LARHYSS Journal P-ISSN 1112-3680 / E-ISSN 2521-9782
Larhyss Journal is an international peer-reviewed journal published quarterly (4 Issues per year) by the research laboratory in subterranean and surface hydraulics (University of Biskra, Algeria) since 2002. All information about the Journal can be found by clicking on the "About" button located at the top left of the page. 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 encompassing aspects of hydraulics including hydrology, water and wastewater treatment based on modern and advanced processes except for the activated or reactivated carbon process which does not bring anything new to water treatment processes, surface and groundwater protection, free and pressurized flows in canals and conduits, the impact of climate change on water resources, Modeling of aquifers and the transport of solutes, design and operation of hydraulic structures such as dams, spillways, ancestral hydraulic structures, underground infrastructures such as sewerage pipes and inferoflux dams, the design, optimization of the performance and safety of hydraulic structures, coupling of hydraulic and economic models applied to development studies and risk forecasting, Hydraulic modelling, etc. However, Larhyss Journal does not publish articles on simulating problems through the use of software of any type. Furthermore, Larhyss Journal does not publish classical articles on water quality, whatever the method or process used. Only articles on water quality that rely on both innovative Technology and analysis processes, which have never been published elsewhere, are eligible for publication in Larhyss Journal. Similarly, Larhyss Journal no longer publishes articles on the hydraulic jump, including the design of Stilling basins, Stepped spillways, or any of the energy dissipation structures; Moreover, issues related to energy dissipation are not published by Larhyss Journal. Furthermore, Larhyss Journal no longer publishes articles on solid transport and the silting of hydraulic structures. In addition, Larhyss Journal does not publish articles related to Hydrogeology. The function of Larhyss Journal is to publicize original or substantive research work on fundamental or applied hydraulics, and thus to contribute to the scientific debate between specialists; it thus differs from journals intended for popularization. Larhyss Journal publishes discussions on all articles since its inception. The discussions are not limited in time. The article published in Larhyss Journal in the form of discussion has become essential in the dialogue between researchers. It identifies unanswered questions, describes work in progress, gives conclusions of recently completed research, describes applications of research, and reviews the state of knowledge. Why Larhyss Journal is different from several other journals? Larhyss Journal is exclusively dedicated to problems related to hydraulic sciences. It is not a multidisciplinary journal as most journals are. Larhyss Journal is not published by a classic publishing house or by an association. It is edited by a hydraulic research laboratory that is at the heart of water-related problems. Common themes in journals dealing with water sciences, modern and advanced water treatment processes, hydrology, In addition to these themes, Larhyss Journal publishes articles related to desalination plants which remain a means of the future account of the scarcity of ground and surface water due to climate change. Larhyss Journal has published and still publishes articles on water treatment based on local raw material which increasingly shows its effectiveness and its ability to establish itself as an essential process, especially for developing countries that have significant deposits of these local materials (bentonite, lime, clays, biosorbents, peels of various fruits), except for the activated or reactivated carbon treatment process, whatever its physical state, which does not bring anything new to the treatment processes. In addition, the treatment using local raw material is ecological giving it the quality of green treatment. Treatments based on local materials do not require a large investment, it is economical. Among the favourite themes of Larhyss Journal are hydraulic works that use the capacity of water to produce energy such as hydroelectric stations. Hydroelectric energy has multiple advantages. Hydro-energy is renewable, we cannot exhaust our resources. Hydraulic energy is green and non-polluting, it is reliable, flexible, and safe. Larhyss journal also publishes articles on hydraulic works that neutralize the harmful effects of water, such as dams and spillways of any type... Larhyss journal is among the very few journals that publish articles on the Foggaras, these ancestral ingenious systems for collecting groundwater conveyed through underground galleries that return water for irrigation purposes, without any motorization and therefore without energy consumption. Despite advances in research on these structures, their operation and socio-economic impact have not yet revealed all their secrets. Larhyss Journal continues to publish the latest developments on this topic. This is the outstanding theme of the journal given the huge number of readings to its credit. Larhyss journal also publishes articles on the evaporation of bodies of water such as that of a dam. These studies are important as they focus on the increase in the water resource stock capacity, especially in arid or semi-arid areas. Many countries are affected by this problem. This is not often addressed by water science journals. Another theme that Larhyss Journal favours, and which is not covered much by other journals on water, is the impact of climate change on water resources. In addition to the environmental and health impacts, climate change is likely to cause a profound disruption of the availability of water resources affecting, consequently, many sectors such as industry, energy production, agriculture, drinking water, sanitation, etc. Regarding drinking water and sanitation, global warming negatively impacts the quantity by increasing water stress and also the quality by the multiplication of pathogens, the salinization of soils and groundwater, etc. of water resources Larhyss journal is also different from many other journals in that it allows discussion of all of its published articles, even if these are peer-reviewed. The research is based on discussion and exchange that allow other perspectives to emerge. On the other hand, diffusion is the pivot on which this exchange should be based. Thus, Larhyss Journal makes its contents visible and accessible without asking either readers or authors to pay. OPEN ACCESS POLICY This journal provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.
