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LARHYSS Journal
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1112-3680
Published by UniversitĂ© de Biskra Homepage  [1 journal]
  • Discussion of "DISCHARGE COEFFICIENT OF SHAFT SPILLWAY UNDER SMALL
           HEADS"

    • Authors: L. AMARA, B. ACHOUR
      Abstract: The discussers would like to thank the authors for their remarkable demonstration aimed at the analytical determination of the discharge coefficient value of a shaft spillway operating under shallow heads. In hydraulic engineering, the determination of the discharge coefficient is one of the underlying issues. As a general rule, it is found out from laboratory tests carried out above a lower limit threshold of the relative heads. The discussers would like to share their point of view relating to this subject by adopting a different theoretical approach which leads to a result of the same magnitude. For the analytical determination of the discharge coefficient, the theoretical approach consists to compute the coefficient of the vertical contraction of the flow considering curvature effects as well as the coefficient of velocity taking accounts the velocity distribution
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • NEW FORMULATION OF THE DARCY-WEISBACH FRICTION FACTOR

    • Authors: B. ACHOUR, L. AMARA
      Abstract: The proper assessment of the friction factor f is of a great importance in the sound resolve of turbulent flow problems. The current rational formulation of f is that developed by Colebrook stating that f depends on the relative roughness and the Reynolds number R, through an implicit equation. The new formulation developed herein presents f as a function not of the usual Reynolds number R but of a dimensionless parameter, denoted , representing the ratio of the friction forces to the viscous forces. Acting as a Reynolds number, it is shown that is governed by an implicit equation of and R. The calculation of the friction factor value using the new formulation gives a maximum deviation of 0.25% in comparison with the exact value of f derived from Colebrook equation. At the end of an additional calculation step, the deviation drops down to a maximum of 0.04% only. This calculation step is recommended for solving problems requiring high accuracy. All the formulas developed herein can be classified in the category of short equations, easily memorized, handy, and of good accuracy.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • CHARACTERIZATION OF THE DROUGHT BY THE SPI AND SPEI INDICES IN THE WEST
           CENTER OF CĂ”TE D'IVOIRE CASE OF THE LOBO BASIN

    • Authors: V.H. N’GUESSAN BI, T.T ADJAKPA, F.B. ALLECHY, M. YOUAN TA, Y.F. ASSA, K. AFFIAN
      Abstract: The drought observed since 1970 in Côte d'Ivoire has often had tragic consequences on water resources, the agricultural sector and the environment. The objective of this study is to characterize the meteorological drought in the Lobo River Basin with a view to raising the awareness of the population in order to take adequate adaptation measures. The method used is based on the calculation of the SPI (Standardized Precipitation Index) and SPEI (Standardized Precipitation and Evapotranspiration Index) at different time scales (3, 6 and 12 months) over the period 1979 to 2013. The results show that the entire Lobo watershed experienced a moderate type of drought, the most remarkable by their intensity and duration being recorded during the periods from 2000 to 2002 and 2005 to 2007. These drought periods were longer in the northern half of the basin according to the two indices on 3 and 6 months’ time scales and longer in the extreme south of the watershed on a 12 months time scale. Drought was more slightly felt in the extreme southern half of the watershed than in the northern half of the Lobo watershed.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • VIRTUAL CEREAL WATER IN ALGERIA: BLESSING OR CURSE'

