Quantification du transport solide par la technique floue, application au barrage de Beni Amrane (Algérie)

Lekfir, Abdelouahab; Ali, Tarik Benkaci; Dechemi, Noureddine

doi:10.7202/013542ar

Cited by 7 publications

(7 citation statements)

References 13 publications

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“…Two indices were used to test the performance of the models and the agreement between measured and simulated results and to compare the efficiency of the three models tested: The χ 2 of conformity [ Uehlinger et al , 1996] given by and the Nash‐Sutcliffe coefficient of efficiency E [ Lekfir et al , 2006; Kliment et al , 2008] by where B meas, i is the measured biomass, B ( t i ) the predicted biomass at time i , ES meas, i is the standard error in B meas, i , is the average of all measured values, and N is the number of measurements. Generally the model is deemed perfect when E is greater than 0.75, satisfactory when E is between 0.36 and 0.75, and unsatisfactory when E is smaller than 0.36 [ Krause et al , 2005].…”

Section: Methodsmentioning

confidence: 99%

Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches

Graba

Moulin

Boulêtreau

et al. 2010

Water Resources Research

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[1] The biomass dynamics of epilithic biofilm, a collective term for a complex microorganism community that grows on gravel bed rivers, was investigated by coupling experimental and numerical approaches focusing on epilithic biofilm-flow interactions. The experiment was conducted during 65 days in an artificial rough open-channel flow, where filtered river water circulated at a constant discharge. To characterize the effect of near-bed turbulence on the chronic detachment process in the dynamics of epilithic biofilm, local hydrodynamic conditions were measured by laser Doppler anemometry and turbulent boundary layer parameters inferred from double-averaged quantities. Numerical simulations of the EB biomass dynamics were performed using three different models of chronic detachment based upon three different descriptors for the flow conditions: Discharge Q, friction velocity u * , and roughness Reynolds number k + . Comparisons of numerical simulation results with experimental data revealed chronic detachment to be better simulated by taking the roughness Reynolds number as the external physical variable forcing chronic detachment. Indeed, the loss of epilithic matter through the chronic detachment process is related not only to hydrodynamic conditions, but also to change in bottom roughness. This suggests that changes in the behavior and dimensions of river bed roughness must be considered when checking the dynamics of epilithic biofilm in running waters.

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Section: Methodsmentioning

confidence: 99%

Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches

Graba

Moulin

Boulêtreau

et al. 2010

Water Resources Research

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“…Demmak, ; Meddi, ; Probst and Amiotte, ; Terfous et al ., ; Benkhaled and Remini, ; Achite and Ouillon, ). Recently, the relationship between water discharge and suspended sediment discharge has also been investigated for the Beni Amrane reservoir located East of Algiers, using the fuzzy logic approach (Lekfir et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Frequency analysis of annual maximum suspended sediment concentrations in Abiod wadi, Biskra (Algeria)

Benkhaled

Higgins²,

Chebana³

et al. 2013

Hydrological Processes

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Sediment transport processes in the Mediterranean semi-arid areas have interested a great number of hydrologists and statisticians. Frequency analysis (FA) procedures are commonly applied for several hydrological events such as floods and droughts. However, in general, FA is not widely applied to treat suspended sediment concentration (SSC), especially in semi-arid regions. In the present study, an FA was performed on SSC data from 1979 to 1991 observed upstream from the Foum El Gherza dam, which is located at Biskra in the South-East of Algeria. This dam is problematic in terms of silting. Therefore, this study is mainly motivated by providing an FA model and risk evaluation in order to assist dam managers to better evaluate the potential of silting resulting from SSC transport to the reservoir. Probability distributions commonly used in hydrology were tested to SSC data recorded at the M'chounech station on Abiod wadi located upstream the dam. All the FA steps were considered; including classical techniques (e.g. goodness-of-fit tests, statistical criteria) as well as recently developed tools (tail distribution classification). Their application led to the selection of the lognormal distribution (LN2) to fit the considered data, and hence an accurate risk assessment could be obtained. Because of the presence of a slight trend, non-stationary models are also considered in the present study.

