Ahmad Sana
@squ.edu.om
Associate Professor, Civil and Architectural Engineering
Sultan Qaboos University
EDUCATION
Ph.D. (Civil Engineering)
RESEARCH INTERESTS
Coastal Engineering, Hydraulic Engineering, Water Supply
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Asma Al-Hadhrami, Ahmad Sana, Talal Etri, Abdullah Al-Mamun, Mohammed Reza Nikoo, and Ghazi Al-Rawas
Elsevier BV
L. N. Gunawardhana, S. Ahmed, A. Sana, and M. S. Baawain
Springer Science and Business Media LLC
Intisar Al-Sulaimi, Jagdeep Kumar Nayak, Abdullah Al-Mamun, and Ahmed Sana
Elsevier BV
Sajjad Ahmad Siddiqi, Sadik Rahman, Abdullah Al-Mamun, Jagdeep Kumar Nayak, Ahmad Sana, and Mahad Said Baawain
Springer Science and Business Media LLC
Maryam Gharekhani, Mohammad Reza Nikoo, Ata Allah Nadiri, Ghazi Al-Rawas, Ahmad Sana, Amir H. Gandomi, Banafsheh Nematollahi, and Venkatramanan Senapathi
Elsevier BV
Prerana Chitrakar, Ahmad Sana, and Sheikha Hamood Nasser Almalki
Elsevier BV
Ahmad Sana, Prerana Chitrakar, Mahad Baawain, and Abdullah Al-Mamun
MDPI AG
The coast of Oman is undergoing huge coastal developments in order to realize Oman Vision 2040, covering all the strategic sectors. Historical data of coastal hydrodynamic parameters is scarce, even though its importance for properly designed coastal structures is recognized. In the present study, Acoustic Doppler Current Profilers (ADCP) were deployed at eleven locations along the coast of Oman. These locations were selected based on their strategic importance for the country. The duration of the deployments were between 60 and 265 days. The measured data of the waves and currents were collected and analyzed using equipment-specific software and Excel. The significant wave heights can reach 2 m along the whole coast of Oman. The southern coast is dominated by swells. The maximum to significant wave height ratio is approximately 1.5, which is less than the value of 2 obtained using the Rayleigh distribution. The coastal currents are stronger along the southern coast than those along the northern coast. The range of current magnitude is between 0.02 m/s and 0.8 m/s. This baseline study will help the public authorities in establishing permanent hydrodynamic measurement stations along the coast of Oman. Moreover, these measurements will serve the practicing engineers in designing coastal structures along the coast of Oman.
Javed Akhtar, Ahmad Sana, and Syed Mohammed Tauseef
Springer Science and Business Media LLC
F. Masoumi, S. Masoumzadeh Sayyar, P. Valizadeh, M. R. Nikoo, A. Al-Nuaimi, and A. Sana
Springer Science and Business Media LLC
Abdullah Al-Mamun, Waqar Ahmed, Tahereh Jafary, Jagdeep Kumar Nayak, Ali Al-Nuaimi, and Ahmad Sana
Elsevier BV
S. Rahman, N.J. Al Balushi, J.K. Nayak, A. Al-Mamun, M. Al-Abri, M. Al Alawi, and A. Sana
Elsevier BV
Mojgan Bordbar, Mohammad Reza Nikoo, Ahmad Sana, Banafsheh Nematollahi, Ghazi Al-Rawas, and Amir H. Gandomi
Informa UK Limited
Javed Akhtar, Ahmad Sana, Syed Mohammed Tauseef, and Hitoshi Tanaka
MDPI AG
The Sultanate of Oman is an arid country in the Arabian Peninsula suffering from insufficient freshwater supplies and extremely hot weather conditions. The only source of recharge is rainfall, which is scarce and varies with space and time, for the aquifers being overexploited for the last few decades. This has led to depleting groundwater levels and seawater intrusion into coastal aquifers. In the present study, Ground Modeling System (GMS) was employed in Wadi Al-Jizi, which is one of the important aquifers in the Al Batinah coastal plain that caters to the needs of the country’s 70% agriculture. MODFLOW and MT3DMS were used to simulate the groundwater levels and solute transport, respectively. These models were calibrated under steady and transient conditions using observed data from twenty monitoring wells for a period of seventeen years (year 2000–2016). After validation, the model was utilized to predict the salinity intrusion due to changes in groundwater abstraction rates and sea level rise owing to climatic change. These predictions show that, by the year 2040, salinity intrusion (TDS > 12,800 mg/L) will transgress by 0.80 km inland if the current abstraction rates are allowed to be maintained. Further deterioration of groundwater quality is anticipated in the following years due to the increased pumping rates. The models and the results from the present study may be utilized for the effective management of groundwater resources in the Wadi Al-Jizi aquifer.