    • Authors: L. ZELLA, D. SMADHI
      Abstract: This work attempts to understand and analyze the concept of virtual water, a newly introduced device used by developed countries to better refine the evolution of the water situation subject to these inter-country water transfers. However, the transfer of this invisible water hides underlying challenges of supporting and promoting the agricultural economies of exporting countries. The key argument put forward in this new concept of international trade is that of water productivity, particularly in cereal production. However, it is clearly still relatively lower in poor and less developed countries. The very ones that matter a lot and export very little. This is the Algerian case where cereal farming is basically rainfed. In this respect, the application of Ricardo's theory of comparative advantages, from which the concept of virtual water derives, is therefore an instrument of unilateral subjection. Because the virtual quantities of water imported with cereals do not really contribute to Algeria's water balance. This is only possible in the case of irrigated crops. It is therefore more sensible and advantageous to redouble efforts to increase yields and the current cereal area, by absorbing the enormous potential of fallow land and mastering the technical route. On the other hand, it is imperative to provide clear answers to this excessive consumption of cereals. In this way, the country hopes to free itself from massive wheat imports.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • EXPLORATION OF MAXIMUM LIKELIHOOD METHOD IN EXTREME RAINFALL FORECASTING
           USING FOUR PROBABILITY DISTRIBUTIONS - THE CASE OF NORTHERN ALGERIA

    • Authors: T. BENKACI, N. MEZENNER, N. DECHEMI
      Abstract: In this research, we have compared four probability distributions: lognormal, Gumbel, gamma and GEV using method of moments (MM) and maximum likelihood (MLE) parameters estimation that we have applied on extreme rainfall in North of Algeria. The main objective of this study is to explore the advantages of MLE method in extreme rainfall frequency analysis. The comparison between the two methods showed that method of moments gives generally better performances than maximum likelihood, especially for GEV distribution comparing to others distributions, this model (GEV) appears least efficient when skewness of data exceeds 1.2. We have concluded that lognormal distribution is the most efficient and stable and gives better simulation of annual maximum daily rainfall using the two methods for the North of Algeria.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • FLOOD RISK REDUCTION STRATEGY IN ALGIERS A BRIEF MODERN HISTORY (XVIthC
           -XIXthC)

    • Authors: N. AROUA
      Abstract: This paper aim is to contribute better know the water related risks management heritage in Algeria while promoting in favor of contemporary cities resilience face to climate and environmental changes. Some relevant technical and organizational measures commonly used in Algiers until the beginning of the XIXth century may be consistent with the UN-disaster risk reduction strategies.Thus specific objectives are to i) characterize the hydro meteorological context and identify the associated flood risk; ii) examine the urban growth and land use patterns consistency with the local water geography and dynamic; iii) assess the adequacy of past prevention and protection measures implemented against current recommending.Results show i) the variability of flood effects over the city; ii) the integrated and pragmatic approach adopted to achieve prevention and protection goals; and iii) the significant role of urban planning in the flood risk reduction strategy.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • EVAPORATION FROM THE WATER SURFACE OF LAKES AND RESERVOIRS OF THE ARID
           ZONE OF THE MEDITERRANEAN: CASE OF ALGERIA

    • Authors: D. BOUTOUTAOU, H. ZEGGANE, S. SAGGAI
      Abstract: The value of water evaporation is a key data in establishing the water balance of lakes and reservoir dams. In general, the evaporation of water bodies is assessed either from observation data from evaporation pan (Colorado pan and class A pan), or by analogy with other reservoir dams for which these data are available. In frequent cases, the evaluation of the evaporation of water bodies becomes impossible by applying the two methods mentioned because of the reduced number of weather stations or the absence of evaporation pans among their equipment. Applying the analogy with other reservoir dams, it can lead to considerable errors. In order to eliminate the difficulty of determining the evaporation of water, often encountered by engineers and operators of reservoir dams, the development of a calculation method simulating the phenomenon of evaporation is essential.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • NEW THEORETICAL CONSIDERATIONS ON THE CRITICAL FLOW IN A CIRCULAR CONDUIT
           (PART 1)

