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LARHYSS Journal
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1112-3680
Published by UniversitĂ© de Biskra Homepage  [1 journal]
  • INVESTIGATION OF VACUUM AND CAVITATION IN A SHAFT SPILLWAY WITH A
           POLYGONAL CROSS SECTION

    • Authors: A. BRAKENI, A.P. GOURYEV, B. HAEK
      Abstract: In this research paper, our study focused on the importance and reliability of the shaft spillway flow in order to avoid the presence of vacuum and the possibility of erosion by cavitation at high flow rates. The proposed characteristics of the intake funnel consist on 12-sections polygonal configuration, on which a total of 124 piezometer gauges in the scale model (including the elbow) was placed to determine the pressure distribution. The physical model in the form of a dodecagon was tested on laboratory flume at the hydroelectric power stations of the State University of Environmental Engineering in Moscow (Russia). This flume having a zero bottom slope, a width of 100 cm and a length of 950 cm is connected to a feed tank whose dimensions are 1.64 m x 2.0m.The results showed that the realization of the crest of the intake funnel in the form of a polygonal cylindrical surface reduces the maximum vacuum by two times compared to the vacuum on the crest of rectilinear weir dams, not exceeding a value of 2 m of water column which is not dangerous for the appearance of the cavitation erosion of the water receiving funnel. It also allows shaft surfaces to be formed with a one-dimensional curvature during construction without the formation of bending edges, thus facilitating flow through the shaft and the discharge gallery.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • WATER QUALITY IN BATRAN, KARAKOUDAROU, NAWARI AND TISSAROU DAM RESERVOIRS
           IN THE DEPARTMENT OF ALIBORI IN THE NORTHERN BENIN

    • Authors: R.M. SOUROGOU, F.C.C. HOUNTONDJI, S. ZAKARI, A.Y.J. AKOSSOU
      Abstract: Dams have been playing very important socioeconomic role for people living in underdeveloped countries. This study evaluates the water quality of four dams (Batran, KarakouDarou, Nawari and Tissarou) in the department of Alibori in northern Benin through physical, chemical and biological parameters. Physical properties including pH, conductivity, temperature, and turbidity were evaluated in situ; and chemical analyzes such as ammonium, bicarbonates, calcium, chlorides, fluorides, magnesium, nitrites, nitrates, phosphates were performed in the laboratory from water samples taken in January. The results indicate that the four dam’s waters did not meet the physical, chemical or biological standards. The water quality indices (WQI) were greater than 50 in most of the dams except Batran; however, we identified four water quality classes: good ( >25 – 50), bad( >50 – 75), very bad(>75 – 100) and out of use ( ˃ 100). An out of use water was observed in the Karakou Darou dam (IQE > 100), and poor quality water (50 ≤ IQE ≤ 75) occurred in Batran, Nawari and Tissarou. Abundant fecal coliforms were found in all the dams, but only Escherichia coli occupied water from Tissarou dam. This information can be important for the proper management of the water from Batran, KarakouDarou, Nawari and Tissarou dams; and to preserve health of neighboring populations of the dams.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • NEW THEORETICAL CONSIDERATIONS ON THE FLOW PARAMETERS IN THE TRANSITION
           AND SMOOTH REGIMES

    • Authors: B. ACHOUR, L. AMARA
      Abstract: Transition and smooth flows are often encountered during experiments in the laboratory and even sometimes in the field. The transition domain occupies a fairly large space in Moody's diagram while the smooth flow is reduced to a curve which represents the lower envelope of the diagram. The characteristic length corresponding to these two domains, such as the width of a channel or the flow depth, is currently calculated by an iterative process such as the trial and error method. To overcome this drawback, the present study presents a direct method consisting of first calculating the characteristic length in the domain assumed to be rough. The characteristic length sought is equal to this length corrected for effects of a dimensionless correction coefficient. In the transition domain, the correction coefficient depends both on the Reynolds number and on the relative roughness corresponding to the rough domain while for the smooth regime the correction coefficient depends only on the Reynolds number in the rough zone. Expressions for Reynolds numbers in the transition and smooth domains are also presented. The governing relationships are practical and differ from those usually found in the literature. Practical numerical examples are provided to show both how the method should be applied and the evidence for its reliability.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • MODELLING OF STREAM FLOWS OF A FORESTED CATCHMENT IN THE TROPICS USING
           HEC-HMS

