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Copyright of Historia Agraria is the property of Historia Agraria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A paramount determinant in the selection of irrigation canal overflow configurations resides in their flow conveyance capacity. This overflow capacity is contingent upon the effective length and geometric characteristics of the weir. In the present investigation, the hydraulic performance and discharge coefficient (Cd) of circular-crested weir were scrutinized through the utilization of FLUENT software. Specifically, the study delved into the impact of geometric parameters, namely the radius and height of the crest, on these hydraulic aspects. Following the execution of calibration and validation procedures using FLUENT in conjunction with laboratory-derived data, the outcomes of the simulation revealed that augmenting the radius of the crest led to a corresponding escalation of 144.28% in the maximum pressure exerted on the crest and a 6.84% increase in flow depth. Conversely, the maximum velocity and Cd experienced reductions of 6.84% and 7.82%, respectively. The elevation of the weir height exhibited negligible influence on the maximum pressure magnitude at the crest. Contrastingly, a reduction in weir height constricted the range of pressure variations on the crest, indicating a more limited domain of pressure changes. Elevating the weir height induces a notable augmentation in the maximum flow velocity at the crest by 44.36%, concomitant with a reduction in both the depth and Cd by 52.66% and 68.96%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of History Studies (13094688) is the property of History Studies and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As one of the fundamental natural resources of life, water and its management within ecosystems has always been the most crucial aspect of any settlement. Prior to urban modernization, water was sourced upstream from rivers or groundwater, supplying settlements, with the runoff being drained further downstream or to sea, creating a series of water flows; our livelihood coexisted with this series. In the rapid city growth led by modernization, due to the creation of uniform and homogeneous new urban areas, water flow became separated for each purpose and began to be specifically manipulated for, and by, human society. This study was designed as one of a series of research projects aiming to highlight the relationship between the historical hydraulic systems and the more recent urban spatial structure, with the focus on Valencia, one of the medium sized cities in Spain. Valencia is ideal as a case study due to the historical mechanisms of hydraulic systems still partially in use, such as irrigation canals in its agricultural regions and sewage canals in its urban areas. In more recent years, the ancient canals and the rivers that were neglected or buried, due to pollution and/or flooding concerns, began to regain significance in the face of the growing interest in and necessity of restructuring green spaces in the city as well as the preservation of the city’s unique identity and history, along with its remaining/evolving ecosystems. The purpose of our research is to interpret the interaction between Valencia’s urban morphology and its historical irrigation systems, particularly its waterways. The target period is from the modernization in the 20th century to their present conditions. [ABSTRACT FROM AUTHOR]

Copyright of Historia Agraria is the property of Historia Agraria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stuckenia pectinata is an invasive submerged weed in the irrigation district in the lower valley of the Colorado River, Argentina. The objective of this study was to analyze the initial growth of S. pectinata from tubers, and its annual growth cycle in irrigation canals, in order to be efficient in adapting future control techniques. Tubers were planted in aquaria in order to evaluate the effect of their size, depth of burial and below zero temperatures on the initial growth. Under field conditions, samples of plants were collected from two irrigation canals, from October to March, in two complete growth cycles. Plant height and biomass of the leaves, stems and spikes were measured. The largest tubers were able to emerge from deep burial and generated larger plants than the smallest tubers. Frozen tubers did not germinate at any burial depths. Maximum biomass in the irrigation canal reached 1660 g DM m-2 with a peak at the beginning of summer. The elimination of biomass at the end of the irrigation season would result in small tubers that would die in the winter time. The information generated could lead to more appropriate and sustainable control. [ABSTRACT FROM AUTHOR]

Irrigation canals network in Egypt for all levels suffer from water deficit and un-equitable distribution of irrigation water among beneficiaries. So, its modernization became omnipresent to overcome the problem of water shortage by the end of canals. One of the improvement sectors of irrigation canals network is replacing an earthen mesqa by upraised lines or buried pipes. The hydraulic performance of the improved irrigation system is explored using a case study canal, where buried pipes system is applied as improved mesqa system. The case study is for the Hadaya canal which is one of the distributary canals that located in Assiut governorate. This canal services 19 mesqas with different lengths and area served. The hydraulic performance of mesqas is examined through different scenarios of operation of the mesqa pumping station and area served. Three scenarios of mesqa valves operation are considered .The first scenario is when all valves are operated at the same time all over the week. The second is when one valve operates for two days per week and the third is when all valves operate for one day. Also, three scenarios are considered for pump operation 14, 16 and 18 hours per day. Moreover, effect of different scenarios of mesqa operation on sudden transition of flow in pipes due to pump shut-down is studied. EPANET software was used for the hydraulic analysis. It was found that operating the pump 14 hours per day fulfill the minimum monthly cost. Also, operating the outlet valves according to scenario no. (3) gives the least operating cost. The maximum velocity in the pipeline is less than 1.2 m/s for all operating scenarios. Besides, effects of mesqas off-takes on the flow in distributary canal are studied. [ABSTRACT FROM AUTHOR]