Hitoshi Tanaka, Nguyen Xuan Tinh, and Ahmad Sana
MDPI AG
According to recent investigations on bottom boundary layer development under tsunami, a wave boundary can be observed even at the water depth of 10 m, rather than a steady flow type boundary layer. Moreover, it has been surprisingly reported that the tsunami boundary layer remains laminar in the deep-sea area. For this reason, the bottom boundary layer under tsunami experiences two transitional processes during the wave shoaling: (1) flow regime transition in a wave-motion boundary layer from laminar to the turbulent regime, and (2) transition from non-depth-limited (wave boundary layer) to depth-limited boundary layer (steady flow boundary layer). In the present study, the influence of these two transition processes on tsunami wave height damping has been investigated using a wave energy flux model. Moreover, a difference of calculation results by using the conventional steady flow friction coefficient was clarified.
Noor Juma Al Balushi, Jagdeep Kumar Nayak, Sadik Rahman, Ahmad Sana, and Abdullah Al-Mamun
MDPI AG
Microbial desalination cells (MDCs) are promising bioelectrochemical systems for desalination using the bacteria-generated electricity from the biodegradation of organic wastes contained in the wastewater. Instead of being a sustainable and eco-friendly desalination technology, the large-scale application of MDC was limited due to the high installation cost of the metal-catalyst-coated cathode electrode and the poor performance of the cathode in long-term operation due to catalyst fouling. Such cathodic limitations have hindered its large-scale application. The cathodic limitation has arisen mainly because of three losses, such as (1) Ohmic loss, (2) mass transfer loss, and (3) activation loss. The catalyst-assisted cathodic reduction reaction is an electrochemical surface phenomenon; thereby, the cathode’s surface charge transfer and thermodynamic efficiency are crucial for reaction kinetics. This review article aims to provide an overview of the MDC process, performance indicators, and summarizes the limiting factors that could hinder the process performance. Then, the article represented a comprehensive summary of the air-cathodic limitations and the mechanisms applied to improve the air-cathodic limitations in MDC to enhance the cathodic reaction kinetics through cathode surface modification through catalysts. The study is significantly different from other review studies by the precise identification and illustration of the cathodic losses and their mitigation strategies through surface modification. The details about the role of photocatalysts in the minimization of the cathode losses and improvement of the performance of MDC were well presented.
Javed Akhtar, Ahmed Sana, Syed Mohammed Tauseef, Gajendran Chellaiah, Parmeswari Kaliyaperumal, Humayun Sarkar, and Ramamoorthy Ayyamperumal
Springer Science and Business Media LLC
Groundwater resources are highly stressed due to their overuse, especially in the arid region. This study is aimed at discovering potential groundwater resource zones using currently available data and state-of-the-art methods. This will lead to effective management of scarcely available and rapidly depleting groundwater resources in the Wadi Al-Jizi catchment, located in the Al-Batinah region. Data on terrain characteristics, geology, and geomorphology was integrated using remote sensing techniques and geographical information system (GIS). The result from this exercise was used for the identification of areas with a high potential for groundwater availability. These areas were classified into five types, namely, excellent, good, medium, low, and very low representing 11%, 59.5%, 26%, and 3.5% of the total area, respectively. The present study shows that the integration of all the weighted parameters shows promising results in the zonation of groundwater. This study shall be useful to the decision-makers in highlighting potential drilling as well as recharge sites in the area.
Sajjad Ahmad Siddiqi, Abdullah Al-Mamun, Mahad Said Baawain, and Ahmad Sana
Elsevier BV
Intisar Nasser Al-Sulaimi, Jagdeep Kumar Nayak, Halima Alhimali, Ahmed Sana, and Abdullah Al-Mamun
MDPI AG
Sewage sludge represents an important resource for reuse in the wastewater treatment field. Hence, thermophilic anaerobic digestion (TAD) could be an alternative technique to recover renewable resources from sludge. In the TAD biodegradation process, volatile fatty acids (VFAs) are the intermediate products of methanogenesis. However, the higher formation and accumulation of VFAs leads to microbial stress, resulting in acidification and failure of the digester. Therefore, several batch TADs have been investigated to evaluate the VFAs production from sludge and their impact on biogas generation and biodegradation efficiency. Three types of sewage sludges, e.g., primary sludge (PS), secondary sludge (SS), and mixed sludge (MS) were used as substrates to estimate the accumulation of VFAs and yield of methane gas. The system showed the maximum total VFAs accumulation from both PS and MS as 824.68 ± 0.5 mg/L and 236.67 ± 0.5 mg/L, respectively. The dominant VFA accumulation was identified as acetic acid, the main intermediate by-product of methane production. The produced biogas from PS and MS contained 66.75 ± 0.5% and 52.29 ± 0.5% methane, respectively. The high content of methane with PS-feeding digesters was due to the higher accumulation of VFAs (i.e., 824.68 ± 0.5 mg/L) in the TAD. The study also predicted the design parameters of TAD process by fitting the lab-scale experimental data with the well-known first-order kinetic and logistic models. Such predicted design parameters are significantly important before the large-scale application of the TAD process.
