Main Canal Research Articles

Typification of Kherson region by water availability for irrigation and its environmental consequences

. The article presents the results of regional typification for the Kherson region by water availability for irrigation, taking into account the possible environmental risk as a result of the increase in irrigated area. The grouping of the territories previously differentiated by water availability into the following subtypes was performed: low rate of natural surface and groundwater water availability; sufficient rate of groundwater availability variously suitable for irrigation; high level of transit river flow availability; provided water supply of different quality from irrigation sources. Also, the territory grouping was made by the zones of ecological risk according to ecological and amelioration qualifications along with the separation of admissible ecological risk zones (potentially conditionally unstable areas with good ecological and reclamation conditions), zones of increased ecological or potentially unstable areas with the satisfactory and endangered condition), zones of sustainable ecological risk (potentially unstable areas with the unsatisfactory or very unsatisfactory land condition), zones of ecological crises development (potentially very unstable with the very unsatisfactory land condition). 
 It was specified that within the Kherson region predominate the areas with low natural water supply from local surface flow in combination with the zones of increased ecological risk (Kakhovka irrigation zone) or with the zones of stable ecological risk (Oleksandrivska irrigation zone, Kalanchak irrigation system). Additional surface water supply for irrigation is provided by the main canals from the Kakhovka reservoir. Further increase in irrigation areas within these typological territories, on the one hand, can be provided with available resources on the other hand, may lead to deterioration of ecological and reclamation condition of irrigated land and aggravation of water and ecological situation, first of all, rising groundwater level.

Comprehensive risk assessment of algae and shellfish in the middle route of South-to-North Water Diversion Project.

Since the main canal of the middle route of South-to-North Water Diversion Project was put into operation, the species, quantity, and biomass of algae and shellfish have responded quickly to the environment, and a single dominant species has appeared in the community, demonstrating the remarkably abnormal proliferation property of algae and shellfish. In order to evaluate the safety risk of abnormal proliferation of algae and shellfish in the middle route and realize dynamic analysis of all kinds of influencing factors, a comprehensive risk evaluation system of algae and shellfish in the middle route of South-to-North Water Diversion Project based on comprehensive weighting and four-element connection number was constructed by integrating the analytic hierarchy process (AHP) and the weight assignment theory of criteria importance through intercriteria (CRITIC). The system consists of 21 evaluation indexes selected from risk factors and carriers. Taking Henan section in the middle route as an example, comprehensive risk evaluation system of algae and shellfish in the middle route of South-to-North Water Diversion Project was applied to calculate the partial connection number of each order and obtain the risk development trend of each indicator. The results showed that algae and shellfish in the middle route were in a very safe state at the safety risk level of level I. Finally, reasonable measures to reduce the risks facing algae and shellfish in the middle route of South-to-North Water Diversion Project are given, which effectively make up the deficiency of existing evaluation methods.

Endodontic treatment of dens invaginatus with periapical lesion

Dens invaginatus or dens in dente represent anomaly of the developing tooth due to invagination of the enamel organinto the dental papilla. Dens invaginatus is usually diagnosed by standard radiological methods (RVG, OPG, and 3DCBCT).Clinical examination may reveal a mottled, dilated or conical shape of the crown. Endodontic treatment of dens invaginatuscan be difficult and complex due to the deviated anatomy. This report describes the successful endodontic treatmentof a maxillary lateral incisor that had dens invaginatus and a large periapical lesion. Clinical examination in a 30-year-oldpatient revealed an acute periapical abscess, and a dens invaginatus type II was diagnosed after radiography. Due to theexisting anatomy, endodontic treatment of the main canal was performed through two access cavities, which enabledchemo-mechanical treatment and access to all parts of the root canal. The canal of the invaginated tooth was treatedthrough the third access cavity.