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“…Two indices were used to test the performance of the model and the agreement between measured and simulated results. These were the χ 2 of conformity (Eqn ; Uehlinger et al ., ) and the Nash–Sutcliffe efficiency coefficient E (Eqn ; Lekfir, Benkaci Ali & Dechemi, ; Kliment, Kadlec & Langhammer, ):

{italicχ}^{2} = {false\sum}_{i = 1}^{N} {()(, \frac{B false(t_{i} false) - B_{meas, i}}{{ES}_{normalmeas, i}})}^{2}

E = 1 - \frac{{false\sum}_{i = 1}^{N} {()(, B_{normalmeas, normali} - B (t_{i}))}^{2}}{{false\sum}_{i = 1}^{N} {()(, B_{normalmeas, normali} - \bar{B_{normalmeas}})}^{2}}

where B meas, i is the measured biomass and B(t i ) is the predicted biomass at time i . ES meas ,i is the standard error in B meas ,i ,

\bar{B_{m e a s}}

is the average of all measured values and N is the number of measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Two indices were used to test the performance of the model and the agreement between measured and simulated results. These were the v 2 of conformity (Eqn 7; Uehlinger et al, 1996) and the Nash-Sutcliffe efficiency coefficient E (Eqn 8; Lekfir, Benkaci Ali & Dechemi, 2006;Kliment, Kadlec & Langhammer, 2007):…”

Section: Validation Of the Modelmentioning

confidence: 99%

Modelling epilithic biofilms combining hydrodynamics, invertebrate grazing and algal traits

et al. 2014

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Summary This model of stream epilithic biofilm biomass dynamics is based on the system of equations from Uehlinger et al. () and the term for autogenic detachment of biofilm from Boulêtreau et al. (). Its new features are (i) a mathematical term based on estimated feeding activity of biofilm‐dwelling invertebrates, (ii) local hydrodynamics considered as the principal factor governing algal traits and biofilm structure and (iii) a variable degree of parameterisation that was adjusted to biofilm biomass conditions. Biofilm biomass was monitored over a one‐year period in the Garonne river in France (September 2008–2009). An allometric approach was used to estimate the feeding activity of biofilm‐dwelling invertebrates based on their energetic requirements. Diatom functional diversity was also monitored to find how it varied with overall biofilm growth patterns. The one‐year monitoring period was divided into six biofilm biomass cycles, with each cycle consisting of a phase of biofilm growth as the main process, followed by detachment. This model reproduced the observed data as a complex of biofilm growth/detachment cycles using different sets of empirical parameters which allowed (i) the dominant processes involved in each biofilm cycle to be evaluated and (ii) the six cycles of biofilm growth/detachment to be reproduced. This accounted for the observed patterns more effectively than a parameterisation using a single set of empirical parameters. High flow had a severe effect on biofilm dynamics through chronic and catastrophic detachment. Presumably as a result, assemblages of diatoms shifted towards species that were firmly attached and protected by mucilage. During low flow (and when temperature was high), biofilm dynamics was mainly affected by autogenic detachment and grazer activity. The grazing pressure of the dominant biofilm‐dwelling invertebrates (Nematoda and larvae of Chironomidae and Trichoptera) was fairly low (a maximum of 6% of biofilm biomass ingested daily); nevertheless, their presence in the biofilm seemed to favour biofilm autogenic detachment.

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Quantification du transport solide par la technique floue, application au barrage de Beni Amrane (Algérie)

Cited by 7 publications

References 13 publications

Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches

Effect of near‐bed turbulence on chronic detachment of epilithic biofilm: Experimental and modeling approaches

Frequency analysis of annual maximum suspended sediment concentrations in Abiod wadi, Biskra (Algeria)

Modelling epilithic biofilms combining hydrodynamics, invertebrate grazing and algal traits

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