Ecole Nationale Supérieure d'Hydraulique
Recent publications
Soil water erosion is a major phenomenon that threatens almost all watersheds in the Mediterranean area, nowadays. The worsening of this phenomenon in Algeria affects soil capacity to ensure its ecological functions and socio-economic purposes which depend on it. Concurrently, the storage capacity of Algeria dams has considerably decreased as a result of excessive silting. The above issue motivated this study, which aims to establish mechanisms for prioritizing to improve the economic efficiency of agricultural land and the long-term viability of dams in the largest metropolitan basin of Algeria “Coastal Algiers 2a basin”. This basin, which is urbanized over 50% of its area, contains six large dams with a total capacity of 540 Million m3 and one of the most important agricultural zones in Algeria. Common decision support frameworks have been implemented to predict the areas that are potentially exposed to erosion and sediment deposition threatening the dam capacity using the Soil and Water Assessment Tool (SWAT) and the Revised Universal Soil Loss Equation (RUSLE). To achieve this, rainfall, climatic, hydrometric, land use, soil, digital elevation, and satellite data were used by the two spatially soil loss models. The results show a dependency between the two statistical models with respect to low, medium and high erosion risk areas and its evolution from the eastern to the western region of the watershed. Regarding the deposition of sediments at the dams, the two models only partially explain the rate of sediments observed at the level of the dams’ basins whose relative errors exceed 4%, 8%, 60%, 30% and 40% respectively for the Meurad, Bouroumi, Keddara, Boukerdane and El Hamiz dams. The canonical analysis (CC) revealed that the average slope, vegetation cover and the available water capacity in the soil of the basin are the most important parameters influencing the soil loss provided by the two models.
The proposed study aims to assess groundwater quality and suitability of the Upper and Middle Cheliff plains (northwest of Algeria) for irrigation and drinking. Here the groundwater is the main source for domestic, agricultural and industrial activities similarly to any other region of the world. The suitability for drinking and for irrigation was evaluated on the basis of water quality index, salinity risk, hardness risk, sodium risk, magnesium risk, permeability index, water infiltration rate, Kelly index and Wilcox and Richards diagrams. The aquifer system is mainly composed of alluvium (gravel, sand, silt, clay, …) from the Mio-Plio-Quaternary. The results of this study highlighted that the majority of the chemical elements analyzed exceed the WHO’s drinking water standards and FAO’s irrigation water standards. Based on the GroundWater Quality Index (GWQI) results, the Upper and Middle Cheliff groundwater plains shows Doubtful class in most of the plains. In addition, the GroundWater Quality Index for Irrigation (GWQII) shows the predominance of the Good/Permissible groundwater quality class in most of the plains. According to these results, drinking water can cause health problems (a danger) for the human consumption making necessary a proper treatment be able to use it. As for irrigation water, it does not present a danger for irrigating for the vast fields of the region, with the exception of sensitive crops such as: garlic, onion, beans and strawberry. The proposed approach demonstrated to be appropriate in assessing the groundwater quality for irrigation and drinking water supply since it can be easy applicable and suitable in humid, arid or semi-arid regions around the world.
Sediment transport and land erosion have specific impacts in Algeria, especially if we know that Algerian lands record the highest soil erosion levels in North Africa. Also, the direct impact of the moving sediments on storage capacities greatly reduces the regularized volumes of the latter. Thus, we studied the erosion phenomena over the coastal watershed of Algiers, which is one of the most important watersheds in Algeria due to its demographic aspect (more than 8 million inhabitants over a small area representing 0.5% of the whole area of the country) and to the important agricultural and industrial activities. The study concerns the sediment transport evaluation with a simple approach using the sediment concentration data of several hydrometric sites within and outside of the watershed in order to estimate the specific erosion or soil degradation and to map it in order to have a global idea about the zones which are most sensitive to erosion and which must have a priority in the watershed management programs. We deduce that the prone zones are in the upstream of Wadi Chiffa and Bouroumi, and along Wadi El Hachem where Boukerdane Dam is located.
