Main Canal Research Articles

Imaginology in the diagnosis and planning of root duct systems: an updated review

Root canal systems present a varied morphological conformation for each group of teeth. Several authors have described the anatomical conformation and its variants in different classifications, including the main, collateral, lateral, secondary, accessory, interduct, recurrent, apical delta and interradicular cavus canals. Currently, radiology still does not allow visualization of all these structures. However, proper use of imaging techniques together with the use of new 3D equipment for adjustments of acquisition parameters with adequate software and algorithms allows greater image precision, facilitating diagnosis and the planning of the most adequate approach for endodontic treatments. The objective of this article was to conduct a review of the literature to identify new concepts and useful imaging tools for better diagnoses.

Desigualdad social y toma de decisiones en los comunales: El gobierno del mayor canal de riego de España (la Acequia Real del Júcar, Valencia) en el siglo XIX

We analyse the management institutions of a community irrigation system in Mediterranean Spain, the Acequia Real (Royal Canal) of the Júcar river, where social inequality among irrigators was high. We look at the changes in the canal's institutions over time. There were two levels of government institutions. Only the elites could participate in the first one, that is, the government of the main canal. Although the local management bodies that governed the successive derivations of the main canal included more people, not every irrigator had the right to be part of them, but there were informal participation mechanisms that allowed everyone to voice.

Investigation of the Salinity Distribution of the Soil along West Main Canal in Ningxia, China

As one of the main irrigation canals in Ningxia, West Main Canal plays a very important role in the irrigation of the land nearby the canal, such as farms, meadows, and tree farms. Because of the long-term use of the Yellow River water for irrigation, the soil salinization in this area become more serious. In this paper, the problem of soil salinization along the West Main Canal in Ningxia is taken as the research object. 82 sample points in the studied area are chosen and a total number of 164 soil samples are measured for the eight main salt ions and pH value. Correlation analysis and principal component analysis are employed to study the distribution of the soil salinity ions and pH value. In addition, two dimensional interpolation is applied to obtain the spatial distribution of the total saltiness. It can be found that Cl−, SO42−, Ca2+, Na+ and HCO3 − are the main salt ions and the main soluble salts are NaCl, KCl, CaSO4, Na2SO4 and CaCl2 in the soil of the studied area. The spatial distribution of the total soil salt is mainly in the patterns of north high and south low, far high and near low, up high and down low.

The state of natural grass at the reclamation facility of Ryazan Meschera

The purpose of the geobotanical survey was to analyze the natural grass stand at the Tinki-II drained object within Ryazan Meschera. When monitoring the former forage lands, the methods of Bogolyubov and Kravchenko, Neshtaev and others were used. The meadow survey area had an area of 10,000 m2 and was located near the main canal, a tree belt area, a settlement and an open collector. Earlier monitoring studies revealed the presence of degradation processes in peat soil that has been drained for 65 years, which manifested itself in the form of peat depletion, an increase in density, and the transformation of peat into a humified mass. The local flora dominated with the inclusion of such species as Elytrigia repens, Hypericum perforatum, etc. Plants with frequent occurrence and high Druda abundance (Elytrígia répens and Alopecúrus praténsis) were identified. The association Elytrígetum urtícetosum was highlighted. The entire variety of phytocenosis was grouped into dynamic series of community development: perennial, biennial, and annual grasses, considering their aboveground mass. The prospects for the development of meadow farming are unsatisfactory due to the low level of development of animal husbandry. At controlled facility Tinki-II, only 5 % of the meadow area leased by the Novoselki agricultural holding is now sown

The problems of agricultural production in Abu- Ghraib district

The search deals with the main problems which face agricultural production in Abu Ghraib district. The researcher found the studied area witnessed a big decline in the agricultural area. That was the result of the natural of the security and economic condition that faced the area because of terrorist acts and unwatering after the control on Fallujah and the destruction of the main feeder canal which caused the population depends completely on waters well to remove deficiency that happened to water which caused the high level of salt in addition to the lack of variety in plated crops which suited their ability to undergo waters well and the migration of population to their level and leaving the agricultural area

