 Subjects -> WATER RESOURCES (Total: 160 journals)
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- Exposure risk to heavy metals through surface and groundwater used for
drinking and household activities in Ifite Ogwari, Southeastern Nigeria
Abstract: Abstract Surface and groundwater are the most common sources of water in Nigeria's rural communities, which are used for a variety of purposes ranging from farming to industrial processes and other domestic household activities including drinking. Water that contains heavy metals in excess of the maximum permitted levels poses a risk to human health. This study aims to evaluate the levels of heavy metals in surface and groundwater in Ifite Ogwari, a rural community in Anambra State, Southeast Nigeria, as well as their ecological indices and human health risks assessment. The concentration levels of Ni, Cr, Cd, Pb, Zn, Fe, Mn, and Cu were determined in fifteen water samples from the major water sources in the study area, viz., streams, river, and hand-dug wells. The water samples were collected using precleaned 500 cm3 glass bottles and were analyzed using Atomic Absorption Spectroscopy (AAS) technique. The results showed that four metals (Cr, Cu, Mn, and Pb) out of the eight heavy metals were not detected in all the samples. The concentration levels of total Ni had a range of 0.029–0.11 mg/L with highest concentration occurring at Isiachala stream, Onowulugbe well, and Omambala river (0.11 mg/L). The Cd levels in the water samples had a range of 0.001–0.036 mg/L, with Isiachala and Iyiutu having the highest values (0.036 mg/L). The concentration of Fe ranged from 0.01 to 0.047 mg/L. Mn was detected at a concentration level of 0.003 mg/L in Iyiutu stream only. The Pearson correlation deduced a strong correlation (> 0.75) and a medium correlation (0.50–0.75) for sample locations and analytes, while three factors (principal component analysis) were produced, which indicates the influence of anthropogenic release rather than natural release. Ecological indices showed the impact of multi-elemental matrices on the ecology, while health risk assessments showed that there was no adverse cancer risk or non-cancer risk across respondents (adults and children). The obtained results showed that anthropogenic release has an extensive mobility influence on the natural level of metals in surface and ground water in Ifite Ogwari, and so proper treatment is advocated. This study has shown that the water sources from Ifite Ogwari pose no adverse health risk to the residents. Consequently, additional research on Ifite Ogwari water is needed to characterize “forever chemicals,” per- and polyfluoroalkyl substances (PFAS) which are ubiquitous, cancerous and have been linked to reproductive and immune system harm, and suggest routes for remediation.
PubDate: 2023-03-25
- Hydrological characteristics and water quality change in mountain river
valley on Qinghai-Tibet Plateau
Abstract: Abstract Management and protection of regional water resources requires an understanding of the hydrological characteristics and water quality changes. In this study, we combined isotopic, geochemical and hydrometric measurements to investigate hydrological characteristics and water quality changes during the interactions between surface water and groundwater in mountain river valley. Our results showed that the stable isotope values in most of the groundwater and river water samples were located above the middle of the local meteoric water line in a mountain river valley. The hydrochemical types of most of the groundwater and river water samples were Ca–Mg–HCO3 and were primarily dominated by rock weathering. The hydrochemical compositions of groundwater and river water were mainly affected by carbonate dissolution and cation exchange, but influences of saltwater intrusion and human activity were found at the lakeside. Precipitation was the main factor affecting the changes in hydrological processes at these groundwater and river water sites and they were also affected by meltwater, soil water and the interaction between groundwater and surface water. The water level of the river increased, and the recharge of the groundwater by river water increased in river valley during the rainy season, which led to an increase runoff path in groundwater. The interaction between the river water and groundwater was affected by the rainfall frequency and intensity, the recharge time of the soil water and the pressure of the river on both sides of the river channels. Additionally, our results indicated that the flow of groundwater into the river will lead to water quality deterioration. The increasing pressure of the river on the groundwater will cause the deterioration of groundwater quality, which will also be affected by saltwater intrusion and human activity. Our results detailed the hydrological characteristics, water quality changes and main influencing factors of the interaction between surface water and groundwater of river valley in mountain, which will be beneficial to promote the reasonable protection of water resources under climate change in the future.