This paper proposes a new design for the shaft spillway of the Djedra dam (East Algeria). The procedure consists of replacing the circular section with a polygonal configuration of twelve (12) sections. The study of the model was divided into five different versions according to the variants of technical modifications of the water intake funnel; this configuration was tested on a hydraulic model in the laboratory of hydroelectric power plants of the Moscow State University of Environmental Engineering. The use of the polygonal section weir can greatly simplify the formwork of the structure, also the free entry funnel increases the discharge coefficient by 20%, without exposing the head of the weir to the risk of cavitation. In the event of submersion, the adopted design can ensure the crossing of an estimated relative flow with a probability of P = 0.01%, which means reducing the height of the dam by 0.68 m, and thus making the hydraulic structure more efficient economically and more reliable. The experimental model was produced on a 1:60 scale of the prototype, which guarantees self-simulation of the hydraulic phenomena of the Djedra dam, and its final design is judged to be hydraulically satisfactory and recommended for construction. HIGHLIGHTS A new design of the weir of the dam is a polygonal configuration.; The polygonal section weir simplifies its structure.; The free entry weir funnel increases the discharge coefficient by 20%.; In the event of submersion, the weir provides an estimated flow rate of P = 0.01%.; The experimental model produced on a scale of 1:60 of the prototype guarantees self-simulation of the hydraulic phenomena of the dam.;
An analysis of rainfall and hydrometric regimes was carried out over the period from 1968 to 2013 on the Cheliff basin situated in the west and the Medjerda basin in the east of Algeria. The Mann–Kendal and Pettitt tests have shown significant downward trends for rainfall, about 30% for the Cheliff basin, and 36% for the Medjerda basin, and about 61% and 43% for the flows at the level of the Cheliff and Medjerda basins, respectively. The continuous wavelet method, used during the study period, has shown three major discontinuities from the wavelet spectrum for the decades 1970s, 1980s and 1990s. Several modes of variability for different stations have been observed: annual (1 yr), interannual (2, 2–4 and 4–8 yrs), and multi-decadal (8–16) yrs. The different scales of precipitation and runoff variability seem to be clearly related to the NAO with different degrees of correlation. Continuous wavelet coherence indicates a strong correlation between the NAO climate index and precipitation with correlations ranging from 60 to 84%, and a strong relationship between the NAO and the runoff with correlations ranging from 67 to 74% for both watersheds. Keywords. Precipitation; runoff; NAO; wavelet method; Cheliff basin; Medjerda basin.
Algeria has experienced catastrophic floods over the second half of the twentieth century, causing many deaths and extensive material damage. This study was conducted to find a suitable event-based rainfall-runoff (RR) model for semi-arid conditions, where continuous data are not available in all regional basins. The study compared, based on data availability, the SCS-CN model based on the antecedent moisture conditions (AMC) and four modified SCS-CN models incorporating antecedent moisture amounts (AMA) in order to find the best model to reproduce the flood hydrographs in two catchments. The modified models were predominant over the SCS-CN method. Nonetheless, the Singh et al. (Water Resour Manag 29:4111–4127, 2015. https://doi.org/10.1007/s11269-015-1048-1) model (M4) and the Verma et al. (Environ Earth Sci 76:736, 2017a. https://doi.org/10.1007/s12665-017-7062-2) model (M5) were superior and demonstrated more stable structures. Coupled with the Hayami routing model, the models showed promising results and were able to reproduce the observed hydrographs’ shape. However, it was impossible to choose the preferred model since they each excelled as to a criterion. Therefore, the corresponding outputs were combined using the simple average (SA) method and the weighted average (WA) method. We found that the WA method showed better results in the two catchments and allowed a more accurate prediction according to the performance criteria.
