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Water scarcity is one of the main challenges worldwide that might propose various engineering and economic issues. Petroleum industries have encountered these issues seriously, which required pretreatment facilities before reinjecting the produced water into the production wells. To assure that the treated water has no side effect on the environment, the treatment processes would perform three times by the photo-Fenton flotation method. This paper, it is aimed to calculate the treated water, required water, and saving water for chemically enhanced oil recovery methods (CEOR), hydraulic fracturing (HF), and other service facilities for completion and drilling performances. According to the results of this study, oil-well#3 has the highest water savings among all the wells with the 89% of daily water-saving, and oil-well#4 has the highest water savings among oil wells with the 75% of daily water saving. Consequently, in Sirri oilfield, the water-saving percentage is about 82% and 72%, which indicated that it is required 18%, 28% of the total water volume for implantation of HF process and CEOR methods, respectively. The total annual required water for this oilfield is 4131 MM m3/Day.

The current water shortage crisis has necessitated an increased focus on improving the irrigation efficiency in groundwater overdraft areas. Consequently, the Chinese government has supported small farmers in installing community-based water-saving technologies (WSTs) providing high irrigation efficiency. Based on the data collected from 620 households located in the groundwater overdraft area of Hebei, North China Plain, this study conducts a stochastic frontier analysis to measure farmers' irrigation water use efficiency (WUE) and analyzes the impact of land fragmentation and WST types on their WUE. The results show that the average WUE of groundwater irrigation is 0.606. The WUE between community-based and household-based WSTs differs based on the degree of land fragmentation. A high degree of land fragmentation restricts community-based WSTs from efficiently improving farmers' WUE, whereas household-based WSTs perform better and are easier to adopt. For high land fragmentation, the WUE of the community-based WST is 9.12% lower than that of the household-based WST. However, the WUE of the community-based WST is 12.55% higher than that of the household-based WST when the degree of land fragmentation is low. Therefore, the government should pay attention to small farmers' adaptability toward WST and promote community-based WSTs on a low degree of land fragmentation. HIGHLIGHTS This study calculated farmers’ irrigation water use efficiency (WUE) and analyzes the determinants of it.; This study constructs a comprehensive insight to explain the phenomenon that community-based (water-saving technology) did not perform well in improving WUE.; In addition to top-down financial support, more attention should be paid to the needs of small farmers and their actual agricultural production conditions.

The impact of wide ridge-furrow planting on maize production are mostly unexplored. The field experiment was conducted to study the effect of four ridge width on growth and water use efficiency (WU...

The shortage of groundwater resources is a considerable challenge for winter wheat production on the North China Plain. Water-saving technologies and procedures are thus urgently required. To determine the water-saving potential of using micro-sprinkling irrigation (MSI) for winter wheat production, field experiments were conducted from 2012 to 2015. Compared to traditional flooding irrigation (TFI), micro-sprinkling thrice with 90 mm water (MSI1) and micro-sprinkling four times with 120 mm water (MSI2) increased the water use efficiency by 22.5 and 16.2%, respectively, while reducing evapotranspiration by 17.6 and 10.8%. Regardless of the rainfall pattern, MSI (i.e., MSI1 or MSI2) either stabilized or significantly increased the grain yield, while reducing irrigation water volumes by 20–40%, compared to TFI. Applying the same volumes of irrigation water, MSI (i.e., MSI3, micro-sprinkling five times with 150 mm water) increased the grain yield and water use efficiency of winter wheat by 4.6 and 11.7%, respectively, compared to TFI. Because MSI could supply irrigation water more frequently in smaller amounts each time, it reduced soil layer compaction, and may have also resulted in a soil water deficit that promoted the spread of roots into the deep soil layer, which is beneficial to photosynthetic production in the critical period. In conclusion, MSI1 or MSI2 either stabilized or significantly increased grain yield while reducing irrigation water volumes by 20–40% compared to TFI, and should provide water-saving technological support in winter wheat production for smallholders on the North China Plain.

