Limited Water Resources Research Articles

Assessment of advanced bioethanol potential under water and land resource constraints in China

Crop residues and energy crops grown on marginal lands can be sources of advanced bioethanol without interfering with agricultural land for food, and can replace traditional fuels with a neutral carbon cycle, but demand additional water for crop growth and energy production. However, existing bioethanol potential assessments ignore the constraints of limited water resources. Here we quantify the bioethanol potential from twelve crops’ residues and two energy crops (sweet sorghum and cassava) grown on marginal lands under both water and land constraints in China, based on bioethanol water footprint accounting, local water scarcity degree and marginal land identification. Results show that the bioethanol potential from crop residues is up to 68.5 Mt (∼1.8 EJ calorific value), approximately 49% lower than the theoretical potential without considering water limits. The suitable bioethanol potentials from sweet sorghum and cassava are in ranges 18.7–32.7 Mt (∼0.5–0.9 EJ) and 14.0–52.4 Mt (∼0.4–1.4 EJ), respectively. Northeast China are more suitable for the development of bioethanol due to their greater productive potential and lower water scarcity, whereas South and Southwest China have advantages in terms of growing energy crops on marginal lands and should be the focus of additional attention.

Sustainable management of water-agriculture-ecology nexus system under multiple uncertainties

The shrinkage and ecological degradation of the Aral Sea resulting from the uncontrolled use of water resources and the unregulated expansion of agriculture activities call for sustainable management of water-agriculture-ecology (WAE) nexus from a basin perspective. However, managers face thorny challenges brought by multiple uncertainties in the management and planning processes. In this study, an interval stochastic fuzzy programming (ISF) method is developed for tackling multiple uncertainties presented as probability distributions, flexible variables and interval parameters. Then, an ISF-WAE model is formulated for Aral Sea Basin, which considers 108 planning scenarios that reflect different food-security and ecology-restoration requirements, as well as risk-response attitudes of decision maker over a long-term planning horizon (2021–2050). Results reveal that for Aral Sea Basin: (i) managers should set strict acreage benchmarks for cereal crops, in which wheat would account for a range of [29.1, 31.2] % of the total agricultural area; (ii) for promoting ecological restoration, the proportion of agricultural water allocation should decrease by a range of [12.7, 16.1] % during the planning horizon; (iii) due to low water requirement and high ecological value of grassland, it is recommended to expand grassland area to improve the sustainability of the Aral Sea Basin in the case of limited water resources.

Quantity and spatial imbalance of supply and demand for water yield services in terrestrial ecosystems under different future land use scenarios in Xinjiang, China

Drylands in northwest China have limited water resources, which negatively impacts economic development, ecological security, and the United Nations Sustainable Development Goals. However, few studies have examined water supply and demand under multiple future spatial patterns of land use, particularly under sustainable development scenarios. Further research is therefore needed to determine how affect water output services under various land use patterns. We used the GMOP-PLUS (Gray Multi-objective Optimization-Patch-generating Land Use Simulation) and the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) models to investigate future land use programs and the current and future trends in water yield services supply and demand in the typical dryland region of Xinjiang, China. The GMOP-PLUS model was used to project the spatial patterns of land use/land cover (LULC) change in Xinjiang in 2025 and 2030 under programs of business-as-usual, rapid economic development, ecological land protection and sustainable development. We then used the InVEST model to project the spatiotemporal evolution of water yield services supply and demand under the four different scenarios. Our results show that Our results show that water production in Xinjiang decreases to 911.30 × 108 m3 in 2020–2030 under the business-as-usual scenario, with an expansion in arable land and a reduction in forested land being the main causes of this decrease. The decline in water production under the ecological land protection scenario is 913.88 × 108 m3. The retention effect of vegetation slows the decline in water production, but the ecological land protection scenario is not effective in controlling the reduction in arable land. The rapid economic development scenario produces a significant increase in water yield of 915.09 × 108 m3, mainly due to an increase in the area of impervious surfaces caused by the expansion of built-up land; however, the rapid economic development scenario leads to a decreasing trend in ecological land. The sustainable development scenario produces 914.15 × 108 m3 of water. The sustainable development scenario increases water production while balancing the development of Constructed and the protection of ecological land, and the arable land also shows a slow growth trend. Between 2025 and 2030, the water security index fluctuates between –0.0225 and –0.0400, with a continued future deficit in water supply and demand in Xinjiang and a high degree of spatial heterogeneity. Programs for advancing sustainable development narrow the supply–demand gap for services that produce water.

