| 1. |
- Abdiyev, Kaldibek, et al.
(författare)
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Review of Slow Sand Filtration for Raw Water Treatment with Potential Application in Less-Developed Countries
- 2023
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Ingår i: Water (Switzerland). - 2073-4441. ; 15:11
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Forskningsöversikt (refereegranskat)abstract
- Providing safe drinking water to people in developing countries is an urgent worldwide water problem and a main issue in the UN Sustainable Development Goals. One of the most efficient and cheapest methods to attain these goals is to promote the use of slow sand filters. This review shows that slow sand filters can efficiently provide safe drinking water to people living in rural communities not served by a central water supply. Probably, the most important aspect of SSF for developing and less-developed countries is its function as a biological filter. WASH problems mainly relate to the spread of viruses, bacteria, and parasites. The surface and shallow groundwater in developing countries around urban areas and settlements are often polluted by domestic wastewater containing these microbes and nutrients. Thus, SSF’s function is to treat raw water in the form of diluted wastewater where high temperature and access to nutrients probably mean a high growth rate of microbes and algae but probably also high predation and high efficiency of the SSF. However, factors that may adversely affect the removal of microbiological constituents are mainly low temperature, high and intermittent flow rates, reduced sand depth, filter immaturity, and various filter amendments. Further research is thus needed in these areas, specifically for developing countries.
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| 2. |
- Absametov, Malis, et al.
(författare)
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Prediction of groundwater drawdown and quality at Kyzylzharma well field in the arid Syr Darya Basin, Kazakhstan
- 2024
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Ingår i: Cogent Engineering. - 2331-1916. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The geologically complex Kyzylzharma groundwater field is located in the south-central part of Kazakhstan in the lower Syr Darya Basin. It supplies the 243,000 population of Kyzylorda City by drinking and agricultural water needs. Numerical modeling was used to predict the consequences of increased groundwater withdrawal for future water supply needs. The results displayed a mean squared error for the groundwater simulations of about 0.6 m and was thus acceptable. The validated transmissivity was between 2 × 10−7 and 2 × 10−5 m/d. These parameters showed that the planned groundwater withdrawal will result in a depression cone reaching 90–100 m below present levels in 2040. Maximum groundwater level drawdown may reach 130 m below present levels. This drawdown increases risks for brackish saltwater intrusion into the main groundwater aquifer. The results point at the depletion of groundwater resources in the Syr Daria Artesian Basin and the risks for groundwater quality, particularly increase in mineralization. The key outcome is the recognition that effective joint management of the Syr Daria Artesian Basin’s groundwater resources, involving both Kazakhstan and Uzbekistan, necessitates development and operation of a joint numerical aquifer model. Building this model is a crucial tool for assessing the sustainable groundwater resources in the region.
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| 3. |
- Afzali, Sayed Fakhreddin, et al.
(författare)
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Quantitative assessment of environmental sensitivity to desertification using the modified medalus model in a semiarid area
- 2021
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Ingår i: Sustainability (Switzerland). - : MDPI AG. - 2071-1050. ; 13:14
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Tidskriftsartikel (refereegranskat)abstract
- Iran is mainly located in the arid and semiarid climate zone and seriously affected by desertification. This is a severe environmental problem, which results in a persistent loss of ecosys-tem services that are fundamental to sustaining life. Process understanding of this phenomenon through the evaluation of important drivers is, however, a challenging work. The main purpose of this study was to perform a quantitative evaluation of the current desertification status in the Segzi Plain, Isfahan Province, Iran, through the modified Mediterranean Desertification and Land Use (MEDALUS) model and GIS. In this regard, five main indicators including soil, groundwater, vegetation cover, climate, and erosion were selected for estimating the environmental sensitivity to desertification. Each of these qualitative indicators is driven by human interference and climate. After statistical analysis and a normality test for each indicator data, spatial distribution maps were established. Then, the maps were scored in the MEDALUS approach, and the current desertification status in the study area from the geometric mean of all five quality indicators was created. Based on the results of the modified MEDALUS model, about 23.5% of the total area can be classified as high risk to desertification and 76.5% classified as very high risk to desertification. The results indicate that climate, vegetation, and groundwater quality are the most important drivers for desertification in the study area. Erosion (wind and water) and soil indices have minimal importance.
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| 4. |
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| 5. |
- Amiri, Vahab, et al.