In order to study whether jujube trees can grow normally under rain-fed conditions in loess hilly areas, we planted jujube trees (Ziziphus jujuba Mill.) 4 years after felling a 23-year-old apple orchard. The growth process of the jujube trees and the variation in soil water content (SWC) were monitored for three consecutive years following planting in order to study the effects of the water-saving pruning (WSP) technique. Results showed the following. (1) The soil at a depth of 0–1,000 cm had been desiccated when the area was an apple orchard. (2) Under rain-fed conditions, the jujube trees with the WSP technique were always able to maintain normal growth while the jujube trees with conventional pruning method had a normal growth stage of only 4 years. The water use efficiency of the jujube trees with the WSP technique was much higher than that of the jujube trees with conventional pruning. We recommend WSP in jujube orchard management, because the jujube trees with WSP could maintain normal growth in the deep dried soils of the loess hilly region, as WSP can reduce the water consumption of the jujube trees and may have a positive effect on soil moisture restoration. HIGHLIGHTS We proposed water-saving pruning for the growth of jujube trees planted in dry soil.; Water-saving pruning can significantly improve water use efficiency of jujube trees planted in dry soil.; Water-saving pruning may have a positive impact on the restoration of soil water in dry soil.

Two field experiments were conducted at Sidi Salem region, Kafr El-Sheikh Governorate, Egypt, during two winter seasons 2018/2019 and 2019/2020 to study the impact of controlled drainage at 0.5, 0.75, 1.25 m and mole drain spacing 2 m on soil salinity, water-saving and sugar beet productivity. Results obtained that using controlled drainage saved irrigation water 24.56 and 11.35% in 1st season and 23.73 and 15.08% in 2nd season for 50, 75 cm depth of water table respectively, compared to 125 cm depth of water table. Application of mole drains seems to be more effective in decreasing soil salinity and sodicity especially, in the topsoil (0-60 cm) and narrow spacing between the plowed lines (2 m).Data showed that the water table level at 0.5 and 0.75 m treatments rose more rapidly and remained higher for longer time than the uncontrolled drainage treatment, the average water table depth was above specified depths between irrigation intervals from 3-7 days depending on the depth. There was a marked variation between the treatments that controlled drainage increased the yield at 0.50 m water table depth by 39 and 30% for both seasons, respectively. It can be concluded that the treatment of controlled drainage may give more profit than the uncontrolled one. At the same time, the contents of K+, Na+, alpha- amino N and alkalinity in root beet were insignificantly affected by controlled subsurface drainage in both seasons.

In Pakistan, orchards are irrigated using flood irrigation system that is considered sub-economical regarding water use efficiency. Considering the importance of natural water resources, there was a need to devise the method of applying irrigation water that would save water consumption, environmentally friendly and easily adopted by the growers. Thus, a research trial was conducted at Citrus Research Institute, Sargodha, Pakistan on 0.41 ha area of Kinnow mandarin. The total area was divided into two parts, half of the area was used for furrow irrigation system and the remaining half was used for flood irrigation system. Tensiometers were installed in the soil in furrow and flood irrigation system to assess the moisture condition in the soil. Irrigations were applied when tensiometer readings reached 40 centibars. The quantity of water used for irrigation was measured with a flume meter and then percentage of water saving was calculated. The study revealed that furrow irrigation system significantly improved the number of fruits per tree (1153), fruit yield (179.89 kg per plant) and juice percentage (48.38%) compared with flood irrigation system where the number of fruits per tree were711, fruit yield was 110.61 kg per plant and juice percentage was 46.31%. However, TSS/acidity ratio, and peel and rag percentage were not affected by the different irrigation systems. In furrow irrigation system 24 irrigations were applied per year with average water saving of 46.14% and water use efficiency (WUE) was 4.58 kg m-3 whereas in flood irrigation system average numbers of irrigations were 15 per year and WUE was 2.34 kg m-3only. Therefore, furrow irrigation system is recommended for the citrus growers to improve the water use efficiency, yield and fruit quality of Kinnow mandarin.