Quantifying the Impact of Coal Mining on Underground Water in Arid and Semi-Arid Area: A Case Study of the New Shanghai No. 1 Coal Mine, Ordos Basin, China

The new Shanghai No. 1 Coal Mine is located in arid and semiarid area of northwest China, which is characterized by scarce rainfall, intense evaporation, and limited water resources. High-intensity coal mining has caused severe damage to groundwater resources. The Baotashan sandstone aquifer of the Jurassic system has abundant water resources, and they are stored in the floor strata of mining coal seams. This poses the risk of high-pressure build-up and water inrush hazards during the mining of coal. To avoid these, the Baotashan sandstone aquifer needs to be drained and depressurized, which can result in a huge waste of water resources. Thus, taking the New Shanghai No. 1 Coal Mine as the basis for the case study, the impact of coal mining on the underground water resources was quantified. Large-scale water release tests were performed under the shaft to determine the hydrogeological properties of the Baotashan sandstone aquifer and a three-dimensional numerical model of the groundwater system was established. The dynamic phenomenon of water drainage was simulated and the drained water discharge was predicted under the condition of safe mining.

Bedouins choice behavior toward the desalinated water in Halaib, Egypt

Insufficiency of water is a growing global problem challenging sustainable development due to its limited water resources. This research aimed to 1) know about Bedouins' sources and uses of water in the Halaib study's area, 2) explore Bedouins’ choice behavior towards desalinated water using consumption value theory, 3) determine factors related to Bedouins’ choice behavior, and 4) determine the reasons for water contamination and propose solutions. Data were collected from a sample of 153 Bedouins through personal interviews using a questionnaire form in November 2021. Data were analyzed and presented using frequency, mean, and step-wise regression analysis. The reliability of the questionnaire (0.864) was estimated by Cronbach’s alpha. The results showed that desalinated water was the most popular clean water source in the examined area and that it was crucial for providing people with safe water. All Bedouins (100%) prefer using desalinated water for cleaning, animal watering, and irrigation. The mean score of respondents’ perception of function value price is 5.78 (96.3% of the total score); the social value is 4.78 (79.67%); the function value quality is 4.57 (76.17%); and the emotional value is 4.49 (74.83%). The quality of the function value explains about 59.1% of the variance in Bedouins' choice behavior towards desalinated water, while the social value accounts for about 12.1% and the emotional value accounts for about 3.6%. There was sufficient evidence to disprove H4, H6, and H7. The results were used to provide suggestions for further research.

Characterization of leaf trichomes and their influence on surface wettability of Salsola ferganica, an annual halophyte in the desert.

Many organisms use functional surfaces to collect water from the atmosphere. Salsola ferganica Drob. is one of the most abundant plants in desert regions and thrives in extreme environments with multiple but limited water resources, including dew and fog; however, its mechanisms of water harvesting remain unclear. We investigated trichome structural characteristics and their influence on the surface wettability of S. ferganica leaves using a variety of approaches (scanning electron microscopy, optical microscopy, immunolabelling staining, x-ray diffractometry, and infrared spectroscopy). Microstructural observations revealed that the trichomes of S. ferganica presented a curved upper part, the 'spindle node'-like structure in the middle, and the micro-grooves structure in between; such unique structures may aid in capturing moisture from the air. The physicochemical characteristics of the trichome surface, including hydrophobic functional groups, hydrophilic pectins, and low crystallinity, may enhance the adhesion of water drops to trichomes. Furthermore, we discovered that the piliferous S. ferganica leaves were more effective in retaining water than the glabrous S. aralocaspica leaves, and the dense trichome layer exhibited a significantly unwettable surface (high contact angle with droplets), whereas the individual trichomes retained water effectively (more so under drought conditions). The combination of these two properties is consistent with the 'rose petal effect', which describes rough surfaces that are hydrophobic but exhibit high adhesion with water. These factors suggest that the evolutionary optimisation of water acquisition by coupling relevant microstructures with the physicochemical properties of trichomes enables S. ferganica to survive harsh conditions in the seedling stage.