Land degradation by erosion occurred after irrigation development in the Harran plain, Southeastern Turkey

A study was made to determine the erosion problem and determine the amount of suspended sediment transport in the drainage channels of the Harran Plain by conducting periodic suspended sediment sampling and discharge measurements in the field between 1997 and 2017. When irrigation in the Harran Plain started in 1990, the production of the agricultural goods quadrupled within a few years. Unfortunately, excessive amounts of irrigation water supplied to irrigate crops also led to the erosion of the soil in the fields by surface runoff. Furthermore, the mixture of clay, silt, and fine sand in the topsoil from certain areas accumulated in the tertiary and secondary drainage systems and reduced the effectiveness of the drainage system. Analysis of the suspended sediment measurements between 1997 and 2017 showed that the yearly averaged sediment transported to Syria by the main drainage canal of the Harran Plain varied between 128 ton.day−1 to 1268 ton.day−1, and the average of the 21-year measurement is about 682 ton.day−1. The logarithmic plot of the suspended sediment rating curve showed that as the discharge of the Cullap Creek increases, the sediment transport rate also increases linearly. It means excess furrow irrigation could cause substantial topsoil loss. Sediment erosion resulting from rainfall events in the Harran Plain is also computed using Revised Universal Soil Loss Equation (RUSLE). The results showed that rainfall erosion from the Harran Plain is 131.5 ton.day−1. A comparison of this value with the 21-year value of average sediment erosion by irrigation shows that approximately 20% of sediment erosion from the Harran Plain was caused by rainfall events, and the remaining 80% was caused by excess irrigation water in the area. A 2D numerical model was constructed with MIKE 21 software applying Van Rijn Method to calculate suspended sediment load due to irrigation, and it allowed to calculate the load with a 6.47% error. Grouping the irrigated and non-irrigated periods and applying independent t test, a statistical approach constituted and resulted in 79.2% of suspended sediment load is caused by irrigation. The numerical model and statistical analysis supported the findings of field data and RUSLE Model results. The study showed that the main reason of the topsoil loss in the Harran Plain is the excess furrow irrigation.

Evaluation of the Sediment Trap Structure Performance in the Saddang Irrigation

Irrigation canals require desilting basin to reduce sediment deposits in the main irrigation canals. The capacity of the Saddang River Irrigation Canal will be increased by 30% to accommodate long-term irrigation discharge needs. To optimize the ability of the desilting basin to trap suspended sediments, an evaluation was carried out using the 2-D finite-volume numerical method for hydrodynamic and sediment transport models. It solves the 2-D dynamic wave equations (the standard depth-averaged St.Venant equations) that are mainly used for river simulation. In addition, the diffusive wave solver is used for watershed runoff simulation and river simulation. The Community Edition SRH-2D model uses a flexible mesh that may contain arbitrarily quadrilateral and triangular cells. A hybrid mesh may achieve the best compromise between solution accuracy and computing demand. The SRH-2D Model solved variables include water surface elevation, water depth, depth averaged velocity, Froude number, and bed shear stress. Sediment Transport Model solved variables include sediment concentration, erosion and deposition, bed elevation, sediment transport rates, bed material D50 size, and bed material gradations. The optimization of the model is useful for improving the lining channel, flushing time period and the performance of the sediment trap.

Development of Control Drainage Operation Model and Utilization Planning of Post-Fire Peatlands

The research aimed to determine the monthly operational groundwater control and land use patterns in fire prevention efforts on peatlands. The research method was carried out using a detailed survey scale method in the representative sample area of 20-30 ha. Observations in the field included measuring the physical properties of soils and observing hydrological components. Group discussions with the community were conducted to explore information on the causes of fires, compilation of plans for operational activities in the field, and land use models. The research results showed that in the soil depth of 0-20 cm the level of peat maturity classified as Sapric (mature), at a depth of 20-50 cm is classified as hemic and at a depth of 50-100 cm belongs to fibric (immature). The effects of blocking canal construction were very significant in raising the water level in the channel and groundwater table. However, due to the low rainfall until December 2019, the groundwater level was not yet able to raise to the point of arrangement 40 cm. Till the end of December 2019, the groundwater level was at 70 cm, however there has been an increase in groundwater level of 30 cm since the beginning of December 2019. In the rainfall conditions < 2500 mm/year, blocking canal operations with a retention system have to begin in April. Agroforestry is the best model and <em>Albizia chinensis</em> (Osbeck) Merr. (sengon) in combination with pineapple plants are the best land use pattern. In addition, some short-term proposals are to provide infrastructure for firefighting, the construction of a road embankment, normalization of main rivers and canals, providing boring wells, making security control posts, training, monitoring, and providing some incentives for farmers to clear land and firefighting teams at the village level.

