Search

Extreme precipitation events play a crucial role in shaping the vulnerability of regions like Algeria to the impacts of climate change. To delve deeper into this critical aspect, this study investigates the changing patterns of extreme precipitation across five sub-regions of Algeria using data from 33 model simulations provided by the NASA Earth Exchange Global Daily Downscaled Climate Projections (NEX-GDDP-CMIP6). Our analysis reveals a projected decline in annual precipitation for four of these regions, contrasting with an expected increase in desert areas where annual precipitation levels remain low, typically not exceeding 120 mm. Furthermore, key precipitation indices such as maximum 1-day precipitation (Rx1day) and extremely wet-day precipitation (R99p) consistently show upward trends across all zones, under both SSP245 and SSP585 scenarios. However, the number of heavy precipitation days (R20mm) demonstrates varied trends among zones, exhibiting stable fluctuations. These findings provide valuable foresight into future precipitation patterns, offering essential insights for policymakers and stakeholders. By anticipating these changes, adaptive strategies can be devised to mitigate potential climate change impacts on crucial sectors such as agriculture, flooding, water resources, and drought.

This work aimed at evaluating the impact of human activity and geology on the surface water quality of the Ouled Mellouk dam (northwestern Algeria). Specifically, methodology aims to assess seasonal variations of several parameters (EC, TDS, pH, SO42−, Cl−, Ca2+, Na+, HCO3−, NO3−, PO43− and Mg2+, organic matter, suspended solids, BOD5, COD) from 2007 to 2013 to define the processes controlling the mineralization and pollution of the surface water. The results show high salinization recorded during the periods of heavy precipitation or flooding, due to leaching of dolomitic limestones and evaporitic deposits from the saliferous formations of the surrounding mountains. High concentrations of NO3−, NO2−, NH4+, and organic matter can instead be attributed to the use of fertilizers in agriculture. Moreover, the PCA application shows that salinization (49.92%), anthropogenic pollution (19.38%) and agricultural pollution (12%) are the most significant degradation factors, respectively. The saturation index of carbonates and gypsiferous minerals shows the carbonates precipitate before the gypsiferous minerals, which allowed the chemical elements coming from the dissolution of gypsum and halite to acquire significant contents. In addition, the evolution of biological oxygen demand and organic pollution shows slight pollution of the dam water. HIGHLIGHTS The study evaluated the impact of human activity and geology formations on the surface water quality of the Ouled Mellouk dam (Algeria).; The results show that saline geological formations, water–rock interaction process, and anthropogenic pollution are the significant degradation factors for the lake's surface water quality.; The lake's water is unsuitable for domestic use and irrigation without a proper treatment.;

Over the last few years, the Eastern Middle Cheliff plain has witnessed remarkable economic growth, particularly in the agricultural sector. However, the overexploitation of the alluvial aquifer, coupled with agricultural practices involving the use of fertilizers and pesticides, significantly contributed to the degradation of groundwater quality. The primary objective of this study is to comprehend the mechanisms governing the water chemistry of the Eastern Middle Cheliff alluvial aquifer. A total of 42 samples were collected and analyzed during the dry periods of the 2012 and 2017. The data processing and representation involved the utilization of analytical tools including Principal Component Analysis (PCA), Piper diagram, Stabler classification, binary diagrams, base exchange indices, saturation indices, and geostatistical methods. The interpretation of these data revealed the following findings: i) the groundwater in both the dry periods of 2012 and 2017 is characterized by the presence of two dominant hydro-chemical facies, namely calcium chloride and sodium chloride, as indicated by the Piper and Stabler diagrams; ii) the hydrochemical quality of the groundwater varies across different regions of the aquifer, fair to poor in the eastern and central regions, with the presence of certain contaminants resulting from the application of nitrates in agricultural activities. The quality is classified as very poor in the western region, primarily due to high salinity influenced by the lithology of the aquifer, the rise of deep salty water through the Cheliff fault due to the earthquake of the year 1980 and possibility by two climatic factors, namely evaporation and rainfall. Overall, this study provides new insights into the water chemistry dynamics of the Eastern Middle Cheliff alluvial aquifer, highlighting the varying hydrochemical facies and the impact of agricultural activities and climatic factors on groundwater quality in different areas of the aquifer.

Soil moisture is a key parameter of soil monitoring for observation of vegetation growth, predicting crop production, and improving water resource management. In this study, the objective is to compare the evolution of soil moisture in different mulches to determine the best mulch and its characteristics of infiltration in the soil. The experiment was conducted during the summer season in July-September 2022 on four different mulches (wood chips, sawdust, straw, mixture), and control at the experimental plot of Blida. The results showed that silt is the main matrix of the soil. The analysis of infiltration data identified modified Kostiakov as the best model of the study site, whose period of plant growth represents the phase during which we have a better infiltration under the mixture. The application of the mulch changes the moisture mainly at 15 cm and the conductivity at 10 cm. In addition, the mixture is the best mulch to conserve moisture in the soil while reducing the frequency of irrigation. The correlation between soil moisture and conductivity was overall very good. This was due to the effect of mulch, soil texture, plant root development, and capillary rise.