Rainwater harvesting is adopted to face water scarcity in arid regions. Many studies were developed in Jordan to estimate the potential of water harvesting for several uses. However, the precise estimation of water saving and cost benefits for the potential of rainwater harvesting from the roofs of residential urban areas is insufficient. Therefore, the objective of this study was to investigate the feasibility of rainwater harvesting from residential rooftops in all the eighty-nine Jordanian districts. The forecast number of buildings was calculated from 2016 to 2025 using building growth rate, where the number of houses and villas was adopted only. The long-term rainfall average from 1937 to 2017 was used. Two scenarios were used to assess the potential of rainwater harvesting; numerical (as scenario 1) and tabulated by plumbing code (as scenario 2) for the years from 2019 to 2025. Also, the growth rate of one cubic meter of water cost was calculated to find the money saving potential for the water companies in Jordan. The results indicated that the water harvesting potential was different between two scenarios in the districts which have annual rainfall more than 100 mm was efficient in scenario 1 compared to scenario 2 with the projected financial return which was increased from $5.4 million at 2019 to reach $33.4 million at 2025, while in the districts which have annual rainfall less than 100 mm was more efficient in scenario 2 compared to scenario 1 with the projected financial return which was increased from $2.4 million at 2019 to reach $14.6 million at 2025.

A field study was carried for two consecutive kharif and rabi seasons of 2013-14 and 2014-15 on farmer’s fields across 15 locations each year during kharif and 9 locations each year - during rabi in Srikakulam district, Andhra Pradesh. We tested five crop establishment methods viz., dry direct sowing using fertilizer-cum seed drill under irrigated conditions, drum seeding, systems of rice intensification (SRI), mechanized transplanting using rice 8 row yanmar transplanter, and manual transplanting. Study findings revealed that transplanting with rice planter emerged as high yielding method of establishment where the grain yield was higher by 9.21% over manual transplanting. Dry direct sowing was found to be highly profitable method of rice establishment by recording higher net returns Rs. 12596/ha compared to manual planting. Dry direct sowing and SRI proved as water productive rice establishment methods which took lesser water by 22.45% and 18.78% compared to manual transplanting during kharif. Whereas during rabi, drum seeding proved as profitable and water saving method of crop establishment in rice.

An environmental friendly superabsorbent composite (SAC) based on rice, (Oriza sativa L.), husk was created by the scientific group at Faculty of Science, Tanta University, and City of Scientific R...

Rainwater is one of the most promising alternative water sources. However, the financial outcomes of the rainwater harvesting (RWH) systems are not always assured as economic performance of RWH systems vary greatly under different climatic conditions.This paper investigates reliability, water saving and benefit-cost ratio of an RWH system with different storage tanks and under three distinct climatic conditions (i.e., wet, average and dry year) at four cities in China. It was found that for a standard building (1,600 m2 roof having 560 people), the rainwater supply reliability varies significantly (3.85–20.55%) across four cities. It was found that Guangzhou (South China) always achieves the highest reliability, greatest annual water saving and highest benefit-cost ratio under three distinct climate conditions. By contrast, Beijing (North China) is mostly ranked as having the lowest one. These findings are well in line with the historical annual precipitation in these regions. Also, it was found that across these four regions, it was not possible for a RWH system to achieve a benefit-cost ratio higher than 1.0. These findings indicate that the RWH systems in most regions of China are currently economically unfeasible without government subsidies.

