Techno-economic assessment of brackish groundwater desalination for irrigation in arid regions: a case study from the Moghra aquifer, Egypt

ABSTRACTIn this study, surface water quality was assessed on the basis of irrigation water quality indices and the irrigation water quality index (IWQI) via GIS. The study was carried out on the basis of analyses of samples collected in August (dry) and November (wet) 2023 from 12 designated points along the Yıldız River in Sivas. The sodium adsorption ratio (SAR), Kelly index (KI), sodium percentage (Na%), permeability index (PI), residual sodium carbonate (RSC), magnesium hazard (MH) indices and IWQI were calculated to determine the classification of irrigation water quality. Additionally, analyses of Ca2+, Cl−, Fe2+, K+, HCO3−, Mg2+, Mn, Na+, pH and SO42− were conducted on the samples. The spatial distributions of the calculated parameters were mapped via GIS, and irrigation water quality assessment was performed according to the US Salinity Diagram and irrigation water quality standards. The IWQI values ranged from 401 to 61 during the rainy season and from 42 to 67 during the dry season. In the rainy season, two surface water samples were classified as ‘poor (MR: moderate restriction, IWQI: 55–70)’ and nine as ‘very poor (HR: high restriction, IWQI: 40–55)’. In the dry season, three surface water samples were classified as ‘poor (MR: moderate restriction)’ and nine as ‘very poor (HR: high restriction)’. According to the US Salinity Diagram, the majority of surface water samples in both the rainy and dry seasons fell into categories C3S1 (high‐salinity hazard–low‐sodium hazard) and C2S1 (medium‐salinity hazard–low‐sodium hazard), respectively. The results highlight the effectiveness of these methodologies in evaluating surface water quality, assisting in the development of informed management strategies for sustainable water resource use in agricultural environments. The IWQI has proven to be a good tool for assessing the quality of irrigation water in the study area and managing water quality and can help decision makers manage water resources more effectively for sustainable agriculture.

Assessment of groundwater quality for irrigation in the arid regions using irrigation water quality index (IWQI) and GIS-Zoning maps: Case study from Abu Dhabi Emirate, UAE

Irrigation has made a significant contribution to supporting the population’s expanding food demands, as well as promoting economic growth in irrigated regions. The current investigation was carried out in order to estimate the quality of the groundwater for agricultural viability in the Algerian Desert using various water quality indices and geographic information systems (GIS). In addition, support vector machine regression (SVMR) was applied to forecast eight irrigation water quality indices (IWQIs), such as the irrigation water quality index (IWQI), sodium adsorption ratio (SAR), sodium percentage (Na%), soluble sodium percentage (SSP), potential salinity (PS), Kelly index (KI), permeability index (PI), potential salinity (PS), permeability index (PI), and residual sodium carbonate (RSC). Several physicochemical variables, such as temperature (T°), hydrogen ion concentration (pH), total dissolved solids (TDS), electrical conductivity (EC), K+, Na2+, Mg2+, Ca2+, Cl−, SO42−, HCO3−, CO32−, and NO3−, were measured from 45 deep groundwater wells. The hydrochemical facies of the groundwater resources were Ca–Mg–Cl/SO4 and Na–Cl−, which revealed evaporation, reverse ion exchange, and rock–water interaction processes. The IWQI, Na%, SAR, SSP, KI, PS, PI, and RSC showed mean values of 50.78, 43.07, 4.85, 41.78, 0.74, 29.60, 45.65, and −20.44, respectively. For instance, the IWQI for the obtained results indicated that the groundwater samples were categorized into high restriction to moderate restriction for irrigation purposes, which can only be used for plants that are highly salt tolerant. The SVMR model produced robust estimates for eight IWQIs in calibration (Cal.), with R2 values varying between 0.90 and 0.97. Furthermore, in validation (Val.), R2 values between 0.88 and 0.95 were achieved using the SVMR model, which produced reliable estimates for eight IWQIs. These findings support the feasibility of using IWQIs and SVMR models for the evaluation and management of the groundwater of complex terminal aquifers for irrigation. Finally, the combination of IWQIs, SVMR, and GIS was effective and an applicable technique for interpreting and forecasting the irrigation water quality used in both arid and semi-arid regions.

