Water-saving Systems Research Articles

A Review of Precision Irrigation Water-Saving Technology under Changing Climate for Enhancing Water Use Efficiency, Crop Yield, and Environmental Footprints

Water is considered one of the vital natural resources and factors for performing short- and long-term agricultural practices on Earth. Meanwhile, globally, most of the available freshwater resources are utilized for irrigation purposes in agriculture. Currently, many world regions are facing extreme water shortage problems, which can worsen if not managed properly. In the literature, numerous methods and remedies are used to cope with the increasing global water crises. The use of precision irrigation water-saving systems (PISs) for efficient water management under climate change is one of them and is a highly recommended approach by researchers. It can mitigate the adverse effects of changing climate and help enhance water use efficiency, crop yield, and environmental footprints. Thus, the present study aimed to comprehensively examine and review PISs, focusing on their development, implementation, and positive impacts on sustainable water management. In addition, we searched the literature using different online search engines and reviewed and summarized the main results of the previously published papers on PISs. We discussed the traditional irrigation method and its modernization for enhancing water use efficiency, PIS monitoring and controlling, architecture, data sharing communication technologies, the role of artificial intelligence for irrigation water-saving, and the future prospects of the PIS. Based on the brief literature review, the present study concluded that the future of PISs seems bright, driven by the need for efficient irrigation water management systems, technological advancements, and increasing environmental awareness. As the water scarcity problem intensifies due to climate change and population growth, the PIS is poised to play a critical role in optimizing and modernizing water usage, increasing water use efficiency, and reducing environmental footprints, thus ensuring sustainable agriculture development.

Effect of water-saving technologies on productivity and profitability of tomato cultivation in Galapagos, Ecuador

We tested the effect of two water-saving systems (Groasis Waterboxx® and Hydrogel polymer), compared with conventional drip irrigation, on the productivity, profitability, and water efficiency of greenhouse tomato cultivation in the highlands of Santa Cruz Island, Galapagos. We measured the weight and volume of individual tomato fruits, along with biweekly production, over a typical growing cycle, and found that tomatoes grown with water-saving systems were significantly heavier and larger than those produced with conventional drip irrigation, which led to a 28% average increase in tomato production using both technologies. compared to drip irrigation, Groasis and Hydrogel also reduced water use by 71 and 48%, respectively. While both systems yielded a net profit, using Hydrogel was 51% more profitable than conventional drip irrigation. Water-saving systems such as Groasis and Hydrogel may provide more sustainable solutions for profitable tomato cultivation in environments with low annual rainfall and limited access to irrigation water, such as the Galapagos Islands.

Deficit Irrigation for Efficiency and Water Saving in Poplar Plantations

Water resources are increasingly limited and less available, so improving water use efficiency is particularly pressing in the agricultural sector, where inefficient irrigation systems are often in operation. Drip irrigation is one of the most water-saving systems that can optimize distribution according to the actual needs of the crop. In the present study, an engineered drip irrigation system was applied to a poplar crop dedicated to the production of biomass for energy use. The aim was to evaluate the influence of the supply of different volumes of irrigation water on crop growth. Four levels of water supply were tested (theses T1, T2, T3, and T4), each determined by different intervention thresholds established by using four soil moisture sensors, one for each thesis (PLOT) (20, 30, 40, and 50 percent, respectively). In the third growing season, the effect of the different amounts of irrigation water supplied on plant growth was particularly evident between control T1 (104 m3 ha−1) compared with T2 (540 m3 ha−1), T3 (1924 m3 ha−1) and T4 (4549 m3 ha−1). Regarding biomass production, no statistical differences were found between T2 (8.97 Mg DM ha−1 year−1), T3 (9.99 Mg DM ha−1 year−1) and T4 (10.02 Mg DM ha−1 year−1), but they were all different from T1 (7.09 Mg DM ha−1 year−1. This leads to the conclusion, at least up to the third growing season, that with equal satisfactory levels of biomass production, water and energy savings can be achieved by choosing intermediate levels of water supply (e.g., with the sensor at 30%) as compared to the maximum value tested.