The Burana Land-Reclamation Board is an interregional water board operating in three regions and five provinces. The Burana Land-Reclamation Board operates over a land area of about 250,000 hectares between the Rivers Secchia, Panaro and Samoggia, which forms the drainage basin of the River Panaroand part of the Burana-Po di Volano, from the Tuscan-Emilian Apennines to the River Po. Its main tasks are the conservation and safeguarding of the territory, with particular attention to water resources and how they are used, ensuring rainwater drainage from urban centres, avoiding flooding but ensuringwater supply for crop irrigation in the summer to combat drought. Since the last century the Burana Land-Reclamation Board has been using innovative techniques in the planning of water management schemes designed to achieve the above aims, improving the management of water resources while keeping a constant eye on protection of the environment.

The performance of three different irrigation systems (drip, sub-surface and sprinkler irrigation) in terms of actual irrigation water requirements, crop yield, water use efficiency and water saving was experimentally investigated under condition of sugar-beet planting in sandy soil. Water saving through the use of the three irrigation systems was studied as a function of change in water regime (100, 75 and 50%) and planting dates (1 Oct., 20 Oct. and 10 Nov.). Water saving was also recorded in the case of planting using compost comparing with the case of planting with no compost. The experimental results reveal to the following: - The highest amount of water saving was recorded under the use of sub-surface irrigation system with 50% water regime in the case of using compost and with delaying planting date to 10 Nov. - The highest values of crop yield and water use efficiency were found under the use of drip irrigation system with 100% water regime in the case of using compost and at 1 Oct. planting date.

An important element of the hydrologic cycle, the hydrometeorological parameter of evapotranspiration (ET), is critical in the development of effective water resources planning and irrigation scheduling. The ET varies in response to changes in resistance at the canopy surface rc and soil moisture content θ, especially under water-saving irrigation (WSI) practices. Drawing on data collected by eddy covariance in WSI rice paddies in eastern China in 2015 and 2016, variations in ET were studied by calculating and analyzing hourly canopy resistance and daily canopy resistance . Discrepancies were noted between true daily ET with respect to the estimated daily ET at different periods [0700–1600 local time (UTC + 8)]. To estimate in the WSI rice fields, the mean value between 0900 and 1000 LT, and between 1000 and 1100 LT performed considerably better than for a single time. Seasonal estimated ET can be accurately calculated by interpolating at different time intervals, thereby achieving a greater correlation and consistency at 2-day intervals. Then a generalized two-segment line of variation was used to calculate , achieving good results and showing that in the absence of observational data, could be easily calculated through a simplified pattern of variability. In conclusion, an ET temporal upscaling method for a WSI paddy, based on variation in and values, was optimized and is recommended for local application. Future work will focus on temporal upscaling of ET by extrapolating remote sensing instantaneous estimates to daily values.

The prolonged issues regarding the quantitative and qualitative characteristics of the water resources in the River Basin District of Thessaly (TRBD) have resulted in the environmental degradation and the reduction of the availability of water. Agriculture is the major water user, constituting up to 95% of total water demand. The pressures anticipated from the ongoing climate change are expected to cause further degradation, given the present status of the water resources. This research attempts to examine and quantify the water saving potential of TRBD, mainly for the agriculture sector, following the recommendations of the European legislation, the principles of sustainable development and environmental protection. Water saving tools are documented in several countries, including technical measures, such as drip irrigation systems and the modernization of the transfer networks, as well as deficit and scheduled irrigation practices and water reuse. These measures and practices are tested for their potential effect on water demand in TRBD, in addition to changing a portion of cotton cultivation areas to olive groves. To this end, the volume of irrigation demand is estimated at 2088×106, while total water demand stands for 2204×106. Afterwards the study proceeds to the evaluation of the water saving potential both independently and combined. The potential of water savings in TRBD is proven high, 14.3% of total water demand for technical measures, 10.7% if deficit irrigation is applied to specific crops, while it may reach 28.8% in case the measures are combined.