Sajjad Ahmad Siddiqi, Abdullah Al-Mamun, Ahmad Sana, Mahad Said Baawain, and Mahbuboor Rahman Choudhury
IWA Publishing
Abstract Leachate originating from municipal solid waste landfills poses a serious contamination threat to public health. The study performed a bio-physicochemical characterization of leachate from two landfills in Oman, i.e., Multaqa landfill leachate (MLL) and Barka landfill leachate (BLL) before and after rainfall. Samples were characterized for 92 parameters. Additionally, the leachate pollution index (LPI) was estimated to assess the expected contamination levels and potential environmental health risks. The study found a high value of the leachate parameters without any rainfall incidents. Pearson correlations (±ve) are seen at more than 90% in all cases, which is a strong association (r>0.75) for the measured parameters in both MLL and BLL. Rainfall significantly reduced the concentrations of organic contaminants and solids in leachate due to dilution. The study revealed about 18%–29% and 14%–28% reductions in the LPI sub-index for organic and inorganic contaminants, respectively, after rainfall. The overall LPI values were higher compared with similar findings from the literature. Such deviations could be attributed to the unsegregated nature of solid waste, resulting in the formation of contaminants or from the disposal of a high volume of solid waste in a smaller area. Therefore, the study recommends efficient management strategies for landfills to reduce potential leachate groundwater contamination.
Al-Mundhar Al-Nasri, Luminda Niroshana Gunawardhana, Ghazi Ali Al-Rawas, Mahad Said Baawain, and Ahmed Sana
Informa UK Limited
Sustainable groundwater resource management requires a better understanding of multilayer interactions, caused by the heterogeneous formations and enhanced by the groundwater withdrawal in aquifers. This phenomenon was studied in Al-Khoud lower catchment in Oman. Water exchange between different layers was observed by measuring piezometric heads of wells located at the same place with screen intervals placed in different layers. In addition, groundwater levels from 8 more wells and pumping rates from 60 wells were used for developing a numerical model in a 156 km2 area. Lithological data from 23 boreholes were used for defining three subsurface layers. Model results under different conditions indicated that 1.9–3.8 m head difference could be attributed to the pumping, while 2.1–6.0 m groundwater-level variations were accounted for the heterogeneity and anisotropic effects. Further analysis showed that the increased pumping rate increased the piezometric head difference between the layers, which enhances the multi-layer interactions.
Ahmed Al Naamani and Ahmad Sana
IWA Publishing
Abstract A water distribution network in an urban area in Muscat region (the capital city of Oman) is assessed for operational performance using the widely accepted methodology proposed by the International Water Association (IWA). The technical performance of this network was assessed using global performance index methods after modifying the performance levels as per local guidelines. A total of 37 operational performance indicators for the network were selected to carry out assessment. Overall operational performance showed high scores whereas some indicators showed unacceptable performance values. The network showed very high technical performance considering nodal pressures. The lower performance for pipe velocity may be attributed to the fact that the network is currently being utilized by 70% of the population for which it was designed. The residual chlorine levels were within the acceptable range of the Public Authority for Water (PAW), showing a very good performance by virtue of water quality. This study will be useful for decision makers to assess the operational, technical and water quality performance of urban networks and take actions for improvements.
Luminda Niroshana Gunawardhana, Fatma Al-Harthi, Ahmed Sana, and Mahad Said Baawain
Springer Science and Business Media LLC
The constant-rate pumping test (CRT) is commonly used to determine the aquifer properties. In this method, measured drawdown in the pumping well and the monitoring wells are usually matched with type curves developed by various analytical methods. However, numerous assumptions used to develop the analytical solution are not always compatible with the actual site conditions. In this study, drawdown records collected in a pumping well and two monitoring wells located near a river, were analyzed to investigate the boundary effects on the estimated aquifer properties. This site condition violates the assumption that the aquifer is of infinite areal extent. Moreover, time varying water heads during the pumping and recovery tests were simulated numerically to determine the effect of hydraulic gradient, which does not satisfy the assumption of horizontal potentiometric surface used in the analytical solution. Calibrated aquifer properties without the boundary effect showed clear differences, where the transmissivity, anisotropy ratio and specific yield varied by 12%, 34% and 53%, respectively, as compared to the results obtained by including the boundary effect. Numerical simulation conducted by considering a horizontal potentiometric surface as in the analytical model produced an averaged root-mean-squared-error (RMSE) of 0.055 m, which was approximately 57% higher than the RMSE value estimated with the effect of the hydraulic gradient. Therefore, it was concluded that the simplified analytical solutions may lead to misleading estimations of aquifer properties when the pumping test was conducted in an area with complex site conditions.
