The “Merdja” is the shallow aquifer of Tebessa plain, located in the northeast of Algeria. The climate is typical of semi-arid steppes, where extensive agro-pastoral activities are dominating. It is ...still the main water resource used by major sectors. Due to its proximity to the City, it is vulnerable to pollution. According to earlier studies, this aquifer undergoes seasonal water quality fluctuations (between wet and dry seasons), induced mainly through anthropogenic activities. The study is utmost important, as it tracks the groundwater quality and aims to gain an understanding of how the local and natural conditions influence this resource at temporal (interannual) and spatial scales, by following up the evolution trend of hydrochemical parameters of the “Merdja” aquifer. Seventy-one groundwater samples were collected and analyzed from drinking/irrigation wells, through four field measurement campaigns (2001, 2006, 2009, and 2010). The results obtained confirm the fact of water pollution. Point-sources of pollution with nitrate and salinity are revealed on the respective maps of these parameters, especially downstream at the nearby areas of Tebessa City. Non-point sources of groundwater pollution are also manifested. The Piper diagram reveals a relative stability of water type and that rainfall plays a role in the natural remediation, by taking part in the aquifer recharge. The ionic ratios and the principal components analysis highlight that the temporal change of groundwater quality results respectively from: (i) ionic exchange process and the dissolution of evaporites; (ii) the sources of nitrate in groundwater remain the excess application of inorganic nitrogenous fertilizers, organic manures, and wastewater effluents.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Meteorological drought is a natural hazard that can occur under all climatic regimes. The drought monitoring is a vital and important part of predicting and analyzing the drought impacts. Due to the ...fact that no single index can represent all facets of meteorological drought, a multi-index approach was used for drought monitoring in this investigation. The ability of eight precipitation-based drought indices was assessed based on analyzing the historical meteorological data (1988–2019) of In Guezzam in the South of Algeria. Those indices are the standardized precipitation index (SPI), percent of normal index (PNI), deciles index (DI), and Z-score index (ZSI), the dry flow index (ISD), normalized hydrological index (IHN), log-decimal index of hydrological deviations (ILDH), and precipitation deciles (PD). Thus, the methodology is tested on a real-world system which allows assessing its applicability within a Drought Watch System in river basins with significant storage works. The obtained results highlighted that the selection of database was more important than the selection of drought index and that the best combinations were the PD, PNI, and DI calculated with SPI and ZSI.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The alarming degradation of soils, particularly in the Moroccan Rif region, is the result of various forms of water erosion processes, leading to significant environmental and economic damage in the ...area. The Oued Lebene watershed is a sub-basin of the Sebou River, located in the central part of the Pre-Rif. Using GIS, remote sensing, and the universal soil loss Equation modified for North African conditions and validated by field observations, this study aimed to measure soil losses, sediment delivery capacity, and sediment yield rates. The estimation of soil loss reveals that the watershed is exposed to a high degree of erosion, reflected by an estimated total annual loss of 6 379 314 t·yr, with an average annual rate of 46.17 t·ha·yr. The severe erosion class covers 52.25% of the study area, contributing to 90.67% of sediment production with an average of 80.11 t·ha·yr-1. The erosion class below the tolerance threshold according to Wischmeier represents 48 108 hectares, or 34.82% of the total watershed area. Analysis of the synthetic sediment delivery ratio (SDR) map shows that the sediment delivery capacity is approximately 0.17, and the sediment yield (SY) in the Oued Lebene watershed is estimated at 770 440.32 t·yr. This is the outcome of the interaction between multiple causative factors, including steep slopes, friable substrates, severely degraded vegetation cover, etc., which increasingly accelerate the degradation of water resources in the downstream Oued Sebou, a source of irrigation for agricultural lands.