Abstract Seepage from irrigation canals can be controlled by interceptor pipe drains located down slope of the canal embankment and parallel to the canal. HYDRUS (2D/3D) is a software that simulates water flow in two-dimensional variably-saturated porous media. This software is used to determine the average water contents of the upper layers, direction of flow and the seepage rate to the pipe drain for different values of evaporation rates, pipe diameters, and horizontal and vertical pipe offsets from the conveyance canal. The results showed that increasing the vertical offset (drain depth) increases the drain discharge. Moreover, increasing the horizontal offset reduces the canal seepage and lower the phreatic surface. The proposed approach can determine drain size and location to cut off canal seepage, ensuring no contribution to the water body under the irrigated lands beyond the drain. The approach accounts for realistic soil formations and considers both saturated and capillary flows. [ABSTRACT FROM AUTHOR]

The study area consists of a Reference site and two Polluted sites which are distinguished by virtue of the nature of combined effluent received by wheat (Triticum aestivum) grown in the agricultural fields. All the growth and yield parameters viz; Average spike weight per plant, Average number of grains per spike, Average weight of grains per spike, Average shoot length, Average biomass per plant with spike and Average weight per grain of wheat at Polluted site II exhibited increase in comparison to the Reference site while Average spike weight per plant, Average number of grains per spike and Average weight of grains per spike at Polluted site I exhibited a decrease in comparison to the Reference site. This is attributed to the fact that at Polluted site II there is direct mixing of combined effluent into the irrigation canal leading to dilution of combined effluent which is used for irrigating the agricultural fields whereas at Polluted site I there is lateral seepage of combined effluents from the drain carrying effluents into the agricultural fields. Hence, combined effluent in diluted form is showing stimulatory effect on wheat and vice-versa. [ABSTRACT FROM AUTHOR]

In a traditional automated upstream controlled canal with a downstream buffer reservoir, the process to fill the buffer reservoir requires one step: the inflow to the canal is increased, and the flow change eventually arrives at the buffer reservoir. This paper describes an attempt to shorten the time necessary to stabilize the new flow rate at the buffer reservoir. The method requires calculated, remote manual adjustments to all the canal check structure gate positions in addition to two flow rate changes made at the head of the canal, followed by a return to automated upstream control. The method was tested in the Upper Main Canal of the Central California Irrigation District both through simulation and in the field. With a canal flow of approximately 20% of the maximum, simulation modeling predicted that a flow rate change arrival at the reservoir would be about 5.5 h in a typical operation, with final stabilization in about 16 h. Simulation of an improved procedure indicated an almost instantaneous increase in flow at the reservoir of half the flow change, with final flow stabilization at 11 h. The field test resulted in almost the full flow change arriving at the reservoir after about 20 min, with gradual stabilization occurring over the next 11 h. Important differences between simulation and actual results are discussed. [ABSTRACT FROM AUTHOR]

The paper is dedicated to the development of methods of waterproofing curtains arrangement for seepage protection of irrigation canals. The analysis of the informational sources in the field of seepage protection of irrigation canals has been conducted together with the use of horizontal directional drilling and the bentonite usage. The innovative technology of such works is proposed. The gist of the innovative technology is the combination of horizontal directional drilling and waterproofing bentonitecontaining mortar injection. The laboratory experiments of the protective curtain arrangement are conducted. Bentonite powder concentration per unit of volume of hardening mortar, discharge pressure (supply) of injection mortar, and duration of mortar supply are chosen as the most influencing technological factors. Soil filtration coefficient is selected as the most important indicator. It is concluded that the combination of values of low bentonite powder concentration and relatively high discharge pressure allows obtaining lowest soil filtration coefficient values. [ABSTRACT FROM AUTHOR]

The roughness coefficient of the concrete irrigation canal is one of the important evaluation criteria to ensure the hydraulic performance or malfunction between water and wall surface. In this study, the roughness coefficient of the concrete irrigation canal was measured using the aerial ultrasonic wave of the transceiver type sensor. The effect of the dispersion of measurement values in relation to the arithmetical mean roughness and the peak to peak value of the reflected wave were demonstrated. The influence of wet and dry conditions of concrete surface and the verification of the measurement range were taken into account. Results obtained showed that the peak to peak value of the reflected wave could measure the arithmetical mean roughness of concrete. It was observed that the average of 15 measured values was sufficient for accuracy. The peak to peak value of the reflected wave was affected slightly under wet condition. The range of the measured diameter of aerial ultrasonic wave sensor was approximately 300 mm and 600 mm from the distance of 550 mm and 1000 mm respectively. It is concluded that the development of the measurement method of arithmetical mean roughness of concrete surface by the transceiver type aerial ultrasonic sensor can be achieved. [ABSTRACT FROM AUTHOR]

The paper presents the design, implementation and field tuning of the (SCADA) system of a Portuguese irrigation canal network upstream controlled by AMIL radial gates and equipped with other Neyrpic devices. In addition to the irrigation district and its main hydraulic system, the paper also presents SCADA architecture, including two synoptics, and their remote terminal units (monitoring and controlling as well as monitoring units). The SCADA manual controllers - direct, gate position and gate flow controllers - are defined for the intakes of main canals and main distributors, in order to permit a pre-defined flow value or a daily flow schedule achievement. SCADA also monitors outflows from the main canals and main distributors - the most important canal-top-side weirs and terminal weirs of the canal. The developed manual gate flow controllers were tuned in the field using collected data readings from two types of acoustic Doppler flow meters. The field procedures for tuning the flow controllers and the obtained parameter values are also presented. [ABSTRACT FROM AUTHOR]

