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

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Dłużewski M. , Kozłowski R. , Szczucińska A.

Ecological Chemistry and Engineering. S

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2017

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

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Szczucińska A. , Dłużewski M. , Kozłowski R. , Niedzielski P.

Ecological Chemistry and Engineering. S

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2019

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tom 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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The Influence of Disturbance Type on Precipitation - Use Efficiency at Functional Group and Species Scales in an Arid Habitat

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Busso C. A. , Montenegro O. A. , Torres Y. A. , Giorgetti H. D. , Rodriguez G. D.

Polish Journal of Ecology

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2016

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tom Vol. 64, nr 2

143--164

EN

We used long-term datasets (1984–1992) to contrast precipitation-use efficiency estimates between various disturbance kinds at a functional group and/or a species scale. Effects of varying amounts of precipitation and plant cover on PUE were also examined. Field studies were conducted at northeastern, arid Patagonia, Argentina (40°39′49″S, 62°53′6.4″W). Within each management kind, biomass was sampled in 0.5 × 0.5m permanent plots (n = 30) over 9 years after defoliation at 5 cm stubble at the end of each growing season, and it was separated into species. Biomass sampling allowed determination of annual net primary production. Thereafter, species were grouped into each of three functional groups. Precipitation-use efficiency (PUE) was calculated as the total dry matter produced per unit surface area on any given year divided by the total rainfall in that year. Plant cover on 20 out of those 30 plots was determined to study the relationship between plant cover and PUE. The contribution of cool-season perennial grasses to total PUE was higher (P <0.05) than that found for the other two functional groups in all management kinds and years. PUE was similar (P> 0.05) in wet than dry years, and it was greater (P <0.05) or similar (P> 0.05), but not lower, on the more than less competitive perennial grass species in all management kinds. The relationship between plant cover and PUE was positive, linear (P <0.0000) and management-kind dependent.

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The Porch and its Interaction with Building Design in Arid Zones

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Berghout B. , Berghout W. , Berghout I.

Civil and Environmental Engineering Reports

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2023

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tom Vol. 33, no. 3

50--62

EN

Improving the energy performance of buildings has thus become a major challenge, as the building sector is now one of the main sources of energy consumption and one of the main contributors to greenhouse gas emissions. Faced with these alarming challenges, current building design in the north is based on minimizing heat loss. However, this logic is not necessarily the most relevant in southern countries, characterized by excessive heat and insufficient, variable rainfall. The best way to achieve this is through sustainable design, with its intrinsic, energy_saving qualities, exploited by effective modeling. This article focuses on ideas and innovations that are helping to overcome these challenges. The results of introducing a porch into building design represent best practice in arid zones and beyond in terms of how it is thermally insulated. This has resulted in a significant reduction in thermal load in the energy ratio of up to 53.55%. This latest research aims to provide construction professionals with concrete examples of the design process, its technical feasibility, optimization and digitization based on climatic data from the arid zone.