PERENCANAAN REHABILITASI SALURAN INDUK DAERAH IRIGASI CIBINUANGEUN DI KABUPATEN LEBAK PROVINSI BANTEN

Irrigation is an effort to provide and regulate water for agricultural land. The main objective of this study is to plan the rehabilitation of the main channel of Cibinuangeun irrigation area, Lebak Regency, Banten Province. The main channel serves to carry water from the main network to the secondary channel and tertiary plot. The material can be made of masonry, concrete or masonry and concrete. The Cibinuangeun main channel relies on a water source from the Cibinuangeun river through the Cibinuangeun weir building. The Cibinuangeun Irrigation Area has a functional area 2570 ha. The condition of the Cibinuangeun main canal currently has a lot of damage, which results in water drainage being not optimal so it is necessary to plan for rehabilitation by directly examining the condition of the canals at the location to determine the volume of damage and calculate the cost of rehabilitation on the channel. The research method used is the Irrigation Planning Criteria issued by the Ministry of Public Works, Directorate General of Water Resources as the basis for standard irrigation planning. The results showed that the trapezoidal trunk channel and the current available flow rate were not in accordance with the initial planning of the Cibinuangeun main channel construction, due to sedimentation and damage to the walls and floor of the leaking channel. The level of damage to the main line reached 47,37% of a total trunk length of 950 meters. The planned cost required for the rehabilitation of the Cibinuangeun main channel is four hundred seventy million four hundred thousand rupiah.

Residence Time Analysis in the Albufera of Valencia, a Mediterranean Coastal Lagoon, Spain

The Albufera of Valencia is a coastal lagoon located in the western area of the Mediterranean Sea, in the Iberian Peninsula. It has an area of 23.1 km2 and an average depth of only 1 m, with a maximum depth of 1.6 m. This lagoon is the remnants of an original and more extensive wetland of about 220 km2 which is now mostly dedicated to rice cultivation. Surface water is supplied through several main and many secondary canals for a total of 64 water entry points and three exit points to the sea. It is difficult to evaluate the residence time due to the lack of reliable measurements of the inflow or outflow, as well as continuous measurements. Between 1988 and 2018, several procedures were used, the results of which are outlined in this document. Overall, a decrease in the inflow during these thirty years was observed and, therefore, it can be concluded that the residence time is increasing. There is a temporal variation during the year due to rainfall and cultivation periods. Likewise, the results found that the natural hydrological zoning of the lagoon causes a spatial heterogeneity with small Northern areas with low residence time of 4.7 days, almost on a weekly basis and large Western extensions with high residence time of 222.9 days. It is impossible to know this information if individual flow measurements are not taken from each of the main watercourses.

Ecological scheduling of the middle route of south-to-north water diversion project based on a reinforcement learning model

The Middle Route of the South-to-North Water Diversion project (MRP) effectively alleviates the problem of serious shortage of water resources in North China. However, owing to the long-term operation of this project, abnormal algal proliferation has occurred in the upper reaches of the main canal, and the water diversion outlet is easily blocked by the large colonies of algae falling into the canal, which has seriously threatened the water quality and water supply safety of the canal. In light of this issue, this study coupled the reinforcement learning model with the one-dimensional hydrodynamic model of the series sluice group to build an ecological scheduling model for prevention and control of algal proliferation in the MRP. The model was applied to the canal section (approximately 300 km long, from No. G2 to No. G17) where in algae grows easily. The results show that: (1) The model can achieve the desired reciprocating adjustment of the canal water level in the process of decline stability rise within 0.8 m and stably maintain the low water level for more than 72 h; (2) during the process of ecological scheduling, the maximum drawdown of water level satisfying the safety regulation and control constraints of the MRP is 1.0 m; (3) for an ecological regulation water level drop greater than 0.3 m, it is more difficult to restore the initial water level, and the water level rise range should therefore be greater than the decrease range; (4) the constructed model exhibits high robustness. Even for an observation error level less than 0.08 m, the success rate of the model can still exceed 80%. The ecological scheduling scheme generated by the model can be used to destroy the algal habitat conditions through hydrodynamic dynamic regulation, whereby decisional support can be provided for the prevention and control of abnormal proliferation of algae in the main canal.