PubDate: 2023-03-25
- Evaluation of water quality of Angereb reservoir: a chemometrics approach
Abstract: Abstract Deterioration of water quality of lakes and reservoirs has become major global concerns that impose serious environmental impacts for both aquatic and terrestrial environments. In the current study, many parameters like temperature (Temp), electric conductivity (EC), dissolved oxygen (DO), turbidity (TU), pH, biological oxygen demand (BOD), chemical oxygen demand (COD), total alkalinity (TA), total dissolved solids (TDS), total organic carbon (TOC), nitrate(NO3−), phosphate (PO43−) and chlorophyll a (chl-a) were determined. The study covered the Angereb reservoir and its tributaries on a monthly basis from January to March 2019 at five sampling stations in accordance with APHA 2017 guide lines for physicochemical analysis. The values of all the investigated parameters, except DO (at AU, AD, KU and KD), COD and TU, were below the maximum permissible limits set by WHO. Thus, the findings for DO, TU and COD demonstrated that remedial actions should be taken to improve the quality of the water in the reservoir and its tributaries. Multivariate statistical methods (PCA and CA) were applied to detect spatial and temporal variations of water quality parameter. The first three principal components were enough to develop the PCA score plot which explained about 71.32% of the total variance in the dataset. The PCA and CA have provided similar information; grouped the 24 samples into 3 significant clusters showing spatial variations but minimal temporal variations were observed within the samples collected in the period of January in the reservoir site. The water quality parameters, TU and BOD, were moderately positively loaded on the space of the first principal component and were found to be associated with each other, whereas the EC and TDS have shown moderate negative loading and positively associated with each other. This study suggested PCA and CA methods found to be useful tools for monitoring and controlling water quality parameters for selected sampling stations of surface water.
PubDate: 2023-03-23
- Investigation of overexploitation groundwater in arid areas: case of the
lower Jurassic aquifer, Bechar province Southwest of Algeria
Abstract: Abstract The conservation of natural non-renewable water resources is an important part of the expectations of the Algerian population, especially in the south of the country. Groundwater is provided in the southwest of Algeria, and the demand for water is high including agriculture. Studies have shown that the quality of these resources has changed after many years of continuous exploitation. To meet the satisfaction and the need for drinking water, for the city of Bechar, located in southwest Algeria, technicians and decision-makers have sought additional water resources, namely in the Jurassic groundwater located at the region of Mougheul (Sahara Algerian). The intense use of pumping at Mougheul has led to serious local problems (rapid drawdown and drying up of the source). The obtained results reveal that the piezometric charts, established in October 2001 and November 2009, show that the main flow of water is from north to south, exactly to the source of Mougheul. The flow rates of the drillings made are very varied, and between 6 and 30 l/s, this amounts to the heterogeneity of the medium. The pumping tests give low transmissivity values varying between 3.22 10–5 and 5.49 10−3 m2/s.
PubDate: 2023-03-23
- Loading of zinc oxide nanoparticles from green synthesis on the low cost
and eco-friendly activated carbon and its application for diazinon
removal: isotherm, kinetics and retrieval study
Abstract: Abstract Diazinon (DZN) has been reported as an important pesticide with wide application in agriculture. The entry of these compounds into water resources has brought serious environmental problems due to their resistance to biodegradation; thus, this study was considered to be done to explore the process of DZN uptake and the influence of effective parameters. The study was performed experimentally and on a laboratory scale. Investigating the structure and morphology of the nanocomposite was done based on different analyses, i.e., FE-SEM, FTIR, and XRD. The experiments based on the Box–Behnken scheme were performed by surveying four important operating parameters (pH, contact time, nanocomposite dose, and DZN concentration). Optimization was performed by experiment design software and using the response surface method and analysis of the proposed model. The DZN removal efficiency was obtained 100% under optimal conditions including pH = 5, nanocomposite dose = 0.83 g/L, reaction time = 55 min, and DZN concentration = 5 mg/L. Considering the high correlation coefficient R2 = (0.9873) and \(R_{{{\text{Adj}}}}^{{2}}\) = (0.9725), the proposed model (quadratic) was approved. The results were indicative of conforming the reaction kinetic to the pseudo-second-order model and the correspondence of reaction isotherm to the Freundlich model (R2 = 0.997). Based on the obtained results, the adsorption process with AC–ZnO nanocomposite could be introduced as an efficient and eco-friendly technique to remove DZN.