Disaster Prevention and Mitigation Index Assessment of Green Buildings Based on the Fuzzy Analytic Hierarchy Process

Assessment systems for green buildings around the world have been developed over many years, but there is a lack of assessment elements for the disaster prevention and mitigation (DPM) capabilities of green buildings in many indicators. DPM indexes based on the four main aspects of structural safety, DPM design, facility settings, and resource utilization are proposed here with consideration to the complex natural disasters that occur in China (fires, earthquakes, floods, etc.) and relevant codes. Then, an assessment system for the DPM indexes of green buildings is established by the fuzzy analytic hierarchy process (FAHP) in order to evaluate the DPM ability of green buildings and to quantify the impact of different indexes on the DPM ability of green buildings; this system is also used to evaluate and compare DPM capability suggestions, taking two green buildings in South and North China as examples. The results show that the DPM capacities of the two green buildings were evaluated as good, but that the scores for the site planning and water-saving systems of the green building in South China were significantly lower—meaning that measures such as optimizing drainage systems, managing stormwater runoff, permeable paving, rainwater gardens, and installing rainwater harvesting equipment should be implemented. Then, the theory of the utilization rate of DPM conversion is put forward, providing a reference for the future development of green building DPM index systems.

Charging for the use of hydromineral and geothermal resources in Brazil as an instrument of rational use of groundwater

Mineral groundwaters in Brazil are managed centrally by the Federal Union, while other water resources are managed regionally by hydrographic basin. The charging method varies according to the usage and the management system, generating an unbalanced charge on mineral water for bottled water. This study presents a comparison of the charging systems for groundwaters using data for a period of 8 years. The analysis evaluates the efficiency of royalty-based charging of mineral groundwaters against charging over consumption volume for non-mineral groundwaters, taking into account the scale of the producers and their locations. The findings show that the royalty-based system depends on market conditions such as demand, supply and the willingness of the user to pay for bottled water, whilst the volume-based charging system depends mostly on the resource availability and the capacity of the producers to save water. The results demonstrated that the royalty-based charging system favors the production of returnable bottles, with lower environmental impact, as the charge for large returnable bottles is approximately 7 times lower than for disposable bottles. The conclusion is that an integrated management system is required, so proper priorities can be established in the use of groundwaters to benefit the population and to minimize environmental impacts. The successful implementation of integrated management and charging systems are likely to require monitoring and control measures such as automated remote systems for monitoring water consumption, official inspections on consumption and audits on water-saving systems.

Evaluating Irrigation and Farming Systems with Solar MajiPump in Ethiopia

Small-scale irrigation in Ethiopia is a key strategy to improve and sustain the food production system. Besides the use of surface water for irrigation, it is essential to unlock the groundwater potential. It is equally important to use soil management and water-saving systems to overcome the declining soil fertility and the temporal water scarcity in the region. In this study, the solar MajiPump was introduced to enable dry season crop production in Ethiopia using shallow groundwater sources. The capacity of the MajiPumps (MP400 and MP200) was tested for the discharge head and discharge using three types of solar panels (150 W and 200 W rigid, and 200 W flexible). Besides, drip irrigation and conservation agriculture (CA) farming systems were evaluated in terms of water productivity and crop yield in comparison to the farmers’ practice (overhead irrigation and tilled farming system). Results indicated that the maximum discharge head capacity of the MajiPumps was 18 m, 14 m, 10 m when using MP400 with 200 W rigid, MP400 with 200 W flexible, and MP200 with 150 W rigid solar panels, respectively. The corresponding MajiPump flow rates ranged from 7.8 L/min to 24.6 L/min, 3 L/min to 25 L/min, and 3.6 L/min to 22.2 L/min, respectively. Compared to farmer’s practice, water productivity was significantly improved under the CA farming and the drip irrigation systems for both irrigated vegetables (garlic, onion, cabbage, potato) and rainfed maize production. The water productivity of garlic, cabbage, potato, and maize was increased by 256%, 43%, 53%, and 9%, respectively, under CA as compared to conventional tillage (CT) even under overhead irrigation. Thus, farmers can obtain a significant water-saving benefit from CA regardless of water application systems. However, water and crop productivity could be further improved in the combined use of MajiPump with CA and drip irrigation (i.e., 38% and 33% water productivity and 43% and 36% crop productivity improvements were observed for potato and onion, respectively). Similarly, compared to CT, the use of CA significantly increased garlic, cabbage, potato, and maize yield by 170%, 42%, 43%, and 15%, respectively under the MajiPump water-lifting system. Overall, the solar-powered drip irrigation and CA farming system were found to be efficient to expand small-scale irrigation and improve productivity and livelihoods of smallholder farmers in Ethiopia.