Biocontrol of multi-drug resistant pathogenic bacteria in drainage water by locally isolated bacteriophage

In areas with limited water resources, the reuse of treated drainage water for non-potable purposes is increasingly recognised as a valuable and sustainable water resource. Numerous pathogenic bacteria found in drainage water have a detrimental impact on public health. The emergence of antibiotic-resistant bacteria and the current worldwide delay in the production of new antibiotics may make the issue of this microbial water pollution even more challenging. This challenge aided the resumption of phage treatment to address this alarming issue. In this study, strains of Escherichia coli and Pseudomonas aeruginosa and their phages were isolated from drainage and surface water from Bahr El-Baqar and El-Manzala Lake in Damietta governorate, Egypt. Bacterial strains were identified by microscopical and biochemical examinations which were confirmed by 16 S rDNA sequencing. The susceptibility of these bacteria to several antibiotics revealed that most of the isolates had multiple antibiotic resistances (MAR). The calculated MAR index values (> 0.25) categorized study sites as potentially hazardous to health. Lytic bacteriophages against these multidrug-resistant strains of E. coli and P. aeruginosa were isolated and characterized. The isolated phages were found to be pH and heat stable and were all members of the Caudovirales order as recognized by the electron microscope. They infect 88.9% of E. coli strains and 100% of P. aeruginosa strains examined. Under laboratory conditions, the use of a phage cocktail resulted in a considerable reduction in bacterial growth. The removal efficiency (%) for E. coli and P. aeruginosa colonies increased with time and maximized at 24 h revealing a nearly 100% reduction after incubation with the phage mixture. The study candidates new phages for detecting and controlling other bacterial pathogens of public health concern to limit water pollution and maintain adequate hygiene.

Optimizing water management practice to increase potato yield and water use efficiency in North China

Potato is one of the staple food crops in North China. However, potato production in this region is threatened by the low amount and high spatial-temporal variation of precipitation. Increasing yield and water use efficiency (WUE) of potato by various water management practices under water resource limitation is of great importance for ensuring food security in China. However, the contributions of different water management practices to yield and WUE of potato have been rarely investigated across North China's potato planting region. Based on meta-analysis of field experiments from the literature and model simulation, this study quantified the potential yields of potatoes without water and fertilizer limitation, and yield under irrigated and rainfed conditions, and the corresponding WUEs across four potato planting regions including the Da Hinggan Mountains (DH), the Foothills of Yanshan hilly (YH), the North foot of the Yinshan Mountains (YM), and the Loess Plateau (LP) in North China. Simulated average potential potato tuber dry weight yield by the APSIM-Potato Model was 12.4 t ha−1 for the YH region, 11.4 t ha−1 for the YM region, 11.2 t ha−1 for the DH region, and 10.7 t ha−1 for the LP region, respectively. Observed rainfed potato tuber dry weight yield accounted for 61, 30, 28 and 24% of the potential yield in the DH, YH, YM, and LP regions. The maximum WUE of 2.2 kg m−3 in the YH region, 2.1 kg m−3 in the DH region, 1.9 kg m−3 in the YM region and 1.9 kg m−3 in the LP region was achieved under the potential yield level. Ridge-furrow planting could boost yield by 8–49% and WUE by 2–36% while ridge-furrow planting with film mulching could boost yield by 35–89% and WUE by 7–57% across North China. Our study demonstrates that there is a large potential to increase yield and WUE simultaneously by combining ridge-furrow planting with film mulching and supplemental irrigation in different potato planting regions with limited water resources.