PubDate: 2023-03-19
- Modeling the impacts of best management practices (BMPs) on pollution
reduction in the Yarra River catchment, Australia
Abstract: Abstract Pollution of a watershed by different land uses and agricultural practices is becoming a major challenging factor that results in deterioration of water quality affecting human health and ecosystems. Sustainable use of available water resources warrants reduction of Non-Point Source (NPS) pollutants from receiving water bodies through best management practices (BMPs). A hydrologic model such as the Soil and Water Assessment Tool (SWAT) can be used for analyzing the impacts of various BMPs and implementing of different management plans for water quality improvement, which will help decision makers to determine the best combination of BMPs to maximize benefits. The objective of this study is to assess the potential reductions of sediments and nutrient loads by utilizing different BMPs on the Yarra River watershed using the SWAT model. The watershed is subdivided into 51 sub-watersheds where seven different BMPs were implemented. A SWAT model was developed and calibrated against a baseline period of 1998–2008. For calibration and validation of the model simulations for both the monthly and annual nutrients and sediments were assessed by using the Nash–Sutcliffe efficiency (NSE) statistical index. The values of the NSE were found more than 0.50 which indicates satisfactory model predictions. By utilizing different BMPs, the highest pollution reduction with minimal costs can be done by 32% targeted mixed-crop area. Furthermore, the combined effect of five BMPs imparts most sediments and nutrient reductions in the watershed. Overall, the selection of a BMP or combinations of BMPs should be set based on the goals set in a BMP application project.
PubDate: 2023-03-17
- Hydrological status of the Dagu River Basin and management suggestions
based on soil and water assessment tool multi-station calibration
Abstract: Abstract Soil and water assessment tool (SWAT) model was used to calculate the runoff, nitrogen and phosphorus emissions in the Dagu River Basin from 2002 to 2012 and provided preliminary suggestions on environmental protection measures. Calibration on hydrological watershed parameters was obtained from data obtained from multiple representative stations. Cluster analysis was used to group all stations, and the parameters of different representative stations were applied to the entire geographical area to reflect the hydrological conditions of the basin. Additionally, the spatiotemporal changes and pollution source characteristics of nitrogen and phosphorus were analyzed. Anthropogenic sources—chemical fertilizer loss and livestock breeding—accounted for 49.9–29.6% of total nitrogen (TN) and 41.4% and 40.3% of total phosphorus (TP), respectively. Non-point sources accounted for 85.8% of the TN and 89.4% of the TP. Six landscape management practices were set up to evaluate the reduction effect on non-point source pollution loads, and comprehensive measures were proposed to reduce TN (TP) by ~ 70%. According to water quality model, the response relationship between river control and nutrient distribution in Jiaozhou Bay is calculated. Based on the findings, we propose an optimal control scheme for non-point source pollution in the Dagu River Basin and other similar basins.