The work presented here is an extension of previous papers that updated the calibration of round (Armco-type) meter gates (three sizes: 0.30, 0.46, and 0.61 m), developed ratings for rectangular gates (two sizes: 0.46 and 0.61 m) on round pipes, and examined errors and uncertainty related to using these devices for water discharge measurement. Previous works examined gate discharge ratings under low supply-channel flow velocity perpendicular to the gate discharge pipeline. Here, additional testing was conducted to test the hypothesis that higher velocities in the supply channel would show decreased meter gate flow compared to the low-velocity ratings, but that the published gate calibration method would still yield accurate flow-rate calculations. All testing was conducted in a test facility with the gate discharge pipe set perpendicular to the supply channel, as is common in field installations. Velocities up to 0.94 m=s (3.1 ft=s) were tested with the smaller gate and 0.66 m=s (2.2 ft=s) for all other gates. These velocities are on the upper end of velocities found in common earthen irrigation canals (and in many lined channels at the farm delivery level) in California. Interestingly, results indicate that the Froude number of the supply-channel flow did not have a statistically significant (at an α-level of 0.01) influence on gate discharge coefficients. Discharge percent error and uncertainty were examined to compare the discharge coefficients presented in the literature to the discharge measured during the testing at different supply-channel velocities. Under recommended operating conditions, the uncertainty was within ±5% without adjustments for supply-channel velocity. This extended work supports earlier recommendations that meter gates can be an accurate flow measurement device for farm water delivery flow measurement if installed and operated correctly. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) has been extensively studied for controlling irrigation canals. Most of the studies use lumped models and fixed target for the controller. This setup works fine if the water delivery is on demand. However, in the case of on-supply delivery, balancing mismatches between demand and supply and spreading mismatches among all users are crucial. A fixed control target will not meet the request due to the mismatches. In this paper, a dynamic target trajectory approach is proposed to calculate changes of control targets that are used by MPC. The dynamic target trajectory calculates the percentage change of each setpoint based on the total volume mismatch spreading over the available capacity in each canal pool. The approach is applied to the Central Main Canal in Arizona. The results demonstrate that the dynamic trajectory can help the optimization find the optimum more quickly and facilitate tuning of the controller. Moreover, the mismatches can be better distributed over canal pools. [ABSTRACT FROM AUTHOR]

The main objective of this study is to determine the optimal distribution of water between upstream and downstream users in a main irrigation canal with a limited supply of water in order to maximize the net revenue derived from existing farming activities. To this end, an economic positive mathematic programming (PMP) model is employed to determine the economic value of the water for each delivery point along the main canal in which there is agricultural activity. This information is added to a model that accounts for the operational aspects of a realistic, large irrigated district in the center of Iran, which is used by a model predictive controller to prioritize the reaches in the main canal according to their potential profit in economic terms. The results show the satisfactory operation of the canal reaches, such that the water levels in the reaches with high economic water value are kept closer to the operational target levels. Accordingly, the water deficit is proportionally divided along the main canals to maximize economic profits from the irrigated district. [ABSTRACT FROM AUTHOR]

Methods of handling drastic inflow fluctuations without any constructional changes in the canal or the off-take structures are studied. Regarding the operational problem, automation of the regulating structures in the main canal is proposed. To this end, a centralized model predictive controller (MPC) is designed to achieve better operational performance in combination with an in-line water storage strategy. The controller is tested in a wide range of operational conditions, representing conventional operation, operation under predictable and unpredictable inflow fluctuations, and operation with and without water storing capabilities within the canal. The test bench is an accurate mathematical model of a canal consisting of five water regulators and seven off-takes. The results show significant improvement for canal operations employing automation. For the predictablefluctuations scenario, the results show that the stored water within the canal effectively handles the fluctuation. Compared to the conventional canal operation scenario, calculated evaluation performance indicators show an approximately 21% improvement for the maximum absolute error (MAE) and a 12% enhancement for the integral magnitude of absolute error (IAE). [ABSTRACT FROM AUTHOR]

Most of the models developed to simulate the cohesive sediment transport processes refer to estuary or marine environments and are generally not developed for the specific characteristics of irrigation schemes provided with the different types of hydraulic structures. The aim of this study is to simulate the cohesive sediment transport in irrigation canals. The fine sediment transport (FSEDT) model was developed using a software program to estimate the sediment transport and deposition rates of cohesive sediments in irrigation canals. The model has been applied in the Gezira Scheme in Sudan, which is threatened by high sediment supply from the Blue Nile River. The model was calibrated and validated using the field data selected during the flood seasons in 2011 and 2012. The hydrodynamic part of the model was verified by comparing the water surface profile obtained by the developed model and by using a microcomputer program for simulating one-dimensional steady/unsteady flow in open canals. The results of the two models show good agreement. The sensitivity of different parameters to the deposition was tested. The model is a useful tool that can be applied to study the mechanism of sediment transport under different operation and maintenance scenarios not only in the Gezira Scheme but also in similar cases. [ABSTRACT FROM AUTHOR]