(författare)
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Fluoride occurrence and human health risk from groundwater use at the west coast of Urmia Lake, Iran
- 2020
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Ingår i: Arabian Journal of Geosciences. - : Springer Science and Business Media LLC. - 1866-7511 .- 1866-7538. ; 13:18
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Tidskriftsartikel (refereegranskat)abstract
- We investigated fluoride (F−) concentration and physicochemical features of groundwater in the Urmia coastal aquifer (northwest, Iran). Groundwater samples were collected during both dry (58 wells) and wet seasons (84 wells). Approximately 15 and 23% of the groundwater samples in the dry and wet seasons, respectively, exceeded the recommended F− value by WHO for drinking water (1.5 mg/L). High F− concentration in groundwater is mainly found in shallow wells. The cause of high F− concentration appears to be mainly caused by human activities. Agricultural fertilizers and industrial waste can result in rapid release of F− into the groundwater. Release of F− into the groundwater can, however, also be triggered by the interaction between rock and water. In the experimental area, high F− concentrations were found close to volcanic rocks. Health risks from exposure to F− in groundwater were analyzed for adults and children. Utilizing sensitivity analysis and Monte Carlo simulation, the uncertainties in the risk estimates were calculated. Sensitivity analyses showed that the most pertinent variables are F− concentration in drinking water, averaging time, exposure time, and ingestion rate of water. Children are more susceptible to the noncarcinogenic risk of F− in groundwater.
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| 6. |
- An, Dong, et al.
(författare)
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Evidence of climate shift for temperature and precipitation extremes across Gansu Province in China
- 2020
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Ingår i: Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 1434-4483 .- 0177-798X. ; 139:3-4, s. 1137-1149
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Tidskriftsartikel (refereegranskat)abstract
- Temperature and precipitation extremes are the dominant causes of natural disasters. In this study, seven indices of extreme temperature and precipitation events in Gansu Province, China, were analysed for the period 1961–2017. An abrupt climate shift was recorded during 1980–1981. Thus, the study period was divided into a preshift (before the climate shift) period 1961–1980 and an aftshift (after the climate shift) period 1981–2017. Comparison of mean extreme indices for preshift and aftshift periods was performed for the purpose of exploring possible increasing/decreasing patterns. Generalized extreme value (GEV) distribution was applied spatially to fit the extreme indices with return periods up to 100 years for preshift/aftshift periods. Singular value decomposition (SVD) was adopted to investigate possible correlation between the extreme climate events and indices of large-scale atmospheric circulation. The results indicate that changes in mean and return levels between the preshift and aftshift periods vary significantly in time and space for different extreme indices. Increase in extreme temperature regarding magnitude and frequency for the aftshift period as compared with the preshift period suggests a change to a warmer and more extreme climate during recent years. Changes in precipitation extremes were different in southern and northern parts of Gansu. The precipitation extremes in the north have increased that can result in more serious floods and droughts in the future. SVD analyses revealed a complex pattern of correlation between climate extremes and indices of large-scale atmospheric circulation. Strengthening of westerlies and weakening of the south summer monsoon contribute to the complex changing patterns of precipitation extremes. Results in this study will contribute to disaster risk prevention and better water management in this area.
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| 7. |
- Arya Azar, Naser, et al.
(författare)
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A hybrid approach based on simulation, optimization, and estimation of conjunctive use of surface water and groundwater resources
- 2022
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 29:37, s. 56828-56844
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Tidskriftsartikel (refereegranskat)abstract
- Due to limited groundwater resources in arid and semi-arid areas, conjunctive use of surface water and groundwater is becoming increasingly important. In view of this, there are needs to improve the methods for conjunctive use of surface and groundwater. Using numerical models, optimization algorithms, and machine learning, we created a new comprehensive methodological structure for optimal allocation of surface and groundwater resources and optimal extraction of groundwater. The surface and groundwater system was simulated by MODFLOW to reflect groundwater transport and aquifer conditions. The important Marvdasht aquifer in the south of Iran was used as an experimental study area to test the methodology. In this context, we developed an optimal conjunctive exploitation model for dry and wet years using two new evolutionary algorithms, i.e., whale optimization algorithm (WOA) and firefly algorithm (FA). These were used in combination with the group method of data handling (GMDH) and least squares support vector machine (LS-SVM) to estimate sustainable groundwater withdrawal. The results show that the FA is more efficient in calculating optimal conjunctive water supply so that about 61% of water needs were met in the worst scenario for surface water resources, while it was 52% using the WOA. By applying the optimal conjunctive model during the simulation period, the groundwater level increased by about 0.4 and 0.55 m using the WOA and FA, respectively. The results of Taylor’s diagram, box plot diagram, and rock diagram with error evaluation criteria, i.e., root mean square error (RMSE), mean absolute error (MAE), and Nash–Sutcliffe efficiency (NSE), showed that the GMDH (RMSE = 6.04 MCM, MAE = 3.89 MCM, and NSE = 0.99) was slightly better than LS-SVM (RMSE = 6.36 MCM, MAE = 4.50 MCM, and NSE = 0.98) to estimate optimal groundwater use. The results show that machine learning models are cost- and time-effective solutions to estimate optimal exploitation of groundwater resources in complex combined surface and groundwater supply problems. The methodology can be used to better estimate sustainable exploitation of groundwater resources by water resources managers.
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| 8. |
- Aziz, Akram, et al.