Biskra University, PO Box 145, 07000, Biskra, Algeria
EFFECTS OF SURFACE GRAVITY WAVES ON RIGID DAMS
This study, based on two-dimensional flow theory, focuses on calculating and analyzing the effects of surface gravity waves on the hydrodynamic pressure distribution of a partially inclined rigid dam subjected to short-term horizontal harmonic excitation at its base, considering the combined effects of surface gravity waves, fluid compressibility, and viscosity within a unified Trefftz-based semi-analytical framework, with a detailed parametric investigation of their coupled influence on hydrodynamic forces. The Trefftz numerical method is used to solve the reduced wave equation. The advantage of this boundary value calculation approach lies in limiting the number of unknowns to the number of Trefftz test functions. Thus, the computational effort is independent of the reservoir area. The unknown coefficients of the problem are obtained by a continuous least-squares treatment of the unsatisfied boundary condition at the dam-reservoir interface. The Newton-Raphson method is then applied to numerically solve the transcendental dispersion relation, thereby integrating the effects of surface gravity waves. The results obtained concern hydrodynamic pressures, shear forces, and the corresponding overturning moments. The effects of surface waves are particularly evident at low frequencies. Although significant, they remain less influential than the inclination of the upstream face. The combined effect is also evaluated. At low frequencies, a substantial reduction in pressure forces is observed. However, as the excitation frequency increases, the effect of surface waves gradually diminishes, giving way to the effects of viscous damping, which becomes apparent near resonant frequencies and significantly reduces the resonance peaks. The results from this approach are very consistent with the trends reported in the specialized literature.
A PROBABILISTIC TWO-REGIME GOVERNING MODEL FOR PREDICTING INFLOW SUSPENDED SEDIMENT CONCENTRATION IN DAM RESERVOIRS
Accurate prediction of inflow suspended sediment concentration is a critical prerequisite for the effective management of sedimentation in dam reservoirs. However, most existing approaches rely on classical formulations that are not predictive by construction and suffer from fundamental conceptual and numerical limitations. In particular, widely used log-scale models introduce an arbitrary offset parameter to circumvent the indetermination of the logarithm at zero concentration, implicitly merge zero-transport and active-transport conditions into a single regime, and induce bias when back-transforming predictions to the physical concentration scale. Likewise, traditional sediment rating curves of the form C = aQb lack dimensional homogeneity, provide no probabilistic interpretation, and are unable to represent the intermittent, event-driven nature of sediment transport. This study develops a new probabilistic two-regime governing model for predicting inflow suspended sediment concentration that explicitly addresses these shortcomings. The proposed framework is derived from first principles by recognizing that sediment time series exhibit two physically distinct regimes: (1) a zero or negligible transport regime, and (2) an active transport regime characterized by strictly positive concentrations. The occurrence of zero sediment is modeled probabilistically through a Bernoulli process, whose probability is linked to hydrometeorological predictors via a logistic formulation. Conditional on active transport, sediment magnitude is modeled using a positive-regime formulation based on an inverse hyperbolic sine transformation, which behaves linearly at low concentrations and logarithmically at high concentrations while remaining well-defined at zero without introducing any arbitrary correction parameter. The resulting predictive model combines the probability of occurrence and the conditional sediment magnitude into a single closed-form forecast expressed as a probability-weighted expectation. All model components are derived explicitly, parameters are estimated through well-defined likelihood-based or least-squares procedures, and the scale parameter governing the transformation is shown to have a clear physical interpretation. A fully worked numerical example demonstrates the transparency, internal consistency, and practical implementation of the proposed approach. Compared to classical log-scale and rating-curve methods, the new two-regime model offers several decisive advantages: it removes the need for ad hoc numerical fixes, preserves dimensional consistency, separates occurrence and intensity mechanisms, provides a probabilistic interpretation of predictions, and directly targets future sediment concentration at a specified lead time. The proposed framework therefore constitutes a robust and physically consistent alternative for predictive sediment modeling and reservoir sediment management.
