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Palm grove groundwater assessment and hydrodynamic modelling Case study: Beni Abbes, South-West of Algeria

Merzougui Touhami, Bouanani Abderezak, Rezzoug Cherif, Mekkaoui Abedrehmene, Hamzaoui Fadoua A., Merzougui Fatima Z.

Journal of Water and Land Development

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2019

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no. 43

133--143

EN

This paper presents the groundwater modelling of Beni Abbes palm grove in Southwest Algeria. Beni Abbes oasis alluvial aquifer is part of the Saoura Valley aquifer system, including a loose slick contained in a Quaternary alluvial embankment that fills the Beni Abbes basin. To address local needs, industry and agriculture, groundwater has been intensively exploited in recent years. Groundwater of the Beni Abbes oasis in the Saoura Valley oasis chain, is composed of a complex system, whose layer of alluvial terraces ensures a vital role for a 40-hectare palm grove. Due to its architectural position in the local aquifer system, the alluvial aquifer is mainly fed by the Great Western Erg and sometimes by the Saoura River floods. Based on the hydrogeological, hydrochemical characterisation and hydrodynamic modelling of the alluvial aquifer system of the Beni Abbes oasis, the mathematical model of finite difference and finite difference at steady state leads to the estimation of the hydrodynamic parameters of the aquifer and the evaluation of the complete water balance. The main results of this study provide a better understanding of the geometry and functioning of this aquifer currently in a state of concern. Furthermore, it is necessary to undertake integrated water resource management in this oasis in order to ensure sustainable development.

PL

W pracy przedstawiono modelowanie wód podziemnych w gaju palmowym Beni Abbes w południowozachodniej Algierii. Aluwialny poziom wodonośny oazy Beni Abbes jest częścią systemu wód podziemnych doliny rzeki Saoura, łącznie z wodami zawartymi w czwartorzędowym aluwialnym obwałowaniu, które wypełnia basen Beni Abbes. Wody te w ostatnich latach były intensywnie eksploatowane, aby zaspokoić potrzeby ludności, przemysłu i rolnictwa. Wody gruntowe oazy Beni Abbes, jednego z elementów łańcucha oaz doliny Saoury, stanowią złożony system, którego warstwa aluwialnych tarasów spełnia kluczową rolę dla utrzymania 40-hektarowego gaju palmowego. Z powodu swojego usytuowania w lokalnym systemie poziomów wodonośnych poziom aluwialny jest zasilany z Wielkiej Pustyni Zachodniej, a czasami także przez wylewy rzeki Saoura. Wykorzystując dane hydrogeologiczne i hydrochemiczne, zbudowano model aluwialnego poziomu wodonośnego oazy Beni Abbes, który umożliwił ustalenie parametrów hydrodynamicznych poziomu i ocenę całkowitego bilansu wodnego. Wyniki tych badań pozwalają lepiej zrozumieć geometrię i funkcjonowanie poziomu wodonośnego, będącego obecnie w stanie zagrożenia. Niezbędne jest zorganizowanie zintegrowanego zarządzania zasobami wodnymi oazy, aby zapewnić jej zrównoważony rozwój.

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Hydrochemical diversity of a large alluvial aquifer in an arid zone (Draa river, S Morocco)

Szczucińska Anna, Dłużewski Maciej, Kozłowski Rafał, Niedzielski Przemysław

Ecological Chemistry and Engineering. S

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2019

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Vol. 26, nr 1

81--100

EN

In arid areas, with rivers functioning episodically, alluvial resources are the main source of water. Considering the intensified regulation of discharge in montane catchments, supplying the intermittent rivers, in the nearest future alluvial aquifers will gain key importance for the functioning of people in arid zones. The research aimed to investigate the diversified chemistry of alluvial waters typical of large intermittent river valleys in hot arid zones as well as to analyse processes determining the water chemistry and affecting its diversity. The detailed study, carried out in October 2015, covered the Draa river valley (1100 km total length) in the region of the Mhamid Oasis. The examined water was sampled from all wells found in the study area. Concentrations of the main cations: Ca2+, Mg2+, K+, Na+, NH4+, and Li+, anions: Cl−, SO42−, HCO3−, and NO3−, as well as trace elements: Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn, were identified. Results were analysed with statistical, hydrochemical, and geochemical modelling methods. Alluvial waters of the eastern and western part of the oasis differed in concentrations of numerous components, what resulted from the regulation of irrigation. Specific electrical conductivity showed a 3.5-fold increase, from 3800 to 13800 μS/cm, consistent with the direction of water flow in the oasis, from east to west. Even a greater rise was observed for ions: Cl− (6x), Na+ (5.5x), Mg2+ (5.0x), Ca2+, and SO42− (3.5x). Such a composition indicated multiionic hydrochemical type of waters dominated by Na+ and Cl−. Additionally, high Pearson correlation coefficients were recorded for Na+ and Cl− (0.98) as well as Mg2+ and Cl− (0.97). The saturation index suggested that the main water components originated from dissolving of minerals such as halite, anhydrite, sylvite, and gypsum. Groundwater chemistry in the Mhamid Oasis was determined mainly by geogenic processes, such as dissolving of evaporates, precipitation of carbonate minerals, and ion exchange.

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Potential use of alluvial groundwater for irrigation in arid zones - Mhamid Oasis (S Morocco)

Dłużewski M., Kozłowski R., Szczucińska A.

Ecological Chemistry and Engineering. S

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2017

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Vol. 24, nr 1

129-140

EN

In arid zones, the availability of fresh water is usually very limited because of high salinity, which greatly limits their use for irrigation purposes. High mineralization of water used for irrigation leads to increased soil salinity. The aim of the study was to examine the potential use of alluvial groundwater for irrigation in arid zones. The works were conducted in the Middle Draa Valley in southern Morocco (the Mhamid Oasis) in October 2015. Water samples of alluvial groundwater were collected for laboratory analysis from 42 wells located in the oasis. In order to determine the possibility to use the water for irrigation purposes, the Sodium Adsorption Ratio (SAR), sodium percentage (%Na), permeability index (PI), Kelly’s ratio (KR), magnesium hazards (MH) and electrical conductivity (EC) were assessed. EC values, exceeding 3000 μS·cm-1 in all the samples, classify the water as unsuitable for irrigation. MH and the KR indexes show that 30% of water samples represent levels making them unsuitable for irrigation. SAR confirms the very high degree of susceptibility of the analyzed waters to salinity hazard. The PI index of these waters is moderate, however in terms of sodium content they can be deemed suitable for irrigation purposes. It has been found that even within a small area of the oasis, a very large differentiation in the alluvial groundwater suitability for irrigation purposes occurs.

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Różnicowanie warunków przepływu wód współczesnych równi zalewowych na Niżu Polskim na przykładzie doliny środkowej Wisły

Falkowski T.

Przegląd Geologiczny

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2015

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Vol. 63, nr 10/1

710--714

EN

Differentiation of groundwater flow conditions within the floodplains of the river valleys in the Polish Lowlands may result from polygenesis of their valleys sections, as well as from the evolution of river systems, which lasts from the end of the Pleistocene. The investigations, which were carried out in the middle Vistula valley showed that important factor for differentiation of groundwater flow conditions within the floodplain could be also the influence of the basement of contemporary alluvia. In the sections where it forms morphological protrusions, the basement affects the flood waters flow which transforms upper part of floodplain lithological profile.