Assessment of Basin-scale Water Stress using Geographic Information System in Southeast Asian Countries with Megacities

Southeast Asian countries are facing unstable water resource situations, experiencing high water stress as a result in their river basins, particularly around large population cities. This research has assessed basin-scale water stress by estimating the amount of water resources and water use for all river basins in Indonesia, Thailand, the Philippines, Vietnam, and Malaysia. A simple water stress assessment methodology using a Geographic Information System revealed the basins vulnerable to high water stress around the capital areas in all five countries. The population ratio was under high-moderate and high water stress at 29.3% in Indonesia, 41.8% in Thailand, 31.9% in the Philippines, 43.3% in Vietnam, and 19.9% in Malaysia. The results imply that large populations depend on limited water resources. The basin-scale assessment conducted in this research could be used in support of the water resources management planning at an inter-basin scale aiming to neutralize water stress.

Estimating the monthly pan evaporation with limited climatic data in dryland based on the extended long short-term memory model enhanced with meta-heuristic algorithms

Accurate estimation of evaporation is of great significance for understanding regional drought, and managing and applying limited water resources in dryland. However, the application of the traditional estimation approaches is limited due to the lack of required meteorological parameters or experimental conditions. In this study, a novel hybrid model was proposed to estimate the monthly pan Ep in dryland by integrating long short-term memory (LSTM) with grey wolf optimizer (GWO) algorithm and Kendall-τ correlation coefficient, where the GWO algorithm was employed to find the optimal hyper-parameters of LSTM, and Kendall-τ correlation coefficient was used to determine the input combination of meteorological variables. The model performance was compared to the performance of other methods based on the evaluation metrics, including root mean squared error (RMSE), the normalized mean squared error (NMSE), the mean absolute error (MAE), the mean absolute percentage error (MAPE), and Nash–Sutcliffe coefficient of efficiency (NSCE). The results indicated that the optimal input meteorological parameters of the hybrid Kendall-τ-GWO-LSTM models are the monthly average temperature, the minimum air temperature, the maximum air temperature, the minimum values of RMSE, NMSE, MAE, and MAPE are 38.28, 0.20, 26.62, and 19.96%, and the maximum NSCE is 0.89, suggesting that the hybrid Kendall-τ-GWO-LSTM exhibit better model performance than the other hybrid models. Thus, the hybrid Kendall-τ-GWO-LSTM model was highly recommended for estimating pan Ep with limited meteorological information in dryland. The present investigation provides a novel method to estimate the monthly pan Ep with limited meteorological variables in dryland by coupling a deep learning model with meta-heuristic algorithms and the data preprocessing techniques.

A novel method for adjusting cropping patterns to climate change

Impacts of climate change on agriculture threaten food security. Limited water resources particularly in semi/arid environment affects agriculture. This study develops a framework to modify cropping patterns through minimizing irrigation water use. To evaluate projected changes, the developed method uses hydrometeorological variables from HadGEM2-ES under climate scenarios (RCP2.6 and RCP8.5) to estimate irrigation water requirement, best planting date, and number of growing days for crops over the Middle East. Results indicate that variety of the crops decreases in lower latitudes (below 30°N). Potato in the west of the Middle East needs to be replaced by maize. Oat is replaced by potato in north and center of the domain and replaced by wheat in east parts of the Middle East. In addition, results confirm that although a large increase of temperature occurs in northeast of the domain, crop pattern adjustment leads to the highest decrease of irrigation water need. In many central parts of the Middle East, the best planting date has been shifted to the wet season under both scenarios particularly RCP8.5 due to a greater increase of temperature. The developed method that can be used in different regions is valuable in climate change mitigation and adaptation for environmental conservation.