    • Authors: B. ACHOUR, L. AMARA
      Abstract: In a circular conduit of diameter D and of a given slope S0, two critical states of the flow may occur for two different discharges. The first one is observed at shallow depths while the second one settles down at greater depths. This statement is the result of the in-depth study carried out on the smooth circular conduit of diameter D = 1m, taken as an example. For this conduit, all slopes S0 greater than S0 = generate the two critical states of the flow. Slopes that are less than this value do not generate any critical state of the flow. The study reveals that the slope S0 =  corresponds to the smallest slope that causes a single critical state of the flow. Other interesting conclusions, fundamental relationships as well as meaningful graphs are drawn from this study, after a detailed examination of the rational equations which govern the critical and normal flows.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • CONTRIBUTION TO THE STUDY OF RUNOFF AND EROSION OF LOW SLOPE HOMOGENEOUS
           HYDROLOGICAL UNITS OF A WATERSHED OF THE MIDDLE VALLEY OF MEDJERDA TUNISIA
           

    • Authors: R. RIAHI, H. BELAID, A. HATIRA, S. BACCOUCHE
      Abstract: The rainfall simulation tests on homogeneous hydrological units soil samples of a Medjerda middle valley watershed show that the characteristics of the upper surface soil layer and types of management practices as well as the rain characteristics (duration, intensity frequency) control the infiltration-runoff process and determine later the rain aggressiveness degree.The hydrological responses of the same hydrological unit are different. That was related to the tillage practices types.The increasing of the intensity of agricultural practices causes intense soil biodegradation (low organic matter content less than 2%) and distracts consequently its structural stability, thus favors rain aggressiveness process. Indeed, a plowed soil exposed to rainfall of intensity of 54 mm / h loses 3.31 g of soil corresponding to 0.13 kg / m2 of specific erosion whereas soil sample of olive trees the loss is equal to 2.24 g and the specific erosion is about 0.1 Kg / m2.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • AWESOME, THE DUST OF THE SAHARA IN THE SKY OF THE AMERICA CONTINENT
           Godzilla, the biggest dust storm in half a century

    • Authors: B. REMINI
      Abstract: Nicknamed Godzilla, a large dust storm from the Sahara Desert flew over the Atlantic Ocean during June 5-26, 2020, reaching the Caribbean and the Americas. By consulting the satellite images for the month of June 2020, the uprising of the dust storm took place on June 5, 2020 in the desert of Tanezrouft (Algeria). It is at the level of the throat area located on both sides of the mega-obstacle: Tassili N’Ajjer -Hoggar, which the harmattan from Libya accelerates following a decrease in pressure. Accordingly, the violence of the wind causes heavy erosion and uplift of fine particles in the air. This is the first departure from the Algerian Sahara of the largest amount of dust in more than half a century.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • ANALYTICAL STUDY OF SEDIMENT EVOLUTION IN THE LAKE OF THE FOUM EL GHERZA
           DAM (BISKRA, ALGERIA)

    • Authors: A. BOUGAMOUZA, B. REMINI, F. SAKHRAOUI
      Abstract: The research carried out as part of this work aims to provide answers to the rhythms and processes of sedimentation in the lake of the Foum El Gherza dam. Based on the bathymetric surveys carried out by the National Dams Agency in the Foum El Gherza dam, we have shown the temporal evolution of the silting up of the dam. As a result, the filling of the lake exceeded 70% of its initial capacity as of 2007. Despite the de-silting of the dam by dredging, the dam is in critical condition. Dredging operations must continue in the short term to extend the life of the structure.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
  • ZARDEZAS (ALGERIA): A DAM THAT IS SILTING UP'

    • Authors: A. TOUMI, B. REMINI
      Abstract: This article examines the phenomenon of the siltation of the Zardezas dam, located in the prefecture of Skikda. Investigations were carried out at the level of the dam as well as its watershed. Data from the bathymetric surveys were made available to us by the services of the National Dams Agency. The results obtained showed that over time, the capacity of the dam has greatly diminished and that currently does not exceed ¼ of its initial capacity. It should be noted that during the period: 2003-2006, the rate of siltation reached 0.4 million m3/year. At the same time, a volume of 0.3 million m3 was removed from the reservoir. The dam is silting and increasingly likely to be filled to 100%.
      PubDate: 2020-09-30
      Issue No: Vol. 0 (2020)
       
 
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