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Showing 3 results for nakhaei
Estimation of Soil Hydraulic and Thermal Conductivity Parameters Using Geophysical and Thermal Methods
M Nakhaei,
Volume 8, Issue 4 (3-2015)
Abstract
For prediction of exact effect of soil temperature, soil water retention, unsaturated hydraulic conductivity and water flow of soils on seep development, information about soil hydraulic, physical properties soil temperature is necessary. In this study, using geophysical and thermal methods the hydraulic properties and thermal conductivity of unsaturated porous media was estimated. Infiltrated water temperature was 50° C and the temperature data used in inverse solution technique was recorded by 2 thermal sensors during 3255 sec. One of thermal sensor was installed at a depth of 50 cm and the soil hydraulic and thermal parameters were estimated using 48 collected data of the injection water temperature variations. In this research 121 geoelectrical sounding with the Wener, Schlumberger and polar-polar arrays configuration were used. Evaluation and interpretation of the sounding curves show that the water table is located at depth of 75 meters. Top alluvium layer (unsaturated zone) is composed of three layers. In this study, to investigate the distribution and diffusion of pollutants in the unsaturated zone, the brine concentration of 20 g/L was used. Wener and polar-polar arrays were used to detect and image the contaminants plume. The polar-polar configuration shows less spreading of contaminated plume in both vertically and horizontally direction than the Wener array.  Particularly by the Wener configuration the plume depth is more underestimated than the real value. Based on water injection visibility in the vicinity of the trenches and observing the water seepage at the trench face, the real velocity of the water at direction of 35 degrees relative to the horizon was measured equal to 0.159 m/h. Horizontal and vertical contaminant plume expansion coefficient was determined equal to 1.4. Evaluation of thermal and hydraulic properties of unsaturated porous media was done by HYDRUS-2D software. In this study five hydraulic parameters &thetar, &thetas, &alpha, n and Ks and five soil heat transfer parameters including the &lambdaL, &lambdaT, Cn, Co and Cw were included in the parameter estimation process. After implementation of the parameter estimation (adjusted for ​​observed and predicted temperature values) Coefficient of Determination  R2 was equal to 0.97 and the objective function value was equal to 11.5. Computational error in the mass balance was about 67 percent. 
Evaluating groundwater hydrochemistry in the Zarabad aquifer (Sistan and Baluchistan province) to determine the quality of the water for agricultural use
Miss Masoumeh Nikbakht, Prof Mohammad Nakhaei, Prof Ata Shakeri, Dr Vahab Amiri,
Volume 16, Issue 4 (Winter 2022)
Abstract
In this study, the hydrogeochemical and qualitative status of groundwater resources of the Zarabad coastal aquifer in southeast Iran has been investigated. The decreasing order of cations and anions is Na+>Ca2+>Mg2+>K+ and Cl->SO42->HCO3-, respectively. The two most water type are Na-Cl (78%) and Ca-Mg-Cl (22%). The water type, chlorine-alkalinity index, ion ratios, and position of the samples on the Gibbs diagram show that cation exchange (direct and reverse), weathering of silicates and evaporites, and seawater intrusion are the main controlling processes of water chemistry. The ionic ratios of SO42-/Cl-, B/Cl-, and Na+/Cl- indicate that saltwater infiltration increases as the distance from the Rabach River increases, particularly in the northwest and southeast regions. This can lead to a decrease in the quality of water resources. Moreover, the water quality for agricultural use is assessed based on some indices, including electrical conductivity (EC), sodium percentage (Na%), sodium absorption ratio (SAR), residual sodium carbonate (RSC), magnesium absorption ratio (MAR), permeability index (PI), Kelly’s ratio (KR), and USSL and Wilcox diagrams. The results showed that about 60% of the samples had unsuitable quality for irrigation. These samples were located in the northwestern and southeastern parts of the plain. About 40% of the samples have suitable quality for irrigation and are located in the vicinity of the Rabach River.
 

Assessment and spatio-temporal zoning of groundwater drought risk in Hashtgerd aquifer by groundwater resource index
Prof. Mohammad Nakhaei, Dr. Amin Mohebbi Tafreshi, Dr. Tofigh Saadi,
Volume 17, Issue 4 (Winter 2023)
Abstract
A sharp drop in groundwater level as a result of indiscriminate extraction over a long period of time leads to the drying up of groundwater flows, which is called the phenomenon of groundwater drought. In this regard, this research aims to investigate the process of change and reduction of groundwater level, which is characterised by the phenomenon of groundwater drought. Based on this, the Groundwater Resource Index (GRI) was used to evaluate the drought condition of groundwater and analyse its spatial and temporal patterns based on groundwater level data of 21 observation wells between 1993 and 2019. ArcGIS software was used to create zone maps. The results of the research show that certain areas of the study area have experienced moderate to severe drought since 2001. In addition, the GRI zonation maps show that the southern and south-eastern regions of the aquifer have been more sensitive to drought than other parts of the aquifer during the defined period. The spatio-temporal pattern of groundwater drought in the aquifer shows that after a period of moderate drought from 2001 to 2003, the condition of the aquifer improved slightly, and generally stable conditions were established from 2001 to 2010, but since 2011, the occurrence of drought has intensified and the aquifer has been in severe to very severe drought conditions. These conditions highlight the need for careful attention and implementation of management measures. One of the study's recommendations is to use satellite data on groundwater levels to assess the progress of the drought, and compare it with the findings of this study.
 

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