Will adoption occur if a practice is win-win for profit and the environment? An application to a rancher's grazing practice choices

Rotational grazing has the potential to provide both economic and environmental benefits; however, the set of ranchers that adopts is much smaller than the set that regards rotational grazing as a win-win practice. To investigate this adoption gap and learn about adoption decisions and motivations, we survey 874 ranchers on the U.S. Great Plains. We find that a large proportion of surveyed ranchers who view rotational grazing as win-win for both profit and the environment do not adopt the practice. We also find that win-win non-adopters are a constrained group for most potential challenges to rotational grazing adoption, especially regarding high initial costs, water resource limitations, and ranch conditions. Some of these impediments could be relieved by capital to which, however, win-win non-adopters have limited access. Win-win non-adopters are more likely to adopt rotational grazing than others when a one-time subsidy is offered, suggesting that win-win non-adopters hold promise as a target group for subsidies to reduce the cost of adoption. Our analysis shows the importance of understanding the specifics of an adoption gap when making and implementing policies.

Hydrochemical Characteristics and Ion Sources of Soil-Soluble Salt in the Water-Level Fluctuation Zone of the Lower Jinsha River Basin

The water-level fluctuation zone of the lower Jinsha River Basin is a fragile ecosystem with limited water resources in the southwest of China. Soil water is critical for maintaining ecological balance and promoting the healthy development of animals and plants in this region. In this study, eight typical soil profiles were monitored for hydrochemistry in soil-soluble salt from upstream to downstream of the lower Jinsha River Basin. The results show that the soil water content was low and had a negative correlation coefficient with major ions in the soil-soluble phase. The soil-soluble salt is slightly alkaline, and Ca2+, Na+, SO42−, and HCO3− are important components for ions in a soluble phase. Major ions in soluble salt originate from various sources, including precipitation, anthropogenic input, silicate weathering, and carbonate weathering, and the contribution rates from each end member were 0.7%, 45.1%, 25.2%, and 29%, respectively. The ion composition in surface soil soluble salt is mainly influenced by precipitation and human activities, while the ions in the 0–50 cm soil layer originate from the precipitation input and water-rock interaction. In addition, rock weathering is a vital process for releasing ions into soil-soluble salt from 50 to 100 cm soil layer. Our findings provide important references for ion sources and the eco-hydrological process in limited water resources in the water-level fluctuation zone of the lower Jinsha River Basin.

Spatial–temporal variations in vegetation with changing water stress in the Kongqi River basin, China

AbstractIdentifying dominant water stress on vegetation growth over the arid basins is essential to better understand ecosystems and water interactions, which are fundamental in managing regional water resources. The Kongqi River basin is an ecologically sensitive area with limited water resources in the northern part of Tarim Basin in northwest China. How is the spatial distribution of vegetation controlled by natural conditions and anthropogenic regulation of water resources is a concern for ecology system protection. This study explores the spatio–temporal variations in the remote‐sensing vegetation index across the basin and identifies water stress forces with the Mann–Kendall trend test and linear regression analysis. Results show that the controls of vegetation change are different among geomorphological units over the past 20 years. In the northern mountains, the increasing vegetation trend mainly responds to climate change, particularly to increased precipitation. In contrast, in the plain area, the vegetation change is controlled by changes in hydrologic and anthropogenic water stresses. A significant rise in surface water and groundwater utilization counteracts the negative effect of the increasing hydrologic water stress in the upstream oasis. However, the increasing anthropogenic water stress contributed to more than 50% of vegetation decay in the downstream area during 2004–2015. The ecological water conveyance beginning in 2016 has promoted vegetation restoration, but the effect decreased with distance to the upstream area and showed a delay in response. This study provides evidence for ecological consequence of anthropogenic water stress that is beneficial to improve water resources management and ecosystem restoration.

Optimal clipping intensity for balancing soil erosion control and runoff production on revegetated slopes