Impact of agitation/activation strategies on the antibiofilm potential of sodium hypochlorite/etidronate mixture in vitro

BackgroundTo investigate the effect of a rotary agitation method or ultrasonically activated irrigation on the antibiofilm effect of a mixture of sodium hypochlorite (NaOCl) and etidronate (1-hydroxyethylidene-1,1-bisphosphonate, HEBP) using a dual-species biofilm model in root canal system.MethodsMature dual-species biofilms of Enterococcus faecalis and Streptococcus gordonii were formed in root canals of mandibular premolars. Teeth were randomly allotted (n = 12) to group 1, XP-endo Finisher (XPF); group 2, ultrasonically activated irrigation (UAI); group 3, syringe-and-needle irrigation (SNI). In all groups, canals were instrumented with a rotary instrument (XP-endo Shaper) prior to irrigant agitation/activation. A mixture containing 2.5% NaOCl and 9% HEBP was used throughout the experiment. Bacterial counts from the canal were determined using qPCR before preparation (S1), after preparation (S2), and after final irrigation agitation/activation (S3). Bacterial viability within the dentinal tubules in the coronal, middle and apical root-thirds was quantified using confocal microscopy after Live/Dead staining. The bacterial counts and viability were compared between groups using one-way ANOVA and post-hoc Tukey’s tests. Paired t-test was used to compare the bacterial counts within groups.ResultsInstrumentation alone could significantly reduce the microbial counts in all the groups (P < 0.0001). Subsequent agitation/activation resulted in significant microbial reduction only in XPF and UAI (P < 0.05), both of which reduced significantly more microbial counts than SNI (P < 0.05). Live/Dead staining revealed that XPF and UAI showed significantly greater percentage of dead bacteria within the dentinal tubules than SNI in the coronal third (P < 0.05); UAI resulted in the significantly highest percentage of dead bacteria in the middle third (P < 0.05); while there was no significant difference between the groups in the apical third (P > 0.05).ConclusionsWhen using the sodium hypochlorite/etidronate mixture for irrigation, final irrigant agitation/activation with XP-endo Finisher or ultrasonic can improve disinfection of the main root canal space and the dentinal tubules in the coronal third, while ultrasonically activated irrigation appears to exhibit better disinfection within dentinal tubules in the middle third.

Evaluation of water delivery performance of right main canal of Bhimsagar medium irrigation scheme, Rajasthan

ABSTRACT This research investigation aims to evaluate the performance of the Right Main Canal (RMC) of the Bhimsagar medium irrigation scheme in Rajasthan, India, employing water delivery and water use indicators, such as adequacy, equity, dependability, relative water supply, and relative irrigation supply. The three minors chosen were Ratanpura at the head, Chaplada at the middle, and Maraita II at the tail reach on RMC. The volume of water diverted into the selected minors from the right main canal was measured during crop season, and crop water demand in the command area of each minor was computed using the CROPWAT 8.0 software. Overall, RMC adequacy was adequate at the head, and middle reach minors but inadequate for the tail reach minor. The water distribution system was determined to be unreliable regarding water supply concerning time, with a dependability value of 0.49. Overall equity was determined to be good to fair for the head and middle reach minors but poor for tail reach minor due to disparity in water distribution. In 2013–14, RWS and RIS showed insufficiency in the command system. The average values of RWS and RIS were found to be 1.00 and 1.43, respectively.

Development of Bionic Semicircular Canals and the Sensation of Angular Acceleration.

To study the sensing process of the human semicircular canals (HSCs) during head rotation, which is difficult to directly measure due to physiological reasons. A 1-BSC (one-dimensional bionic semicircular canal) and 3-BSC were prepared with soft SMPFs (symmetric electrode metal core polyvinylidene difluoride fibers), which could sense deformations similar to human sensory cells. Based on these models, experiments were carried out to study the principle of the HSCs. Deformations of the bionic ampulla (BA) depended on the angular acceleration. Gravity had a strong influence on the deformation of the BA in the vertical plane. When the 3-BSC was subjected to angular acceleration around one of its centerlines, the three BAs all deformed. The deformation of the BAs was linearly related to the angular acceleration. The deformation of the BA in the main semicircular canal was exactly three times that of the other two BAs.