A Lopac gate is one type of upstream control structures in irrigation canals. Advantages of a Lopac gate include performing as an overflow structure, letting sediments and floating bodies pass simultaneously, as well as easy automation. The structure has recently attracted the attention of researchers for detailed investigations. One effective tool to study control structures is a mathematical model. Due to the unsteady nature of flow in irrigation canals, incorporation of the mathematical model of control structures with hydrodynamic models is necessary. In this research, a mathematical model of Lopac gates is developed and linked with the ICSS (irrigation conveyance system simulation) hydrodynamic model. The Lopac gate model was developed as a boundary condition in four subroutines, including steady flow conditions, operation, unsteady flow conditions, and updating information. The developed model is validated using physical model data. The maximum error obtained was 6%, which is acceptable for practical purposes. The model was tested on a canal of DEZ irrigation network in Iran under many different conditions. The results showed that the model is performing well for tested applications and could be used in various studies of irrigation canals equipped with this structure. [ABSTRACT FROM AUTHOR]

This article considers development and research issues of creating impervious screens with enhanced reliability for irrigation canals, ponds and reservoirs using geo-composite materials (geomembranes, bentonite mats and other). In this connection, the authors conducted the present research and impervious screens that provide a high impervious effect and a long service life were developed. Also, the process of water permeability of probable damage inlets in the geocomposite screen was conducted in the form of small holes using Comsol Multiphysics software package. A hydro-mechanical method based on the conformal mappings method was used to find an analytical solution for the problems. Dependences were obtained to estimate the permeability of the geocomposite screens design for plausible accidental damages: seepage losses per unit damage and the average filter coefficients, given the size of the damage and the frequency of distribution. Based on the calculations, using the derived formulas, a graph was drafted, summarizing the degree of permeability of the geocomposite screens, based on which the rational field of their application was determined and the requirements for impermeability indices were set. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present a multivariable linear parameter varying (LPV) controller with a gain scheduling Smith Predictor (SP) scheme applicable to open-flow canal systems. This LPV controller based on SP is designed taking into account the uncertainty in the estimation of delay and the variation of plant parameters according to the operating point. This new methodology can be applied to a class of delay systems that can be represented by a set of models that can be factorized into a rational multivariable model in series with left/right diagonal (multiple) delays, such as, the case of irrigation canals. A multiple pool canal system is used to test and validate the proposed control approach. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to clarify the factors affecting the species diversity of plant communities around an irrigation pond, we surveyed Obaste-oike Irrigation Pond in Nagano Prefecture, Japan. The pond is comprised of three subdivided ponds, Kami-ike, Naka-ike, and Shimo-ike. Despite being adjacent to each other and connected by streams, the water levels in the three ponds differ. Five plant communities were studied, and one or two survey plots were selected in each community along each subdivided pond. A 32-m2 quadrat was established in each plot of grassland, and a 400-m2 quadrat was established in each plot of forest. The results of the distribution of species revealed that approximately 40% of the species were endemic to each subdivided pond in the terrestrial communities, whereas over 60% were endemic in the hydrophytic communities. To increase species diversity in irrigation ponds, especially in hyrdophytic communities, we suggest that dividing the ponds into several zones with distinct water levels and managing them in a sustainable manner is important. [ABSTRACT FROM AUTHOR]

In Japan, following changes in socioeconomic conditions, such as financial deterioration, an increase in social capital, and a decrease in population, ideas about infrastructure improvement have greatly changed. Recently, irrigation canals possessing historic value have attracted the attention of the public as assets for community development. The present study focused on the Soja district, in which many historical and cultural resources exist but where these resources have not been developed. A questionnaire was administered to the local residents and revealed the value of the Tenguiwa Irrigation Canal as an environmental asset. The present study also examined the relationship between the value of the Tenguiwa Irrigation Canal as an environmental asset and the direction of community development in the Soja district. [ABSTRACT FROM AUTHOR]

In this study, a systematic framework is introduced to prioritize several practical canal operation alternatives applying to modernization and rehabilitation projects. Several operation techniques, ranging from improved manual canal operation to centralized automatic operation, are considered. Ten different operation methods are selected as alternatives for the modernization and rehabilitation project. Mathematical models of the proposed alternatives are designed and potential applications of them are examined. The designed models are tested on an accurate simulation model of a large canal system in Iran. In regards to multicriteria inherent in selecting an appropriate operation method, multiple criteria are considered including 13 technical, social, operational, and economic criteria. Two well-known multicriteria decision-making (MCDM) methods of technique for order preference by similarity to ideal solution (TOPSIS) and simple additive weighting (SAW) have been applied to prioritize alternatives. The relative weights of each criterion are determined based on aggregation of entropy method and decision-maker's preferences during the decision making procedure. The obtained results show that Alternative 9, representing a centralized control method, has been the first-ranked alternative with the score values of 0.845 and 0.854, respectively, based on TPOSIS and SAW methods. Based on demands and expectation of the local water authorities, each of the proposed alternatives can be selected with different levels of satisfaction. According to the results, in the cases that automatic control application is restricted, the improved manual methods would be reasonable operational alternatives. [ABSTRACT FROM AUTHOR]