PubDate: 2023-03-17
- Efficiency assessment of the environmental variables in the Qanat systems
based on major hydrological basins in Iran
Abstract: Abstract Qanat system, as a great human heritage, contributes to the sustainable management of groundwater in the arid and semiarid regions of the world. The main aim of this paper was to efficiency assessment of the environmental variables in the construction of the Qanat system in Iran. Using the geographical information system (GIS) and statistical method of receiver operation characteristic (ROC), the efficiency of 20 environmental variables was assessed based on divisions of 30 major hydrological basins. Results revealed that most physical parameters and anthropogenic characteristics have significant effects on the construction of Qanat water lines with an AUC index > 0.6. The Pearson correlation test also confirmed the positive and significant relationships between the Qanat system and mentioned environmental parameters. From a geological viewpoint, the results highlighted the effective role of Quaternary aged alluvial sediments with very high permeability and low density of crust rocks in arid soils of arid and semiarid regions, such as playa fields in NamakTehran, Kavir, Lut, and Siahkuh basins. Regarding the spatial expansion of the Qanat system in Iran, the higher effects of some test variables, such as the climatic element of temperature, fault density, and drainage density, were rejected due to poor discrimination values of the AUC index < 0.6.
PubDate: 2023-03-17
- Studying the destruction of pollutant in the presence of photocatalysts
based on MWCNTs with controlled values of TiO2 nanoparticles
Abstract: Abstract The main goal of the present research is the synthesis of new photocatalysts to reduce the amount of organic pollutants in aquatic environments. For this purpose, the amount of TiO2 nanoparticles in the synthesized samples containing MWCNTs is controlled to synthesize two types of photocatalysts named as MCT#1 and MCT#2. Samples characterizing using XRD reveal that the TiO2 nanoparticles have a combined phase of rutile and anatase. So that in both of photocatalysts, the percentage of anatase phase is higher than rutile. The analysis of the degradation rate demonstrates that intensification level of TiO2 nanoparticles in MCT#2 compared to the MCT#1 leads to enhancement of photocatalytic activity of MCT#2. Design of experiment results shows that the destruction amount of MO is affected by irradiation time and pH. Based on ANOVA study, it is observed that both factors have a significant effect on reducing of MO concentration. Analyzing the results based on Duncan's multiple range test at α = 0.05 confirm that all the studied levels of the main parameters have a logical influence on MO destruction. Meanwhile, it can be deducted that the most and the least of destruction is observed at pH = 7 and pH = 3, respectively.
PubDate: 2023-03-17
- Effect of three commonly used aquaculture chemicals against
enteropathogenic Escherichia coli and Salmonella spp.
Abstract: Abstract Enteric bacteria such as Escherichia coli and Salmonella spp. are significant fish pathogens and related to thousands of cases of food-borne diseases every year in human. Since aquatic environments are reservoirs of these pathogens, they may contaminate the food fish and result in outbreaks. Therefore, it is crucial to reduce or eliminate these pathogens from aquaculture facilities. We tested effectiveness of three commonly used aquaculture chemicals, viz., lime, hydrogen peroxide and zeolite on bacterial load, Escherichia coli and Salmonella spp. under laboratory and earthen pond conditions where they were applied at a dose recommended for freshwater aquaculture. Results of the bacteriological study showed that lime had a significant role in reducing bacterial abundance from an initial value of 1.5 × 103 to 1.9 × 103 cfu/ml and 3.9 × 103 to 6.3 × 103 to a final value of 1.2 × 103 to 1.5 × 103 cfu/ml and 1.9 × 103 to 6.3 × 103 cfu/ml within 24 h under aquaria and pond condition, respectively. A complete inactivation of E. coli was observed in lime treated aquaria and ponds 24 h post-treatment, whereas Salmonella spp. remained unaffected in pond water but inactivated under aquarium condition after same period. However, neither hydrogen peroxide nor zeolite treatment reduced total bacterial count as well as E. coli and Salmonella even after 1-week post-treatment. It is, therefore, recommended that the water treatment chemicals should be applied in aquaculture ponds at appropriate dose, and farmers need to adopt biosecurity measures to ensure food safety.