Incorporating DNA-level microbial constraints helps decipher methane emissions from Chinese water-saving ground cover rice production systems

• Relating CH 4 fluxes to methanogens and methanotrophs under GCRPS remains unclear. • GCRPS reduced CH 4 emissions and the yield-scaled CH 4 emissions. • GCRPS decreased the abundance of mcrA gene while stimulated that of pmoA gene. • Microbial parameters are useful to better predict CH 4 emissions from rice paddies. While water management has been documented to regulate CH 4 emissions from rice paddies, the mechanisms behind the association between CH 4 emissions and functional microbes remain unclear under water-saving ground cover rice production systems (GCRPS). In GCRPS, the soil is kept aerobic by maintaining 80 %–90 % of the water holding capacity but without standing water over the entire rice-growing season, and the soil surface is covered with rice straw or plastic film to reduce water evaporation. A split-plot field experiment was conducted to examine the effects of various GCRPS-related water-saving regimes on CH 4 emissions by linking to CH 4 -related microbes over the 2015 and 2016 rice growing seasons in a typical Chinese rice field. Methane fluxes and related functional genes [methanogens ( mcrA and methanogenic archaeal 16S rRNA ) and methanotrophs ( pmoA )] abundances were simultaneously measured using the closed chamber method and molecular techniques, respectively. The results showed that relative to the conventional waterlogged control (WRPS), GCRPS-related water-saving practices consistently reduced CH 4 emissions, which was largely attributed to the decreased relative abundance of the methanogenic functional gene mcrA while the methanotrophic functional gene pmoA increased. When averaged over the two rice seasons, the grain yield was 17.38 % and 12.22 % greater under the GCRPS -straw and GCRPS -film water-saving systems relative to WRPS, respectively. Water-saving regimes decreased the yield-scaled CH 4 emissions as compared with the WRPS, especially under GCRPS -film . The CH 4 fluxes showed a positive correlation with the relative abundance of mcrA and its ratio to pmoA , but a negative correlation with the relative abundance of pmoA . The performance of CH 4 -simulated models could be improved by incorporating microbial parameters to predict CH 4 emissions from rice fields. Overall, this study updates our understanding of the microbial mechanisms underlying CH 4 emissions from water-saving GCRPSs. We proposed the GCRPS regime with biodegradable film mulching as a desirable water-saving strategy to reconcile high yields and low CH 4 emissions in rice production.

Performance analyses of existing sanitary sewers with the selection of household water-saving schemes.

The widespread uptake of household water-saving systems (i.e. appliances, fittings, rainwater harvesting tanks, etc.) usually aims to reduce the gap between water demand and supply without considering the performances of downstream sanitary sewers (SSs). This paper presents an analysis approach that examines the lifespan interaction of water-saving schemes (WSSs) and operation of existing SSs. Examined are three probable ways of using (or not using) these water systems, including the conventional (baseline), full application and optimal selection of efficient WSSs. For optimality, a method that maximises the WSS potential efficiency (overall) and minimises the cost of WSSs including the associated savings across the entire existing SS subject to constraints at the end of the planning horizon has been formulated. The problem is solved using a non-dominated genetic algorithm to obtain optimal solutions. Decision variables include various water use (or saving) capacities of water-saving schemes at different inflow nodes (locations). The method was demonstrated on the subsystem of the Tsholofelo Extension SS. The results indicate impactful and revealing interactions between water use efficiency, instantaneous hydraulic performances and existing SS upgrade requirements due to different applications of WSSs. The impacts and revelations observed would inform decisions during lifespan operations and management of SSs.