Clipping management by reducing the above-ground parts of grassland has been gradually introduced to offset some of the additional issues caused by large-scale vegetation restoration, such as the formation of a dry soil layer, approaching the limits of watershed water resources, and reducing the sustainability of vegetation. Therefore, there is a scientific and practical need to evaluate the effectiveness of clipping management on runoff and erosion processes to ensure a balance between erosion control, surface water supply, and vegetation sustainability. In this study, simulated rainfall experiments with four levels of clipping intensities (no clipping, light clipping, heavy clipping, and clear clipping) were conducted to explore the mechanism of runoff and soil loss response under three rainfall intensities (i.e., 60, 90, and 120 mm·h−1) and three slope gradients (i.e., 18, 36, and 58 %) using structural equation modeling and variation partitioning. The results showed that the runoff depth increased by 42 %, 119 %, and 299 %, respectively, and the soil loss increased by 76 %, 80 %, and 470 %, respectively, in the light, heavy, and clear clipping treatments compared with the no clipping treatment, indicating that the increase in the percentage of runoff production and soil loss was not synchronized. According to the optimizing results of response surface method, the recommended vegetation cover after clipping was 23 % − 48 %, and the slope gradient of clipped vegetation should not exceed 36 %, which increased surface runoff while limiting soil erosion within an acceptable range. Runoff production and soil loss were primarily determined by rainfall intensity, followed by clipping intensity and slope gradient. Increasing rainfall intensity and slope gradient increased the effect of clipping on soil loss. Therefore, local rainfall and topography need to be considered in the application of clipping management. This study provides valuable insights into the use of clipping treatment as a sustainable management strategy for mitigating soil erosion and conserving surface water resources, and has important implications for developing restoration plans to promote sustainability in semi-arid ecosystems.

Development of an Embedded Software and Control Kit to Be Used in Soilless Agriculture Production Systems.

Traditional agricultural methods, which are still adopted today, depend on many factors. Food production processes face serious risks, such as limited clean water resources and supplements such as phosphorus, in addition to weather conditions due to climate change, the distribution of pests and soil-borne diseases, and increasing demand due to population growth, which can lead to famine. In particular, there may be cases where the soil nutrient content is insufficient and the soil structure is not suitable for cultivation. Therefore, soilless farming techniques have become popular, where the producer is entirely in control of the process. Additionally, many factors affect conventional farming techniques, including restrictions on land suitable for agriculture, climate-increased transportation costs from production areas to central regions, and environmental sanctions. Therefore, soilless farming techniques and the use of technology have rapidly gained importance. The use of technology has two crucial parameters: hardware and software. Today, no device can simultaneously control the electrical conductivity, pH, dissolved oxygen, and temperature of the solution in systems cultivated with soilless farming techniques. The present study was conducted to find a solution to the needs in this area. An automatic control system was developed and tested, employing a microcontroller, various sensors, appropriate open-source codes, and original software. Electrical conductivity (EC), power of hydrogen (pH), dissolved oxygen (DO), and temperature (T) values were determined successfully by the developed control system. The area where the experiment was conducted is a fully controlled and closed area established within Ankara University. The ambient temperature was 22 °C and the humidity was 39%. The coordinates of the experimental area are 39.962013 and 32.867491. Three different artificial lighting intensities (165.6 µmol m-2 s-1, 248.4 µmol m-2 s-1, and 331.2 µmol m-2 s-1) and a desired photoperiod duration can be applied to the site.

Engineering application of BIM in saving water and energy conservation

With the improvement of living standards, people are more and more eager to improve the efficiency of energy conservation and emissions reduction of buildings. Pursuant to this, the application of BIM technology in the water supply and drainage engineering of green buildings is proposed. Firstly, the BIM model is built to draw the axis network and axis height and transform the spatial position of family components, which is conductive to addressing the problem of the loss of engineering information. Then, the energy-saving pathways of green building water supply and drainage projects are analyzed, Concretely, the drainage energy consumption can be reduced by decreasing the overall head of the water pump. The pipe resistance and drainage efficiency can be respectively reduced and improved through reasonable selection of parallel drainage pipelines. Also, the principle of "avoiding the peak and filling valley" can be adopted to reduce pump operation in peak period and water draining in valley period, thereby saving drainage cost. By optimizing the control strategy of the drainage system and improving the utilization rate of water resources, the final results of the study show that BIM technology can realize 69% energy saving of the total savings in water supply and drainage engineering of green buildings, decrease cost consumption and improve the quality of water supply and drainage system, so as to make full use of limited water resources to achieve the effect of energy conservation and emission reduction.