PubDate: 2023-03-17
- De-noising groundwater level modeling using data decomposition techniques
in combination with artificial intelligence (case study Aspas aquifer)
Abstract: Abstract Considering the recent significant drop in the groundwater level (GWL) in most of world regions, the importance of an accurate method to estimate GWL (in order to obtain a better insight into groundwater conditions) has been emphasized by researchers. In this study, artificial neural network (ANN) and support vector regression (SVR) models were initially employed to model the GWL of the Aspas aquifer. Secondly, in order to improve the accuracy of the models, two preprocessing tools, wavelet transform (WT) and complementary ensemble empirical mode decomposition (CEEMD), were combined with former methods which generated four hybrid models including W-ANN, W-SVR, CEEMD-ANN, and CEEMD-SVR. After these methods were implemented, models outcomes were obtained and analyzed. Finally, the results of each model were compared with the unit hydrograph of Aspas aquifer groundwater based on different statistical indexes to assess which modeling technique provides more accurate GWL estimation. The evaluation of the models results indicated that the ANN model outperformed the SVR model. Moreover, it was found that combining these two models with the preprocessing tools WT and CEEMD improved their performances. Coefficient of determination (R2) which indicates model accuracy was increased from 0.927 in the ANN model to 0.938 and 0.998 in the W-ANN and CEEMD-ANN models, respectively. It was also improved from 0.919 in the SVR model to 0.949 and 0.948 in the W-SVR and CEEMD-SVR models, respectively. According to these results, the hybrid CEEMD-ANN model is found to be the most accurate method to predict the GWL in aquifers, especially the Aspas aquifer.
PubDate: 2023-03-06
- Modeling the river-aquifer via a new exact model under a more general
function of river water level variation
Abstract: Abstract The interaction between surface water and groundwater is a significant topic in groundwater-related problems. This study suggests an exact model based on Laplace transformation to calculate the groundwater flow in river-aquifer systems. Exact models play an important role in simulating the future behavior of river-aquifer systems. Therefore, investigation of the exact models for river-aquifer systems is a hot topic in the hydraulics of groundwater flow modeling. The objective of this research is to present new exact models for simulating the hydraulics of groundwater flow in river-aquifer systems with a more general function of river level variation under recharge by means of Laplace transform method. A general function is adopted to describe the river level variation, in which some situations such as linear, exponential and power of time variations in the river level can be treated as special cases. The effects of variations in aquifer parameters on groundwater hydraulic head are evaluated. It is shown that the groundwater hydraulic head grows slower in aquifers with a greater thickness or hydraulic conductivity. In addition, the effect of changes in specific storage is too little on the groundwater hydraulic head. The variations in hydraulic heads due to changes in recharge rate with different values of thickness, hydraulic conductivity, specific storage, and length are analyzed. It is observed that the groundwater hydraulic head in an aquifer with a lesser length, higher hydraulic conductivity or higher thickness is less sensitive to a change in the recharge rate than in an aquifer with a higher length, lesser hydraulic conductivity or lesser thickness. Furthermore, it is shown that the differences in hydraulic heads due to the increase in recharge rate are not significant for different values of specific storage. The results of the present new exact models are successfully verified by the results obtained from the analytical solution of Bansal and Das. Also, for more reliability, the results are compared with those results of MODFLOW. The results show that the presented new exact models are accurate, robust and efficient. One of the advantages of the solutions is to investigate the sensitivity analysis of aquifer parameters, which has been carried out in this paper. Furthermore, in the present research a more general function describing river level variation is considered, in which the linear, exponential and power of time variations are special cases.
PubDate: 2023-03-06
- Optimal design and cost analysis of water distribution networks based on
pressure-dependent leakage using NSGA-II
Abstract: Abstract Leakage from water distribution networks (WDNs) is inevitable. Therefore, during design a WDN, engineers add a percentage of each nodal water demand as leakage discharge to total node demand. The amount of leakage depends on the pressure, which is not known at the design stage. Considering a constant percentage of node demand in lieu of its leakage makes the problem worse. In this study, the effect of leakage on the optimal WDN design was investigated by developing the matrix form of the gradient algorithm while accounting for leakage using the pressure-dependent model. Non-dominated genetic algorithm version II (NSGA-II) was used as the optimization engine with two objectives which includes minimizing the network construction cost and minimizing the total network pressure deficiency. Two well-known two- and three-loop WDNs in literature were studied. The results indicated that the pressure-dependent leakage varies between 12.9 and 29.44% of the node demand while the network construction cost stays the same if compared with the fixed percentage leakage model, and the construction cost would increase by 17–31%, if leakage is not accounted for. This is expected the optimized diameters and hydraulic characteristics of the networks being affected by the leakage calculation method.