Study on Ecological Water Demand and Ecological Water Supplement in Wuliangsuhai Lake

Wuliangsuhai Lake is the largest shore lake in the upper reaches of the Yellow River and has become an important ecological barrier and habitat for birds in northern China. In recent years, pollutants and nutrient loads have been partially reduced, and the water quality in the lake area has been alleviated to a certain extent. However, the overall water treatment of Wuliangsuhai Lake is worrying and needs to be improved urgently. In this paper, according to the current situation of water quality and the goal of ecological environment protection, the ecological water demand of Wuliangsuhai Lake was estimated by using the dynamic viewpoint. The calculation of ecological water demand mainly considered: water of evaporation and leakage in the lake, and water demand of pollutant dilution. The requirements of ecological water demand in Wuliangsuhai Lake were solved in four ways: agricultural wastewater in the irrigation area; strengthening water saving in the main canal; carrying out water-saving system reform; and transporting ecological water use for washing salt to Wuliangsuhai Lake during an irrigation gap period. For Wuliangsuhai Lake in the Mengxin Plateau, which is located in a serious water shortage area, it is of great significance to protect the ecological environment by ensuring the amount of water entering the lake, maintaining the existing water surface of the lake, and giving full play to its water ecological function.

WATER MANAGEMENT IN GHATERA BABAJI MINOR IRRIGATION PROJECT, MADHYA PRADESH, INDIA

Water is a vital component of nature, which brings life in land; therefore the judicious utilization of water is needed for all types of human advancement. India is a monsoon dependent country for its water resources. Irrigation sector has been fundamental to India’s economic development and poverty alleviation, since 25% of India’s Gross Domestic Product (GDP) and 65% of employment are based on agriculture (MOWR GOI, 2006). The world’s total irrigated area was 249.5 M ha in 2011 in which India has 21.7% share in irrigated area in the world. The global consumption of water in agriculture is around 71% of the total water use (FAO, 2008). Considering the importance of irrigation management and the water user’s participation in increasing water productivity and the development of existing irrigation command area, this study was carried out to assess the present irrigation system of command area and to perform diagnostic study for the possible improvement in command area of Ghatera Babaji tank canal situated in Betwa River basin. The study area has a gross command area of 147 ha out of which cultivable area are 127 ha. Irrigation is supplied during Rabi season in about 121 ha. Main canal is 1360 m long with a slope of 1 in 1000. The command area has 101 land holdings ranging from 0.23 ha to 6.32 ha belonging to 87 farmers. Majority of farmers have small and marginal holdings (up to 2 ha), middle age (&gt; 39 yrs) and with low income (&lt; Rs 50,000 per annum) and have education up to primary or middle school level. The basic infiltration rate varies from 0.2 cm/hr to 2.4 cm/hr. The major crop of the area is Wheat followed by small area under Gram and Vegetable during Rabi, whereas, Soybean is grown during Kharif season. Discharge measured in main canal varies from 0.066 m3 /sec at head reach to 0.013 m3 /sec at tail reach. Discharge reaching to farmer’s field is changing from 3.82 to 5.36 lps. Seepage losses in main canal are measured to be 38.83 m3 / Mm2 to 16.04 m3 / Mm2 wetted area. Overall irrigation efficiency is computed to be 35 per cent. Productivity of Wheat crop varies from 4.5 to 35.1 q/ha which when converted to water productivity ranges from 0.33 to 1.55 kg/m3 . Water productivity for Gram varies from 0.97 kg/m3 to 1.86 kg/m3.

The Impact of Rainfall -Runoff on the Performance of Main Irrigation Canal and Cross Drainage of Omo-Kuraz I and II Sugar Project (The Case of Omo-Gibe Basin)