Dallisgrass (Paspalum dilatatum Poir.) reduces discharges in irrigation canals and causes problems in operation and maintenance of canals. This study has been conducted to determine roughness coefficient in vegetated canals caused by dallisgrass and to investigate the relationship between available soil phosphorous and dry mass of dallisgrass. The study also aims to find out the relationships among roughness coefficient, dallisgrass density and soil phosphorous in vegetated canals in Moghan plain, Iran. The results showed that the roughness coefficient varied from 0.01 to 0.32 and averaged at 0.09. The variation in roughness coefficient in vegetated canals by dallisgrass may be explained solely by the flow velocity and canal slope, assuming that there are no spatial variability's of the other affecting variables. Therefore, a regression model comprises both the roughness coefficient as a dependent variable and the flow velocity and canal slope as an independent variable is developed. The available soil phosphorus both on the sides and at the bottom of vegetated canals were from 4.2 to 37 mg kg-1. The highest dry mass of 16 kg per 100 m² was acquired from the canal with soil phosphorus of 16.7 mg kg-1. Also, another model was developed to describe the roughness coefficient as a function of the flow velocity, canal slope, dallisgrass density and soil phosphorous. It is recommended that identifying phosphorus sources and limiting its distribution in irrigation canals is necessary to reduce the dallisgrass density in canals. [ABSTRACT FROM AUTHOR]

One of the main problems in the water management of irrigation canals is the control of water distribution among users' outlets. This is because of the difficulty of measuring the removing flows correctly because they are highly variable in both time and space. To help solve this problem, a mathematical algorithm, the so-called canal monitoring algorithm, which determines the history of lateral extractions, is propounded. It uses the water depth measurements at checkpoints and the gate and other control device trajectories, which are implemented on the canal during a past period of time, and then obtains water withdrawals that happened at the outlets. The method also gives an estimation of the current state of the canal for model predictive control purposes. The algorithm solves the classical inverse problem, in which the unknowns are the parameters that define the flow rate trajectories of canal outlets, which are defined as piecewise functions of time in this paper. The algorithm is on the basis of the Gauss-Newton method and uses the complete Saint-Venant equations for the computation of the least-squared function. Numerical tests with excellent results have highlighted its computational efficiency, converging in a few iterations to the exact final results. These properties make the algorithm adequate to operate in real time. A laboratory canal test for verification shows accuracy in detecting water withdrawals at canal outlets when the Manning roughness coefficients are known. The test also reveals a functional relationship between the discharge removed and the empirical coefficients. [ABSTRACT FROM AUTHOR]

The evaporation from irrigation canals was estimated by the aerodynamic method based on the double-deck surface air layer model (called “DSAL model” for short hereafter). The DSAL model describes the surface air layer over a canal as a composite air layer with two sublayers, the lower sublayer and the upper sublayer. The lower sublayer is a few tens of centimeters thick and formed by the flowing water, in which there is no advection; the upper sublayer is over the lower sublayer and formed by the surface wind. The results were compared to those obtained by the heat balance method; field experiments were conducted in the middle reaches of the Heihe River in northwestern China. Results showed that cumulative evaporation instances estimated by the DSAL model were equal in order of magnitude to those by the heat balance method on observed days during the daytime (0700~1900 BST). We infer from these experimental results that the evaporation loss in transport in this region is of the order of one percent at most. [ABSTRACT FROM AUTHOR]

Normal and critical epths are important parameters in the design, operation, and maintenance of open channels. Semielliptical, prefabricated channels are widely used as tertiary canals in irrigation networks. In semielliptical channels, the governing equations are highly nonlinear in the normal and critical flow depths; thus, the solution of the implicit equations involves numerical methods. The main challenge with semielliptical sections is the calculation of the wetted perimeter. The wetted perimeter of semielliptical sections can be expressed in terms of incomplete elliptic integrals of the second kind. The elliptic integrals can be computed simply using commercial mathematical software, but most engineers who use a simple tool such as Microsoft Excel need a simple yet accurate expression for computing the wetted perimeter. Because elliptic integrals cannot be directly computed using Excel, a simple and accurate expression with maximum error less than 0.07% (near exact solution) is proposed for computing the wetted perimeter. In this study, explicit solutions for semielliptical channels have also been obtained using the nondimensional forms of the governing equations. The maximum errors of critical and normal flow depths are less than 0.1%. Proposed explicit equations have high accuracy, easy calculation, and wide application range. [ABSTRACT FROM AUTHOR]