PubDate: 2023-03-06
- Hydrogeochemical characterization of groundwater resources in Wadi Araba
Basin, Southern Jordan
Abstract: Abstract Groundwater quality is an important factor that determines its usage for drinking and irrigational use. This study was carried out along the quaternary alluvial aquifer which extends along Wadi Araba groundwater basins, in southern Jordan. Chemical and physical parameters were measured and analyzed for thirty-seven groundwater samples collected from twenty-one wells in the study area during two periods in the year 2019; the spring season (April–May) was represented by fourteen samples and the autumn season (August–September) represented by twenty-three samples were collected to determine its suitability for drinking and irrigational purposes. The groundwater in the study area is generally of low alkalinity with an average pH value of less than 8 for both spring and autumn seasons. The water of the area is excessively mineralized due to salinity, and the increase in water salinity of the southern Wadi Araba basin is less expressed than in the northern part. The hydrochemical characterization shows that most wells of the study area are characterized by HCO3–Ca–Mg and HCO3–SO4–Ca–Mg types in the eastern escarpments of Wadi Araba (i.e., recharge area) and Cl–SO4–Na and Cl–Na types in the discharge area. There is no substantial change in the hydrochemical composition during the two seasons. Based on the Piper diagram, most of the groundwater samples (91.8%) belong to class “E” as “earth alkaline water with increased portions of alkalis with prevailing sulfate and chloride.” The Durov diagram reveals that most groundwater samples (62.2%) lay in the water genesis “field 6” which indicates that the water may be related to the reverse ion exchange of Na–Cl. The chemical composition of the water samples was compared with the drinking water standards of the World Health Organization and the Jordanian Standard. Groundwater from this area was not suitable to be a source for direct drinking based on total hardness and total dissolved solids. The dominant cation is sodium, while the dominant anion is chloride. The calculations of saturation indices for the two sampling campaigns for different minerals showed negative values of (SI) for carbonates minerals (anhydrite, gypsum, sylvite, and halite). This suggests that the groundwater in the alluvial aquifer is undersaturated with respect to these minerals in most of the study area. This is indicative of the fact that these minerals are undergoing the process of dissolution. The mineral saturation indices suggest that the dominating hydrochemical processes were dissolutions of evaporite minerals (halite and gypsum), carbonate minerals (such as calcite, dolomite, and rhodochrosite), the manganese oxide minerals (such as jarosite-K, hausmannite, pyrochroite, and pyrolusite) and reverse ion exchange.
PubDate: 2023-03-06
- Numerical investigation of labyrinth-shaft spillway
Abstract: Abstract In the present study, a new type of hybrid spillway termed labyrinth-shaft spillway was introduced to improve the discharge capacity and efficiency of the spillway. An advanced computational fluid dynamics (CFD) technique was used to analyze the performance of the labyrinth-shaft spillway. The hydraulic performance of the new model was investigated for different labyrinth geometries with a verified computational model. The analysis results demonstrated that the discharge capacity of the labyrinth-shaft spillway was better when compared to that of the conventional shaft spillways with the same weir heads. The discharge coefficient that reflects the efficiency of the labyrinth-shaft spillway was also much better when compared to the conventional spillway, while the opposite was observed with relatively small nappe heads. Similarly, the comparison with the findings of previous studies on labyrinth weirs in the literature demonstrated that labyrinth-shaft spillways performed better when compared to the conventional labyrinth weirs in-channel flow conditions, especially with high nappe heads. A new formula was also developed in the present study with regression analysis conducted on the collected data to calculate the discharge coefficients of the labyrinth-shaft spillway for H/P > 0.2.