Growth and physiology of basmati rice under conventional and water-saving production systems

ABSTRACTConventionally flooded rice (CFR) requires enormous water and labor inputs. Water scarcity aspires for cultivation of water-saving rice. Growth response and physiology of basmati rice genotypes under the water-saving production systems has not been reported yet. Studies were conducted for 2 years to compare the growth and physiology of three rice cultivars (Super Basmati, Basmati-2000 and Shaheen Basmati), under high (CFR), medium (alternate wetting and drying [AWD]) and low water input (aerobic rice [AR]) systems. Leaf area index, crop growth rate, leaf area duration and dry matter accumulation were higher for AR followed by AWD and CFR, respectively. Shaheen Basmati had a lower growth and relative water contents than Super Basmati and Basmati-2000, probably due to its shorter stature and shorter life cycle. Photosynthetic rate and stomatal conductance of rice cultivars in the different production were affected only at reproductive stage. Basmati-2000 grown as AR had the highest photosynthetic rate followed by the same cultivar under AWD. The results of this study provide us an idea that basmati cultivars can attain a high growth and development with low water input. This would be helpful to grow rice successfully under water-short rice-growing environments.

Exploring policy impacts for servicising in product-based markets: A generic agent-based model

The shift to markets based on servicising, i.e. market-level transitions from product-based to service-based production and consumption patterns, may contribute to achieve absolute decoupling, i.e. the combined development of economic growth and environmental impact reduction. However, the potential of this contribution is largely unknown. In this paper a generic agent-based model of servicising is presented with which this potential can be explored further, taking into account decision making procedures of business and consumer agents, including market research, preferences, and willingness to pay. The details of the servicising model are presented, and the model's abilities are demonstrated through three case studies from different sectors: car and bike sharing, crop protection, and domestic water-saving systems. Absolute decoupling was found to occur in some of the policy scenarios, but results vary widely between cases. It is concluded that the model can be used to explore the impact of public policy on the uptake of servicising and on absolute decoupling in various sectors, and is therefore a useful support tool for policy makers who aim to promote servicising, as well as for researchers studying potential servicising impacts.

Leaf emergence, tillering, plant growth, and yield in response to plant density in a high-yielding aerobic rice crop

The traditional transplanted and flooded rice cropping system is threatened by water shortage and labor cost increase in many Asian countries and is currently evolving toward direct-seeded and water-saving systems. However, yield penalties generally accompany this evolution and ongoing research targets their mitigation. In a previous research, slower plant development rate was observed in aerobic crops, possibly caused by the increased plant density. This possible factor was tested in experiments conducted at IRRI’s farm, Los Baños, Philippines, in 2012 and 2013. One elite variety was direct-seeded at three plant distances (6, 10, and 20cm×20cm) and sprinkler-irrigated to keep the soil water potential above −10kPa. Weekly measurements were made to dissect crop and plant physiological differences. Data from previous experiments on tillering in the greenhouse of four varieties and in fields in aerobic and flooded conditions were added to strengthen the results from the current experiment.The last upper leaves of the main stem appeared faster at higher plant density, thus increase plant density was not the cause for the slower leaf appearance in aerobic than in flooded crops. Plants at higher plant density also had earlier panicle initiation, earlier earing, and 0.8 leaf less than plants at low density. The number of outgrowing tillers was linked to the number of leaves on the main stem by a variety-specific relationship that is independent from plant density and water management. Tiller density was regulated by the cessation of the outgrowth of tillers triggered by the onset of stem elongation at 20-cm plant distance and occurred earlier at shorter distances probably in response to the high root density. Grain yields were significantly higher at higher plant density (6-cm and 10-cm plant distances) and correlated with a higher tiller density. Thus for aerobic crops, seedling density higher than 50 plantsm−2 remains the way to get high yields for the type of variety used in this study.