The northeastern of Algeria is the rainiest region of the country, where regional catchments are often subject to devastating floods. To improve the management of water resources, there is a need to develop rainfall–runoff models. This study was conducted to propose an event-based flood prediction model adapted to the region. Thereby, available rainfall–runoff data were used in several models to find the best one able to reproduce the flood hydrographs in three catchments. These models are based on the coupling of both production and transfer functions. For this purpose, five production functions were tested: the Soil Conservation Service–Curve Number (SCS-CN) model, including three antecedent moisture conditions, and four modified Mishra and Singh models, incorporating antecedent moisture amounts. Three transfer functions were also tested: the Nash, Clark, and Weibull models. The tested models were all calibrated through a multi-objective optimisation using the genetic algorithms method. It was found that the MMS models were better than the SCSCN method according to the performance criteria. Moreover, the proposed modified empirical equation (M4) improved runoff prediction. Furthermore, combined with the Nash model as a transfer function, the coupled model was found to be the best performing model, giving satisfactory results.
This work aims to identify the potential groundwater recharge zones in the Mitidja plain (north Algeria) using the multi-criteria approach. The analysis was based on the use of geographical information system (GIS) and remote sensing to establish eight thematic maps, weighted, categorized and inserted, that allowed us to establish the potential zones’ map for groundwater recharge. Three potential groundwater recharge classes were defined corresponding, respectively, to low (26%), moderate (47%) and high (27%). The best groundwater potential zones are situated in the piedmont of the Blidean Atlas (the south of the study area), precisely, upstream near to wadis (wadi El Harrach, wadi Djemaa, wadi Mazafran) and the western aquifer limit, where the hydrogeological units are formed by the alluvium formation which is characterized by high hydraulic conductivity, high water flow, low slope, low drainage, low quantity transported sediments and good water quality. The obtained results, in this work, describe the groundwater recharge potential areas and supply information for a suitable mapping and the management of aquifer resources in the study area.
In last decades, the impact of climate change started to appear in the semi-arid regions of the Mediterranean Basin. The severity and frequency of drought events in Northwestern Algeria have affected water resources availability and agriculture. This study aims to evaluate the temporal evolution of drought events characteristics, such as drought duration, frequency and severity, of the Beni Bahdel Dam catchment, Northwestern Algeria. Drought characteristics have been derived from the Standardized precipitation index (SPI) computed for the period from 1941 to 2100 using precipitation data from observations and simulations of the regional climate model RCA4 (Rossby Centre Atmosphere model, version 4). The RCA4 model was forced by the global circulation model MPI-ESM-LR under two Representative Concentration Pathways (RCPs) scenarios. The ability of the model simulations was firstly assessed to reproduce the drought characteristics from observed data (1951–2005). Then, future changes in drought characteristics over the twenty-first century were investigated under the two scenarios (RCP4.5 and RCP8.5). Results show an amplification of drought frequencies and durations in the future under the RCP8.5 scenario.
This study aims to estimate hydrological drought risk using probabilistic analysis of bivariate drought characteristics to assess both past and future drought severity and duration in three basins located in the widest karst massif of northern Algeria. The procedures entail: (1) identification of extent of meteorological drought that could trigger corresponding hydrological drought through their characteristics; (2) assessment of future risk of extreme drought according to two emission scenarios of the representative concentration pathway (RCP 4.5 and 8.5); and (3) estimation of drought return periods using bivariate frequency analysis and investigation of their future change rates under climate change. Hydrological droughts were computed by using the bias-corrected future climate projections from nine global climate models downscaled using the Rossby Centre Regional Climate model (RCA4), and GR2M hydrological model. The analysis revealed a connection between meteorological and hydrological droughts occurrences and the response time depends on the memory effect of the considered basin. We also found strong consensus between past drought events return periods, determined by bivariate frequency analysis, and those determined by climate models under RCP8.5 scenario. Finally, in regards to drought return periods (10, 50 and 100-years), the risk of extreme drought recurrence in the future has been projected to be larger than the reference period.