PubDate: 2023-03-06
- Synthesis of activated carbon from cherry tree waste and its application
in removing cationic red 14 dye from aqueous environments
Abstract: Abstract The environment is threatened by a diversity of pollutants, and synthetic dyes are considered a foremost environmental pollutant among them. The characteristics detected for the dye, e.g., toxicity and carcinogenicity, have brought severe problems for humans and aquatic organisms. The present study was done to clarify the potential of activated carbon made from cherry tree wood (CWAC) in the adsorption of cationic red 14 dye. In our experimental-laboratory study, the changes in removal efficiency were assessed by considering the changes in values of pH, concentration, adsorbent dose, contact time, and temperature. In addition, the nature of our prepared adsorbent was defined based on scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier-transformed infrared (FTIR) spectroscopy techniques. The concentration of dye after the completion of experiments was recorded using a spectrophotometer at 514 nm. Evaluating the attained data by isotherm and kinetic models were also considered. Our results demonstrated the enhancement in the efficiency of the studied process at higher contact times, temperatures, and pH and its decline at higher initial dye concentrations. pH = 11, time of 45 min, dye concentration of 50 mg/L, and AC mass of 0.25 g/l were optimal values in obtaining the highest removal of the studied dye. Langmuir isotherm and pseudo-second-order (PSO) with (R2 = 0.9972) and (R2 = 0.9947) were the best isotherms and kinetic models in the description of the observed data, respectively. Considering the results, CWAC could be effectively utilized for the adsorption of cationic red 14 dye from solutions.
PubDate: 2023-03-06
- The reallocation of water and ecosystem service values in arid ecosystems
with the implementation of an ecological water diversion project
Abstract: Abstract The rational allocation of the water resources in drylands and the scientific evaluation of their values are important for the regional sustainable development. We estimated the water consumption of each ecosystem in Ejina Oases in the arid area in northwest China based on the water balance equation, then assessed their ecosystem service values (ESVs) using the value per unit area method and the value equivalent factor per unit area method considering the cost of water consumption, respectively, and calculated their water productivities from 1990 to 2015. With the implementation of the ecological water diversion project (EWDP) in 2000, the deciduous broadleaf forest dominated by Populus euphratica had an increasing trend, meanwhile, lakes had a changing process from shrinking and drying up to recovery and expansion from 1990 to 2015. The total water consumption in Ejina Oases decreased from 5.26*108 m3 in 1990 to 4.79*108 m3 in 2000, and then increased continually to 5.97*108 m3 in 2015. The water consumption of forest, grassland and cultivated land hardly changed, while the water consumption of water or wetland changed obviously. The total ESVs estimated using the value per unit area method in Ejina Oases decreased from 1052.6 to 787.3 million ¥ in the period of 1990–2000, then increased to 1500.6 million ¥ in 2015, while the ESVs estimated using the value equivalent factor per unit area method decreased from 6368.7 million ¥ in 1990 to 5892.0 million ¥ in 2000, then increased to 7139.9 million ¥ in 2015, and the latter method was more reasonable. The results showed that the EWDP started in 2000 led to the reallocation of water resources and transfer of ESVs among ecosystems, which had obvious performance in the ecological environment and social economy. This study provided a comprehensive view of water use and management, ecological restoration and socio-economic development in this key ecological function zone, and will help decision-makers to formulate the scheme of rational allocation and efficient utilization of water resources in the basin.
