Water supply sources for irrigation (e.g. rivers and reservoirs) are critically important for agricultural productivity. The current rapid increase in irrigation water use is considered unsustainable and threatens food production. In this study, we estimated the time-varying dependence of irrigation water requirements from water supply sources, with a particular focus on variations in irrigation area during past (1960-2001) and future (2002-2050) periods using the global water resources model, H08. The H08 model can simulate water requirements on a daily basis at a resolution of 1.0 degrees x 1.0 degrees latitude and longitude. The sources of irrigation water requirements in the past simulations were specified using four categories: rivers (RIV), large reservoirs (LR) with a storage capacity greater than 1.0 x 10(9) m(3), medium size reservoirs (MSR) with storage capacities ranging from 1.0 x 10(9) m(3) to 3.0 x 10(6) m(3), and non-local non-renewable blue water (NNBW). The simulated results from 1960 to 2001 showed that RIV, MSR and NNBW increased significantly from the 1960s to the early 1990s globally, but LR increased at a relatively low rate. After the early 1990s, the increase in RIV declined as it approached a critical limit, due to the continued expansion of irrigation area. MSR and NNBW increased significantly, during the same time period, following the expansion of the irrigation area and the increased storage capacity of the medium-size reservoirs. We also estimated future irrigation water requirements from the above four water supply sources and an additional water supply source (ADD) in three future simulation designs; irrigation area change, climate change, and changes in both irrigation area and climate. ADD was defined as a future increase in NNBW. After the 2020s, MSR was predicted to approach the critical limit, and ADD would account for 11-23% of the total requirements in the 2040s.
► Indicators according to crop type, irrigation method, soil texture, and plot size. ► The influence that each individual factor permits to improve irrigation performance. ► Irrigation is deficient given that the value of the RIS indicator is relatively low. ► RWS indicator achieves higher values indicating that evaporation demand can be met. This paper examines irrigation water management in the Genil-Cabra Irrigation District of the Province of Cordoba (southern Spain) using three irrigation indicators: relative irrigation supply (RIS), relative water supply (RWS), and relative rainfall supply (RRS). The three indicators are calculated both globally and by grouping the data according to crop type, irrigation method, soil texture, and plot size. Then, it is possible to determine the influence that each individual factor has on irrigation management and take subsequent measures to improve irrigation performance. All of the information regarding agronomic and hydraulic variables has been included in a geographical information system (GIS) to facilitate data management. The results show that irrigation is deficit given that the mean value of the RIS indicator is relatively low, around 0.60. However, the RWS indicator achieves higher mean values, normally above 0.80, indicating that evaporation demand can be met throughout the crop development cycle. The RRS indicator shows less variability with mean values around 0.40. This indicator, together with the RWS indicator permits the evapotranspiration fraction covered by rainfall to be determined. The mean values of the calculated indicators are very useful for gaining a better understanding of irrigator behavior and general irrigation trends, although the study sample is still insufficient to characterize a large irrigation area as a whole.
The purpose of this study is to compare pressures at the apical foramen created by conventional syringe irrigation and the GentleWave™ System, which releases high-velocity degassed irrigants to the pulp chamber and uses broad-spectrum sound energy for cleaning.The apical pressure generated during irrigation was measured for palatal and distobuccal root canals of four extracted maxillary molars after no instrumentation, minimal instrumentation to a size #15/.04, instrumentation to a size #40/.04 taper, and after perforating the apical foramen to size #40. The root canals opened into an air-tight custom fixture coupled to a piezoresistive pressure transducer. Apical pressures were measured for the GentleWave™ System and syringe-needle irrigation at different irrigant flow rates, with the needle tip at 1 and 3 mm from the apical foramen using 30-gauge (G) open-ended or side-vented safety tip needles.The GentleWave™ System generated negative apical pressures (P < 0.001 compared with syringe irrigation); the mean pressures were between −13.07 and −17.19 mmHg. The 30 G needles could not reach the 1 and 3 mm from the working length in uninstrumented and 1 mm in minimally instrumented canals. The mean positive pressures between 6.46 and 110.34 mmHg were measured with needle irrigation depending on the flow rate, needle insertion depth, and size of the root canal.The GentleWave™ System creates negative pressure at the apical foramen during root canal cleaning irrespective of the size of canal instrumentation. Positive apical pressures were measured for syringe irrigation.Negative pressure during irrigation contributes to improved safety as compared to high-positive pressure.
Abstract Introduction The purpose of this study was to evaluate the effectiveness of different irrigating methods in removing the smear layer at 1, 3, 5, and 8 mm from the apex of endodontic canals. Methods Sixty-five extracted single-rooted human mandibular premolars were decoronated to a standardized length of 16 mm. Specimens were shaped to ProTaper F4 (Dentsply Maillefer, Ballaigues, Switzerland) and irrigated with 5.25% NaOCl at 37°C. Teeth were divided into 5 groups (2 control groups [ n = 10] and 3 test groups [ n = 15]) according to the final irrigant activation/delivering technique (ie, sonic irrigation, passive ultrasonic irrigation [PUI], or apical negative pressure). Root canals were then split longitudinally and observed by field emission scanning electron microscopy. The presence of debris and a smear layer at 1, 3, 5, and 8 mm from the apex was evaluated. Scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Results The EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK) was significantly more efficient than PUI and the control groups in removing the smear layer at 3, 5, and 8 mm from the apex. The EndoVac System (Discus Dental, Culver City, CA) removed statistically significantly more smear layer than all groups at 1, 3, 5, and 8 mm from the apex. At 5 and 8 mm from the apex, PUI and the EndoVac did not differ statistically significantly, but both performed statistically better than the control groups. Conclusions In our study, none of the activation/delivery systems completely removed the smear layer from the endodontic dentine walls; nevertheless, the EndoActivator and EndoVac showed the best results at 3, 5, and 8 mm (EndoActivator) and 1, 3, 5, and 8 mm (EndoVac) from the apex.