(författare)
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Noninvasive Monitoring of Subsurface Soil Conditions to Evaluate the Efficacy of Mole Drain in Heavy Clay Soils
- 2023
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Ingår i: Water (Switzerland). - : MDPI AG. - 2073-4441. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Soil degradation and low productivity are among the major agricultural problems facing farmers of the newly reclaimed agricultural area in the Nile Delta region, Egypt. High content of clay and silt characterizes the soil texture of all farms in the area, while farmers still rely on the traditional mole drainage (MD) system to reduce the salinity of the farm soil. We present a comparison of innovative geo-resistivity methods to evaluate mole drains and the salinity affected clay soils. Geoelectrical surveys were conducted on three newly reclaimed farms to image the subsurface soil drainage conditions and to evaluate the efficiency of using the traditional MD systems in these heavy clay environments. The surveys included measuring the natural spontaneous potential (SP), apparent resistivity gradient (RG), and electrical resistivity tomography (ERT). Integrating the results of the three methods reduced the ambiguous interpretation of the inverted ERT models and allowed us to determine the subsurface soil structure. The inverted ERT models were suitable for locating the buried MDs and delineating the upper surface of the undisturbed clay beds. The proximity of these layers to the topsoil reduces the role played by MDs in draining the soil in the first farm and prevents the growth of deep-rooted plants in the second farm. Time-lapse ERT measurements on the third farm revealed a defect in its drainage network where the slope of the clay beds opposes the main direction of the MDs. That has completely obstructed the drainage system of the farm and caused waterlogging. The presented geo-resistivity methods show that integrated models can be used to improve the assessment of in situ sub-surface drainage in clay-rich soils.
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| 9. |
- Baghban, Sahar, et al.
(författare)
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Mitigation and Adaptation Measures
- 2022. - 1
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Ingår i: Climate Change in Sustainable Water Resources Management. - Singapore : Springer Nature. - 2364-8198 .- 2364-6934. - 9789811918971 - 9789811918988 ; , s. 331-360
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Bokkapitel (refereegranskat)abstract
- Climate change has directly and indirectly impacted natural and human systems across the globe in recent decades.
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| 10. |
- Bali, Khaled M., et al.
(författare)
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Nutrient and salinity management for spinach production under sprinkler irrigation in the low desert region of California
- 2021
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Ingår i: Irrigation Science. - : Springer Science and Business Media LLC. - 0342-7188 .- 1432-1319. ; 39:6, s. 735-749
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of irrigation, as well as optimization of nutrients, affect spinach yield in all growth stages. In this study, the sensitivity of spinach (early and mature yields) to shallow saline groundwater and the effect of fertigation treatments on mature yield were experimentally investigated. The sprinkler irrigation experiments were conducted on 0.47 ha of silty clay soil at the University of California Desert Research and Extension Center (DREC) in Imperial Valley, California. Twelve beds in the experimental field were chosen randomly to investigate the effect of three fertigation treatments on spinach yield. Three rates of urea ammonium nitrate (UAN-32) fertilizer; T1: 200 kg ha−1 (150%), T2: 133.3 kg ha−1 (100%), and T3: 66.7 kg ha−1 (50%) in four replicates were applied. Soil samples to depths of up to 120 cm were collected at baby leaves and mature harvesting dates (17th October and 19th November 2019, respectively) for salinity measurements. Additionally, soil matric potential through the 120 cm soil depth was measured and groundwater levels in five observation wells were recorded during the growing season. Results showed that average soil salinity at baby leaves harvesting stage through the top 60 cm active root zone depth ranged from 0.61 to 1.48 dS m−1, which is lower than the spinach salinity threshold limit (2 dS m−1), while the average groundwater depth was 1.90 m with salinity ranging from 6.35 to 10.60 dS m−1. Correlation analysis showed that the baby spinach leaves yield was weakly correlated (r = 0.40) to the average soil salinity in the top 60 cm soil depth. Although groundwater and top 60 cm soil salinity showed an increase at the mature yield harvesting stage, the mature yield was weakly correlated to soil salinity (p = 0.116). As the UAN-32 rate increased, the mature spinach yield increased. The mature spinach yields were 17.31, 14.00, and 12.54 ton ha−1 for T1, T2, and T3 fertigation treatments, respectively. However, only a 10% reduction in yield occurred in T3 treatment corresponding to a 50% reduction in UAN-32 rate by 66.7 kg ha−1. Based on the results of this study, shallow saline groundwater has little impact on spinach yield. In addition, the 50% increase in UAN-32 rate had a significant impact on mature spinach yield. The 150% UAN-32 rate resulted in an increase in spinach yield and could be used in arid and semiarid regions with similar conditions to the Imperial Valley but additional measures to minimize the leaching of nitrate from the root zone and to reduce the load of nitrogen in drainage water are needed to minimize the potential negative impact of over-fertigation on the environment.
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