PubDate: 2023-03-06
- Optimization of saturated hydraulic conductivity estimation using kriging
in drainage networks
Abstract: Abstract Statistical analysis of saturated hydraulic conductivity is the fundamental of engineering plans for water resource projects. In the other words, project solutions and designs depend directly on the accuracy of these statistical analyses and the methods that develop them to studied area. One of the recent methods was used to estimate the variables such as hydraulic conductivity is Kriging method. In this study, GIS software was used for this purpose and kriging method was used to estimate the saturated hydraulic conductivity of the soil. Spherical model with nugget effect of 0.0039 and sill of 0.0262 was the best variogram for determining soil hydraulic conductivity in this method, which expressed the high strength of regional variable structure in the studied area. The results showed that the simple kriging method with a regression coefficient of 0.82 has the highest accuracy in modeling the saturated hydraulic conductivity function. Also, the results showed that the geostatistical kriging method for modeling soil hydraulic conductivity index has a higher accuracy in determining saturated soil hydraulic conductivity than the traditional Thiessen method.
PubDate: 2023-03-06
- Hydrogeochemical studies of groundwater in semi-arid areas of northern
Ethiopia using geospatial methods and multivariate statistical analysis
techniques
Abstract: Abstract The present study focused on evaluating the groundwater hydrogeochemical of shallow aquifers in the semi-arid areas of northern Ethiopia, using geospatial modelling and multivariate statistical techniques. Physico-chemical parameters, including pH, major ions, electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), pollution index (PI) and other parameters, from 22 samples have been used to assess water quality, sources of various ions, water types and factors controlling groundwater chemistry. Results showed that the spatial distribution of major ions, EC, TDS, TH and PI values in these samples significantly differ from one location to another due to geological variations and anthropogenic activities of the area. The quality of most groundwater is generally unfit for drinking due to their PI, EC, TH, calcium, potassium, total iron and bicarbonate (HCO3−) values that found to be above the permissible limits of WHO and Ethiopian standards. The parameters like sodium percentage, sodium adsorption ratio (SAR), residual sodium bicarbonate, permeability index, magnesium hazard and Kelly’s ratio revealed good quality of groundwater for irrigation utilization, whereas EC of irrigation water (ECiw), combined effects of ECiw − SAR and bicarbonate hazard values indicated that majority of groundwater are not suitable for irrigation use. Piper trilinear diagram classified majority of samples under temporary hardness with Ca–Mg–HCO3 type. Further, Gibbs diagram reveals that water–rock interaction is the major hydrogeochemical processes governing the water chemistry of the study area. Therefore, it is recommended to perform a constant water quality checking program and improvement of tangible management practices for sustainable utilization of groundwater resources.
PubDate: 2023-02-28
- Sensitive analysis of meteorological data and selecting appropriate
machine learning model for estimation of reference evapotranspiration
Abstract: Abstract This study applies three methods, Gene Expression Programming (GEP), M5 tree (M5T) model and optimized Artificial Neural Network by Genetic Algorithm (ANN-GA) for estimation of reference evapotranspiration in Ahvaz and Dezful in the southwest of Iran. Comparison between results of the FAO Penman-Monteith (FPM) method and the mentioned three methods shows that ANN-GA with the Levenberg-Marquardt training method is the best method and the M5T model is the second appropriate method for estimation of reference evapotranspiration. In Ahvaz, R2 and RMSE of ANN-GA method are 0.996, 0.184 mm/day. For M5T method, these values are 0.997 and 0259 mm/day, and for GEP method, they are 0.979 and 0.521 mm/day. In Dezful, R2 and RMSE of ANN-GA method are 0.994, 0.235 mm/day. For M5T method, these values are 0.992 and 0265 mm/day, and for GEP method, they are 0.963 and 0.544 mm/day. In addition, sensitivity analysis shows that the maximum temperature is the most effective parameter, and the wind speed is second effective parameter. In Dezful, the effect of the maximum temperature is more than those of Ahvaz but the effect of wind speed is less than those of Ahvaz. Because Ahvaz is more flatter than Dezful (the movement of wind in Ahvaz is freer than those of Dezful). The third effective meteorological parameter is the average relative humidity in Ahvaz and the sunny hours in Dezful. The reason for this subject is the less distant of Ahvaz from the Persian Gulf (it is source of moisture).
PubDate: 2023-02-28
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