The field experiment was conducted during 2014 and 2015 to assess the water saving, yield parameter, water use efficiency and economics of various drip irrigation systems like surface drip irrigation with mulching, surface drip irrigation without mulching and subsurface drip irrigation with each system having three sub treatment, viz. 80 100 and 120 per cent ET using drip irrigation. The above parameters are varied from season to season. For first season yield varied from 71.18 t/ha (80 per cent ET) of surface drip irrigation with mulching to 45.91 t/ha (120 per center) of subsurface drip irrigation and same trend followed in the second seasons. For first season (WUE) varied from 18.71 kg/m3 (80 per cent ET) of surface drip irrigation with mulching to 8.10 kg/m3 (120 per cent) of subsurface drip irrigation and same trend followed in the second seasons. The highest B: C ratio was found in 80 per cent ET (5.21) of surface drip irrigation with mulching and the lowest B: C ratio was found in 120 per cent ET (4.26) with subsurface drip irrigation and same trend followed in second season. The water saved in drip irrigation over 120% ET was found to be 32.90% and 16.5% for 80% and 100% ET respectively in first season and same trend followed in second season.

The impact of regulated drip-irrigation on productivity and fruit quality of tomato ‘Tofane’ has been studied under a warm dry desert climate in southern Algeria. Yield, fruit weight and size, water content and parameters of fruit quality – total soluble solids, phenolic compounds, carotenoids, vitamin C, pH and titratable acidity were determined. Two irrigation treatments were applied in 2012 and 2013: T1, optimal irrigation (100% evapotranspiration – ETc) during the whole growth period (growth stages I, II and III); T2, optimal irrigation during I and II stages, and regulated deficit irrigation (67% ETc) during stage III (from fruit set to full fruit maturity of first and second bunch). T1 treatment during the whole season showed the highest values of soil water potential (Ψsoil), between −0.02 MPa and −0.06 MPa, on depths of 0.3 and 0.6 m, respectively. During stage III, regulated deficit irrigation caused the lowest Ψsoil values, which were between −0.1 MPa and −0.12 MPa on a soil depth of 0.3 and 0.6 m, respectively. Deficit irrigation caused significant decrease of water content in fruits and not significant decrease of fruit weight and size, as well as fruit yield while water saving for irrigation amounted to 10%. Comfort-irrigated tomato plants produced fruits containing significantly higher titratable acidity, total soluble solids and vit. C content. There was a tendency to decrease carotenoid content and increase phenolic content in both years of the study. Due to the possibility of water saving with not significant yield decrease, it seems that the reduction of water use in growth stage III would be an adequate strategy for tomato cultivation in hot, dry climate.

Cooling towers are widely used not only for commercial and industrial purposes but also for cooling power plant. In Korea, coal-fired power plants and nuclear power plants are generally located on the coast, while most combined-power plants are located inland and use cooling towers to condense steam. The operation rate of power plants in Korea highly depends on government energy policies. In the future, it is expected that the need for cooling tower water for inland power plant will increase. Since power plant is one of the massive water-consuming facilities, methods for water saving of cooling tower should be prepared. Also, in the industrial sector, plume is constantly raising social conflicts between residents and manufactures. Basically, similar technologies can be applied to water saving and plume abatement. In this study, the performance of the condensing module (outdoor-air-condensing method) using outside air was tested first. This module has an advantage in that cooling heat source is not necessary. But an excessive increase of fan air volume is required. We tested a membrane-dehumidification method that selectively transfers water vapor by applying a membrane module. The results showed that membrane module required a large amount of energy to generate vapor pressure difference and it had a disadvantage in energy usage. Since the membrane method considered requires a high bypass airflow for higher dehumidification, it also has a disadvantage similar to that of the outdoor air module. Finally, the dehumidification/regeneration module (heat-pump method) gave the best performance in terms of water saving and plume abatement.

It is important to reveal the physiological mechanism of water saving and yield increasing of mulched drip irrigation. Three treatments were applied at aspring maize field in Northeast China: mulch...

