English Larhyss journal is an international peer-reviewed journal published by the research laboratory in subterranean and surface hydraulics since 2002. The scope of the Journal covers the fields in which the teams of the research laboratory in subterranean and surface hydraulics are active. Original research papers, short communications and critical reviews from all fields of science and engineering related to water are welcomed. Larhyss journal is devoted to the rapid publication of research in water engineering, acting as a link between the diverse research communities and practitioners in the field of hydraulics. The journal accepts manuscripts exclusively in English. Larhyss journal publishes articles on all aspects of hydraulics including hydrology, water and wastewater treatment, surface, and groundwater protection, flow in channels, and pipes, hydraulic modeling… Français LARHYSS journal est une revue scientifique internationale publiée par le laboratoire de recherche en hydraulique souterraine et de surface depuis 2002. La portée du Journal couvre les domaines dans lesquels les équipes du laboratoire de recherche en hydraulique souterraine et de surface sont actives. Des documents de recherche originaux, des communications brèves et d'analyses critiques de tous les domaines de la science et de l'ingénierie liées à l'eau sont les bienvenus. LARHYSS Journal est consacré à la publication rapide de la recherche en ingénierie de l'eau, agissant comme un lien entre les communautés de recherche diverses et praticiens dans le domaine de l'hydraulique. La revue accepte des manuscrits exclusivement en anglais LARHYSS journal publie des articles sur tous les aspects de l'hydraulique, y compris l'hydrologie, le traitement des eaux, la protection des eaux souterraines et de surface, ecoulements dans les canaux et conduites, modelisation hydraulique...








Sourogou Masso Roger,  Hountondji Fabien,  Sissou Zakari,  Akossou Arcadius, 

Résumé: 1.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 dams 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. 2.RESUME Les barrages jouent un rôle socioéconomique très important dans la vie des populations des pays sous-développés. Cette étude a évalué la qualité de l’eau de quatre barrages (Batran, KarakouDarou, Nawari et Tissarou) dans le département de l’Alibori au Nord Bénin à travers leurs paramètres physiques, chimiques et biologiques. Ainsi, des observations in situ de paramètres physiques (pH, Conductivité, Température, Turbidité) et des prélèvements d’eau réalisés au mois de janvier pour des analyses chimiques (dosages d’ammonium, de bicarbonates, de calcium, de chlorures, de fluorures, de magnésium, de nitrites, de nitrates, de phosphates) de laboratoire ont été effectués. Les résultats obtenus indiquent que les eaux testées ne répondaient pas aux normes en vigueur aussi bien physiques, chimiques que biologiques. Elles étaient caractérisées par des indices de qualité de l’eau (IQE) supérieurs à 50 dans la plupart des barrages, excepté le barrage de Batran. Quatre classes de qualité (bonne, mauvaise, très mauvaise et hors usage) ont ainsi été identifiées. L’eau hors usage est observée dans le barrage de Karakou Darou (IQE >100). L’eau de mauvaise qualité (50 ≤ IQE ≤ 75) a été observée à Batran, Nawari et Tissarou. Tandis que, l’eau de très mauvaise qualité (75 ≤ IQE ≤ 100) a été observée dans les barrages de Batran, de Nawari et dans la zone proche de la digue de Tissarou. On note la présence importante des coliformes fécaux dans tous les barrages et des Escherichia coli uniquement dans le barrage de Tissarou. Ces informations sont importantes pour une bonne gestion des eaux de ces barrages et pour la préservation de la santé des populations riveraines.

Mots clés: Dam water, feacal coliforms, Water quality index, North Benin. Eau de Barrage, coliformes fécaux, Indice de qualité de l’eau, Nord Bénin.


Abderrezak Brakeni,  Alim Petrovic Guryev,  Buchra Haek, 

Résumé: 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-section 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.

Mots clés: Shaft spillways ; polygonal section ; receiving funnel ; vacuum ; erosion by cavitation.


Fernando Melisha Shavindi,  Gunawardena Medhisha Pasan,  Najim Mohamed Mujithaba Mohamed, 

Résumé: 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.

Mots clés: HEC-HMS ; Forested Catchment ; Flows ; Simulation ; Flood ; Calibration ; Validation


Achour Bachir,  Amara Lyes, 

Résumé: 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.

Mots clés: Characteristic length ; transition domain ; smooth regime ; correction coefficient ; friction factor


Achour Bachir,  Amara Lyes, 

Résumé: 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

Mots clés: Rough turbulent flow ; Moody diagram ; Manning-Strickler formula ; relative roughness ; Darcy-Weisbach friction factor ; Nikuradse equation ; characteristic length


Hariri.asli Hossein,  Nazari Sajad, 

Résumé: 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 the optimum level in the water system. Inside the reservoirs, the mixing operation may not perform well. The water reservoirs with low delivery time, meet 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 from it. In this regard, this work focused on the effect of dimension, number, and optimal location for locating baffles on water spoilage factors and the 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.

Mots clés: computational modeling ; reservoir ; baffle ; water retention time ; Non Revenue Water


Chaplot Barkha,  Peters Makama,  Birbal Prashant,  Pu Jaan,  El-shafie Ahmed, 

Résumé: 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 standardized 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.

Mots clés: Gene-Expression Programming ; Manning’s Roughness Coefficient ; Open-Channel Flow


Kulkarni Ketaki,  Hinge Ganesh, 

Résumé: 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.

Mots clés: Additive Manufacturing ; 3D Printing ; Compound Broad Crested Weir ; Discharge Coefficient ; Flow 3D ; CFD


Zegait Rachid,  Remini Boualem,  Bensaha Hocine, 

Résumé: 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.

Mots clés: Urban discharge ; Groundwater pollution ; Vulnerability methods ; Mapping