FLOW-DURATION-FREQUENCY CURVES IN HIGH-FLOW CONDITIONS. A STRATEGIC DECISION-MAKING TOOL FOR SELECTED STREAMS IN THE CONSTANTINOIS COASTAL BASIN, NORTHEASTERN ALGERIA
Effective management of surface water resources in the Constantinois Coastal Watershed (northeastern Algeria) is challenged by strong climatic variability and complex geomorphological conditions. This semi-arid Mediterranean basin (11,509 km²) is characterized by highly variable and intermittent flow regimes driven mainly by episodic runoff. Conventional hydrological approaches, such as descriptive statistics and rating curves, are inadequate as they do not simultaneously account for flow duration and frequency. This study develops a frequency-based approach using hydrometric discharge series, whose observation periods vary between stations and extend approximately from 1946/1947 to 2006/2007, to construct Discharge-Duration-Frequency (QdF) curves. Mean discharges calculated over successive durations were associated with their occurrence frequencies, following a framework analogous to Intensity–Duration–Frequency (IDF) curves used in rainfall analysis. Results indicate an average annual runoff of approximately 3,250 hm³. In the Kebir-East wadi, 30-day accumulated runoff volumes are estimated at about 160 and 196 hm³ for return periods of 10 and 20 years, respectively, with uncertainties below 20% based on the Generalized Extreme Value (GEV) distribution. This work offers an original contribution by extending the QdF approach to intermittent Mediterranean hydro-systems, where hydrological variability and data limitations remain critical constraints. By integrating duration and frequency within a unified probabilistic framework and applying GEV-based synthetic data generation, the proposed method enhances the robustness of flow characterization. It provides a transferable and decision-support tool for water resources management, flood risk mitigation, and hydraulic infrastructure design in semi-arid regions facing increasing hydroclimatic variability
GEOSTATISTICAL MODELLING OF HYDRODYNAMIC PARAMETERS OF ALLUVIAL AQUIFERS USING ORDINARY KRIGING
Groundwater resources are the most conventional source usable in arid and semi-arid regions southeastern Algeria (Biskra city). This region is known for its many oases and famous dates and has been affected by drought in recent years. The extreme climate and less frequent rainfall have contributed to a decrease in the availability of groundwater. Therefore, estimating and mapping Transmissivity (T) and Hydraulic conductivity (K) are essential for understanding and evaluating the hydraulic properties of alluvial aquifers in the Biskra study area. In this context, the present research applies geostatistical techniques to estimate the spatial variability of hydrodynamic parameters using measurement data to yield a probability map. The estimation of hydrodynamic parameters T and K was mapped by ordinary kriging, where the best-fitted variogram is a Spherical model for Transmissivity and a Gaussian model for log10 (Hydraulic conductivity). It was validated by the cross-validation test with the root mean square error (RMSE). The results show that the geostatistical approach using ordinary Kriging is an important tool for estimating the spatial variability of hydrodynamic parameters in alluvial aquifers.