Water saving is crucial for the survival of agriculture in Saudi Arabia. Natural ground water resources are depleting by the extensive water use for agriculture. At the Estidamah research center in Riyadh water saving technologies for protected horticulture are evaluated in the harsh climatic conditions. Different levels of technology, viz., low, mid and high-tech were evaluated based on water use, energy consumption and production. The low-tech greenhouse is a plastic tunnel greenhouse cooled using a pad and fan system. This type of greenhouse is normally used for year-round production. The mid-tech greenhouse has a glass covering and is also cooled using the pad and fan system though here the amount of ventilation can be regulated using frequency-controlled fans. Finally, the high-tech greenhouse was considered which is a closed greenhouse. The cooling and dehumidification were done using coolers. The center is now in operation for more than two years so the water use over the year for the various types of greenhouse technologies can be evaluated. The water use for cooling in the mid-tech greenhouse is 30% less than what is used in the low-tech greenhouses. The water saving in the high-tech greenhouse is more than 95%.

Melange yarns have the advantages of energy saving, water saving and emissions reduction in their manufacturing. In order to further reduce water consumption and wastewater discharge from the source of product design, the cradle-to-gate water footprint and carbon footprint assessment of melange yarns were performed based on the ReCiPe method. The primary data of the melange yarns were collected by the on-site investigation. The results have shown that the recycled water is beneficial to reduce environmental burdens in manufacturing, and the indirect water consumed in the cotton cultivation is 35 times larger than the direct water consumption.

Nature-based solutions can significantly contribute to restoration projects in areas affected by desertification processes, where they are necessary for reversing land degradation. Currently, one innovative solution is The Cocoon™, which has been designed as a new ecotechnology for improving seedling establishment. The Cocoon consists of a doughnut-shaped container made of recycled cardboard that provides water and shelter at least during the first year of a seedling, which is the most critical for plant establishment. To determine the effectiveness of this ecotechnology under different conditions, the Cocoon was tested on a variety of soils, climates, vegetation, and land uses. Six planting trials were performed in Spain and Greece, which covered a range from humid to arid climates. With the objective of studying its functionality, the survival of the seedlings, their vigor, and growth were monitored for 2 years. Compared with conventional planting systems, the Cocoon has effectively increased seedling survival, especially under dry growing conditions (low rainfall, soils with low water holding capacity). The Cocoon also allowed for higher growth of some species (olive trees, holm oaks, and Aleppo pines). Moreover, a positive correlation between the rainfall on the site and the biodegradation degree of the Cocoon device was observed. Overall, the Cocoon becomes more efficient in arid climates or adverse growing conditions., EU Life Program, Grant/Award Numbers: LIFE15 CCA/ES/000125, LIFE19 CCM/ES/001199

The cutoff technique has not been adequately investigated despite being the most practiced among smallholder farmers. This study aimed at scenarios of improving water application efficiency...

In drinking water production from groundwaters, biological rapid sand filters (RSFs) can be used for ammonium and manganese removal in aerobic conditions. However, in some boreholes, a start-up duration of several months is required to reach the required removal capacity, leading to significant water losses. Moreover, in specific industrial cases, no exogenous biomass under the form of backwash water or activated sludge can be added to accelerate the process, and different approaches are seldom considered in the literature. With the aim of saving water, start-up strategies coupling water temperature increase and substrate dosing were studied to accelerate the installation of biological activities in a pilot plant fed with borehole water. These set-ups enabled a substantial acceleration of nitrification but no improvement of manganese oxidation in the experimental conditions, although the experiments showed no clear negative influence of nitrification, through nitrite accumulation, on biological manganese oxidation. To further save energy and reduce water loss, outlet water recirculation at a rate of 75% during the start-up phase was validated. The proposed start-up strategy enabled the complete installation of active biofilms with a mean start-up time reduction of 36% and water use reduction of 84% compared to the reference natural conditions.