    • Authors: H.M.S. FERNANDO, M.P. GUNAWARDENA, M.M.M. NAJIM
      Abstract: Singharaja and adjacent forested areas drains into two major rivers in Sri Lanka and they are crucial sources of drinking water downstream and contributes to frequent floods. This study was done to model stream flows and evaluate the applicability of the model for a dense tropical forest catchment. Hydrological model HEC-HMS was calibrated (2009-2014) and validated (2015-2019) for river flow simulation and evaluated using the residual method. R2 values of the best calibration and validation were 0.7070 and 0.7797, respectively. In the best calibration, 73.7% and 92.3% of residuals fell within +1SD and +2SD, and in the best validation, 74.3% and 93.6% of residuals fell within +1SD and +2SD, respectively. The results indicated that HEC-HMS can be used to simulate flows of a catchment covered with tropical forests reliably, especially during high rainfall and flow conditions. The model could be used to model rainfall and flow events leading to floods with greater accuracy than previous applications in other Sri Lankan catchments. It further confirms that the HEC-HMS model is a good tool to predict flows from a catchment covered with dense natural evergreen forests and planted forests in the tropics. HEC-HMS can reliably be used as a tool in biodiversity conservation in the tropical forest and streams fed by the catchment as these streams are the habitat for many endemic and endangered life.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • NEW THEORETICAL CONSIDERATIONS ON THE ROUGH TURBULENT FLOW PARAMETERS

    • Authors: B. ACHOUR, L. AMARA
      Abstract: The field of rough turbulent flow occupies an important place in the practical applications of hydraulic engineer. It is for this reason that the present study is interested in the most important parameters of this flow namely the characteristic length, the average velocity, the Reynolds number, and the hydraulic diameter. To express these parameters, new theoretical considerations are developed based on the combination of Darcy-Weisbach and Nikuradse rational relationships. The implicit form of the equation which governs the characteristic length has been transformed into an explicit power law by a correlation procedure with a very high coefficient of determination. An exact analytical solution in terms of Lambert function was also developed. Thus, the characteristic length can be evaluated explicitly provided the flow rate, the absolute roughness, the channel bed slope and the aspect ratio of the wetted area are given, which is generally the case in practice. The explicit characteristic length equation has been judiciously used to derive the mean flow velocity relationship. This is in the form of that of Manning-Strickler but with slightly different coefficients. The interest of the new velocity model lies in the fact that the resistance coefficient has been determined analytically contrary to the empirical nature of the Manning and Strickler coefficients. The resistance coefficient is explicitly related to absolute roughness and gravity through a physically justified relationship. The last two parameters studied namely the Reynolds number and the hydraulic diameter were deduced from mathematical manipulations and expressed by simple and practical relationships which do not contain the characteristic length.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • GEOLOGICAL AND HYDROGEOLOGICAL REAPPRAISAL OF THE GUARANÍ AQUIFER
           SYSTEM IN THE URUGUAYAN AREA

    • Authors: E. MERONI, G. PIÑEIRO, P. GOMBERT
      Abstract: The lack of knowledge of water resources in a region and the absence of obvious symptoms of their deterioration do not favour the establishment of effective management mechanisms for their preservation. This problem is exacerbated in the case of transboundary aquifers such as the "Guaraní Aquifer System" (GAS), a large multi-layered aquifer system in central-eastern South America. We present here a reappraisal of some important aspects that contribute to a better knowledge of the GAS in the Uruguayan area, as for instance an integrated stratigraphic, chronostratigraphic and sedimentological (paleoenvironmental) study of the sequence that encloses their constituent aquifers in order to identify the main hydraulic, hydrochemical and hydrogeological paths that define this fundamental resource. Moreover, we also provide a well-supported re-evaluation of the SAG outline, by including the outcropping areas of the San Gregorio-Tres Islas and the Yaguarí and Cerro Conventos aquifers in the Cerro Largo County. Some hydraulic interconnections between the GAS aquifers has been previously detected but more work needs to be done to evaluate this behaviour within already proposed conceptual flow models. Some evidence for aquifer-river relationships between the GAS and the main rivers such as the Paraná, Uruguay and their tributaries is herein also discussed.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • USE OF GENE-EXPRESSION PROGRAMMING TO ESTIMATE MANNING’S ROUGHNESS
           COEFFICIENT FOR A LOW FLOW STREAM

    • Authors: B. CHAPLOT, M. PETERS, P. BIRBAL, J.H PU, A. SHAFIE
      Abstract: Manning’s roughness coefficient (n) has been widely used to estimate flood discharges and flow depths in natural channels. Therefore, although extensive guidelines are available, the selection of the appropriate n value is of great importance to hydraulic engineers and hydrologists. Generally, the largest source of error in post-flood estimates is caused by the estimation of n values, particularly when there has been minimal field verification of flow resistance. This emphasizes the need to improve methods for evaluating the roughness coefficients. Trinidad and Tobago currently does not have any set method or standardised procedure that they use to determine the n value. Therefore, the objective of this study was to develop a soft computing model in the calculation of the roughness coefficient values using low flow discharge measurements for a stream. This study presents Gene-Expression Programming (GEP), as an improved approach to compute Manning’s Roughness Coefficient. The GEP model was found to be accurate, producing a coefficient of determination (R2) of 0.94 and Root Mean Square Error (RSME) of 0.0024.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • WATER AGE AND LEAKAGE IN RESERVOIRS; SOME COMPUTATIONAL ASPECTS AND
           PRACTICAL HINTS

