Line Canal Research Articles

Coupled effects of canal lining and multi-layered soil structure on canal seepage and soil water dynamics

Ponding tests were conducted in the Shiyang River Basin in Northwest China to assess canal leakage characteristics. Four anti-seepage constructions (concrete lining, pebble lining, clay lining plus compacted canal bed, compacted canal bed only) were performed on four canal sections, which were situated in multi-layered soils. The canal sections were tested using a two-stage approach: First, a stable water level was maintained; second, a stage where the water level in the canal section was permitted to drop. The canal seepage rate and the soil water content near the canal bed were monitored during each stage and in each canal section. Soil texture, bulk density and hydraulic conductivity were determined in each canal section and soil layer. Double ring infiltration tests were performed to investigate infiltration behaviour from the canal sections. The saturated–unsaturated flow model HYDRUS-2D was applied to simulate canal seepage and the local soil water response. The simulation results compared well with the monitored data, indicating that the model can reliably simulate canal seepage under these complex soil structures and different canal liners. Both experimental results and numerical modelling show that the clay lining plus compacted canal bed provides the best anti-seepage performance, followed by compacted canal bed only, then pebble and concrete lining. Simulation results also predicted that the soil water content was discontinuous at the interface of distinct soil layers, and that the range and form of wetting front varied greatly in the four canal sections, with a larger wetted area for the more permeable canal. Simulations were performed to study the sensitivity of canal seepage to the permeability of each soil layer and canal liner. The results, confirmed by the double-ring infiltration tests, indicated that the canal lining is not the only factor affecting canal seepage: The soil permeability can also influence the seepage, especially where there is a low permeability layer (e.g., compacted soil layer) close to the canal.

Correlation of panoramic radiographs and cone beam computed tomography in the assessment of a superimposed relationship between the mandibular canal and impacted third molars

PurposeThis study evaluated the association between cone beam computed tomography (CBCT) and panoramic radiographs in the assessment of a superimposed relationship between the mandibular canal and impacted third molars.Materials and MethodsThe study samples consisted of 175 impacted third molars from 131 patients who showed a superimposed relationship between the mandibular canal and third molars on panoramic radiographs and were referred for the examination of the mandibular canal with CBCT. Panoramic images were evaluated for the darkening of the root and the interruption of the mandibular canal wall. CBCT images were used to assess the buccolingual position of the mandibular canal relative to the third molar, the proximity of the roots to the canal, and lingual cortical bone loss. The association of the panoramic and CBCT findings was examined using a Chi-square test and Fisher's exact test.ResultsPanoramic radiographic signs were statistically associated with CBCT findings (P<0.01). In cases of darkening roots, lingual cortical bone loss or buccally positioned canals were more frequent. In cases in which the mandibular canal wall was interrupted on panoramic radiographs, contact or lingually positioned canals were more frequent.ConclusionThe results of this study suggest that contact between the mandibular third molar and canal and a lingually positioned canal could be more frequently observed in cases of the interruption of the white line of the mandibular canal and that there could be more lingual cortical loss in cases of darkening roots.

Identification of the Root Canal and Its Centreline from Dental Cone Beam CT Records

This paper presents a novel image processing procedure dedicated to the automated detection of the medial axis of the root canal from dental cone beam CT records. The 3D model of root canal is built up from several dozens of parallel cross sections, using image enhancement and a fuzzy chain based segmentation algorithm, center point detection in the segmented slice, three dimensional inner surface reconstruction and curve skeleton extraction in three dimensions. The central line of the root canal can finally be approximated as a 3D spline curve. Several visualization methods have been developed using 3D surfaces, planar sections and 3D curves. The proposed procedure can help prepare several kinds of endodontic interventions.

Determination Method of Water Saving Threshold in Arid Area

Aiming at the positive and negative effects induced by water saving measures, these two hydrological and ecological effects in arid region are analyzed in detail. Water use efficiency and underground water level are selected as two indexes to evaluate the positive and negative effects of water saving activities respectively, and then the theory value and acceptable range of suitable water saving threshold are determined. With the constructed regional hydrological model, the changes of water use efficiency and underground water level of various canals lining rate are quantified. The results show that the 34.8% of canal lining rate is feasible water saving threshold in arid area.