Occurrence of perfluorinated carboxylic acids in Mexico City's wastewater: A monitoring study in the sewerage and a mega wastewater treatment plant

An analytical method based on liquid chromatography coupled to mass spectrometry was validated to quantify five perfluorinated carboxylic acids (PFCA) namely, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), and perfluoroundecanoic acid (PFUnA), in wastewater produced in a megacity. Sampling was performed on a monthly basis, obtaining samples from the undergrounded sewerage system and the main open-air canal transporting wastewater out the city. Steady levels of the sum of the target PFCA (ƩPFCA) were determined on both sites through the study: 419.4 ± 24.3 ng L−1 in undergrounded sewage and 591.1 ± 39 ng L−1 in the open-air canal. Short-chain PFCA (PFBA, PFHxA, and PFHpA) were abundant, while concentrations of PFOA and PFUnA remained lower in both sampling sites. The open-air canal was transected in four sampling points, which were sampled throughout the monitoring campaign, finding that furtive discharges of municipal and industrial wastewater increased the levels of short-chain PFCA, while those of PFOA and PFUnA were depleted. Relevant concentrations of PFBA (176.9 ± 3.3 ng L−1), PFHxA (133.4 ± 2.5 ng L−1), PFHpA (116.6 ± 3.9 ng L−1), PFOA (133.1 ± 3.5 ng L−1), and PFUnA (23.5 ± 6.5 ng L−1) were found 60 km downstream, where the wastewater transported by the open-air canal is used in irrigation. A fraction of sewage is treated in a conventional wastewater treatment plant. The concentration of short-chain PFCA increased in effluent, adding extra loads of PFBA, PFHxA, and PFHpA to the environment.

Analysis of Water Resources in Irrigation Channels as Kinetic Energy Sources

Water resources can be utilized for various human needs including household needs, industrial needs, irrigation needs for agriculture as well as potential energy and kinetic energy for electricity generation. Sindupraja Primary / Primary Channels, which are the main canals serving irrigated areas covering 87,803 ha spread across Cirebon Regency and Indramayu Regency, with a water discharge of 10.3 m3 / sec and good discharge capacity and the large dimensions of the channel make it more optimal not to use only as a provider of irigas for agriculture but also as a potential and kinetic energy source for electricity generation. The purpose of this study was to determine the water resources in terms of hydraulics contained in irrigation channels, especially the Sindupraja Main Canal, which can be optimized as a source of kinetic energy. The purpose of irrigation is the use of water that is comprehensive and supports agricultural productivity in order to increase agricultural production, besides optimizing the management of irrigation water resources because there is stored energy namely potential energy (in falling water) and kinetic energy (in running water), where This energy can be used as the main medium to drive turbines and generators as a source of electrical energy. The amount of potential and kinetic energy produced from these water resources depends on the amount of water debit available, the speed of flowing water flow, and the consistency of water discharge in a certain size. Utilizing the potential of water resources contained in irrigation canals, water energy can be used as a source of MHP where kinetic energy contained in the flow of water in irrigation canals is used as a driver of waterwheels, where the waterwheel is used as a medium or means to convert water energy into energy mechanical form of torque on the wheel shaft to produce electrical energy. the amount of power produced depends on the water flow and speed of the water flow.