Water resources scarcity in Algeria, their fragility and their unequal distribution have resulted in a serious shortage, which, in spite of all the efforts, seems inevitable. This study consists in evaluating the human activity impact on the water quality of Aïnzeda lake (NE Algeria), a typical case study of the difficulties posed by the problem of the surface water quality in semi-arid regions. The Principal Component Analysis (PCA) and the trend method were applied to interpret the physico-chemical data of monthly analyzed samples, over a 25 years period (1988–2012). The trend method results show that most chemical elements have a direct relationship with urbanization and agricultural practices in the area. The change of the watershed climatic conditions (increasing of 9% in air-temperature, 7% in the lake water-temperature, and decreasing of 8% in precipitation) is also responsible for the degradation of the water quality. The PCA shows that salinization (51.73%), and anthropogenic and agricultural pollution (13.49%) are the most significant degradation factors. These two approaches have enabled us to prove that aridity and anthropogenic or agricultural activities have a negative impact on the lake surface water quality.
The floods that Algeria has experienced in recent years are among the most significant natural disasters recorded by the country. These disasters, whose amplitude and frequency have tended to become increasingly irregular in space and time, in the current context of global climate change, encourage us to improve our flood management and forecasting strategies, notably through the re-evaluation of protection structure capacities, designed on the basis of hydrological data analyzed by statistical adjustment of past rainfall hazards. The objective of this study is to develop a minimalist conceptual numerical model for flood forecasting and management under GIS environment for the north-east region of Algeria. This model was developed by analyzing hydrographic data that can be adapted to climate data collected in real time, to predict short-term flood hydrographs in all segments of the hydrographic network, based on the Sokolovsky model for construction of synthetic hydrographs, combined with the Horton architecture for basin discretization. We obtained accuracy on past rainfall hazard simulations around 65.2% for peak flow amplitudes and 88.3% for surface runoff base times. This low-cost simple model opens the way to more possibilities in flood management, and can be improved through better spatialization and calibration with more field data.
Drought is the most frequent natural disaster in Algeria during the last century, with a severity ranging over the territory and causing enormous damages to agriculture and economy, especially in the northwest region of Algeria. The above issue motivated this study, which is aimed to analyse and predict droughts using the Standardized Precipitation Index (SPI). The analysis is based on monthly rainfall data collected during the period from 1960 to 2010 in seven plains located in the north-western Algeria. While a drought forecast with 2 months lead-time is addressed using an artiBcial neural network (ANN) model. Based on SPI values at different time scales (3-, 6-, 9-, and 12-months), the seven plains of north-western Algeria are severely aAected by drought, conversely of the eastern part of the country, wherein drought phenomena are decreased in both duration and severity. The analysis also shows that the drought frequency changes according to the time scale. Moreover, the temporal analysis, without considering the autocorrelation eAect on change point and monotonic trends of SPI series, depicts a negative trend with asynchronous in change-point timing. However, this becomes less significant at 3 and 6 months’ time scales if time series are modelled using the corrected and unbiased trend-free-pre-whitening (TFPWcu) approach. As regards the ANN-based drought forecast in the seven plains with 2 months of lead time, the multi-layer perceptron networks architecture with Levenberg–Marquardt calibration algorithm provides satisfactory results with the adjusted coefBcient of determination (R2 adj) higher than 0.81 and the rootmean-square-error (RMSE) and the mean absolute error (MAE) less than 0.41 and 0.23, respectively. Therefore, the proposed ANN-based drought forecast model can be conveniently adopted to establish with 2 months ahead adequate irrigation schedules in case of water stress and for optimizing agricultural production.