Sajjad Ahmad Siddiqi, Abdullah Al-Mamun, Mahad Said Baawain, and Ahmad Sana
Springer Science and Business Media LLC
Groundwater quality levels are currently deteriorating in Gulf Cooperation Council (GCC) countries due to excessive surface and subsurface human activities. Agricultural and industrial activities, landfill seepage and seawater intrusion have been attributed to the deterioration of groundwater quality in GCC states. Such a deterioration of groundwater quality could affect water security in the region, including human health and the ecosystem. Therefore, this review aims to identify the key causes of groundwater contamination across the GCC countries from the published literature. In addition, the review summarizes the major components of the groundwater contaminants across the GCC countries. The results have shown that heavy metals, several cations and anions are the leading cause of groundwater pollution. In most cases, the level of metals and ion contaminants exceeds both the local and international water quality standards. The results have observed the presence of high levels of coliform and radioactive elements in groundwater, especially Uranium and Radium, thereby posing additional risk to human health through consumption. Considering the scarcity of freshwater resources in GCC, urgent actions are required from the decision-makers and relevant regulatory bodies to set up and implement long-term mitigation strategies and stringent policies that will protect the groundwater resources from the adverse effects of anthropogenic activities.
Sadik Rahman, Tahereh Jafary, Abdullah Al-Mamun, Mahad Said Baawain, Mahbuboor Rahman Choudhury, Halimah Alhaimali, Sajjad Ahmad Siddiqi, Bipro Ranjan Dhar, Ahmad Sana, Su Shiung Lam,et al.
Elsevier BV
Abstract Shortage of potable water is the driving force behind desalination practices mainly performed by conventional thermal and membrane-based technologies. However, conventional desalination technologies are unsustainable due to their high energy requirements. This highlights the necessity of developing more sustainable and eco-friendly alternatives. As an emerging technology, microbial desalination cell (MDC) has attracted a great deal of attention due to its ability to desalinate seawater, treat wastewater, and recover electricity and value-added products in a single reactor. The technology produces electricity through the biodegradation of organics present in wastewater. The recovered electricity derives the migration of ions, and is subsequently collected as value-added product. The present review summarizes the prospects of MDC as (i) a sustainable green desalination technology, (ii) a cost-effective approach for simultaneous wastewater treatment and recovery of value-added products (i.e., HCl, NaOH, H2O2, H2, humic and fulvic acid), and (iii) an electrochemical process for + removal of targeted pollutants (i.e., NH4+-N, Cu, Cr, Pb, Ni, As). Despite the favorable environmental and economic attributes of MDCs, large-scale application of those technology is limited due to a number of engineering and operational challenges. Therefore, this review carefully summarizes all the challenges associated with engineering parameters (i.e., reactor design, internal resistance, cost-effectiveness of electrodes and membranes, membrane fouling), and operating factors (i.e., pH imbalance due to ion migration, low ion transport rate, growth and adhesion of electroactive biofilms, and biofilm inhibition). The interrelationships between the engineering/operational challenges and MDC performances are also concisely explained. Finally, research needs to scale up MDCs for simultaneous desalination, wastewater treatment, and energy-resource recovery are proposed.
S. Al-Hashmi, L. Gunawardhana, A. Sana, and M. Baawain
Springer Science and Business Media LLC
Sustainable groundwater aquifers are critical in arid and semiarid countries due to the scarcity of surface water and precipitation. Management of groundwater resources requires estimation of aquifer properties and interaction between multilayers in heterogeneous aquifers. A three-dimensional groundwater flow model was implemented to simulate a complex multilayer aquifer in Oman. Steady-state model was calibrated using groundwater level data in July 2016. Both the automated parameter calibration technique and manual trial and error method were applied for calibrating hydraulic conductivity, groundwater recharge, and anisotropy of soil layers. The optimum set of parameters of 14 observation wells was obtained from the simulation with minimum root mean square error of 0.8 m for groundwater water level. The calibrated model was validated using measured data for October 2016, and root mean square error was found to be 0.81 m for groundwater water level. Among the observation wells which were used in the above analysis, 4 of them were directed to different aquifer depths and each two observation wells were in the same location. These two sets of wells, therefore, were used for analyzing interactions among different aquifer layers. Results showed that increased pumping rates enhanced water transfer between multilayers due to increased hydraulic gradient. The effect was more dominant in layers with high vertical hydraulic conductivity. Also, the sensitivity analysis was performed and results indicated that the predicted water level was less sensitive to vertical anisotropy. The findings of this study could be useful for decision-makers for better management of groundwater resources in arid regions.