The Effects Atmospheric Changes Have on Runoff

Over the last century, the earth has seen unprecedented atmospheric concentrations contaminate our ecosystems due to human activity. Predictions state the introduction of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFCs), will increase temperatures, and change the amount and location of precipitation causing more runoff. This could potentially result in disturbance events such as floods, to be more frequent and severe. This study aims to perform an assessment of the effects of a range of hypothetical climate changes on runoff in the North-east Pond River watershed, located in Newfoundland.
 To carry this out a watershed runoff model simulates runoff in the basin for current climatic conditions and for hypothetical climatic conditions that represent a range of possible climate changes (Bobba et al., 1997). The hypothetical changes in climate will showcase the effects of a 2oC increase in temperature on the total annual precipitation. This will then be compared to flood forecasting models to analyze how runoff will be affected by various climatic conditions, inducing unusual flooding events (Wijayarathne & Coulibaly, 2020). Previous studies have indicated the runoff sensitivity in watersheds to changes in temperatures which raises concerns as to the adverse effects this may cause in limiting water resources in the semi-arid regions in parts of Canada and the U.S. Thus, there is a need to increase the understanding of the sensitivity of water resources in Canadian watersheds to climate variability and climate change as effects of this magnitude on the North-east Pond River could have significant environmental implications.

Identifying Key Influences on Surface Water Quality in Freshwater Areas of the Vietnamese Mekong Delta from 2018 to 2020

Urbanization, industrialization, and the loss of freshwater resources are leading to an increased awareness of the importance of surface water quality worldwide. Limited ground water resources, prolonged drouths, and flooding are creating pressure on the availability of freshwater sources in the Vietnamese Mekong Delta. However, the surface water quality in this region is measured mainly at the provincial level, without reference to the water quality of adjacent regions. In order to identify and understand the key factors that contribute significantly to the quality of surface water, it is necessary to consider the delta region as a holistic system and to systematically investigate the influence of different land uses on water quality. In this study, surface water quality was evaluated during the dry season, when flow is low and water exchange is limited. For this purpose, the temporal variation in the surface water quality of 12 water quality parameters at 132 monitoring stations was analyzed according to their surrounding type of land use. To further investigate the impact on low-hierarchy canals, a correlation analysis between the river and canal class hierarchy and all investigated water quality parameters was performed. The results show that surface water quality suffers particularly in the case of a low dissolved oxygen (DO) content, with a measured minimum of 0.48 mg/L, and in cases of organic pollution in the form of total suspended solids, biochemical oxygen demand, and chemical oxygen demand, with values up to 146 mg/L, 75.0 mg/L, and 41.0 mg/L, respectively. As the main factors influencing surface water pollution, freshwater aquaculture and industrial activities were identified. This could have a relevant impact on future sustainable land use planning.

Analysis of Desalination Performance with a Thermal Vapor Compression System

Multi-effect distillation with thermal vapor compression (MED-TVC) is a highly energy-efficient desalination technology that can provide a reliable and sustainable source of high-quality water, particularly in areas with limited energy infrastructure and water resources. In this study, a numerical model based on exergoeconomic approach is developed to analyze the economic performance of a MED-TVC system for seawater desalination. A parallel/cross feed configuration is considered because of its high energy efficiency. In addition, a parametric study is performed to evaluate the effects of some operational parameters on the total water price, such as the top brine temperature, seawater temperature, motive steam flow rate, and number of effects. The obtained results indicate that the total water price is in the range of 1.73 USD/m3 for a distilled water production of 55.20 kg/s. Furthermore, the exergy destructions in the effects account for 45.8% of the total exergy destruction. The MED effects are also identified to be the most relevant component from an exergoeconomic viewpoint. Careful attention should be paid to these components. Of the total cost associated with the effects, 75.1% is due to its high thermodynamic inefficiency. Finally, the parametric study indicates that adjusting the top brine temperature, the cooling seawater temperature, the motive steam flow rate, and the number of effects has a significant impact on the TWP, which varies between 1.42 USD/m3 and 2.85 USD/m3.