ASSESSMENT AND VALIDATION OF GROUNDWATER POTENTIAL ZONES USING ANALYTICAL HIERARCHY PROCESS (AHP) AND OBSERVED YIELD DATA IN THE CENTRAL KHARUN RIVER BASIN, CHHATTISGARH, INDIA
Groundwater is an essential natural resource used in multiple grounds such as municipal, agricultural, and industrial water supply. To sustainably manage groundwater resources, it is important to assess groundwater potential zones (GWPZs). This study adopted a combination of the Analytical Hierarchy Process (AHP) and Geographic Information System (GIS) techniques to systematically assess and map groundwater availability zones within the Central Kharun River basin, which is located in parts of Durg and Raipur Districts of Chhattisgarh, India. Thematic layers are created for nine significant factors, including depth to groundwater level, lithology, rainfall, soil, slope, geomorphology, lineament, drainage density, and land use and land cover (LULC) of the study region. These thematic layers are prepared by using GIS techniques. Based on relative contributions of each factor in groundwater occurrence, weights have been assigned using the AHP method. The model results have been validated against 15 observed well yields from monitoring wells by plotting the receiver operating characteristic (ROC) curve and area under the curve (AUC). Overall, the study classifies the basin into three distinct GWPZs: low, moderate, and high. Sensitivity analysis (SA) highlights that groundwater level exhibits highest mean sensitivity index (SI = 0.39), followed by lithology (SI = 0.24) and rainfall (SI = 0.15), indicating them as the most significant factors that influence GWPZs. The findings of the analysis demonstrate the effectiveness of the integrated AHP-GIS approach and provide valuable guidance for the planning and sustainable resource management of groundwater resources.
AN ACCESSIBLE POTENTIAL ENERGY BUDGET (APEB) FOR DENSITY CURRENTS IN STRATIFIED DAM RESERVOIRS
Density currents in stratified dam reservoirs play a central role in sediment transport, water quality, and reservoir operation, yet existing models primarily describe how such currents evolve once established rather than whether they can persist as coherent flows. Classical gravity-current formulations rely on local force balances, geometric intrusion criteria, or empirical entrainment closures, and do not explicitly quantify the energetic feasibility of sustaining a density current in a stratified environment. In this study, we introduce an Accessible Potential Energy Budget (APEB) framework that explicitly links reservoir stratification to the mechanical energy available to drive and maintain density currents. The word “budget” is used in a strict physical and energetic sense, accounting of sources and sinks of mechanical energy derived from buoyancy. Thus, the term "Budget" used in this study should be understood as "Balance, Accounting, or Quantification”. Starting from classical layer-averaged formulations for mass, buoyancy dilution, and momentum, we identify the neutral depth as a stratification constraint and define a new quantity: the accessible buoyancy work per unit mass, obtained by integrating the ambient density profile along the vertical adjustment path of the inflow. This quantity converts a measured density stratification into an energetic scale directly comparable to dissipation processes. By multiplying the accessible buoyancy work by the inflow mass flux, we obtain a buoyancy-derived power input that represents the maximum mechanical energy available from stratification. We then introduce an explicit decomposition of the dissipation demand, including (1) internal turbulent mixing and entrainment power, (2) bed-friction losses, and (3) interfacial drag with the ambient fluid. The resulting APEB persistence criterion states that a coherent density current can exist only if accessible buoyancy power exceeds the total dissipation demand. A worked numerical example using real reservoir temperature-depth data demonstrates how the framework is applied in practice. The example shows how the shape of the ambient density profile strongly controls the accessible energy through a dimensionless stratification factor, explaining why currents with identical inflow density and discharge may persist in some reservoirs but collapse rapidly in others. The proposed framework extends classical density-current theory by introducing an explicit energetic gatekeeper for current formation and persistence. It unifies underflows and interflows within a single energy-based perspective and provides a physically interpretable criterion that can be evaluated directly from field data, offering new predictive capability for reservoir management and environmental hydraulics.