The study of the influence of climate change on the evolution of floods in areas under the influence of a Mediterranean climate is very important. This work aims to provide new analytical elements to ...decision-makers in flood management and forecasting in three Mediterranean catchments (Lonquen, Evrotas, and Azzaba), in order to better understand their hydrological behavior and to quantify the flow and its vulnerability to climate change. A semi-distributed conceptual model (HBV-A model) was used to simulate flows with a daily time step. The model results (simulated flows) were used to examine the evolution of high flows using two different approaches (linear regressions and statistical test). The Chilean and the Greece catchments show a decrease in flooding. However, the Moroccan catchment reacts differently, since a positive trend in high flows is observed. The overall results confirm the influence of climate change on the rainfall/runoff relationship.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The understanding of the characteristics and the effects of drought is essential for an effective drought assessment and management in all regions of the globe. The south-east of Morocco is ...characterized by an arid and semi-arid climate, and the High Ziz watershed, which is part of this region of Morocco, is the area in that this study was conducted, consisting of the evaluation and characterization of the meteorological and the hydrological drought, respectively, through the application of the Standardized Precipitation Index (SPI), and the standardized Streamflow Index (SSI) indices on the time scales of 3, 6 and 12 months. The analysis of the indices shows that the study area has experienced several drought events with different characteristics depending on the time scale of calculation. In addition, this analysis has enabled the behavior of meteorological and hydrological drought.
Flood risk management often requires the use of geomorphological features to identify flood zones, and the use of hydraulic models to predict inundation dynamics and related impacts on the ...surrounding area. In this study, we used a hydraulic river simulation model to identify potential flood-prone zones on a small scale. It concentrated on a 2.5-kilometer section of the Larbaâ Wadi, which crosses the rural center of Sebt Boukellal. For estimating the peak discharge that occurs in the return periods of 10, 20, 50, and 100 years of the drainage area, we used the Rational method. Standard tables to estimate Manning’s coefficient and direct field measurements to feed the model. Model simulation has shown stability of the steady state, which witnesses the accuracy of the estimated and measured characteristics of the river system. During the calibration phase, we compared the model outputs to the observed floods and made adjustments to align the simulation with the field observations. Indeed, the 50-year flood remarkably matched the extent of the flood that occurred on September 27, 2000. The obtained results have shown that even for a 10year return period, the overflow affects properties within the floodplain. The 100-year flood exceeded the river’s capacity, causing water to spill onto the rural center’s streets and cultivated fields. The water level reached an elevation of 552.14 meters at Sebt Boukellal’s marketplace. These results were consistent with recent floods and confirm previous observations, indicating that the model precisely predicted the river’s behavior. The findings have shown that floods spanned large regions and suggested urgent intervention to protect lives and properties.
Water erosion is one of the main causes of soil degradation around the world. In M orocco, In M orocco, the watersheds have very significant soil wastes, related to various physical and anthropic ...factors. The Oued Inaouene watershed is concerned because of its location in the eastern part of the Saïss basin, between the Middle Atlas and the Pre-Rif, where water erosion is more accentuated. This basin covers a total area of 3597.13 Km
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and it is marked by a semi-arid climate with relatively abundant (989.68 mm), irregular rainfall and strong anthropic pressure. This will have an impact of overexploiting natural resources in general and soils in particular. The excessive use of agricultural land has led to their fragility and aggravation of their susceptibility to erosion. These conditions, both natural and anthropic, have induced a rather intense erosive dynamic, which can be visible in its various forms, including gullying and landslides. The erosive dynamics leads progressively and certainly to impoverish the soils of the watershed and the silting of the dam Idris 1st located downstream of the Oued Inaouene, hence the interest of this study. The use of the “EPM” model for the estimation of soil losses approaches the severity of the erosive phenomenon. The average soil loss due to water erosion according to the model used is estimated at 53.34 t/ha/year. The maximum losses are about 597.642 t/ha/yr per plot. Total annual losses for the watershed are approximately 211084195 t/yr. Furthermore, the analysis of these results allowed, with the help of GIS, to determine the factors that control water erosion and which are, in order of importance: rainfall, slope, and soil sensitivity Soil protection. If anti-erosion measures aren’t adopted in the threatened parts of the watershed, this will have serious consequences for the dam and water quality .