Research on Construction Technology and Formation Deformation of Shield Tunneling Under River

In view of the construction technology and formation deformation of the existing rivers under the subway shield interval tunnel, relying on Zhengzhou rail transit line 17 shield tunnel through the south-north water transfer channel project, using the trial tunneling method of shield tunnel test section to optimize all kinds of construction parameters, and the formation analysis and calculation of the determined digging pressure, noting the final parameters that are determined by comparison between the extractive parameters such as pulp pressure, and they are used in MIDAS GTS/NX finite unit analysis software for numerical simulation analysis, combined with on-site testing, to study the variation of different depth formation subsidence values and horizontal displacement values when passing through the south-north water transfer canal under water conditions, and put forward the reinforcement scheme of shield tunneling through the general river bed and hole. The results show that the maximum subsidence of the trunk canal shield through the bottom is 11.3 mm, and the verification parameters are reasonable and feasible. The horizontal subsidence trough of the soil above the over-soil layer at the top of the main canal embankment is distributed by Gauss. The sinking distribution can be estimated using the Peck formula, the middle of the layer subsidence trough is distributed horizontally, and the soil subsidence trough below it is inverted hump-like distribution, with the peak point directly above the center line of the two tunnels, and the vertical zero horizontal displacement surface is located in the middle line position between the two tunnels, and the horizontal zero horizontal displacement surface is located. The horizontal displacement curve of the soil layer above the soil layer is inverted S-type, the maximum displacement appears at the anti-bending point of the surface sedimentation trough curve, the horizontal displacement curve of the soil layer on the horizontal zero horizontal displacement surface is zero, and the lower soil layer curve is double-inverted S-shaped. In the construction, we should pay attention to the monitoring of the vertical subsidence and horizontal displacement of the deep soil, adjust the shield parameters and reduce the horizontal and vertical shearing effect of the deep soil on the surrounding pipeline, inner pile base and other structures during the construction of the shield.

Assessment of the presence of a second mesiobuccal canal in maxillary first molars according to the location of the main mesiobuccal canal-a micro-computed tomographic study.

To investigate the root canal morphology of mesiobuccal (MB) roots in maxillary first molars, and to assess the presence of a second mesiobuccal canal (MB2) according to the location of the main MB canal. A total of 72 extracted permanent maxillary first molars were collected from dental clinics and were scanned with micro-CT and reconstructed three-dimensionally. The root canal systems were recorded according to Vertucci's classification, and the occurrence of accessory canals was also recorded. The root canal dimensions were measured at the coronal (furcation plane), middle, and apical root levels. The long (D) and short (d) diameters as well as the palatal (P) and buccal (B) distances from the center of the first mesiobuccal canal (MB1) to the root surface were measured, and the ratios of D/d and P/B were calculated. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic accuracy of using the ratio of P/B for predicting the presence of an MB2 canal. The best cut-off point was determined according to the sensitivity and specificity. The MB roots most frequently had a type 2-2 root canal with an incidence of 37.5% (27/72), followed by the type 1-1 (23.6%, 17/72) and type 2-1 (16.7%, 12/72) canal forms. Type 1-2 canals were detected only in 5 molars (6.9%), and type 2-1-2 canals were detected in 6 molars (8.3%). The other 5 cases included 1 case of type 1-2-1 canal and 4 cases of triple canals. MB2 canals were detected in 76.4% (55/72) of the total sample teeth. The incidence of accessory canals was 56.9% (41/72). The mean ratio of D/d was generally "greatest to least": coronal level > middle level > apical level for different root levels and MB single > MB1 > MB2 for different canals, which reflected a trend from a flat to a circular cross-sectional shape. ROC curve analysis showed that at the coronal and middle root levels, areas under the ROC curve (AUC) were greater than 0.99 (P < 0.01), and the best cut-off point was 1.58 and 1.55, respectively; at the apical level, the AUC was 0.94 (P < 0.01), and the best cut-off point was 1.77. The MB2 canals may be present in the MB roots of maxillary first molars with a high occurrence rate at various levels, and the P/B ratio of the MB1 is a good index for predicting the presence of an MB2. However, since all the sample teeth were collected from a Chinese population, clinicians have to be cautious while trying to apply the conclusions on teeth of other ethnic populations. By calculating the P/B ratio, an index reflecting the buccal deviation of the MB1, clinicians can predict the presence of an invisible MB2 in cone-beam computed tomography images with inadequate resolution.