Adjusting the agricultural planting structure is one of the important means to realize agricultural water-saving, especially in inland river basin with droughts and water shortages. In this paper, taking Shiyang River Basin in Northwest arid inland river basin as an example, on the basis of determining the crop water production function, a multi-objective optimization model was constructed, which comprehensively considered the maximization of economic benefits, the green water utilization rate and ecological benefits. The optimized planting structure was obtained by using GAMS (General Algebraic Modeling System) model solver. The results showed that: after optimization, the sown areas of wheat, tubers, vegetables and cotton all increased, of which the sown area of tubers increased the most by 8.81×104ha. The sown areas of corn, oil-bearing crops and fruits all decreased, of which the sown area of corn decreased the most by 8.03×104ha. The optimization results of planting structure were different in different counties and districts. The average contribution rate of planting structure adjustment to total water saving was 75.24%, indicating that planting structure adjustment was the key to water-saving. The water consumption of the same crop was different in different counties. Oil-bearing crops and vegetables were more suitable for planting in the lower reaches, while corn and tubers were more suitable for planting in the middle reaches.

Eco-friendly showers aim to lower energy and water consumption by generating smaller water droplets than those produced by traditional systems. To evaluate the risk of users inhaling the contaminants associated with such water droplets—namely, chemical components or opportunistic bacterial pathogens such as Legionella—we modeled the behavior of water droplets aerosolized by water-atomization technology at a flow rate of 2.2 L/min and compared the results obtained using this model with those determined experimentally in a typical shower stall. Additionally, we monitored the number and mass of inhalable water droplets emitted by twelve showerheads—eight using water-atomization technology and four using continuous-flow technology—which have distinct characteristics in terms of water flow rate, water pressure, spray angle, and number of and diameter of nozzles. The water-atomizing showers tested not only had lower flow rates, but also larger spray angles, less nozzles, and larger nozzle diameters than those of the continuous-flow showerheads. We observed a difference in the behavior of inhalable water droplets between the two technologies, both unobstructed and with the presence of a mannequin. The evaporation of inhalable water droplets emitted by the water-atomization showers favored a homogenous distribution in the shower stall. In the presence of the mannequin, the number and mass of inhalable droplets increased for the continuous-flow showerheads and decreased for the water-atomization showerheads. The water-atomization showerheads emitted less inhalable water mass than the continuous-flow showerheads did per unit of time, however, they generally emitted a slightly higher number of inhalable droplets (1.6 times more), including those large enough to carry a bacterium each—only one model performed as well as the continuous-flow showerheads in this regard. Further experiments are needed to assess whether this slight increase in the number of inhalable water droplets increases the biological risk.

For thermal power generation, the natural draft hybrid cooling system (NDHCs) with airflows in parallel design gives a multi-objective solution for water saving, performance enhancement and maintenance issues, like corrosion, by switching the loads of wet and dry sections. Performances of dry and wet sections interact with each other in the highly integrated system, increasing the complexity of operation strategies. In this context the present paper examines eight different operation schemes to reveal the relationships of ambient conditions and operation schemes. Comprehensive comparisons in the view of cooling efficiency with a same water inlet temperature are conducted firstly. Results show that there exists energy-saving potentials of the water evaporated rate, cooling performances and the pump power for different schemes. Based on the practical boundary conditions, including those of weather data, operation hours and market factors, optimal operation strategies of hybrid cooling are designed to minimize the operation costs of the energy system. For the 660 MW power generating unit integrated with a natural draft dry cooling system (NDDCs), operation costs based on NDHC after optimization decreased about 0.8% in 2010 and 0.35% in 2018 compared with that of the basic system. When comparing with the designed operation modes of hybrid cooling, 0.07 million dollars is saved after optimization.