We explored the notion that small canals could be good experimental proxies of streams by documenting physiochemical parameters and macroinvertebrate community development in an aridland irrigation canal. Further, we tested the production-compensation hypothesis between benthic invertebrates and invertebrates in the water column (drift). If the hypothesis held, invertebrates in the drift would be low until the benthic carrying capacity was reached; then organisms in the drift would increase as individuals avoided overcrowded conditions in the substrate. In a small, naturalized freshwater canal, we sampled macroinvertebrates in the substrate and those in the drift once every 2 weeks over 170 days (May-October). We placed macroinvertebrates into functional feeding groups (FFG) and examined these groups along with total density and taxa richness. We found no density-dependent relationship either in FFG or total density between the benthos and invertebrates in the drift. Our negative results might indicate that the stream benthos did not reach carrying capacity (partially affected by adult emergence in the autumn), the invertebrate dynamics in the canal did not adequately represent those occurring in a natural stream, or the duration of our study was too short. However, the invertebrate community in the canal did follow community buildup patterns for small streams reported in the literature, and it also resembled the community in a nearby natural stream. We suggest that naturalized canals could be used as 'mesocosms,' mimicking small natural streams, in which highly manipulative experiments could be conducted. In addition, the effects of temporary and permanent canals across the arid western landscape have been understudied and represent a new area of ecological research. [ABSTRACT FROM AUTHOR]

Biotic homogenization in freshwater ecosystems is a growing concern among conservation biologists. Recent phylogeographic data has shown low genetic structure between some basins from Central Chile, suggesting that either current dispersal through irrigation canals or incomplete lineage sorting due to recent divergence might explain the observed patterns. However, these hypotheses remain untested despite their potential implications for freshwater biodiversity and conservation. We used a statistical, model-based framework (approximate Bayesian computation) to investigate the relative support for each of these hypotheses in the freshwater catfish Diplomystes cf. camposensis , an endangered species from Central Chile. Our results show strong support for the model involving current migration between basins, and rejected the model of recent divergence without migration. These results strongly suggest that irrigation canals are facilitating the dispersal between basins, posing a serious threat to biodiversity in Central Chile, an area considered a biodiversity hotspot. Finally, these results highlight the utility of model-based approaches for determining demographic processes with potential conservation implications, even with the lack of extensive molecular data. [ABSTRACT FROM AUTHOR]

Copyright of Economics of Agriculture / Ekonomika Poljoprivrede is the property of Institute of Agricultural Economics (IAE) / Belgrade and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The normal depth is an important hydraulic element for canal design, operation and management. Curved irrigation canals including parabola, U-shaped and catenary canals have excellent hydraulic performance and strong ability of anti-frost heave, while the normal depths in the governing equations of the current common methods have no explicit analytical solution. They are only indirect methods by using trial procedures, numerical methods, and graphical tools. This study presents new direct formulas for normal depth in curved irrigation canals by applying for Marquardt method. The maximum relative error of the proposed formulas is less than 1% within the practice range by comparative analysis, and they are simple and convenient for manual calculations. The results may provide the reliable theoretical basis and useful reference for the design and operation management of irrigation canals. [Copyright &y& Elsevier]

Highlights: [•] We use a real irrigation canal as case study, modeled within the simulator SOBEK. [•] The set of control agents is partitioned in independent coalitions. [•] Cooperation between agents is promoted when it results in a performance improvement. [•] No need of continuous information exchange across the whole system. [•] Problem complexity is reduced w.r.t. centralized control, with comparable results. [ABSTRACT FROM AUTHOR]

Phuleli Canal (Sindh), Pakistan is one of the irrigation canals of the Kotri Barrage which provides water for irrigation as well as for drinking purpose. Quality of the canal deteriorates while passing through Hyderabad city, 2nd largest city of Sindh, Pakistan because highly toxic effluent from plastic factories, illegal cattle pens, slaughterhouses and municipal sewage water are directly discharged into the Phuleli Canal without any treatment. That polluted water has put lives of millions ofpeople at risk living at downstream in district Tando Muhammad Khan. Human health problems due to waterbome diseases are commonly reported in newspapers in Phuleli Canal Command area. Present study7 was thus conducted to investigate the effect of disposal of untreated domestic and industrial sewage water and waste into Phuleli canal on the quality of canal water. The sftidy was conducted during the year 200S-2009 to observe seasonal variation of trace and heavy metals at different location (reduced distance, RD = 1000 ft.) along the length of Phuleli Canal. Water samples were collected during four seasons (summer, autumn, spring and winter) with three replications each from seven locations (RD-O, RD-30, RD-50, RD-70, RD-90, RD-110 andRD-130). The samples collected were analyzed for their trace elements and heavy metal concentrations including zinc, manganese copper, iron, cadmium, chromium, lead and arsenic. The water analysis results were then compared with international organizations i.e. FAO and WHO standards of water for irrigation and human consumption respectively. Fe, Cd and Cr concentrations in water were higher than WHO permissible limits, and Cu and Mn were greater than FAO permissible limit at downstream of the canal. Comparatively heavy metals viz. Cd, Cr, Pb and As were higher towards downstream reaches as compared to upstr-eam reaches during winter. As the season changed the values of these parameters showed decreasing tr-end (autumn >spring>summer). [ABSTRACT FROM AUTHOR]