Irrigation alleviates poverty in arid and semi-arid regions, such as Ethiopia, necessitating a water suitability assessment. This study evaluates irrigation water quality in the Irob catchment, Northern Ethiopia. It differs by using combined parameters of the irrigation water quality index (IWQI) for comprehensive assessment beyond standard comparisons. Eighteen water samples were collected and analyzed using ultraviolet spectrometry, titration, and atomic absorption spectrometry. The evaluation considered electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), sodium adsorption ratio, sodium percentage, residual sodium carbonate, permeability index, magnesium ratio, Kelley's index, potential salinity, and the IWQI. The findings revealed that 22.2, 38.9, 88.8, 66.7, 83.3, 66.7, 100, 72.2, and 55.6% of samples exceeded recommended standards for EC, TDS, TH, permeability index, manganese, cobalt, copper, cadmium, and nickel, respectively. Most water quality parameters meet standards, but improved irrigation management is crucial to reduce risks. The IWQI indicates that 22.2% of water samples have minor restrictions, while 77.8% have no restrictions. This method provides key insights for evaluating irrigation water quality in similar hydrogeological and environmental conditions, particularly in semi-arid and arid regions. The findings enhance the understanding of sustainable water quality, supporting local authorities in developing resilient irrigation strategies for regional agricultural sustainability.

This study aims to present a comparative assessment of hydrochemical characterization and groundwater quality in karst aquifers with the support of GIS which is essential to correlate the source of water with climate and geology, and to evaluate suitability of water for various uses. The study area is the Altinova region in Turkey where intensive agricultural activities prevail and travertine covers 85% of the study area. A total of 25 groundwater wells were monitored by seasonal field measurements and extensive water quality analyses for a period of one year to establish correlation between groundwater quality, its source, regional climate, and geology. A comprehensive analysis was conducted to assess the groundwater's suitability for irrigation based on electrical conductivity, sodium adsorption ratio, sodium percentage, magnesium hazard, permeability index, residual sodium bicarbonate, Kelly’s ratio, and an irrigation water quality (IWQ) index. This multi-parameter evaluation was further integrated with geospatial analysis using ArcGIS, providing a detailed spatial understanding of hydrochemical variations across the area. Major cations and anions dominance were identified as Ca2+ > Na+ > Mg2+ > K+ and HCO3− > Cl− > SO42−, respectively. Spatial mapping identified high concentrations of Ca2+, TDS, TH, and SO42− in non-karstic areas, occasionally exceeding WHO guidelines. Nitrate concentrations displayed varied spatial distribution. The SAR values generally matched C2-S1 and C3-S1 classes, suggesting medium to high salinity risks and low sodium presence. Based on the IWQ index and observed correlations with total dissolved solids, the groundwater in Altinova’s karstic aquifer is considered suitable for irrigation, with salinization largely due to ionic interactions and geology. The presented comparative assessment provides a holistic approach for understanding hydrochemical characteristics of karst aquifers, and analyzing the impacts of natural factors and anthropogenic pollution sources on groundwater quality.

Evaluating grouLindwater quality and associated hydrochemical properties is critical to manage groundwater resources in arid and semiarid environments. The current study examined groundwater quality and appropriateness for agriculture in the alluvial aquifer of Makkah Al-Mukarramah Province, Saudi Arabia, utilizing several irrigation water quality indices (IWQIs) such as irrigation water quality index (IWQI), total dissolved solids (TDS), sodium adsorption ratio (SAR), potential salinity (PS), magnesium hazard (MH), and residual sodium carbonate (RSC) assisted by multivariate modeling and GIS tools. One hundred fourteen groundwater wells were evaluated utilizing several physicochemical parameters, which indicating that the primary cation and anion concentrations were as follows: Na+ > Ca2+ > Mg2+ > K+, and Cl− > SO42˗ > HCO3˗ > NO3˗ > CO32˗, respectively, reflecting Ca–HCO3, Na–Cl, and mixed Ca–Mg–Cl–SO4 water facies under the stress of evaporation, saltwater intrusion, and reverse ion exchange processes. The IWQI, TDS, SAR, PS, MH, and RSC across two studied regions had mean values of 64.86, 2028.53, 4.98, 26.18, 38.70, and − 14.77, respectively. For example, the computed IWQI model indicated that approximately 31% of samples fell into the no restriction range, implying that salinity tolerance crops should be avoided, while approximately 33% of samples fell into the low to moderate restriction range, and approximately 36% of samples fell into the high to severe restriction range for irrigation, implying that moderate to high salt sensitivity crops should be irrigated in loose soil with no compacted layers. The partial least squares regression model (PLSR) produced a more accurate assessment of six IWQIs based on values of R2 and slope. In Val. datasets, the PLSR model generated strong estimates for six IWQIs with R2 varied from 0.72 to 1.00. There was a good slope value of the linear relationship between measured and predicted for each parameter and the highest slope value (1.00) was shown with RSC. In the PLSR models of six IWQIs, there were no overfitting or underfitting between the measuring, calibrating, and validating datasets. In conclusion, the combination of physicochemical characteristics, WQIs, PLSR, and GIS tools to assess groundwater suitability for irrigation and their regulating variables is beneficial and provides a clear picture of water quality.