Estimating long-term regional groundwater recharge for the evaluation of potential solution alternatives to waterlogging and salinisation

Summary Accurate estimation of the groundwater recharge is essential for efficient and sustainable groundwater management in arid and semi-arid regions, as water resources are critical to economic development in these areas. Various techniques are available to quantify recharge. The hydrological budget model proposed herein is unique, simple, and easy to apply. It uses data on groundwater level, groundwater extraction, and distributed specific yield information for estimating groundwater recharge. The Model is employed to estimate the seasonal long-term (35 years, e.g., from 1974 to 2009) groundwater recharge of an irrigated semi-arid area located in Haryana State of India, where groundwater levels are rising, continuously. The results are analysed to provide an overview of the process dynamics that led to imbalance of the system. Groundwater recharge analysis during the study period reveals that percolation from irrigated fields is the main recharge component with 49% contribution to the total recharge. An annual groundwater table rise of 0.14 m has been estimated for the study area. Various potential solution alternatives are evaluated to mitigate the problems of waterlogging and salinisation, considering the socio-economic issues which have wider policy significance on sustainability. Several suitable water management strategies such as reduction in rice area, increase in pumping volume and using the groundwater conjunctively with higher quality canal water, and lining of canal networks are suggested to bring the watertable down to a safe limit and to prevent further rising of the watertable. Among the potential solution alternatives studied, the one which considers 10% reduction in rice area along with 2% increase in pumping volume and 20% canal lining, yields best result for mitigating the waterlogging problems.

An extensin-rich matrix lines the carinal canals in Equisetum ramosissimum, which may function as water-conducting channels.

The anatomy of Equisetum stems is characterized by the occurrence of vallecular and carinal canals. Previous studies on the carinal canals in several Equisetum species suggest that they convey water from one node to another. Cell wall composition and ultrastructure have been studied using immunocytochemistry and electron microscopy, respectively. Serial sectioning and X-ray computed tomography were employed to examine the internode-node-internode transition of Equisetum ramosissimum. The distribution of the LM1 and JIM20 extensin epitopes is restricted to the lining of carinal canals. The monoclonal antibodies JIM5 and LM19 directed against homogalacturonan with a low degree of methyl esterification and the CBM3a probe recognizing crystalline cellulose also bound to this lining. The xyloglucan epitopes recognized by LM15 and CCRC-M1 were only detected in this lining after pectate lyase treatment. The carinal canals, connecting consecutive rings of nodal xylem, are formed by the disruption and dissolution of protoxylem elements during elongation of the internodes. Their inner surface appears smooth compared with that of vallecular canals. The carinal canals in E. ramosissimum have a distinctive lining containing pectic homogalacturonan, cellulose, xyloglucan and extensin. These canals might function as water-conducting channels which would be especially important during the elongation of the internodes when protoxylem is disrupted and the metaxylem is not yet differentiated. How the molecularly distinct lining relates to the proposed water-conducting function of the carinal canals requires further study. Efforts to elucidate the spatial and temporal distribution of cell wall polymers in a taxonomically broad range of plants will probably provide more insight into the structural-functional relationships of individual cell wall components or of specific configurations of cell wall polymers.

O1-S02.03 Multiple sex partners and lack of condom use for anal sex are associated with multiple anal HPV infections among men having sex with men: the HIM study

BackgroundHuman Papillomavirus (HPV) infection is the primary cause of anal cancer. While multiple HPV infections in the anal canal may accelerate disease progression, there are no reports of behavioural factors...