Flood is serious economic losses like damage main irrigation canal and installed infrastructure on sugar project. The objective of this research was to provide an estimation of rainfall-runoff effect on main canal irrigation scheme. The hydrograph characteristics of observed and simulated events are compared using various evaluation criteria consisting of Nash-Sutcliffe coefficient (NSE) is between 0.8 and 0.9, relative volume error (RVE) between -10 and 10%, and coefficient of determination (r2) is between 0.8 and 0.9 during calibration and validation period. Among the catchments of the basin that are used in the regional modeling work and nine Model Parameters are selected among those commonly used in regionalization studies. Four parameter regionalization methods (linear regression, spatial proximity, area ratio and sub-basin mean) were applied to transfer model parameter values from the gauged to the un-gauged catchments except area ratio method. In regional model, gauged catchments Model Parameters and Physical catchment characteristics of un-gauged catchments were used to develop the equations in order to predict discharge of un-gauged catchments. To have better understanding of model parameter performance, the sensitivity analysis of nine model parameters were performed manually by trial and error. The evaluation demonstrations that time of concentration (TC), storage coefficient(R), maximum storage (MS) and constant rate (CR) are more sensitive than others. Therefore, spatial proximity method is recommended in predicting discharge for un-gauged catchments for this research and obtained 85.1m3/s, 1.6m3/s, 9m3/s, 0.6m3/s,1.1m3/s, 14.3m3/s and 28.2m3/s peak flow for cross drainage three, culvert outlet four, culvert outlet three, culvert outlet two, culvert outlet one, cross drainage thirteen and cross drainage fourteen un-gauged sub catchments respectively. To determined predicted peak discharge using L-moment method in flood frequency analysis of selected gauged catchment. Finally, flood damage protection structures like dyke must be recommended for temporary, but redesign depend on peak discharge is necessary. Keywords: HEC-HMS, Regionalization, Stream flow simulation, L-moment, un-gauged catchments, Omo-Gibe sub-basin DOI: 10.7176/CER/14-2-02 Publication date: April 30 th 2022

The Chronology of Helmand Changes in Seistan

The Helmand River has three distinct beds in Seistan: the North Channel, the Trākun River, and the Sanā Rūd. Over the ages, the Helmand has undergone repeated changes and shifted from one bed to the other. This article reconstructs the Helmand channel alterations based on fieldwork observations, existing archeological investigation reports, and the writings of ancient geographers. It seeks to identify ancient cities, locate ancient weirs and main canals, and establish the chronology of changes of the river channel. It shows that the river flowed in the channel of the Sanā Rūd during the period c.3200-c.1800 BC, in the channel of the Trākun River during the periods c.1800-c.1300 BC, c.200 BC-AD c.400, AD c.1100-c.1700 and finally in the North Channel during c.1300-c.200 BC, AD c.400-c.1100, AD c.1700-present.

Sedimentation in small-scale irrigation schemes in Ethiopia: Its sources and management

Numerous irrigation schemes in sub-Saharan Africa (SSA) exhibit excessive sedimentation, resulting in underperformance and high maintenance costs. In the current study, a participatory monitoring program was used to investigate sediment causes and sources, measure the annual sediment load, and monitor desilting campaigns in two small scale irrigation schemes in Ethiopia, Arata-Chufa (100 ha) and Ketar (430 ha), for three years (2016–2018). Sedimentation quantities were huge, where the annual river sediment influx ranged from 220 m3 for the Arata-Chufa scheme to 1,741 m3 for the Ketar scheme. On average 0.3 m3/m of sediment were removed from the main canal for Arata-Chufa costing 794 days of labor per year. In Ketar, sediment quantities were even greater: 1.1 m3/m was removed requiring 3,118 days of labor per year. The sediment influx from the river source amounts to up to 95% for Arata-Chufa and moderately reaches 46% for Ketar, with the remainder of the sediment entering with overland erosion flows. Farmers reported increased sedimentation over time and difficulty paying operation and maintenance fees instead preferring to contribute labor for the desilting campaigns. Sedimentation management is fragile and mainly involves frequent desilting campaigns and unharmonized efforts to reduce overland sediment inflows. Factors contributing to sediment deposition include mild longitudinal bed slopes, the location of the intake, canal layout, and lack of canal banks for protection against surface water inflow in addition to sub-optimal canal operations. Excessive sedimentation is a major challenge resulting in underperformance of numerous irrigation schemes in SSA, and the stakeholders’ lack of awareness of the sources of sedimentation is an underlying factor aggravating sedimentation problems. It is concluded that investigating the sources, extent, and types of sedimentation entering a small-scale irrigation scheme is the basis for reducing maintenance costs and for effective management of sedimentation problems.