Groundwater is an important water resource in arid and semi-arid regions. Therefore, this study aimed to assess groundwater's suitability for drinking and irrigation using the Water Quality Index (WQI) and the Irrigation Water Quality Index (IWQI). To this end, groundwater data were collected from 58 sites in 2019 (wet season) and 61 samples in 2020 (dry season) in the Meskala-Ouazzi sub-basin. The Piper diagram showed that Ca–Mg–Cl was the dominant groundwater facies type. The confinement due to COVID-19 has significantly improved the water quality of the Meskala-Ouazzi sub-basin. Instead, approximately 50% of sites showed improved water quality when calculating the WQI and IWQI. However, the sodium adsorption ratio (SAR) showed that most samples below 10 are found in all of the examined samples, which are mostly found, indicating excellent irrigation water, and the Wilcox diagram depicted 20.14% of samples lying in the unsuitable region. Stable isotopes (δ18O and δ2H) of groundwater reveal that local precipitation is the main source of recharge. However, groundwater recharge is affected by the evaporation process due to the different geological conditions caused by topographic differences in the study area. The present study is useful for proper planning and managing water resources available for consumption and irrigation.

The Sidi Bouzid region is one of the main centers of agricultural production in Tunisia, especially for vegetable crops (18% of national production), arboriculture (13% of almond production and 10% of olive oil), and milk production (125 million liters in 2012 around 12% of national production) [PREDD (Plan Regional d’Environnement et de Developpement Durable du gouvernorat de Sidi Bouzid), 2014]. Therefore, the groundwater quality of Sidi Bouzid aquifer was studied to evaluate the quality of the hydrochemical parameters to determine its suitability for both agricultural and drinking purposes. Thirty groundwater samples were collected and analyzed. The obtained results showed that the groundwater contains high values of dissolved ions dominated by SO4, Mg and Ca. Gypsum, anhydrite and halite dissolution, as well as direct and reverse ion exchange are the main processes of chemical evolution in the Sidi Bouzid aquifer. Multivariate statistical techniques, such as PCA and HCA, helped to focus on the hidden yet important variables and understand their roles in affecting the groundwater quality. Compared to the World Health Organization (Guidelines for drinking water quality, 3rd edn, vol 1. Recommendations. WHO, Geneva, 2008) and National Water Exploitation and Distribution Company SO.N.E.D.E (NT.09.14) guidelines for drinking water, results showed that the concentrations of major and trace elements were within the admissible concentration rate. Chemical indices such as the percentage of sodium (Na%), sodium adsorption ratio (SAR), Kelly’s ratio, and permeability index (PI) showed that more than 70% of the analyzed samples can be used for irrigation. The irrigation water quality index (IWQI) classes vary from severe (SR) to moderate restriction (MR). The visualization of the IWQI distributions, using GIS software, shows that the moderate restriction class (MR) is the dominant class.

The assessment of groundwater for irrigation was a crucial step towards sustainable water resource management. Traditionally, irrigation water suitability was carried out by assessing several irrigation parameters individually. In this research, an attempt was made to develop a new irrigation water quality (IWQI) index by integrating various irrigation water suitability parameters i.e., sodium adsorption ratio (SAR), Magnesium Adsorption Ratio (MAR), residual sodium carbonate (RSC), Exchangeable sodium ratio or Kelly ratio (KR), Soluble Sodium Percentage (SSP), total hardness (TH), Electrical Conductivity (EC), Permeability index (PI) and fluoride (F−). A stretch of the Dwarka River basin was selected as a type area for this research. Water sample collection, analysis followed by classification of water parameters into five different classes, and assigning weights and ranks were the principal methodologies adopted for the building up of the Irrigation water quality index (IWQI). The order of abundance of anions in the study area was HCO3− > Cl− > CO3−2 > SO42− > F− and cation are Ca+2 > Na+ > Mg+2 > K+. A total of 607 water samples were collected and the computed IWQI with respect to the present study reveals that 95.38% (579 samples) of the total water sample were suitable for irrigation whereas the remaining 4.61% (28 samples) of the total sample show unsuitability for irrigation. Nawapara, Junidpur, Chakpara, Bhelian were among the most polluted village. Outcomes of the present study can be a first-hand tool to the policymakers, planners, and government officials for sustainable water resource management in the study area.