In this study, a statistical analysis of historical and projected values of the annual, seasonal, and supra-seasonal precipitation concentration index (PCI) was conducted for different stations in the Cheliff watershed. Statistical methods such as breakpoint and trend analysis using Pettitt and Mann–Kendall tests were used for the PCI values of annual, monthly, and supra-seasonal precipitation data between 1950 and 2014. The PCI values varied between 14.24% and 24.86% annually, between 10.75% and 18.74% seasonally, and between 11.23% and 26.98% supra-seasonally. According to the Pettitt and Mann–Kendall tests, there was an insignificant change in precipitation distribution during the study period. Spatial analysis using the inverse distance weighting (IDW) method confirmed the minor variability in precipitation distribution in the study area. The Pearson correlation coefficient between oscillation indices and PCI values at different scales showed significant values with the Mediterranean Oscillation index (MOi), North Atlantic Oscillation (NAO), and Western Mediterranean Oscillation index (WeMOi), highlighting their potential influence on annual PCI values. For the climate projection scenarios, projected PCI values align with historical PCI values. Application of Pettitt and Mann-Kendall tests to the projected PCI series shows that there will not be a significant change in future precipitation distribution.

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. HIGHLIGHTS The study aims to assess groundwater quality of the Upper and Middle Cheliff plains (northwest of Algeria) for irrigation and drinking water supply.; Groundwater Quality Index for drinking shows a predominance of the Doubtful class in the plains.; Groundwater Quality Index for Irrigation shows a predominance of the Good/Permissible class in the plains.;

L’analyse statistique est devenue un outil indispensable d'aide à la décision en matière de bonne gestion des ressources en eaux, De ce fait, une analyse statistique des débits maximaux annuels a été réalisée dans le bassin-versant moyen et le bas de Chéliff. L’estimation statistique a été faite en sélectionnant les maxima annuels. Les stations sélectionnées sont au nombre de treize stations hydrométriques. Ces stations disposent de longues séries de mesures de plus de 30 ans. Le choix de la classe d’appartenance de la loi, la plus adéquate aux fins de modélisation des débits maximaux annuels, a été opéré par le système d’aide à la décision (SAD) du logiciel Hyfran plus. Les résultats obtenue montre que toutes les séries des stations appartiennent à la classe D. Pour le choix du meilleur ajustement nous avons utilisé les critères d’information Bayésien (BIC) et d’Akaike (AIC). Ces deux critères permettent de construire un classement des modèles statistiques tenant compte du principe de parcimonie. Le meilleur ajustement, pour chacun des deux critères, correspond à la plus faible valeur de son coefficient. Les principaux résultats des analyses statistiques montrent que les treize stations étudiées sont mieux ajustées à la loi Gamma.

Drought is one of the most severe natural disasters worldwide, but with a particular emphasis in sub-humid and semi-arid climates. Several indices have been created to appropriately identify drought’s characteristics and variability. The main objectives of this study consisted of analyzing the behavior of different indices applied in northeast Algeria and comparing them across a long-term data set (1961–2014). The SPI and RDI at 9-month time scales were compared to the PDSI and MedPDSI based on 123 rainfall stations and gridded PET data interpolated to all the locations. A principal component analysis (PCA) in S-mode with varimax rotation (RPC) was applied to the monthly values of all indices to analyze the spatiotemporal patterns of droughts. Two principal components were retained, which identified two sub-regions with coherent differences related to their distance from the Mediterranean Sea and the UNEP aridity index. Trends in the RPC scores were assessed using the modified Mann–Kendall (MMK) test and Sen’s slope estimator, which showed a fundamental difference between the two sub-regions. The RPC of all drought indices showed trends of decreases in the frequency and severity of droughts in the northern sub-region, and trends of increases in the frequency and severity of droughts in the southern region, where the climate is mostly semi-arid and arid. Only a few cases were statistically significant, mostly when using the PDSI and MedPDSI for the southern sub-region. The spatial patterns of moderate, severe, and extreme drought occurrences were similar for the SPI and RDI pair of indices based on the probability of rainfall anomalies, and for the Sc-PDSI and MedPDSI pair based on water balance anomalies. The interpretation of the spatial variability of droughts, mainly of the extreme ones, was supported by an analysis of semi-variograms. The novel index MedPDSI compared well with the other indices and showed advantages of performing the soil water balance following the FAO56 dual Kc method with the actual olive evapotranspiration instead of PET, and of better explaining the spatial variability of extreme droughts; in addition, the trends detected were significant for both the northern and southern sub-regions.