Seawater for phosphorus recovery from urine

The direct use of seawater as secondary quality water for toilet flushing can function as a free unlimited magnesium source for phosphorus recovery from urine through chemical precipitation. This research assessed the precipitation of phosphorus present in urine in the form of struvite as a result of mixing with seawater. Taking into account the different feces and urine collection systems available, seawater was mixed with (a) non-hydrolyzed urine to mimic water-flush urinals and (b) hydrolyzed urine to mimic water-free urinals. Different seawater-to-urine mixing ratios were analyzed taking into account the water volume commonly used by conventional toilets, urinals and urine-diverting toilets. Up to 99% phosphorus removal was observed at seawater-to-urine ratios below 3.3:1.0 (as the ones reached by water-less and water-saving urinals). Above this ratio the hydrolysis process in non-hydrolyzed urine is inhibited. Phosphorus removal occurred through the formation and precipitation of struvite; less struvite crystals were observed at Ca/PO4-P ratios higher than 0.8. Seawater can be used as a source of ions for phosphorus recovery from urine; water-free urinals, diverting toilets and water-flush urinals operating with seawater-to-urine ratio lower than 3.3:1.0 (like water-saving systems) can provide better conditions for phosphate precipitation using seawater as magnesium source.

Irrigation water management in Southern continental oasis of Tunisia

Although the available water resource is sufficient, it doesn't manage to satisfy the requirements of practiced crop (mainly date palms) in the small continental oasis Lazala (75 ha) situated in the South of Douz (Southern Tunisia). Indeed, the oasis showed a low frequency of water delivery turn for the whole irrigated surface (especially in summer). This incited us to evaluate the irrigation performance. To reach this objective, a comparative survey of the features of exploited water resource (60 l/s), the crop water requirements, the proprieties of irrigation network and the water management within the plots has been undertaken. The flow rate measurements that were carried along the hydraulic network and the spatial and temporal following of water management in some plots (experimental plots) during the 2012/13 irrigation season showed a poor overall irrigation efficiency (Eo = 28.41 %), a relatively low water application efficiency (Ea = 44.6 %) and a moderate value of water distribution uniformity (DU = 67 %) which are related mainly to the context of the region (climatic conditions and soil type), the technical dysfunctions of the hydraulic infrastructure and the individual farmer's practices within the plots (high irrigation duration, absence of water-saving systems in many irrigated areas and the bad land leveling).

Resource use analysis of Pangasius aquaculture in the Mekong Delta in Vietnam using Exergetic Life Cycle Assessment

Depletion of marine fish stocks has become a global problem. Aquaculture is seen by many as the best way to meet the growing demand for fish products. The question then arises whether aquaculture is a truly environmentally sustainable alternative. Every type of aquaculture is different, therefore each one merits its own case study. To date, Life Cycle Assessment (LCA) studies have mainly examined Western culture systems, although Asia predominates the world aquaculture production by quantity. In this research, we focus on a vertically integrated Vietnamese top exporter of Pangasius food products in the Mekong Delta. Along with a tremendous expansion of this sector in recent decades, intensification coincided with an increased material and energy demand. Therefore, we focus on resource extraction (from cradle to farm gate), expressed as the Cumulative Exergy Extraction from the Natural Environment (CEENE). Hotspots in resource demand are identified over the life cycle stages (juvenile production, feed production and culturing to marketable-sized fish). The life cycle resource footprint includes mainly land (62%, mainly for feed production), water (31%, mainly for on-site farming of the fish) and fossil fuels (4%, mainly for energy needs throughout the feed supply chain). Main methods for reducing this resource demand should be lowering the feed and water input into the ponds and improving the efficiency of the feed supply chain. Pros and cons of closed-loop water-saving systems are discussed. The feed supply chain plays a key role in improving the resource use efficiency. Vietnamese Pangasius producers should be introduced to life cycle thinking and encouraged to pay attention to the environmental performance of their suppliers across the world. For the last goal, a new metric system to score the Feed Conversion Ratio (FCR), i.e. the CEENE FCR, is introduced here.