    • Authors: H. HARIRI ASLI, S. NAZARI
      Abstract: The existence of reservoirs in the water system guarantees the stability of the system. Therefore, the level of water stored in the reservoirs should always be kept at optimum level in the water system. Inside the reservoirs, the mixing operation may not perform well. The water reservoirs with low delivery time, meet to the stationary water in the corners of the reservoirs. This can lead to water corruption and increase the risk of water leakage. Another factor that can increase the water retention time in the reservoirs is the shape and geometry of the reservoirs. The main purpose of the present work is to determine the impact of reservoir design specifications on the probability of water leakage and economic losses resulting by it. In this regard, this work focused on the effect of dimension, number, and optimal location for locating baffles on water spoilage factors and probability of water leakage. As a result, the use of three baffles with the same intervals perpendicular to the flow, created the least water retention time and water age. This case is the most optimal option to reduce economic losses and water leakage probability between the investigated options.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • PERFORMANCE ENHANCEMENT IN DISCHARGE MEASUREMENT BY COMPOUND BROAD CRESTED
           WEIR WITH ADDITIVE MANUFACTURING

    • Authors: K.H. KULKARNI, G.A. HINGE
      Abstract: Manufacturing compound weirs for exact discharge measurement has been a challenge, according to studies so far. The length of the weir crest (L), weir height, and weir width all affect the efficacy of compound broad crested weirs as flow monitoring devices. As a result, the flow characteristics of a given flume are determined by changes in weir geometry, particularly the discharge coefficient (Cd), which varies proportionally with the h/L ratio. For varying h/L levels, many researchers have maintained an average range of Cd. The experimental and Computational Fluid Dynamics simulations for measuring discharge by compound broad crested weir are presented in this work. Validation in the results is achieved using CFD FLOW 3D software. For enhanced accuracy in free surface simulations, the model uses the renormalized group (RNG) approach with the volume of fluid (VOF) method. Laboratory models were employed in an attempt to analyse and validate the CFD model. The model is fabricated using PVC material first and later resorted to additive manufacturing for targeting accurate discharges. The shape of the compound broad crested weir was modified to achieve constant Cd by comparing three-dimensional computational fluid dynamics models to experimental measurements. The performance of the CBC weir for precise measurement of a wide range of discharges is confirmed by numerical simulations and experimental measurements, with a reasonably constant design input value of discharge coefficient of 0.6. When compared to empirical methods, CFD-based weir geometry optimization produces more exact model predictions. Moreover, manufacturing this optimized model with 3D printing technology using Poly Lactic Acid plastic material has validated the weir performance with accurate estimates between theoretical, experimental and CFD outputs.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • NON-REVENUE WATER (NRW) AND 3D HIERARCHICAL MODEL FOR LANDSLIDE

    • Authors: H. HARIRI ASLI, A. HOZOURI
      Abstract: The landslide is triggered by a specific event such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others. The landslide can cause Non-revenue water (NRW) in water reservoirs, water transmission pipelines and water distribution network.  In present work, based on the analytical methods for landslide phenomenon, the water facility accidents and water loss were investigated for the highland city named Masal in the north of Iran. The Geospatial Information System (GIS) as a conceptualized framework provides the ability to capture and analyses spatial and geographic data in present work. The ArcGIS software analyzed the geospatial data. The Analytic Hierarchy Process (AHP) as an analysis algorithm was applied for finding the percentage of landslides based on the GIS. As a final result, the slopes of 10 to 30 degrees accounted for the highest percentage of landslides. These slopes were assumed as hazard and important cases for the water facilities disaster
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
  • GROUNDWATER VULNERABILITY ASSESSMENT IN THE M’ZAB VALLEY - SOUTHERN
           ALGERIA

    • Authors: R. ZEGAIT, B. REMINI, H. BENSAHA
      Abstract: The water pollution risk is considering a topical subject in Algeria and throughout the world, especially in view of the problems of water scarcity and the climate change phenomena. The infiltration of untreated urban waste into the subsoil presents a major risk of pollution for groundwater close to the surface and which constitutes an important source of water in arid areas.In the Algerian Sahara, the M'Zab valley has recently experienced a critical health and environmental situation, the latter is due to major urban discharges into nature without any means of protection and preservation and especially at El-Atteuf oasis in the downstream of the M'Zab wadi. In this regard, the main objective of this work is to assess the intrinsic vulnerability to pollution of the phreatic aquifer in the M'Zab valley. In this work and through several parameters, the vulnerability study was carried out by applying three methods (GOD, DRASTIC and SINTACS) using piezometric observations for 62 wells. The results are presented in the form of several maps developed by GIS. These maps can be considered as a helper tool for planners and managers to improve the environmental situation of the M'Zab valley.
      PubDate: 2021-12-26
      Issue No: Vol. 48 (2021)
       
 
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