Determining the link between rainfall and flow for a watershed is one of the most imperative problems and challenging tasks faced by hydrologists and engineers. Conceptual and Box-Jenkins hydrological models represent suitable tools for this purpose in circumstance of data Scarce and climate complexity. This research consists in a comparative study between conceptual models and Box-Jenkins model, namely, GR2M, ABCD, and the autoregressive moving average (ARIMA) which has a numerical design. The three models were applied to three catchments located in the north-west of Algeria. Basins have been selected according to the availability of long-time series of hydrological and climatic data (more than 30 years) to calibrate parsimonious models, taking into account the climatic variables and the stochastic behavior of the natural stream flow. Overall, the conceptual models perform similarly; whereas the results show that the GR2M model performed better than the ABCD in the validation stage, the stochastic model shows better results as opposed to conceptual models in the case of the Mellah Wadi which presents high permeability in its behavior. This is due to the simplicity of the model needed for data (only runoff data) and the ability of the stochastic model to produce stream flow in complex catchments. Such circumstance could be caused by different motivations. On the one hand, the diverse number of model parameters that make the ABCD the less parsimonious approach, with four parameters to be calibrated. On the other hand, the inability of the ABCD and the ARIMA model to capture and describe the groundwater processes, important for the cases study. Moreover, the validation period includes a large drought period, started in the late 1980s, which makes difficult model adaptation to different hydrological regimes.
The groundwater resources management of the wadi Mya basin, located in the North East of the Algerian Sahara and witnesses a hyper-arid climate, poses salinity problems. In order to identify the mechanisms involved in causing these problems, physicochemical analyses were performed on 114 water samples. The hydrogeological system of Complexe Terminal of the wadi Mya basin is very weakly recharged and contains two highly mineralized aquifer levels. These are the Mio-Pliocene sands aquifer and the underlying Senonian carbonates aquifer. They are separated to a great extent by an intermediate evaporitic Eocene layer. Both aquifers show analogous hydrochemical facies indicating, thus, intercommunication between them. The overall mineralization is dominated by chloride sulfate, sodium and magnesium facies and is explained by the dissolution of the evaporitic components of the intercalations in the aquifer matrix, but also by the old character (fossil) of water and cationic exchange reactions resulting from water-rock interactions over time. The salinity variation exhibit a trend that conform to the groundwater flow direction. Vertical transfer of water, sometimes saltier downward from the phreatic aquifer, sometimes softer upward from the deep Albian sandstone aquifer, was noticed. Areas of low mineralization were also identified in the western edge of the basin, where wadi’s floods, which drain the eastern side of the M’zab dorsal, are wide spread.
Climate and anthropogenic changes impact on the erosion and sediment transport processes in rivers. Rainfall variability and, in many places, the increase of rainfall intensity have a direct impact on rainfall erosivity. Increasing changes in demography have led to the acceleration of land cover changes from natural areas to cultivated areas, and then from degraded areas to desertification. Such areas, under the effect of anthropogenic activities, are more sensitive to erosion, and are therefore prone to erosion. On the other hand, with an increase in the number of dams in watersheds, a great portion of sediment fluxes is trapped in the reservoirs, which do not reach the sea in the same amount nor at the same quality, and thus have consequences for coastal geomorphodynamics. The Special Issue “Modeling and Practice of Erosion and Sediment Transport under Change” is focused on a number of keywords: erosion and sediment transport, model and practice, and change. The keywords are briefly discussed with respect to the relevant literature. The papers in this Special Issue address observations and models based on laboratory and field data, allowing researchers to make use of such resources in practice under changing conditions.