Drought is a slow-onset, creeping natural hazard and a recurrent phenomenon in the arid and semi-arid region of the Mekerra watershed. Numerous drought indices have been used in different countries ...to implement drought mapping and monitoring of water resources management. This investigation proves meteorological drought index combined with remote sensing drought index, but had unsteady spatial and temporal variation.
The results highlight that droughts occur in semi-arid climatic region of Sidi Bel Abbes at the Northern part of the watershed. The various drought indices differ in their detection and classification of this extreme climatic event in the study area. There is high correlation (r > 0.68) among the eight indices, with PD (Precipitation deciles), DI (Deciles Index), and PNI (Percent of Normal Index) showing the highest relationship to SPI (r = 0.95 and r = 0.99 respectively). The differences observed among the drought indices in detecting drought events in the study area can be reduced by using multiple drought indices in addition to the use of SPI (Standardized Precipitation Index) in drought assessments especially at the area of Sidi Bel Abbes since technological advancement in drought monitoring software’s has made it easier. In addition, it is worthwhile to investigate on why drought detection varies with indices. Furthermore, considering the advantages and disadvantages of the mentioned drought predictors in this study area will enhance the understanding of vegetation responses to drought threatens.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Understanding the spatiotemporal distribution of future droughts is essential for effective water resource management, especially in the Mediterranean region where water resources are expected to be ...scarcer in the future. In this study, we combined meteorological and hydrological drought indices with the Soil and Water Assessment Tool (SWAT) model to predict future dry years during two periods (2035–2050and 2085–2100) in a typical Mediterranean watershed in Northern Morocco, namely, Bouregreg watershed. The developed methodology was then used to evaluate drought impact on annual water yields and to identify the most vulnerable sub-basins within the study watershed. Two emission scenarios (RCP4.5 and RCP8.5) of a downscaled global circulation model were used to force the calibrated SWAT model. Results indicated that Bouregreg watershed will experience several dry years with higher frequency especially at the end of current century. Significant decreases of annual water yields were simulated during dry years, ranging from −45.6% to −76.7% under RCP4.5, and from −66.7% to −95.6% under RCP8.5, compared to baseline. Overall, hydrologic systems in sub-basins under the ocean or high-altitude influence appear to be more resilient to drought. The combination of drought indices and the semi-distributed model offer a comprehensive tool to understand potential future droughts in Bouregreg watershed.
The risk related to embankment dam breaches needs to be evaluated in order to prepare emergency action plans. The physical and hydrodynamic parameters of the flood wave generated from the dam failure ...event correspond to various breach parameters, such as width, slope, and formation time. This study aimed to simulate the dam breach failure scenario of the Yabous dam (northeast Algeria) and analyze its influence on the related areas (urban and natural environments) downstream of the dam. The simulation was completed using the sensitivity analysis method to assess the impact of breach parameters and flooding on the dam break scenario. The flood wave propagation associated with the dam break was simulated using the one-dimensional HEC-RAS hydraulic model. This study applied a sensitivity analysis of three breach parameters (slope, width, and formation time) on five sites selected downstream of the embankment dam. The simulation showed that the maximum flow of the flood wave recorded at the level of the breach was 8768 m3/s, which gradually attenuated along the river course to reach 1972.7 m3/s at about 8.5 km downstream the dam. This study established the map of flood risk areas that illustrated zones threatened by the flooding wave triggered by the dam failure due to extreme rainfall events. The sensitivity analysis showed that flood wave flow, height, and width revealed positive and similar changes for the increases in adjustments (±25% and ±50%) of breach width and slope in the five sites. However, flood wave parameters of breach formation time showed significant trends that changed in the opposite direction compared to breach slope and width. Meanwhile, the adjustments (±25% and ±50%) of the flood hydrograph did not significantly influence the flood parameters downstream of the dam. In the present study, the HEC-RAS 1-D modeling demonstrated effectiveness in simulating the propagation of flood waves downstream of the dam in the event of dam failure and highlighted the impact of the breach parameters and the flood hydrographical pattern on flood wave parameters.
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