APPLICATION OF GEOMEMBRANE TO CONTROL PIPING OF SANDY SOIL UNDER CONCRETE CANAL LINING (CASE STUDY: MOGHAN IRRIGATION PROJECT, IRAN)

ABSTRACTFine sandy soils have always been known as one of those problematic soils which will erode rapidly and cause piping due to water flow. This phenomenon has caused the destruction of many concrete canal linings around the world. In the present study, the history of the design, construction and operation of a canal in the Moghan Irrigation and Drainage Network, in north‐west Iran, is reviewed and the main causes of destruction of the concrete lining of the canal are discussed. Based on the results of geotechnical studies, it was found that the canal was constructed on wind‐blown deposits consisting of very fine to fine sand and loess. During operation of the canal, the fine, clean sandy subgrade soil was highly eroded due to water seeping under the canal lining, causing severe piping and consequently destruction of the lining. Following field and laboratory investigations, the main cause of the problem was diagnosed as “physical dispersivity” of the subgrade soil, and application of a geomembrane under the concrete lining was chosen as the most economical and practical measure to remedy the problem. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Influence of Cement-Voids Ratio on Stress-Dilatancy Behavior of Artificially Cemented Sand

The addition of cement is an interesting remediation technique when the project requires improvement of the local soil for the construction of pavement base layers, in slope protection of earth dams and canal linings, as a support layer for shallow foundations and to prevent sand liquefaction. The present study was carried out to quantify the influence of the amount of cement and the porosity in a cement-voids ratio, defined as the ratio between the volume of cement and the volume of voids of a mixture, on the stress-dilatancy behavior of an artificially cemented sand. A program of triaxial compression tests considering three distinct cement-voids ratios was carried out with two combinations of volumes of voids and volumes of cement at each cement-voids ratio. Results showed that the stress-dilatancy relationship is alike for a given cement-voids ratio and that the stress-strain behavior is also similar. The cement-voids ratio is therefore an appropriate parameter to assess stress-dilatancy of the sand-cement mixture studied.

Experimental Investigation on the Polypropylene Fiber Concrete Performance of Yellow River Canal Lining in the Middle Line of South-to-North Water Transfer Project

In order to meet the running needs of the first-stage construction in the middle line of South-to-North Water Transfer Project, the canal lining of both sides of Yellow River Tunnels Project need the use of mechanized equipment construction in order to improve the quality and efficiency of lining construction, there is a need to study the feasibility of the use of polypropylene fiber concrete instead of reinforced concrete in canal lining. This paper analyzes the effect of polypropylene fiber on concrete shrinkage and crack resistance. The results show that all three polypropylene fibers have properties of a low density and high elongation, the dispersivity test results show that dispersivity is better when stirring fiber A after a certain period of time. After the incorporation of polypropylene fibers, the concrete splitting tensile strength is significantly increased, altogether with ultimate tensile value and frost resistance. The incorporation of polypropylene fibers increases the tensile strength of concrete and improve the toughness of it. Compared with standard concrete, the early shrinkage of polypropylene fiber concrete is significantly lower, the incorporation of polypropylene fibers can take the place of steel mesh in concrete cracking, especially in the early control of concrete cracks, it can effectively prevent and suppress the cracks formation and development. This paper recommends the concrete proportioning parameters meeting the requirements of canal lining concrete technology and construction.

Using MODFLOW and GIS to Assess Changes in Groundwater Dynamics in Response to Water Saving Measures in Irrigation Districts of the Upper Yellow River Basin

The irrigation districts of the upper Yellow River basin are highly productive agricultural areas of North China. Due to the severe water scarcity, application of water-saving practices at both farm and district levels are required for sustainable agricultural development. An integrated methodology was developed adopting loose coupling of the groundwater flow model MODFLOW with ArcInfo Geographic Information System to assess the impacts of irrigation water-saving practices and groundwater abstraction foreseen for the year of 2020 on the groundwater dynamics of the Jiefangzha Irrigation System (JFIS) in Hetao Irrigation District, upper Yellow River basin. The model was calibrated and validated with datasets of years 2004 and 2005; the model efficiency EF was respectively 0.98 for calibration and 0.99 for validation. Results of the simulation of the groundwater dynamics of the study area show that water-saving practices referring to canal lining and upgrading hydraulic structures applied in 60% of the area, and upgraded farm irrigation technology in 50% of the area may consist of a reasonable solution. Their implementation would lead to reduce groundwater evaporation by 43 mm and the total diversions from the Yellow River by 208 mm, i.e. about 20% of present volumes diverted. Most of routines and strategies for model construction may also be used for other regions, especially for irrigation districts in the upper Yellow River basin.