Evaluation of Water Delivery Performance and Conveyance Efficiency in Gatto Small-Scale Irrigation Scheme, Southern, Ethiopia

Irrigation could serve as a viable solution to address the problem of food insecurity by increasing, boosting agricultural production. This research work was conducted to evaluate the performance of Gatto irrigation scheme using some selected performance indicators specifically, water delivery performance, conveyance efficiency and maintenance indicators of the scheme with in the investigation period of October to December 2017. The discharge measurement was performed at twelve measuring points on main canal and eight at two secondary cannels by using VALEPORT automatic current meter and 3-inch Parshall flumes for each selected nine tertiary offtakes from three each at the head, middle and tail end of the scheme. Water delivery performance evaluated with respect to adequacy, equity, efficiency and dependability was focused on variability in discharges of water distribution from head to tail reach and, during the crop season from October to December with overall average value equal to 0.70, 0.44, 0.89 and 0.53 respectively. Thus, the irrigation scheme when compared with Molden and Gates (1990) standards was found under poor condition in adequacy, equity and dependability and under good condition in efficiency. Estimated overall water conveyance efficiencies of the main, first and secondary canals were 86.3%, 77.53% and 73.13% respectively. However, the result found in the scheme was smaller than FAO (1989b) recommended value (95%) and (90%) for lined and unlined cannels with clay soil type. The design depth of water based on the design document was 0.42m nevertheless the actual depth of water in the main canal was 0.26 m due to this the relative change of the water level was 38.1% this greater than 0 value indicates that the intended water level in the main canal has not been achieved due to sediment accumulation in the canal. The result of Gatto small scale irrigation scheme of effective of infrastructures is reckoned to be 57.2 percent and sustainability of irrigation scheme is 88%. Many of the structures are demolished and became dysfunctional because of scouring, sedimentation and silt accumulation. Generally, the performance of the system is poor, it mainly results due to inadequate operation and maintenance provisions and over abstraction of water by upstream users. Therefore, adequate maintenance and other suitable management and operation approaches are required to improve the irrigation system performance. So, all stakeholders must work together in order to minimize factors that hinder the good performance of the irrigation system.

ПУТИ ОЦЕНКИ ОСТАТОЧНОГО РЕСУРСА МОСТОВЫХ ПЕРЕЕЗДОВ НА МАГИСТРАЛЬНЫХ КАНАЛАХ ПРИ ВОЗРАСТАЮЩИХ НАГРУЗКАХ

The article deals with the issues of assessing the residual life of bridge crossings on main canals under increasing loads on the example of a bridge crossing located between the village of Mikhailovskoye and the Sverdlovsky farm in the Seversky district of the Krasnodar Territory. Ways are proposed that allow timely prevention of negative phenomena, namely defects and damage to the bearing elements of the crossing. With the help of a full-scale survey of the technical condition of a bridge crossing over the main canal, the following defects were identified: wetting of structural elements of load-bearing structures, deep destruction of concrete and the formation of efflorescence and rusty streaks; longitudinal and transverse cracks with an opening width of up to 6 mm, chips and destruction of the protective layer of concrete 15 mm thick on the bearing elements, followed by corrosion of the working reinforcement and loss of section. The concrete strength of the building structures of the bridge crossing over the main canal was tested by ultrasonic surface probing using the Pulsar-2.1 device. The evaluation of the strength parameters of concrete for each tested structure was carried out in the amount of six measurements in a marked place. According to the results of a visual inspection, the technical condition of the bearing elements of the bridge crossing over the main canal is tentatively assessed as emergency. This is explained by the fact that defects and damages were revealed in these structures, indicating the exhaustion of the residual resource. After the results of two methods of surveying the structure, an assessment was made of the technical condition of the bridge crossing over the main canal, followed by recommendations to bring it to suitability and extend further operation. Fixed defects that reduce the bearing capacity, but after analyzing the results obtained during the instrumental examination, the risk of sudden destruction, loss of stability or overturning is completely absent. Further operation of the bridge across the main canal is likely either with conditional control of the technical condition of the supporting structures or during the implementation of the necessary measures for the restoration or strengthening of structures and further control of the technical condition.

