Simulation of water resources management scenarios in western Algeria watersheds using WEAP model

The question of water constitutes a permanent challenge for the countries of North Africa in general and Algeria in particular. For over 20 years, western Algeria region had significant rainfall deficits that resulted in severe droughts, which seriously affected the water resources in terms of quality and quantity. This research presents one of the Water Evaluation and Planning (WEAP) model applications in watersheds of western Algeria. The model is applied to evaluate and analyze the existing balance and expected future water resources management scenarios by taking into account the different operating policies and factors that may affect demand until 2030. The results showed that neither domestic demand nor agricultural demand is met for the basis year 2006. The results also showed that domestic demand can be satisfied for the considered scenarios. Demand management and development of standard of living are the necessary procedures for proper management of the available resources. However, agricultural demand cannot be satisfied for Development of Large Irrigation System scenarios. The results confirmed that WEAP software offers a solid basis to assist planners in developing recommendations for future water resource management by revealing hot spots of action.     

Filtrage par reconnaissance des formes d’un profil sismique vertical Vertical seismic profile filtering through the use of pattern recognition

To improve the signal to noise ratio of the vertical seismic profile recordings, we used a filtering method based on pattern recognition. It consists in recognizing along the seismic trace, corresponding to the arrivals of various events, the shape of the P wavelet considered as the training signal. This recognition is made of projections which retain only the signals similar in shape to the P wavelet, the others being attenuated according to their degree of resemblance to the training wavelet. The study undertaken on synthetic and real data shows that this method acts as an effective filter. However, it still depends on a training signal that must be well defined and identifiable.     

Assessment of water quality index for the groundwater in the upper Cheliff plain,Algeria

Assessment of groundwater suitability for drinking and agricultural purposes was carried out in the plain of upper Cheliff. The study area covers an area of 375 km² and lies in a semiarid climate. Groundwater is the major source for domestic and agricultural activity in this area. Groundwater samples were collected from 19 wells during dry and wet periods in 2012, and they were analyzed for major cations and anions and compared with drinking and irrigation specification standards. The concentration of the majority of chemical constituents exceeds the standards of WHO as a result of various sources of pollution. It indicates the dominance of groundwater types: Ca-Mg-Cl, and Ca-Mg-HCO₃. Suitability of groundwater for drinking was evaluated based on the water quality index; it shows more than 60% of samples have very poor quality for dry and wet periods, which means water is severely contaminated and unsuitable for drinking purpose. In terms of the irrigation usage, generally groundwater is suitable for both periods in the major part of the plain. The Mineralization processes in this area is determined by the lithology of the aquifer (exchange water-rock), by anthropogenic factors (discharges of urban sewage, use of fertilizers) and also by evaporation (semi-arid climate).     

The zircon evidence of temporally changing sediment transport—the NW Gondwana margin during Cambrian to Devonian time (Aoucert and Smara areas,Moroccan Sahara)

International Journal of Earth Sciences - Detrital zircon provenance studies are an established tool to develop palaeogeographic models, mostly based on zircon of siliciclastic rocks and isotope...     

Water use efficiency of olive tree under two water treatments in Tunisian semi-arid conditions

Olive trees are grown under high evaporative demand and less precipitations that are variable in time and space especially in semi-arid conditions. The objective of this work is to determine the most efficient water treatment applied in an olive field (Olea europaea L. cv Chemlali) from the 98th to the 294th Julian day, in Tunisian semi-arid conditions. The choice of this time frame was done to control the effect of irrigation on the trees behavior in the irrigation period of the year (from April to October) and determine the most sensitive phenological stages to irrigation. For this reasons, two water treatments were applied: T100% (irrigation at 100% of Available Water Content (AWC)) and T50% (irrigation at 50% AWC). The results show that, according to leaf water potential, carbon isotope discrimination, and olive production parameters, the T50% AWC water treatment is the most efficient. The leaf water potential of the two water treatments applied has not exceeded ?2.5 MPa during the whole experiment which indicates that the trees of the two water treatments were not stressed. The T50% AWC shows a water use efficiency of 5.18 g/l compared to 2.93 g/l for T100% water treatment. This result demonstrate that Chemlali cultivar valorizes better low quantities of water rather than high quantities, so saving 50% of water resources applied will ensure the sustainability of water resources and stability of olive production.     