Abstract: Irrigation canals are open-flow water hydraulic systems, whose objective is mainly to convey water from its source down to its final users. They are large distributed systems characterized by non-linearity and dynamic behavior that depends on the operating point. Moreover, in canals with multiple reaches dynamic behavior is highly affected by the coupling among them. The physical model for those systems leads to a distributed-parameter model whose description usually requires partial differential equations (PDEs). However, the solution and parameter estimation of those PDE equations can only be obtained numerically and imply quite time-consuming computations that make them not suitable for real-time control purposes. Alternatively, in this paper, it will be shown that open-flow canal systems can be suitably represented for control purposes by using linear parameter-varying (LPV) models. The advantage of this approach compared to the use of PDE equation is that allows simpler models which are suitable for control design and whose parameters can be easily identified from input–output data by means of classical identification techniques. In this paper, the well-known control-oriented, model named integral delay zero (IDZ), that is able to represent the canal dynamics around a given operating point by means of a linear time-invariant (LTI) model is extended to multiple operating points by means of an LPV model. The derivation of this LPV model for single-reach open-flow canal systems as well as its extension to multiple-reach open-flow canals is proposed. In particular, the proposed methodology allows deriving the model structure and estimating model parameters using data by means of identification techniques. Thus, a gray-box control model is obtained whose validation is carried out using single-pool and two-pool test canals obtaining satisfactory results. [Copyright &y& Elsevier]

Abstract: Alexandria port is the main Egyptian port at the Mediterranean Sea. It is connected to the Nile River through Nubaria canal, which is a main irrigation canal. The canal was designed to irrigate eight hundred thousand acres of agricultural lands, along its course which extends 100km. The canal has three barrages and four locks to control the flow and allow light navigation by some small barges. Recently, it was decided to improve the locks located on the canal. More than 40million US$ was invested in these projects. This decision was taken to allow larger barges and increase the transported capacity through the canal. On the other hand, navigation through canals and restricted shallow waterways is affected by several parameters related to both the channel and the vessel. Navigation lane width as well as vessel speed and maneuverability are affected by both the channel and vessel dimensions. Moreover, vessel dimensions and speed will affect the canal stability. In Egypt, there are no guide rules for navigation through narrow and shallow canals such Nubaria. This situation threatens the canal stability and safety of navigation through it. This paper discussed the characteristics of Nubaria canal and the guide rules for navigation in shallow restricted water ways. Dimensions limitation for barges navigating through Nubaria canal is presented. New safe operation rules for navigation in Nubaria canal are also presented. Moreover, the implication of navigation through locks on canal discharge is estimated. [Copyright &y& Elsevier]

The reverse force on the returning blade of a water turbine can be reduced by setting a deflector on the returning blade side of a rotor. The deflector configuration can also concentrate the flow which passes through the rotor so that the torque and the power of turbine can be considerably increased. The placing of Savonius in Darrieus rotor is carried out by setting the Savonius bucket in Darrieus rotor at the same axis. The combination of these rotors is also called a Darrieus-Savonius turbine. This rotor can improve torque of turbine. Experiments are conducted in an irrigation canal to find the performance characteristics of presence of deflector and Savonius rotor in Darrieus-Savonius turbine. Results conclude that the single deflector plate placed on returning blade side increases the torque and power coefficient. The presence of Savonius rotor increases the torque at a lower speed, but the power coefficient decreases. The torque and power coefficient characteristics depend on the aspect ratio of Savonius rotor. [ABSTRACT FROM AUTHOR]

This paper presents the application of a distributed model predictive controller (DMPC) to the control of an accurate model of an actual irrigation canal in Spain. The canal is modeled using the Saint-Venant equations and implemented using the well-known Simulation of Irrigation Canals (SIC) modeling software for irrigation canals. The DMPC algorithm has been implemented in Matlab and interfaced to SIC. In the distributed-control algorithms, the local controllers exchange information so that their control policies are optimal in the sense of getting the best value of a performance index. The results show that the proposed distributed-control algorithm obtains better control performance than a more-conventional decentralized control scheme without information exchange. This better performance translates directly into money and resource savings. [ABSTRACT FROM AUTHOR]

Storing water in main irrigation canal reaches could be an influential strategy to improve the existing operational activities in the irrigation canals. However, the control of such a canal system will become much more complicated due to freeboards of the reaches temporarily decreasing. In this paper, Model Predictive Control (MPC) is applied to control the water level of an accurate model of a realistic main canal, which consists of 13 canal reaches, using an in-line storage operational strategy. Four different test scenarios are selected to cover a range of conventional to unconventional operational strategies by imposing limitations on the head-gate opening. Different target bands are created between the predefined allowed maximum and minimum water level for the canal reaches and the MPC is obliged to keep the water levels within these ranges. The results show that the in-line storage improves current operational performance of the canal system by compensating the existing delay times of flow traveling in the canal and gradual increasing and decreasing of the inflow that avoids large wave occurrences in the canal reaches. [ABSTRACT FROM AUTHOR]

