increases non-linearly with river discharge. Averaged over the 6.5 weeks observations covered by the benchmark survey, the tidally averaged suspended sediment flux was estimated at 2 Mt y−1. Considering the wet conditions during the observation period, this figure may be considered as an upper limit of the yearly averaged flux. This flux is significantly smaller than what could have been expected from the characteristics of the catchment. The consequences of ongoing clearing of rainforest were explored using a plot scale erosion model. When rainforest, which still covered 50–60 % of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment flux in the Berau river would impose a severe sediment stress on the global hotspot of coral reef diversity. The impact of land cover changes will largely depend on the degree in which the Berau estuary acts as a sediment trap.

scholarly journals Suspended Sediment Concentration and Sediment Loading of Bernam River (Perak, Malaysia)

2020 ◽  
Vol 22 (2) ◽  
pp. 1-14
Author(s):  
Sumayyah Aimi Mohd Najib ◽  
Syazwani Aliah ◽  
Husna Nabilah Hamidon
Keyword(s):  
Suspended Sediment Concentration ◽  
Sampling Period ◽  
Sediment Concentration ◽  
High Flow ◽  
Low Flow ◽  
Sediment Loading ◽  
Land Uses ◽  
Rating Curve ◽  
Sediment Rating Curve ◽  
Rain Events

Abstract This paper presents some of our preliminary results on the sediment discharge and load based on weekly sampling starting from Oct 2017 to January 2018. Results show that sediment rating curve of Bernam River was R2 = 0.86 high flow and R2 = 0.5 low flow. Average sediment loading throughout this sampling period is 1,144 t. Land use activity is expected to be the main contribution for the highest sediment concentration during rain events. The amount of annual sediment yield was estimated at 23 t/km2/year and is comparable to other studies having similar land uses in the catchment area.

scholarly journals Decline of Fine Suspended Sediments in the Madeira River Basin (2003–2017)

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 514 ◽  
Author(s):  
Irma Ayes Rivera ◽  
Elisa Armijos Cardenas ◽  
Raúl Espinoza-Villar ◽  
Jhan Espinoza ◽  
Jorge Molina-Carpio ◽  
...  
Keyword(s):  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Water Discharge ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Hydropower Potential ◽  
Madeira River ◽  
Fine Suspended Sediment ◽  
Porto Velho ◽  
Madeira River Basin

The Madeira River is the second largest Amazon tributary, contributing up to 50% of the Amazon River’s sediment load. The Madeira has significant hydropower potential, which has started to be used by the Madeira Hydroelectric Complex (MHC), with two large dams along the middle stretch of the river. In this study, fine suspended sediment concentration (FSC) data were assessed downstream of the MHC at the Porto Velho gauging station and at the outlet of each tributary (Beni and Mamoré Rivers, upstream from the MHC), from 2003 to 2017. When comparing the pre-MHC (2003–2008) and post-MHC (2015–2017) periods, a 36% decrease in FSC was observed in the Beni River during the peak months of sediment load (December–March). At Porto Velho, a reduction of 30% was found, which responds to the Upper Madeira Basin and hydroelectric regulation. Concerning water discharge, no significant change occurred, indicating that a lower peak FSC cannot be explained by changes in the peak discharge months. However, lower FSCs are associated with a downward break in the overall time series registered at the outlet of the major sediment supplier—the Beni River—during 2010.

Experimental Study of Sand Sediments Effects on Submerged Hydraulic Jump Properties

2012 ◽  
Vol 212-213 ◽  
pp. 366-371
Author(s):  
Siavash Haghighi ◽  
Mohammad Reza Kavianpour ◽  
Keyvan Nasiri
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Suspended Sediment Concentration ◽  
Sediment Load ◽  
Sediment Concentration ◽  
Relative Energy ◽  
Sluice Gate ◽  
Jump Length ◽  
Submerged Hydraulic Jump ◽  
Whole Sediments

Abstract. In this study, the effect of sediment concentration on submerged hydraulic jump (SHJ) characteristics such as jump length, submerged depth on the gate and the energy dissipation is investigated. Experiments were carried out in a flume of 46 cm depth, 12 m length. The width of the flume changes from 10 cm (at the entrance) to 60 cm (at the exit). Sediment load and flow concentration have an influence on submerged hydraulic jump characteristics including submerged depth on the gate, jump length and relative energy dissipation. It is shown that at high Froude numbers increasing the suspended sediment concentration to 28.7 gr/l leads to a reduction in the submerged depth on the gate up to 6% and jump length up to 10%. Also, the energy dissipation of the submerged hydraulic jump increases by 4% and turbulence resulting from the jump leads to upright distribution of concentration at the end of the jump. Also in concentrations higher than 30 gr/l, flow is not able to carry the whole sediments and subsequently leads to their deposition in subcritical area and behind the sluice gate.

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