Performance of geocomposite and granular drains under irrigation canal linings

ABSTRACT: In many irrigation projects, where the groundwater table is high, part of the canal may be located below the water table. In such cases the groundwater would apply uplift pressure to the bottom and side panels of the lining. This phenomenon may cause deformation, displacement or rupture of the concrete panels, or other damage, which would cause high maintenance costs for the project. The most effective way to control the uplift pressure is to provide a filter drainage system under the canal lining. At present, granular filters are the most common material in use. However, the application of granular materials is not an easy task in some cases, owing to the high costs involved, and the environmental impacts. Therefore, in recent years, geosynthetic materials (geocomposites) have been employed as a replacement for granular filters. In the present study, the behaviour of geocomposite material as a filter drainage layer under canal lining has been investigated, using a physical laboratory model. The results of the experiments show that a geocomposite layer with adequate thickness can fully relieve the uplift pressure and discharge the drained water effectively. The efficiencies of the filter drainage under the bottom concrete panels, as well as under the bottom and side concrete panels, were studied. The results show that providing a filter under the side panels has no significant effect on the drainage capacity of the system.

Preparation and Performance of Compound Polyurethane Foam Plastic Board for Freezing Prevention in Channel Lining

The influence of different particle size and filling amount of particles of cornstalks on the density and compressive strength of polyurethane foam plastic board has been studied in this paper. The results indicate that the comprehensive properties of polyurethane foam plastic board is better when the particle size varies from 0.45 to 1.5mm and the filling amount is 30% which could meet the needs of avoiding the frost heaving failure in the canal lining blocks. And compared with the foam plastic board without filling particles, the property can be equal with particles of cornstalks filled in, but the cost can be reduced about 25%. Meanwhile, the cornstalks are fully reused, which also help protect the environment.

Comparison of Periapical Radiography and Limited Cone-Beam Computed Tomography in Mandibular Molars for Analysis of Anatomical Landmarks before Apical Surgery

Introduction The purpose of the present study was to evaluate the detectability and dimensions of periapical lesions, the relationship of the mandibular canal to the roots of the respective teeth, and the dimension of the buccal bone by using limited cone-beam computed tomography (CBCT) in comparison to conventional periapical (PA) radiographs for evaluation of mandibular molars before apical surgery. Methods The study comprised 38 molars with 75 roots. The type of PA lesion as diagnosed on PA radiographs was compared with the type of lesion seen on sagittal and coronal CBCT sections. The distances of the apices of the first mandibular molars and basal border of the PA lesion to the coronal lining of the mandibular canal were assessed with PA radiographs and corresponding sagittal and coronal CBCT images. Furthermore, coronal CBCT images were used to measure the distance from the apices to the buccal bone surface and the corresponding width of the cortical bone plate. Results Of 58 detected PA lesions, 15 (25.9%) lesions diagnosed with sagittal CBCT slices were missed with PA radiography. The distance between the apices and the upper border of the mandibular canal was only measurable in 24 of 68 radiographs (35.3%) by using PA images. The cortical bone wall had a mean thickness of 1.7 mm, whereas the total buccal bone wall (cortical and spongious) measured 5.3 mm on average. Conclusions The present study highlights the advantages of using limited CBCT for treatment planning in mandibular molars before apical surgery.

Identification of the Dental Root Canal from Micro-CT Records Using 3D Curve Skeleton Extraction

AbstractThis paper presents a novel image processing procedure dedicated to the automated detection of the medial axis of the root canal from dental micro CT records. The 3D model of root canal is built up from several hundreds of parallel cross sections, using image enhancement and an enhanced fuzzy c-means based partitioning, center point detection in the segmented slice, three dimensional inner surface reconstruction and curve skeleton extraction in three dimensions. The central line of the root canal can finally be approximated as a 3D spline curve. The proposed procedure can help prepare several kinds of endodontic interventions.