Interrelationships of Air Canal Adaptation in the Leaves of Water Lilies and Water Depth of Lebak Swampland in Kalimantan Selatan

Nymphaea pubescens grows in Lebak swampland in its different levels of water depth. This aquatic plant has an absorption system that moves gases through the laminae and has a convective flow system through air canals in midrib and petiole. This study aims to determine the adaptive structure of air canal in the water lilies (Nymphaea pubescens) laminae and how its structure varies along with water-depth fluctuations. The research was conducted by observing plants in 4 (four) different zones of water depth: (1) water depth between 28-95 cm (zone I), (2) 28-99 cm (zone II), (3) 54-112 cm (zone III), and (4) 55-124 cm (zone IV).&#x0D; Every lamina area, lamina thickness, and cross-sectional area (XS) of petiole, a number and area of air canals in midrib and petiole were collected for analysis. The results showed that the cross-sectional area of the laminae N. pubescens increased along with water depth, but the correlation with laminae thickness decreased. The midrib air canals are symmetrically divided and there was one main canal pair, an additional three pairs of canals, and a pair of smaller canals.&#x0D; The cross-sectional area of the midrib and air canal increased along with water depth. The calculation of the area of four pairs of air canals is 75%. Air canals make up 34% of midrib cross-sectional area. The midrib air canals produced one pair of air canals, an additional two pairs of canals and a pair of smaller canals. The calculation of the area of three pairs of airways is 93%. Air canals make up 31% of the cross-sectional area of the petiole. The length of the petiole, the volume of the petiole, and the volume of the air canal increased along with water depth, but the cross-sectional area of the petiole and the air canal were not related by water depth.

Simulation model of water temperature variation in dual‐purpose canals considering return flow from upstream paddy fields

AbstractHigh ambient air and water temperatures can cause high‐temperature damage to ripening rice grains after rice heading and has recently become a major issue of concern. Spill‐over irrigation (also referred to as continuous irrigation with running water) is an effective countermeasure that involves simultaneous irrigation and drainage to reduce the ponded water temperature in paddy fields. However, it is necessary to understand the impact of this technique on downstream water temperatures. In this study, the discharge and water temperature variations in a dual‐purpose canal (also referred to as irrigation‐cum‐drainage canal) were measured along the main canal of the Tedori‐gawa Shichika canal system in Japan. The discharge and water temperature variations in a branch drainage canal were also monitored to analyse the influence of the return flow on the water temperature in the main canal. Based on these observations, a new numerical model was developed to simulate the water temperature variations in the main canal considering meteorological conditions, heat transfer of water in the open canal, and return flow from upstream paddy fields. Finally, the model was applied to examine possible global warming scenarios and discuss the effectiveness of paddy water management in mitigating high‐temperature damage in downstream paddy fields.

Optimal Annual Allocation Model of Large Storage Based Irrigation Project by Multi Level Approach

The effective management of water available for irrigation in arid and semi-arid regions has increased in importance due to limited water supply. The need for allocation of water resources optimally in a water limiting condition has already been recognized, and much research has been carried out. In the present study, an annual irrigation planning model is formulated for Nagarjuna Sagar Project command in the semi-arid region of South India dealing with optimal allocation of annual available water among command areas of each main canal taking off from the reservoir and reallocating the available land and water of each command area to different seasons of a year and finally allocating the available land and water of each season among crops grown in that season, maximizing the total annual benefit of the project. The problem is solved in three stages. In the first stage, fortnightly crop water requirements are calculated from the evapotranspiration model by Penman – Monteith method. In the second stage, seasonal crop water production functions are developed using the single crop intraseasonal allocation model for each crop of all seasons. In the third stage, allocations of area and water are made at seasonal, interseasonal and at reservoir levels by deterministic dynamic programming, maximizing the net annual benefit from the project. Optimal cropping pattern and irrigation water allocations are made with full and deficit irrigation strategies for various levels of probability of exceedences of expected annual water available and results obtained are discussed.