Poor irrigation water management associated with water scarcity is the major reason for underperformance of most small-scale irrigation schemes in Ethiopia. In order to devise appropriate measures for rehabilitation of the failing schemes and to enhance farmers’ adaptation capacity to water scarcity, it is important to assess site specific plot and scheme level water management practices, challenges, farmers’ perceptions and adaptation strategies. So far, there is no such study in the context of Tigray, Ethiopia. A survey was conducted on 109 farmers in three groups based on the source of irrigation water, which included canal, seepage and both canal and seepage water users. Focus group discussions with elders, water users association (WUA) committee and women headed households were also made. Furthermore, random field measurements on conveyance loss, groundwater depth and quality (EC) were also taken to verify the farmers’ perception. The respondents’ perception of severe water scarcity at scheme level and poor on-farm and scheme level water management practices are among the major causes for aggravating water scarcity, crops yield decline and soil salinization were in line with field observations. Despite several adaptation strategies of the farmers at plot and at scheme level, yield is still declining. The only adaptation strategy that has been enforced by the local government authority was reduction of the irrigated land. However, in the 2016 irrigation season the farmers were allowed to make their own decisions that resulted in innovative water scarcity adaptation strategies and that doubled the irrigated land as compared to the local authority plan. This showed the significance of allowing the beneficiaries to make their own decisions. To rehabilitate Gumselassa irrigation scheme as well as to enhance the adaptation capacity of the farmers to water scarcity capacity building and empowerment of the WUA and improvement on the existing water structure is required.
The aim of the GREDRIP model (Part I) is to provide centralized management of an irrigation network, with a minimum energy cost at the pumping station, based on irrigation scheduling to guarantee crop water requirements in the irrigation network. In this paper, the combined use of GREDRIP and MOPECO models was used to improve water and energy consumption by applying Regulated Deficit Irrigation (RDI) to crops in the SORETA irrigation network (Albacete, Spain) for crop distribution and weather conditions during irrigation seasons 2015 and 2016. The MOPECO model was used to determine irrigation schedules and to estimate the relationship between irrigated crop yield and net water applied. The aim of this paper was to validate the GREDRIP model under different water demand conditions, and to study the financial impact on the irrigation network under drought conditions. Results show that GREDRIP is suitable for management of an irrigation network such as SORETA, reducing the energy cost by 32%, in comparison with the current situation. The financial analysis carried out shows that a 25% reduction in water consumption would have reduced the gross margin (GM) in SORETA by 30% (from 1199 to 839 € ha ) in 2015 and 16% (from 914 to 771 € ha ) in 2016, when RDI is applied to all crops. When RDI is only applied to less profitable crops (extensive herbaceous but not horticultural crops such as onion or garlic), a GM reduction of only 9% is obtained under 2015 and 2016 conditions, respectively. The water saved could be used for other purposes, such as increasing the crop area with higher GM, or simply to recharge the aquifer at risk of overexploitation, which would greatly benefit the environment. The combined use of GREDRIP and MOPECO can help to improve water and energy management in irrigation networks through crop irrigation scheduling. This can increase the profitability of agriculture by analyzing the financial effects of different irrigation management systems.
Growth control of container-grown hardy nursery stock generally requires substantial labour investment. Therefore the possibility of alternative growth control using deficit irrigation is appealing. Increasing water costs and limited availability of abstraction licences have added further incentives for nursery stock producers to use deficit irrigation. There are still, however, concerns that inherent non-uniformity of water uptake under commonly used overhead irrigation, and differing irrigation requirements of diverse crops and substrates, may limit the commercial relevance of a protocol developed for single crops growing in 100% peat and irrigated with a high precision drip system. The aim of this research was to determine whether growth control of hardy nursery stock is possible using deficit irrigation applied with conventional overhead irrigation. Over two years, crop growth under an overhead irrigation system was compared under full irrigation and two severities of deficit irrigation. Initially, two crops of contrasting canopy structure i.e. and were grown. In a subsequent experiment one crop ( × ) was grown in two substrates with contrasting quantities of peat (60 and 100%). Deficit irrigation was found to be highly effective in controlling vegetative growth when applied using overhead irrigation—with similar results as when drip irrigation was used. This comparable response suggests that deficit irrigation can be applied without precision drip irrigation. Scheduling two very different crops with respect to their water use and uptake potential, however, highlighted challenges with respect to application of appropriate deficits for very different crops under one system; responses to deficit irrigation will be more consistent where nursery management allows for scheduling of crops with very different architecture and water use under different regimes. The effectiveness of deficit irrigation in controlling the growth of was similar when a reduced peat based substrate was compared with pure peat; additionally, flowering was enhanced.
The openings of the sphenoid, ethmoid and frontal sinuses are located at the top of the nasal cavity. Irrigation can only reach these openings when the head is positioned upside down. This can be achieved by instilling the irrigation solution from a syringe, with the head in supine position and then tilted backward into nearly an upside down position, over the edge of a bed or over an exercise ball. When the person sits up, the liquid is drained into a bowl, aided by a vigorous outbreath through the nose.