The periesophageal celom of the articulate brachiopod Hemithyris psittacea (Rhynchonelliformea, Brachiopoda)

The celomic system of the articulate brachiopod Hemithyris psittacea is composed of the perivisceral cavity, the canal system of the lophophore, and the periesophageal celom. We study the microscopic anatomy and ultrastructure of the periesophageal celom using scanning and transmission electron microscopy. The periesophageal celom surrounds the esophagus, is isolated from the perivisceral cavity, and is divided by septa. The lining of the periesophageal celom includes two types of cells, epithelial cells and myoepithelial cells, both are monociliary. Some epithelial cells have long processes extending along the basal lamina, suggesting that these cells might function as podocytes. The myoepithelial cells have basal myofilaments and may be overlapped by the apical processes of the adjacent epithelial cells. The periesophageal celom forms protrusions that penetrate the extracellular matrix (ECM) of the body wall above the mouth and the ECM that surrounds the esophagus. The canals of the esophageal ECM form a complicated system. The celomic lining of the external circumferential canals consists of the epithelial cells and the podocyte-like cells. The deepest canals lack a lumen; they are filled with the muscle cells surrounded by basal lamina. These branched canals might perform dual functions. First, they increase the surface area and might therefore facilitate ultrafiltration through the podocyte-like cells. Second, the deepest canals form the thickened muscle wall of the esophagus and could be necessary for antiperistalsis of the gut.

A GIS model for preliminary hazard assessment of swelling clays, a case study in Harran plain (SE Turkey)

Swelling behavior of clayey soils regarded as a hidden disaster, causes a great deal of damage in light hydraulic structures such as drinking water network, irrigation pipes or open canal linings through which water can easily leak and penetrate into soil during loading and unloading stages. Early identification during site investigation and laboratory testing is extremely important to ensure that the appropriate design strategy is adopted. The clay soils having swelling potential are generally found in arid and semi-arid regions, such as in the Şanliurfa-Harran plain located in the southeast of Turkey. The problems associated with swelling clays occurred for the lightweight hydraulic structures constructed in Turkey have been met during the construction of irrigation structures in the scope of Southeast Anatolian Project as the Turkey’s greatest water resources project. Therefore, the identification of such soils and the assessment of their swelling potential parameters are necessary for hazard mitigation planning and land-use management. In this scope, extensive geotechnical study is executed for an investigation area. The samples were obtained from the Harran plain where many irrigation canal structures are constructed, and geotechnical study was performed on these samples. Atterberg limit tests often provide the basic field information to substantiate the soil’s swelling nature. The plasticity index (PI) and liquid limit (LL) values are also used extensively for classifying swelling soil and should always be determined during preliminary investigations. Because of this, LL and PI are assessed by using geographical information system (GIS)-based computer software, and LL and PI contour maps are created. Swelling percentages of the soil samples were carried out on both undisturbed and compacted soil samples by using direct methods. As a result of this extensive study, the values of swelling percentages determined for each location are used to obtain the swelling potential hazard map of the area by means of a GIS program. The results of GIS analyses for this area indicate that the analyses based on a lot of data introduce meaningful results for this study. It is expected that these maps will be a useful tool for planners and engineers in their efforts to achieve better land-use planning and to decide necessary remedial measures.

Assessing the groundwater dynamics and impacts of water saving in the Hetao Irrigation District, Yellow River basin