Water is becoming a scarce and expensive commodity, allowing to irrigate limited areas. Irrigation is poorly managed and this situation allow salts accumulation and soil degradation. The rainwater retained by soil is important and must be studied, first by its volume and thereafter by its fluctuations over time. The actual soil volume exploited by roots, viable and economic plant species that would be able to value such water potential should also be evaluated. The principal constraint to solve for development of these soils would be maintaining an adequate water supply of crops. The present paper aims to search the means and measures necessary to manage this water rationally. During one year (2007-2008), we investigated soil water reserve in each parcel considered (Rapeseed, fallow). The water profile analysis shows that fallow lose more water than cultivated siol over this period. The understanding of water flux through the soil, and its relationship with the plant-atmosphere may be also used for the optimization of rainwater.

Abstract 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 SCS‐CN 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.

Abstract Extreme hydrologic events are commonly described by several dependent characteristics, such as duration, volume and peak flow for floods. Traditionally in Algeria and North Africa, flood frequency analysis (FFA) is conducted as a univariate approach focusing separately on each single of flood characteristics. On the other hand, elsewhere, multivariate FFA studies have been conducted focusing on some FFA steps (especially modelling). The current study aims to consider complete multivariate FFA at‐site case studies in northern Algeria using 11 hydrometric stations. It is also among the first studies dealing with multivariate FFA in a complete way by considering all the required steps of the analysis (multivariate outliers detection, multivariate assumptions testing and copula fitting) and on datasets from Algeria. Multivariate stationarity, homogeneity and independence assumptions have been well verified before modelling. The Weibull distribution is mostly selected as margin distribution for the duration, volume and peak flow series. Frank, Clayton and Gumbel copulas are commonly selected to describe the dependence structure on the three flood pairs of variables. These findings should be interesting in water management and flood risk assessment in these regions. Combining these flood characteristics enables the design of more efficient hydraulic structures.

Study Region: Three major river basins the Cheliff, Tafna and Macta in North-West Algeria. Study focus: The purpose of this work is not to test the different climate models but rather to study the sensitivity of hydrological parameters to future climate change. This is achieved using the GR2M hydrological model and climate scenario data from the CNRM-CM5 model. New hydrological insights: In terms of observed trends, the monthly flows decreased significantly between 1970 and 1999, mainly due to the decrease in precipitation combined with the increase in the potential evapotranspiration (PET), caused by rising temperatures. According to the RCPs8.5 and 4.5 scenarios projections, the decrease in Winter discharges will continue in the future. For the Spring, RCP8.5 forecasts a moderate increase, while RCP4.5 shows a downward trend. Keywords: Algeria, Climate change, CNRM-CM5, PET, Flow, GR2M

The objective of this study is to model discharge and solid erosion quantification through a small agricultural watershed by applying the SWAT model (Soil and Water Assessment Tools) on the Wadi Harraza’s basin of which is part of Wadi Cheliff’s basin, with an average altitude of 500 m, drains an area of 568 sq km. Soil and Water Assessment Tool (SWAT, version 2009) model integrated with Geographic Information System (ArcGIS, version 10.0) were used to simulate the discharge and sediment concentration of Wadi Harraza’s basin for the period from 2004 to 2009. Model calibration and validation were performed for monthly time periods using Sequential Uncertainty Fitting 2 (SUFI-2, version 2) within SWAT-CUP. Our calibration and validation outputs for monthly simulation showed a good model performance for discharges. Thus the evolution of the average total annual sediment in the Wadi Harraza’s basin which will be deposited in the Wadi Cheliff, is estimated at 54.24 t ha−1. Keywords: SWAT model, Basin, Wadi Harraza, SUFI-2, Discharges, Sediment

Study region: North Algeria. Study focus: The semi-arid to arid Chéliff–Zahrez basin faced several droughts with severe impacts on agriculture due to the high temporal and spatial distribution of rainfall. We explored the potential of the Standardized Precipitation Index (SPI), Markov chain models, the Drought Index and time series modelling to characterize meteorological drought. Time series of annual precipitation (1960–2010) from 65 meteorological stations across the basin were used. The basin was subdivided into five subbasins to account for spatial variability. New hydrological insights for the regions: The analysis of the Standardized Precipitation Index showed few droughts in the period 1960–1970, whereas in the 1990s a multi-year drought occurred with SPIs as low as −2 (extremely dry) in many subbasins. The Markov chain analysis learnt that the probability of having two consecutive drought years appears to be higher in the southern subbasins. The Drought Index derived from transition probabilities indicates that the southern and the southwestern parts of the Chéliff–Zahrez basin are most drought prone. Time series modelling was applied to compute the SPI for different return periods (6‐17 years). Eleven models were tested and it appeared that the Asymmetric Power Autoregressive Conditional Heteroskedasticity (APARCH) approach was best performing based on several information criteria. For a return period of 17 years, the SPI is lower than −1.5 (severely dry) in many subbasins. Keywords: Meteorological drought, SPI, Markov chain, Time series modelling, Drought maps, Chéliff–Zahrez basin