The Laalam (Algeria) damaging landslide triggered by a moderate earthquake (M<Subscript>w</Subscript> = 5.2)

On March 20th, 2006, a moderate earthquake (M_w = 5.2) struck the Laalam (NE-Algeria). The damage was centred in the Laalam village where four deaths, 68 injured and more than 40 housing units destroyed making dozens of peoples homeless. Damage and casualties are directly related to an earthquake-induced landslide occurred at 10 km far from the epicenter (ISC relocation). The landslide rupture, mapped by using a ground based survey, is striking NE-SW along a 1-km length rupture with a 45 cm of lateral displacement. The rupture plan is dipping 40° at the surface and showing horizontal striations. A 75 cm of pre-2006 lateral displacement is also observed indicating a repetitive behaviour of the landslide. The last time where the landslide was activated extends back to 1974 following another moderate earthquake. This landslide reminds us the high level hazard of induced ground failures due slope instabilities in mountainous zones of seismically active areas.     

Clay and Marl Formation Susceptibility in Mila Province,Algeria

In Mila Province, Algeria (a.k.a Mila Wilaya), sensitive clays presenting shrinkage-swelling phenomena are widespread, covering large areas. Due to this, constructions and infrastructures sustainability built on such soils is questionable. Such clays sensitivity is amplified by seasonal rainfall deficits which reaches extreme magnitudes. In order to develop disasters’ prevention measures, we present in this work, areas mapping susceptible to shrinkage-swelling phenomenon by adopting a French method developed by B R G M. This method takes into account three measurable characteristics: i.e. lithological, mineralogical and geotechnical, of clayey formations identified in the studied sector. Based on these characteristics, three scores are attributed for each formation. Then, the susceptibility index is the obtained score average for each clayey formation. The susceptibility map is established on this index basis with three classes: low, medium, high.     

Evaluation and numerical modeling of seawater intrusion in the Gaza aquifer (Palestine)

A numerical assessment of seawater intrusion in Gaza, Palestine, has been achieved applying a 3-D variable density groundwater flow model. A two-stage finite difference simulation algorithm was used in steady state and transient models. SEAWAT computer code was used for simulating the spatial and temporal evolution of hydraulic heads and solute concentrations of groundwater. A regular finite difference grid with a 400 m² cell in the horizontal plane, in addition to a 12-layer model were chosen. The model has been calibrated under steady state and transient conditions. Simulation results indicate that the proposed schemes successfully simulate the intrusion mechanism. Two pumpage schemes were designed to use the calibrated model for prediction of future changes in water levels and solute concentrations in the groundwater for a planning period of 17 years. The results show that seawater intrusion would worsen in the aquifer if the current rates of groundwater pumpage continue. The alternative, to eliminate pumpage in the intruded area, to moderate pumpage rates from water supply wells far from the seashore and to increase the aquifer replenishment by encouraging the implementation of suitable solutions like artificial recharge, may limit significantly seawater intrusion and reduce the current rate of decline of the water levels.     

Tectonique quaternaire et plis de rampe dans le golfe d'Hammamet (offshore tunisien)

The Jriba trough is an Upper Miocene graben located within the Tunisian offshore Gulf of Hammamet area, east of the Atlas front. This distensive structure suffered a compressive event during the Early Quaternary (Villafranchian). The Jriba structure was previously interpreted as ‘flower structure’, which possibly complicated by halokinetics movements. A new analysis of a set of seismic lines crossing the Jriba trough allows us to propose a new tectonic model where the Villafranchian deformation is characterized by (1) occurrence of a decollement level cutting Messinian to Pliocene layers; and (2) the growth of fault-related folds (fault-propagation fold). The NE–SW Miocene, inherited normal faults, locate the position of the ramps and folds whereas the NW–SE inherited normal faults are reactivated as tear faults. These NW–SE tear faults define various domains of different shortening values (one kilometre at maximum). To cite this article: M. Ben Romdhane et al., C. R. Geoscience 338 (2006).     

Manifestations tectono-diapiriques synsédimentaires et polyphasées d'âge Crétacé supérieur–Quaternaire dans la région de Zag Et Tir (Tunisie centre-nord)

The geodynamic evolution of the diapir of Zag Et Tir is the result of the coexistence of the diapiric and tectonic activity from the Upper Cretaceous until the Quaternary. The interference of the tectonic and diapiric phenomena is at the origin of the basin individualization with differential sedimentation during the Miocene. This explains the current distribution of the Neogene deposits on both sides of Zag Et Tir Triassic structure. The submeridian faults that subdivide our sector played a significant role during the Atlasic compression, inducing an unequal distribution of the folds on both sides of these accidents, as well in kind as in number, showing the anteriority of the faults compared to the folds. To cite this article: R.A. Gharbi et al., C. R. Geoscience 337 (2005).