Treatment of type III dens invaginatus in bilateral immature mandibular central incisors: a case report

BackgroundDens invaginatus (DI) is a developmental anomaly, Oehlers Type III DI is the most complex type and early diagnosis and treatment is complicated and challenging. This report presents a rare case of a type IIIb DI associated with a periapical lesion in bilateral immature permanent mandibular central incisors.Case presentationAn eight-year-old boy referred to our clinic manifesting with pain along with swelling in the mandibular incisors for the past one month. Radiographic examination showed periapical radiolucency exhibiting a scantly defined border, as well as an invagination which had a central invaginated canal extending from the pulp chamber throughout the apical foramen in both mandibular central incisors. We performed two different treatment procedures on the basis of the condition of the main pulp of the mandibular central incisors. in which only the invagination root canal was treated in the right mandibular central incisor, while the invagination and main root canals were treated in the left mandibular central incisor. During the 18-month follow-up period, the teeth were clinically asymptomatic. Imaging examinations indicated complete healing of the periapical lesion and revealed that the wall of the root canal was thickened and the open apex was closed.ConclusionFor young permanent teeth with type III Dens invaginatus, it is particularly important to keep pulp vitality, which could maintain root development and allow a good long-term prognosis.

Risk assessment of sectional water quality based on deterioration rate of water quality indicators: A case study of the main canal of the Middle Route of South-to-North Water Diversion Project

The Middle Route of South-to-North Water Diversion Project of China (MRSNWDPC) is the most important inter-basin water diversion project. This study screened out 8 water quality indicators, including pH, ammonia nitrogen (NH3-N), fecal coliform (F. coli), dissolved oxygen (DO), permanganate index (PI), five-day biochemical oxygen demand (BOD5), fluoride (F-), sulfate (SO42-), which were from monthly monitoring data of 29 sections between January 2016 and December 2018, and analyzed the probability distribution characteristics of water quality deterioration rate (WQDR) samples, compared the advantages of three kinds of probability density function parameter optimization method, then the probability density model of each water quality indicator is constructed. By defining the section water quality risk and setting the threshold, the risk level of harmful water quality events (“ degradation ”or“ standard exceedance ”) in the next one month was calculated based on the real-time monitoring data. The main conclusions include: (1) The probability density of WQDR samples in the MRSNWDPC basically corresponded to the p-III distribution, and the optimum line method can be used as the parameter optimization method of the distribution function. (2) The water quality risk assessment method proposed in this paper could calculate sectional risk based on real-time monitoring data of water quality and play an early warning role in the occurrence of harmful water quality events in the next one month. (3) From 2016 to 2018, water quality deterioration existed in the MRSNWDPC, and the probability of pH, DO and BOD5 with higher risk level was higher than other indicators. However, further research is needed to confirm whether a stable trend of water quality deterioration exists. This study redefines the concept of risk of sectional water quality from the perspective of the probability of occurrence of harmful events and sets the threshold value of risk level in combination with the water body function, so as to predict the future water quality risk level in the next month, which plays a good warning role in the water quality management of the MRSNWDPC and can help relevant management departments to make response plans in advance. It is worth mentioning that the method proposed in this paper has been applied to the water quality monitoring and early warning integrated management platform of the main canal of the MRSNWDPC.

Present status and future directions: Microbiology of endodontic infections.

Apical periodontitis has a microbial aetiology and is one of the most common inflammatory diseases that affect humans. Fungi, archaea and viruses have been found in association with apical periodontitis, but bacteria are by far the most prevalent and dominant microorganisms in endodontic infections. Bacterial infection of the root canal system only occurs when the pulp is necrotic or was removed for previous treatment. In some specific cases, including acute and chronic abscesses, the bacterial infection may reach the periradicular tissues. Intracanal bacteria are usually observed as sessile multispecies communities (biofilms) attached to the dentinal root canal walls. Infection in the main root canal lumen can spread to other areas of the root canal system. Although more than 500 bacterial species have been detected in endodontic infections, a selected group of 20 to 30 species are most frequently detected and may be considered as the core microbiome. There is a high interindividual variability in the endodontic microbiome in terms of species composition and relative abundance. Obligate anaerobic species are more abundant in the intraradicular bacterial communities of teeth with primary apical periodontitis, while both anaerobes and facultatives dominate the communities in post-treatment apical periodontitis. Bacterial interactions play an essential role in determining the overall virulence of the community, which has been regarded as the unit of pathogenicity of apical periodontitis. This article reviews the microbiologic aspects of endodontic infections and provides perspectives for future research and directions in the field.