Abstract: This paper applies a model predictive controller (MPC) to an automatic water canal with sensors and actuators controlled by a PLC network (programmable logic controller), and supervised by a SCADA system (supervisory control and data acquisition). This canal is composed by a set of distributed sub-systems that control the water level in each canal pool, constrained by discharge gates (control variables) and water off-takes (disturbances). All local controllers are available through an industrial network managed by the SCADA system, where the centralized predictive controller runs. In this paper a complete new platform connecting the SCADA supervisory system and the MATLAB software (named SCADA–MATLAB platform) is built, in order to provide the usual SCADA systems with the ability to handle complex control algorithms. The developed MPC-model presents a novelty in the control of irrigation canals as it allows the use of industrial PLCs to implement high complex controllers, through the new developed SCADA–MATLAB platform. Experimental results demonstrate the reliability and effectiveness of the proposed strategy in real-life typical situations, including gate malfunctioning and extreme water off-take conditions. [Copyright &y& Elsevier]

Abstract: In the present study, artificial neural networks method (ANNs) is used to estimate the main parameters which used in design of stable alluvial channels. The capability of ANN models to predict the stable alluvial channels dimensions is investigated, where the flow rate and sediment mean grain size were considered as input variables and wetted perimeter, hydraulic radius, and water surface slope were considered as output variables. The used ANN models are based on a back propagation algorithm to train a multi-layer feed-forward network (Levenberg Marquardt algorithm). The proposed models were verified using 311 data sets of field data collected from 61 manmade canals and drains. Several statistical measures and graphical representation are used to check the accuracy of the models in comparison with previous empirical equations. The results of the developed ANN model proved that this technique is reliable in such field compared with previously developed methods. [Copyright &y& Elsevier]

Although polyacrylamide (PAM) use for reducing soil erosion and increasing water retention is common in agriculture, research suggests PAM application may also be effective in reducing seepage in unlined irrigation canals. A polymer application test was conducted on a 457-m-long section of the Bordeaux lateral canal near Wheatland, Wyoming. Flow rating curves were developed by combining discharge and water level data, and the curves were used to convert real-time water level data into real-time discharge data. Falling head permeameters (FHP) provided a spatial method of quantifying seepage. Real-time stage discharge data showed a mean pretreatment flow loss over the entire test reach of , whereas the mean posttreatment loss was (), which corresponds to a 21% increase in seepage. The FHP tests also showed an increase in seepage as a result of PAM treatment. On the basis of the results of this study, it appears that PAM and suspended sediment concentrations were too low during the test to cause significant seepage reduction. [ABSTRACT FROM AUTHOR]

Irrigation districts in the American West and throughout the world have extensive canal networks that could be utilized to generate a significant amount of hydropower. As the world attempts to become less dependent on carbon-based energy resources, small-scale hydropower (SSH) is an attractive potential resource for new energy development. The Middle Rio Grande Conservancy District (MRGCD) in central New Mexico has an extensive canal network, and hydropower is being considered as a viable form of renewable energy. Currently, the MRGCD has identified and categorized nine potential hydropower sites within its system with the goal of maximizing its contribution to the region's energy needs. This paper addresses key issues related to hydropower in irrigation districts and examines the feasibility of incorporating hydropower generation in the MRGCD canal system. With full year-round implementation of SSH generation at the nine locations investigated, the MRGCD could have a generating capacity of 2.2 MW and produce over during the year. This represents an income from power generation for the MRGCD of $1.032 million at the current power prices. More importantly, implementation of SSH would result in 1,340 homes being powered by clean, renewable energy while concurrently delivering water to irrigators. It is the hope of the authors that the case study presented will aid irrigation districts investigating the incorporation of hydropower in their canal networks. [ABSTRACT FROM AUTHOR]

Abstract: Climate models predict a general future increase in air temperatures and, therefore, an augmentation of water requirements for agricultural purposes. However, without an appropriate management of the water resource, the competition between agriculture and other sectors risk to worsen the water scarcity crisis. Reducing the losses from irrigation canals will surely improve the efficiency of the irrigation systems, but lining the irrigation channels is an extremely expensive procedure sustainable only in the presence of h gh losses. Moreover, the two most known methods for determining losses from irri ation canals (inflow-outflow and ponding test) are quite expensive and time-consuming. In this context, the EM (Electromagnetic Induction) system has been used for decades for mapping soil properties: it is a fast and user friendly technique, easy for field applications and not excessively expensive. In this study we verified the usefulness of the EM system to determine the presence of leakage of irrigation canals. To this aim we selected three canals in the Piedmont plain (northwest of Italy) representatives of the most common regional typologies. Electrical conductivity values, collected using an EM device, were combined with data measured with traditional techniques such as inflow-outflow measurements (acoustic Doppler profiler and propeller flow meter), and soil water content measurements (TDR - Time Domain Reflectometer). EM electrical conductivity measurements were performed at different discharges values in permanent flow, h nce, at different water leve heights. The two replications were necessaries to investigate the variation of electrical conductivity versus the water level height. Results show that EM allows detecting seepage losses. Namely, these las s cause a lowering of the soi electrical conductivit*y values in steady conditions of soil water content. [Copyright &y& Elsevier]