Abstract Water resources allocated to the agricultural sector in the Yellow River basin are being reduced due to severe water scarcity and increased demand by the non-agricultural sectors. In large-scale irrigation districts, the application of water-saving practices, e.g., improving the canal system, using water-saving irrigation technology and adjusting cropping patterns, is required for the sustainable agricultural development and the river basin environmental equilibrium. Adopting water-saving practices leads to lowering the groundwater table and to controlling salinity impacts related to excessive irrigation. However, assessing the effects of water-saving practices on the groundwater system requires further investigation. The Jiefangzha Irrigation Scheme of the Hetao Irrigation District is used as a case study for analyzing the temporal and spatial dynamics of the groundwater table. A lumped parameter groundwater balance model has been developed with this purpose and to assess impacts of various water-saving practices. The model was calibrated with monthly datasets relative to the non-frozen periods of 1997–1999 and validated with datasets from 2000 to 2002. Results indicate that canal seepage and deep percolation account for respectively 48% and 44% of the annual groundwater recharge. Groundwater discharge by direct evaporation and plant roots uptake represents 82% of the total annual groundwater discharge. After validation, the model was applied to assess the impacts of various canal and farm irrigation water-saving practices. It was observed that improvements in the canal system (e.g., canal lining, upgrading the hydraulic regulation and control structures, improving delivery schedules) might lower the groundwater table by 0.28–0.48 m, depending upon the level of implementation of these measures. Higher declines of the groundwater table are predicted when water-saving technologies are applied at both the canal and the farm systems. That decline of the water table favours salinity control and reduces capillary rise, thus reducing the groundwater evaporation and uptake by plant roots; that reduction may attain 128 mm. However, predictions may change depending on the way how water-saving measures are applied, which may be different of assumptions made; therefore, there is the need to perform a follow-up of the interventions in order to update predictions. Results indicate the need for appropriate research leading to improved irrigation management when the decline of the groundwater level will reduce groundwater contribution to vegetation growth.

Myxobolus neurophilus: morphologic, histopathologic and molecular characterization

Archived tissues from affected yellow perch Perca flavescens, as well as fresh submissions of juvenile yellow perch, walleye, fathead minnows, golden shiners and smallmouth bass cultured in the same pond or from a shared water source were examined for the presence of Myxobolus neurophilus. Archived tissues were sectioned and stained with hematoxylin and eosin or with Giemsa, revealing myxozoan spores consistent with M. neurophilus. The myxospores were found beneath the ependymal lining of the central canal of the brain or free within the stratum periventriculare, with minimal or no inflammation. Unstained and stained (Wright Giemsa or Lugol's iodine) touch impressions of the brains from fresh submissions of all 5 fish species revealed similar myxozoan spores only in the brains of yellow perch. These were Giemsa-positive, with no iodinophilous vacuoles evident. Portions of the affected brains were fixed in neutral buffered 10% formalin and sectioned for histology. Pseudocysts containing myxospores were only evident in sections of the brains and spinal cords of yellow perch. Mild mononuclear meningoencephalitis was present when myxospores appeared outside of the pseudocysts. Brains fixed in 5% gluteraldehyde for scanning electron microscopic examination revealed pyriform myxospores with a smooth capsular surface. Sequencing and phylogenetic analysis of the 18S small subunit ribosomal DNA gene placed the organism within the family Myxobolidae, with no direct matches to sequences available via GenBank. Aquatic annelids from sediment obtained from the affected pond were negative for actinospores.

Canal water management: Case study of upper Chenab Canal in Pakistan

AbstractIncreasing world population requires that crop production from irrigated areas needs to be enhanced by as much as 40% by the year 2025. This necessitates that the canal water management system be revisited and possible improvements suggested and implemented. The daily reference evapotranspiration for the Upper Chenab Canal (UCC) is estimated using the Penmann–Monteith equation 2000. Meteorological data of Sialkot station has been employed on a daily basis for a period of 8 years (1999–2006). The crop water requirements have been estimated using reference evapotranspiration, crop coefficients and cropping periods for different crops cultivated according to existing cropping pattern. Crop staggering has also been incorporated into the study. The comparison of actual canal water supplies and crop water requirements indicated an annual shortage of more than 40%, which may reduce slightly if allocated water supplies according to the Water Apportionment Accord 1991 can be ensured. The maximum deficit is 320 m3 s−1 and occurs in the month of August. This shortfall is normally met by pumping low‐quality groundwater, which is increasing secondary salinity in the area. Possible options for better water management in the UCC command area to optimize crop yields are presented, and it is recommended to look into demand side management including canal lining and on‐farm water management practices. Copyright © 2010 John Wiley &amp; Sons, Ltd.