In the Zeroud basin, a diverse array of methodologies were employed to assess, simulate, and predict the quality of groundwater intended for irrigation. These methodologies included the irrigation water quality indices (IWQIs); intricate statistical analysis involving multiple variables, supported with GIS techniques; an artificial neural network (ANN) model; and an XGBoost regression model. Extensive physicochemical examinations were performed on groundwater samples to elucidate their compositional attributes. The results showed that the abundance order of ions was Na+ > Ca2+ > Mg2+ > K+ and SO42− > HCO3− > Cl−. The groundwater facies reflected Ca-Mg-SO4, Na-Cl, and mixed Ca-Mg-Cl/SO4 water types. A cluster analysis (CA) and principal component analysis (PCA), along with ionic ratios, detected three different water characteristics. The mechanisms controlling water chemistry revealed water–rock interaction, dolomite dissolution, evaporation, and ion exchange. The assessment of groundwater quality for agriculture with respect IWQIs, such as the irrigation water quality index (IWQI), sodium adsorption ratio (SAR), sodium percentage (Na%), soluble sodium percentage (SSP), potential salinity (PS), and residual sodium carbonate (RSC), revealed that the domination of the water samples was valuable for agriculture. However, the IWQI and PS fell between high-to-severe restrictions and injurious-to-unsatisfactory. The ANN and XGBoost regression models showed robust results for predicting IWQIs. For example, ANN-HyC-9 emerged as the most precise forecasting framework according to its outcomes, as it showcased the most robust link between prime attributes and IWQI. The nine attributes of this model hold immense significance in IWQI prediction. The R2 values for its training and testing data stood at 0.999 (RMSE = 0.375) and 0.823 (RMSE = 3.168), respectively. These findings indicate that XGB-HyC-3 emerged as the most accurate forecasting model, displaying a stronger connection between IWQI and its exceptional characteristics. When predicting IWQI, approximately three of the model’s attributes played a pivotal role. Notably, the model yielded R2 values of 0.999 (RMSE = 0.001) and 0.913 (RMSE = 2.217) for the training and testing datasets, respectively. Overall, these results offer significant details for decision-makers in managing water quality and can support the long-term use of water resources.

This study was conducted to determine the financial feasibility of African weaver ants (Oecophylla longinoda) as biological control agents in cashew and mango orchards. It was compared to chemical insecticides and control based on the experimental data in 2012/13 and 2013/14 cropping seasons. Three important discounted financial indicators were used in the study; they are the Net Present Value (NPV), Benefit-Cost Ratio (BCR) and Internal Rate of Return (IRR). Three scenarios concerning the increase of costs and benefits were used. The results of the study showed that all indicators for financial feasibility analysis were positive and accepted in each treatment. In cashew, African weaver ant without feeding indicated highest NPV (TZS 32 640), BCR (2.5:1) and IRR (57%). In mango, conflicting results were observed in feasibility ranking. But African weaver ants without feeding gave highest acceptable NPV of TZS 66 926. The three scenarios showed that setting much higher costs and benefits at five percent the NPV for African weaver ant was highest than other treatments. The findings of this study suggest that African weaver ant without feeding are financially feasible to be adopted and was recommended.

Among the methods of assessing the economic justification of investment projects which are based on the discount technique, the method of net present value and the method of internal rate of return have primary importance. In case where there are independent projects, the main rule is that the project will be accepted if its net present value is positive, i.e., if the internal rate of return is higher than the discount rate, that should not be implemented if its net present value is negative, i.e., the internal rate of return less than the discount rate. It usually happens that a project with a higher net present value has a higher internal rate of return, but it is not uncommon for a project with a higher net present value to have a lower internal rate of return and vice versa, that a project with a higher internal rate of return has a lower net present value. If investment projects with such characteristics are mutually competitive, in the sense that accepting one of them means rejecting the other, there is a problem in their ranking, in terms of answering the question which of the alternative projects is better, the one with higher net present value or the one with a higher internal rate of return? Such cases are treated in the literature as conflict situations in ranking. In this paper, we will limit ourselves to the application of one method of their solving, the method of additional interest rates, in one specific type of investment projects that are characterized by one-time investments in zero period and one-time effects that are promising in different time periods.