SIMPLIFIED MODEL OF REGIONAL FLOWS IN THE LOWER AND MIDDLE OUEME VALLEY IN BENIN
Models of geothermal reservoirs, essential tools for estimating resources, simulating subsurface behavior, and optimizing heat exploitation, have been developed by several researchers. Pressure and temperature data have been determined for the Hêtin-Sota geothermal reservoir, but regional flow data are still lacking. This article has enabled the development of a simplified model of the Hêtin-Sota geothermal reservoir. The objective of this study is to understand the regional flow dynamics in the large-scale underground reservoir (aquifer), i.e. to map the flow directions, in order to improve the management of groundwater resources in the Lower and Middle Ouémé Valley, to which the locality of Hêtin-Sota belongs. The natural regional flow of the Hêtin-Sota geothermal reservoir aquifer was assessed using piezometric, groundwater depth, and borehole depth maps of the Benin coastal sedimentary basin. This map, extracted from the aquifers of the Benin coastal sedimentary basin, was produced in 2024 by Benin Water Directorate (DGEau). The average depth of the static level, that is, the depth of the water measured from the ground surface, is estimated to be less than 10 m. The hydraulic gradient, which is the decrease in hydraulic head (total energy) per unit length in the direction of water flow, was estimated at approximately 0.2%, graphically derived from the piezometric map extract. Mapping the depth of the reservoir in this basin, based on iso-depth curves, indicates that the Cretaceous sand aquifer of the hydrogeological unit to which Hêtin-Sôta belongs is located at a depth of approximately 400 m. This limit value confirms the depth of the Hêtin-Sôta artesian thermal well, which is 417 m. The piezometric map, which presents a reserve of water contained in the pores of saturated aquifer rocks, located below the surface of the Hêtin-Sota aquifer allowed for the representation of aquifer flow at the regional scale but not at the local scale of the study area. Thus, four (04) radiating directions (A, B, C and D) were identified, confirming the phenomenon of radial flow towards the study area. These directions indicate a radial flow from the recharge zone (high loads: 70 m) towards the depressions (low loads: 5 m), favoring high flow rates at the boreholes, confirmed by the artesian and thermal borehole of Hêtin-Sota delivering a flow rate of 60.16 m³/h before heading towards the bed of the Ouémé river. The hypothesis of relatively homogeneous regional flows of low amplitude, characteristic of the Hêtin-Sota reservoir alone, appears too restrictive. These results, which are currently partial, serve both as support for and as a constraint on the flow model because of the variation in water temperature which induces convection flows, which do not follow the pressure gradient in a simple way, given that it is a geothermal reservoir (water temperature at the top of the borehole of 53°C and above 30°C).
SPATIO TEMPORAL ASSESSMENT OF LULC CHANGE IMPACTS ON BASIN HYDROLOGY IN THE INDIAN UPPER GODAVARI BASIN
This study investigates the spatiotemporal dynamics of land use and land cover (LULC) change and its implications for basin-scale hydrological behaviour in the Upper Godavari Basin, Maharashtra, India. Multi-temporal satellite-derived LULC datasets for 2018, 2021, and 2024 were analyzed to quantify changes in major land-cover classes and identify dominant transformation trends within the basin. The results reveal a consistent increase in built-up area accompanied by a gradual decline in cropland, indicating progressive urbanization and anthropogenic modification of the landscape. Minor variations were also observed in water bodies, tree cover, and range land. These land transformations are hydrologically significant, as the expansion of impervious surfaces reduces infiltration capacity and increases surface runoff, particularly during the monsoon period. Simultaneously, changes in vegetation cover influence evapotranspiration processes, soil moisture retention, and the overall water balance of the basin. The observed trends suggest a shift toward a more rapid hydrological response, with potential implications for flood generation, groundwater recharge, and seasonal water availability. The study highlights the importance of integrating LULC dynamics into basin-scale water resources planning and watershed management strategies. The findings provide a scientific basis for understanding how recent land transformations may influence hydrological processes in semi-arid river basins and support informed decision-making for sustainable water resource management in the Upper Godavari Basin.