The objective of the presented study was to develop a high-temporal-resolution stochastic rainwater harvesting (RWH) model for assessing the dual benefits of RWH: potable water savings and runoff reduction. Model inputs of rainfall and water demand are used in a stochastic manner, maintaining their natural pattern, while generating realistic noise and temporal variability. The dynamic model solves a mass-balance equation for the rainwater tank, while logging all inflows and outflows from it for post-simulation analysis. The developed model can simulate various building sizes, roof areas, rainwater tank volumes, controlled release policies, and time periods, providing a platform for assessing short- and long-term benefits. Standard passive rainwater harvesting operation and real-time control policies (controlled release) are demonstrated for a 40-apartment building with rainfall data typical for a Mediterranean climate, showing the system’s ability to supply water for non-potable uses, while reducing runoff volumes and flows, with the latter significantly improved when water is intentionally released from the tank prior to an expected overflow. The model could be used to further investigate the effects of rainwater harvesting on the urban water cycle, by coupling it with an urban drainage model and simulating the operation of a distributed network of micro-reservoirs that supply water and mitigate floods.

Rice production in Tanzania, with 67% of its territory considered semi-dry and having average annual rainfall of 300 mm, must be increased to feed an ever-growing population. Water for irrigation and low soil fertility are among the main challenges. One way to decrease water consumption in paddy fields is to change the irrigation regime for rice production, replacing continuous flooding with alternate wetting and drying. In order to assess the impact of different irrigation regimes and nitrogen fertilizer applications on growth, yield, and water productivity of rice, a greenhouse pot experiment with soil from lowland rice ecology was conducted at Sokoine University of Agriculture, Tanzania during the 2019 cropping season. The experiment was split-plot based on randomized complete block design with 12 treatments and 3 replications. Water regimes were the main factors comparing continuous flooding (CF) and alternate wetting and drying (AWD) with nitrogen fertilizer levels as the subfactor, comparing absolute control (no fertilizer) with 0 (P and K fertilizers), 60, 90, 120, and 150 kg Nha−1. Alternate wetting and drying (AWD) significantly improved water productivity by 8.3% over CF (p &lt, 0.05). Water productivity (WP) ranged from 0.6 to 1.5 kg of rice per m3 of water. Average water use ranged from 36 to 82 L per season, and water saving was up to 34.3%. Alternate wetting and drying significantly improved yields (p &lt, 0.05) by 13.3%, and the yield ranged from 21.8 to 118.2 g pot−1. The combination of AWD water management and 60 kg N ha−1 nitrogen fertilization application was found to be the optimal management, however there was no significant difference between 60 and 90 kg N ha−1, in which case 60 kg N ha−1 is recommended because it lowers costs and raises net income. Nitrogen levels significantly affected water productivity, water use, and number of irrigations. Nitrogen levels had significant effect (p &lt, 0.05) on plant height, number of tillers, flag leaf area, chlorophyll content, total tillers, number of productive tillers, panicle weight, panicle length, 1000-grain weight, straw yield, grain yield, and grain harvest index. The results showed that less water can be used to produce more crops under alternative wetting and drying irrigation practices. The results are important for water-scarce areas, providing useful information to policy makers, farmers, agricultural departments, and water management boards in devising future climate-smart adaptation and mitigation strategies.

Nowadays, water savings on industrial plants have become a significant concern for various plants and sections. It is vitally essential to propose applicable and efficient techniques to retreat produced water from onshore and offshore production units. This paper aimed to implement the PFF (Photo Fenton Flotation) method to optimize the water treatment procedure, as it is a two-stage separation technique. The measurements were recorded for the HF (hydraulic fracturing) and CEOR (chemically enhanced oil recovery) methods separately to compare the results appropriately. To assure the efficiency of this method, we first recorded the measurements for five sequential days. As a result, the total volume of 2372.5 MM m3/year of water can be saved in the HF process during the PFF treatment procedure, and only 20% of this required fresh water should be provided from other resources. On the other hand, the total volume of 7482.5 MM m3/year of water can be saved in CEOR processes during the PFF treatment procedure, and only 38% of this required fresh water should be provided from other resources. Therefore, the total water volume of 9855 MM m3 can be saved each year, indicating the efficiency of this method in supplying and saving the water volume during the production operations from oilfield units.