Modelling the impact of lining and covering irrigation canals on underlying groundwater stores in the Nile Delta, Egypt

AbstractCanal seepage losses can contribute significantly to groundwater aquifers in arid and semi‐arid regions worldwide. In addition, surface water evaporation and evapotranspiration from adjacent riparian vegetation directly affect surface water availability across these regions. This study aims to evaluate interactions between irrigation canals and the Nile Delta groundwater aquifer in Egypt under four operational scenarios: (i) decreased stream flows in the four main diversion canals associated with upper Nile diversions and climate change, (ii) concrete lining of irrigation canals, (iii) combined lining and use of Photo‐Voltaic (PV) Solar Panel covers on canals and (iv) enclosure of the canals in closed conduits. We investigated the effects of these scenarios on regional groundwater supplies and levels using MODFLOW and water budget analyses. Decreased streamflow (scenario 1) resulted in decreased aquifer recharge (from 732 910 to 483 800 m3 day−1) and lower groundwater levels as compared to the base case (present) conditions. Moreover, groundwater flows from the aquifer to the four main canals noticeably increased from 23 176 to 79 364 m3 day−1. Water budget analyses associated with canal lining scenarios (2, 3, &amp; 4) indicated that canal leakage to the aquifer accounted for 146 582, 146 582, and 73 291 m3 day−1 respectively. The changes in canal efficiencies reached 29.3%, 67.1%, 75.3%, and 91.8% while the changes in aquifer recharge efficiencies were 66%, 20%, 20%, and 10% for the four scenarios, respectively. Overall, we found that canals lining is likely the most suitable solution for managing water resources in the Nile Delta. Further aspects to be considered in future studies include the loss of biodiversity along streams embankments due to channel lining.

Результаты натурных исследований магистрального канала в Республике Калмыкия

The purpose of the research was to assess the current technical condition of the main canal of the Sarpinskywater supply-irrigation system, as well as to determine its hydraulic characteristics based on the data of fi eld surveys. As a topographical basis for studying the route of the BP-1 of the main canal of the water supply-irrigation system, an interactive map of the study of the territory of the Russian Federation of the Federal State Budgetary Institution «Rosgeolfond», as well as data from satellite maps, was used. Materials for studying the parameters of irrigation canals and hydraulic structures of the system under consideration were the technical reports of the Sarpinsky branch of the Federal State Budgetary Institution«Kalmmeliovodkhoz» Administration», as well as the passports of the main and inter-farm canals of the BP-1 and «Bypass» system. The technical condition of the canal and hydraulic structures was assessed according to GOST 31937-2011. The hydraulic operating conditions of the main canals in the site of the hydrometric post are characterized by an increased value of the roughness coefficient, which exceeds the standard value for canals with a water fl ow of no more than 25 cubic meters/s by 1.16 times. The increase in the roughness coefficient is a consequence of siltation of the canal bottom and overgrowth of the canal along the banks, taking into account the long-term period of its operation. With an increase in the flow of water supplied to the canal to normal and maximum values, it is possible to reduce the flow capacity of the canal and increase the normal depth of water in the canal.

Japanese Maxillary First Molar Root Canal Morphology: An Ultrastructural Study Using Micro-Computed Tomography

The present study used ultra-high-resolution micro-computed tomography (CT) to clarify the classification of root canal morphologies and the incidence of accessory canals in the maxillary first molar mesiobuccal (MB) root. Aspects of the relationship with root canal reinfection during or after molar endodontic treatment were also investigated. Molar three-dimensional structure, pulp cavity, and accessory canals were examined on micro-CT images of 100 Japanese maxillary first molars from the collection at the Department of Anatomy, Tokyo Dental College. The most common Vertucci’s classification of the main root canal of the Japanese maxillary first molar mesial root canal was Type I, followed by Type V. Accessory canal incidence was 75.0%, which was higher than previously reported; however, the majority of such canals were within the apical 3 mm. Many accessory canals were observed even with the single canals of Type I, suggesting that the existence of accessory canals should always be considered even if diagnostic imaging clearly shows a Type I classification.