A NOVEL RIGOROUS EXPLICIT FRAMEWORK FOR CRITICAL FLOW DEPTH IN TRAPEZOIDAL OPEN CHANNELS
The determination of critical flow depth in trapezoidal open channels remains a classical yet inherently implicit problem in hydraulic engineering, as the governing relationship is strongly nonlinear and does not admit a closed-form solution in terms of elementary functions. This study develops a rigorous, unified, and practically implementable framework that overcomes this limitation by combining exact analysis with highly accurate explicit formulations. Starting from the classical critical-flow condition and trapezoidal geometry, a compact dimensionless governing equation is derived using physically meaningful parameters, namely a shape parameter and a normalized discharge parameter. Through an appropriate change of variables, the problem is recast into a canonical algebraic form equivalent to a trinomial sextic equation with a unique physically admissible root, thereby establishing a rigorous exact foundation. On this basis, two complementary solution strategies are proposed. First, a quasi-exact computational approach is developed using a normalized formulation combined with a highly efficient initial estimate and a one-shot Newton iteration, yielding a maximum deviation strictly below 3.6 10-5 % over the entire admissible range. Second, a fully explicit analytical formulation is derived through a Transformed Asymptotic-Taylor Reconstruction Method, producing a closed-form expression for the governing parameter with a maximum deviation of only 7.1 10-6 %. The proposed formulation preserves the correct asymptotic behavior and rigorously recovers the classical rectangular and triangular channel solutions as limiting cases, ensuring full physical consistency. A key feature of the study is that the developed models remain valid for unsymmetrical trapezoidal channels through the introduction of an equivalent side-slope parameter, which constitutes an exact transformation rather than an approximation. The resulting formulations eliminate the need for iterative procedures, graphical methods, or empirical fits, while maintaining quasi-exact accuracy. The study thus provides a new generation of analytical tools that combine mathematical rigor, computational efficiency, and broad applicability for hydraulic design and analysis.
PERFORMANCE AND ASSESSMENT OF FUTURE WATER MANAGEMENT USING THE WEAP AND RRV INDICATORS IN MAGHNIA MUNICIPALITY, NORTHWESTERN ALGERIA
The municipality of Maghnia is experiencing increasing pressure on its water resources due to rapid socio-economic development and agricultural expansion. The growing imbalance between supply and demand raises concerns regarding the long-term sustainability of the local water system. To address these challenges, an integrated approach based on the Water Evaluation and Planning (WEAP) system was implemented to simulate water supply-demand dynamics through 2050, incorporating various management options and operational policies affecting municipal demand. Three performance indicators, namely reliability, resilience, and vulnerability (RRV), were employed to evaluate unmet water demand under both anthropogenic and optimized management scenarios. These indicators were subsequently integrated into a composite Sustainability Index (SI) to provide a comprehensive assessment of system performance. Results indicate that under the anthropogenic scenario, agricultural expansion generates substantial unmet demand, leading to low sustainability levels (SI ≈ 0.30-0.40). The domestic and public services sectors exhibit moderate stress, while the industrial sector remains comparatively less vulnerable. In contrast, the optimized scenario significantly reduces unmet demand across all sectors and improves system sustainability (SI ≈ 0.65-0.75), particularly through combined demand management and supply enhancement measures. The findings demonstrate that integrated intervention strategies are essential to mitigate future water deficits and strengthen adaptive capacity. This work provides a robust decision-support framework for sustainable water resource management under increasing anthropogenic pressures.
NATURAL DESALINATION OF SEA AND BRACKISH WATER
This paper explores the idea of moving towards the natural desalination of seawater and brackish water. It simply requires replicating the vast natural seawater desalination plant that supplies the planet Earth. The natural water cycle, for example, can serve as a model for a thermal desalination plant. Three essential elements are all that is needed to provide drinking water for the entire planet: the oceans and seas, the sun to produce solar energy, and the earth, a site of mineralization that replenishes the distilled water with mineral salts. In addition to their role in regulating the climate by mitigating global warming, the oceans and seas represent the Earth's water tower. Compared to the Earth's natural desalination plant, we could install seawater desalination plants in northern Algeria and brackish water demineralization plants in southern Algeria. Create copies of Earth's seawater desalination plants. Consider the available space for solar panels and the construction of plants using the distillation process. The mineralization phase must be carried out outside the plant by replenishing groundwater with distilled water, while the post-treatment phase must be done on land. Brine from thermal desalination plants is free of chemicals due to their absence in the pre-treatment phase, such as reverse osmosis.