Conveyance Efficiency and Maintenance Performance Evaluation of Canals at Serenta Irrigation Scheme, Northern Ethiopia

Evaluation of conveyance efficiency and maintenance performance of canals in irrigation schemes is very important to improve the productivity of the irrigation scheme as whole. Thus, results help to improve the canals problem and the water loss. However, canals conveyance efficiency of Serenta irrigation scheme is not yet evaluated. Therefore, this study was conducted to evaluate the canals conveyance efficiency and maintenance performance of the Serenta Irrigation Scheme. To evaluate the canals conveyance efficiency, canals flow were measured using Parshall flumes (for secondary and tertiary canals) and Floating method (for main canal). The results from the field measurement revealed that, the average conveyance efficiency of the main canal measured from five observations was 96.2%. The average discharge of this canal was 0.104m³/s at upper measuring point and 0.1m³/s at lower position. Thus, the amount of water lost was estimated to be 4 l/s or 0.0076 l/s/m. The source of loss was observed during the field visiting and measurement, which was due to seepage loss. From the 4 (four) secondary canals of the irrigation scheme, the average conveyance efficiency ranged from 75.86% to 91.9% with an overall mean efficiency of 86.3%. The lowest conveyance efficiency (75.86%) was observed in secondary canal 3 (SC-3). This reflected that the high amount of water loss, due to broken and cracked condition of the structure at this particular canal, which contributed for deep and off farm loss. And, the average conveyance efficiencies of the tertiary canals ranged from 63.5% to 91.3%, with the overall mean value of 76.6%. The low conveyance efficiency observed in tertiary canal 6 (TC-6), implied for high mount of loss, due to the weak earth work canal (small width), a lot of water was flowing over the canal. Unlike the main canal the secondary and tertiary canals were under performance. So to reduce water loss and improve the performance the irrigation scheme, the conveyance efficiency of the irrigation scheme should be improved through regular canal cleaning and maintenance of the broken structures by mobilizing farmers to participate on the activities.

Walking-Type Bidirectional Incremental Launching and Mid-Span Closure Technology for Steel Box Girders with Long Cantilevers

Unidirectional incremental launching is not applicable for the incremental launching construction of large-span bridges owing to the span capacity of steel box girders is restricted by the cantilever length and the setting of temporary piers. Aiming at the limitation, by taking Qingdao (Shandong Province)–Lanzhou (Gansu Province) expressway bridge crossing over the main canal in the South-to-North Water Diversion Project as the engineering background, a key construction technique, that is, bidirectional incremental launching and mid-span closure of steel box girders with long cantilevers was proposed. On this basis, the walking-type incremental launching device system and the technique of bidirectional incremental launching and mid-span closure were explored and also a finite element analysis model was established to compute the pre-camber. Moreover, the results of the alignment control of structures during the construction were compared and analyzed. The research result showed that during the construction using bidirectional incremental launching and mid-span closure, it was unnecessary to set the steel launching nose and it was able to greatly improve the span capacity of steel box girders and the construction efficiency during incremental launching. The research provides reliable experience in engineering practice for the future similar engineering.

Dynamic Simulation Research on Operation Safety of Main Canal of South-to-North Water Transfer Based on Risk Input

The South-to-North Water Diversion Project will pose a great threat to the lives and property safety of people along the route once a dangerous situation occurs. Therefore, this paper analyzes the historical risk data of the South-to-North Water Transfer Project to identify risk sources, combs the actual risk occurrence process with the basic structure of "Risk Factor→Destruction Link→Destruction Mode", and builds a main canal system risk interpretation model. At the same time, taking the typical high-fill section of the main canal of the South-to-North Water Transfer Project as an example, a typical failure evolution process is selected to construct a dynamic simulation model based on system dynamics to simulate the failure process of the canal embankment under three kinds of manual intervention, as the channel operation under risk input scheduling decisions provides new ideas.