Groundwater quality and associated health risk in the arid environment, Rabigh basin, Western Saudi Arabia, was assessed using an integrated approach namely groundwater suitability zone (GWSZ) maps, drinking water quality index (DWQI), irrigation water quality (IWQ) parameters, irrigation water quality index (IWQI), chronic daily index (CDI), and hazard quotient (HQ). Groundwater samples were collected (n = 50) and analysed. Groundwater is alkaline (80%), fresh to brackish, and hard to very hard, and 78% of samples exceeded the international drinking water safe limit. The DWQI indicates that groundwater samples are excellent (24%), good (24%), poor (20%), very poor (10%), and unsuitable (22%) classes for drinking use. Total HQ (HQoral F- + HQoral NO3-) indicated that 68%, 80%, and 72% of samples express non-carcinogenic health threat to adult, children, and infant, respectively, in the study region. IWQ parameters, namely, EC, sodium adsorption ratio (SAR), Kelly's ratio (KR), sodium percentage (Na%), permeability index (PI), and magnesium hazard (MH), suggest that 72%, 66%, 64%, 98%, and 92% of samples have SAR < 6, KR < 1, MH < 50, PI > 25%, and Na% < 60%, respectively, which are suitable for irrigation. USSL classification implies that groundwater is suitable only for salt-tolerant crops and high permeability soil. IWQI values suggest that groundwater in 12%, 82%, and 6% of wells are low, medium, and highly suitable, respectively, for irrigation. Furthermore, only 42% of samples are recommended for livestock uses due to high F- (> 2). GWSZ maps, DWQI, and IWQI imply that groundwater in the upstream region is suitable whereas groundwater in the downstream is not recommended for any uses. Hence, this study recommended proper groundwater augmentation methods to reduce the salinity and improve the water quality in the shallow aquifer in the arid environment. The GWSZ, DWQI, and IWQI maps will aid to identify the suitable zones for groundwater development and sustainable management.

There are numerous methods while assessing efficiency of investment ventures that are based on discount technique and which take into consideration time value of money. All these methods have both good and bad sides. Hence the methods of net present value and internal rate of return represent basic methods in this group; we will focus our attention on those flaws which result in paradoxical situation in ranking projects and alternative decision-making while choosing specific investment variations. When it comes to independent projects there is a rule that if the project has positive net present value or in other words if the internal rate of return is higher than the rate of investment criterion, the project should be accepted; otherwise, if the net present value is negative or if the internal rate of return is lower than the rate of investment criterion, the project should be rejected; if the net present value is equal to zero or in other words if the internal rate of return is equal to the rate of investment criterion, one should behave indifferently towards such investment proposal. In case of choosing one among many projects that are available to a decision-maker while all of them are assessed with positive net present value and with internal rate of return higher than rate of investment criterion, should one give advantage to a project with higher net present value and less internal rate of return or to a project with less net present value and higher internal rate of return?.

Currently, a well-developed combination of irrigation water quality index (IWQIs) and entropy water quality index (EWQIs) for surface water appraisal in a polluted subtropical urban river is very scarce in the literature. To close this gap, we developed IWQIs by establishing statistics-based weights of variables recommended by FAO 29 standard value using the National Sanitation Foundation Water Quality Index (NSFWQI) compared with the proposed EWQIs based on information entropy in the Dhaleshwari River, Bangladesh. Fifty surface water samples were collected from five sampling locations during the dry and wet seasons and analyzed for sixteen variables. Principal component analysis (PCA), factor analysis (FA), Moran's spatial autocorrelation, and random forest (RF) model were employed in the datasets. Weights were allocated for primary variables to compute IWQI-1, 2 and EWQI-1, 2, respectively. The resultant IWQIs showed a similar trend with EWQIs and revealed poor to good quality water, with IWQI-1 for the dry season and IWQI-2 for the wet season is further suggested. The entropy theory recognized that Mg2+, Cr, TDS, and Cl- for the dry season and Cd, Cr, Cl-, and SO42- for the wet season are the major contaminants that affect irrigation water quality. The primary input variables were lessened to ultimately shortlisted ten variables, which revealed good performance in demonstrating water quality status since weights have come effectively from PCA than FA. The results of the RF model depict NO3-, Mg2+, and Cr as the most predominant variables influencing surface water quality. A significant dispersed pattern was detected for IWQImin-3 in the wet season (Moran's I>0). Overall, both IWQIs and EWQIs will generate water quality control cost-effective, completely objective to establish a scientific basis of sustainable water management in the study basin.