Significant changes in regional climates have been observed at the end of the twentieth century, taking place at unprecedented rates. These changes, in turn, lead to changes in global climate zones with pace and amplitude varying from one region to another. Algeria, a country characterized by climate conditions ranging from relatively wet to very dry (desert-like), has also experienced changes in its climate regions, notably in the country’s wet region, which represents about 7% of its total surface area, but is home to 75% of its population. In this study, the pace of climate zone changes as it is defined by Koppen–Geiger was analyzed for the period from 1951 to 2098 using climate data from observation and regional climate simulations over Algeria. The ability of the CORDEX-Africa regional climate models simulations to reproduce the current observed climate zones and their shifts was first assessed. Future changes over the whole of the twenty-first century were then estimated based on two Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios. Analysis of the shift rate of climate zones from 1951 to 2005 found a gradual but significant expansion of the surface area of the desert zone at an approximate rate of 650 ± 160 km2/year along with the abrupt shrinking, by approximately 30%, at a rate of 1086 ± 270 km2/year, of the warm temperate climate zone surface area. According to projections for the RCP8.5 scenario, the rate of expansion of desert climate will increase in the future (twenty-first century), particularly during the period from 2045 to 2098.
Water quality is one of the fundamental parameters effecting the irrigation. In this work we used Geostatistical process (co-kriging method) to examine the spatial variability of groundwater quality parameters such as (electrical conductivity (EC) and sodium adsorption ratio (SAR)). We collected and analysed 40 groundwater samples, in wadi Nil plain (Jijel, North-East Algeria). Results showed that co-kriging exponential model has low RMSE (more accurate) compared to the other two methods (kriging and Inverse Distance Weighted). The prepared map using the above mentioned method showed that the electrical conductivity (EC) increases from the south to the north. High values are located in northern part of the plain (coastline) likely related to sea water contamination. The spatial distribution of SAR shows an exceptional increase from the central area to the north. Very high values of SAR in this part of the plain could be associated with both the anthropic contamination and the marine invasion. The obtained quality map for irrigation, may be the necessary tool that farmers can use for agricultural irrigation. To recover the polluted area (northern part), it is necessary to identify the main sources and amount of the pollution.
Dams are very costly structures that are often built in areas prone to seismicity due to geological and geomorphological considerations. To protect such structures against seismic actions, in-depth studies on their vulnerability should be undertaken.This study deals with the seismic vulnerability of a concrete gravity dam. The Oued El Fodda dam on the Oued Chelif River, west Algeria, is considered as a case study. The dam is studied under near- and far-fault ground motions. To derive fragility curves, non-linear time history analyses are performed by using a Latin hypercube sampling numerical simulation procedure. Damage probabilities are determined for each defined limit state. The results show the vulnerability of the dam under high-level seismic motion. A sensitivity analysis was performed to evaluate the influence of uncertain parameters on structural responses. The most important parameters are then identified.
Intensity-duration-frequency (IDF) curves are one of the most common rainfall statistical models used in hydrologic design and analysis projects. The uncertainties related to the elaboration of these IDF curves have nevertheless seldom been evaluated in the past. The article will recall the existing link between the IDF formulation and some properties of the rainfall series such as simple scaling and multifractal structure. Assuming that these properties are valid, the IDF curves formulation is then the product of a dimensionless (i.e., reduced) distribution function for the annual maximum rainfall intensities/depths and a duration-dependent scaling factor. Its parameters can be evaluated in an integrated way (i.e., based on a unique pooled sample of peak intensities over a range of durations: from 15 min to 24 hr). The use of likelihood-based Bayesian Markov chain Monte Carlo statistical inference methods for this evaluation provides consistent uncertainties for all the parameters of the IDF relation and for the corresponding rainfall quantiles. This methodology has been tested, via a local analysis, on a large data set of 48 rain gauge records, spread over the north central part of Algeria (25,000 km²), under various climatic regimes. The integrated approach is undoubtedly consistent with estimates from annual maximum rainfall fitted to single durations. Furthermore, credibility intervals are significantly reduced. Also, this integrated approach appears to be robust: Unlike the traditional method based single durations, it generally provides rational quantile estimates, even when short observed series are available. This is a significant advantage for engineering applications.
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178 members
Dahmane Mouloud
  • Génie hydraulique
Abdelhadi Ammari
  • Hydraulique Urbaine
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