Abstract The exposure of the Earth’s surface to the energetic input of rainfall is one of the key factors controlling water erosion. While water erosion is identified as the most serious cause of soil degradation globally, global patterns of rainfall erosivity remain poorly quantified and estimates have large uncertainties. This hampers the implementation of effective soil degradation mitigation and restoration strategies. Quantifying rainfall erosivity is challenging as it requires high temporal resolution(

L’eau devient un bien rare et coûteux, et ne permet d’irriguer que des surfaces de plus en plus limitées. Les irrigations sont mal maîtrisées, permettent une accumulation de plus en plus importante de sels et participent à la dégradation des sols. L’eau de pluie retenue par le sol est importante et doit être étudiée tout d’abord par son volume et par la suite par ses fluctuations dans le temps. Le volume réel de sol exploité par les racines, les espèces végétales viables et économiques qui seraient capables de valoriser de telles potentialités hydriques doivent également être évalués. La principale contrainte à résoudre pour la mise en valeur de ces sols serait le maintien d’une alimentation équilibrée en eau des cultures. Au cours de ce travail, nous allons traiter simultanément la réserve hydrique du sol sous chaque parcelle considérée (Colza, jachère), durant l’année 2007-2008. L’analyse des profils hydriques montre que les sols maintenus en jachère perdent plus d’eau durant cette période que les sols cultivés. Il est temps de chercher les moyens et les mesures nécessaire pour utiliser rationnellement cette eau. Cela passera nécessairement la compréhension des flux hydriques dans le sol, ses rapports avec la plante et l’atmosphère. Mots clés : Eau de pluie, Propriétés du sol, Espace végétale, Profil hydrique, Réserve hydrique.

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.

Soil erosion by rain and surface runoff is an important problem in the Mediterranean countries. The study of the relationship between erosion and sediment transport with hydrological and climatic factors have b een conducted in many countries around the world. The aim of this work is to show ra infall impact on the variability of spatial and temporal concentration in twelve drainage basins in the west of Algeria. We will also seek to find a representative parameter of rainfall erosive potential on a Time and spatial scale. When studying sediment transport in twelve drainage basins of the Centre and the west of Algeria, we have found that the modified Fournier index Which explains much of the specific degradation comp ared to the Fournier index. The study of the temporal variability of the annual rain fall series, modified Fournier index and concentration of the precipitation in the year for a series from 1930 to 2007 showed a negative trend of the two variables. The a nnual rainfall and modified Fournier index have declined by more than 20%. This de cline is more significant in inland areas.

The objective of this study was to follow-up on the evolution of the hydro-pluviometric schemes and particular elements of Wadi Mina (6048 km2) to the Sidi M’Hamed Ben Aouda Dam to evaluate the silting origin and status of this dam situated in the northwest of Algeria. The pluviometric study targeted a series of rains during 77 years (1930–2007), the liquid discharge data cover a period of 41 years (1969–2010) and the solids and suspended sediment concentrations data cover very variable periods, starting from 22 to 40 years for the entire catchment area. The statistical tests for ruptures detection on the chronological series of rains and discharges indicate a net reduction of rains of more than 20% on the entire basin since 1970. The evolution of solids inputs was quantified: the maximum values are registered on autumn start and at the end of spring. The Wadi Mina basin brings annually 38 × 106 m3 of water with a specific degradation of 860 t·km−2·year−1. By comparing the results found, we thus observe that the basin upstream of SMBA (1B) Dam is the greatest sediment producer towards the dam because it shows a specific degradation equal to 13.36 t·ha−1·year−1.

In Algeria, the weather of the last three decades has a negative impact on water resources. The aim of this paper is to determine their impact on the rivers of the Macta basin (North-West of Algeria). The study of annual rainfall (September to August) over the period 1930-2002 shows a sharp decrease of rainfall from the first half of 1970. The flow of Trois Rivières station (wadi El Hammam), Sidi Ali Ben Youb station and Sidi Bel Abbes station (wadi Mekerra) were affected. Over the period 1976-2002, the annual average depth of runoff of runoff is 28 to 36% lower than for the period 1949-1976. On average, rainfall may be lower for all seasons, but the flows are not reduced in the autumn.