Residues of Two Herbicides in Water in Irrigation Canals

Weeds ◽  
1967 ◽  
Vol 15 (4) ◽  
pp. 353 ◽  
Author(s):  
P. A. Frank ◽  
R. H. Hodgson ◽  
R. D. Comes
Keyword(s):  
Irrigation Canals

Methodology for determining water losses from irrigation canals

2020 ◽  
pp. 16-18
Author(s):  
Elena Makarycheva
Keyword(s):  
Filtration Rate ◽  
Darcy Law ◽  
Filtration Flow ◽  
Irrigation Canals ◽  
Power Functions ◽  
Two Phase ◽  
Water Losses ◽  
Irrigation Channels ◽  
Unsteady Filtration ◽  
S Curve

The aim of the article is to develop a method for calculating water losses from irrigation channels in determining the permeability of rock in the zone of filtration flow on the basis of the law of infiltration A.N. Kostyakov using the results of studies of free filtration from pits and foundation pits in loess loams. Pressure movement of water in irrigation canals is subject to the laws of two-phase flow, in which – in contrast to the Darcy law for the zone of saturation plays an important role, the volume and its change in time. The filtration rate (VF) increases with increasing rock moisture (θ) along the S-curve, while the pressure gradient (I = dh/dz) decreases. The dependences of these parameters on the pressure are represented by power functions, and their product CDP = VFI does not change in time and can serve as a characteristic of the filtration flow under the channel. When installing paired piezometers near the water chore line in the channel and determining the graph I(t) by the value of the twophase flow constant CDP, it is possible to calculate the filtration rate at a number of times and the water losses during unsteady filtration. Water losses from the channels at equilibrium humidity increases with increasing head according to the formula A.N. Kostyakova, in which the water permeability of rocks is characterized by a steady filtration rate at a head of 1.0 m, and the gradient is the function of pressure. The application of the proposed method of calculating losses in the design of irrigation systems will increase the reliability of the justification of the volume of anti-filtration measures and the forecast of the groundwater level.

Selling their Best for Little: The Riddle of Ecuador's Failed Attempt to Assist Communal Farmers

2004 ◽  
pp. 123-142
Author(s):  
María José Castillo ◽  
Richard Beilock
Keyword(s):  
Development Strategies ◽  
Irrigation Canals ◽  
Irrigation Systems ◽  
Access To Credit ◽  
Reservation Prices ◽  
Failed Attempt ◽  
Santa Elena

In the 1980s, Ecuador began an expensive project providing primary irrigation canals to the Santa Elena Peninsula. The intended beneficiaries were the region's communal farmers. Instead, virtually all irrigable lands have been sold to large farmers and land speculators, usually at exceedingly low prices. While political and economic abuses explain some of these sales, introduction into a communal setting of an innovation which improved returns to capital relative to labor made land divestitures almost inevitable. With effectively no access to credit, communal farmers had little ability to invest in secondary irrigation systems. Moreover, because users of irrigable lands did not fully control communal sales decisions, as these lands became attractive to others, dispossession risks rose. The net result was that reservation prices for holding these lands fell among communal farmers at the same time of increased demands for these assets by those outside the comunas. Implications for development strategies are also discussed.    

Stranding cases of endangered Ganges river dolphins in the Ghaghara–Sharada irrigation canals, Ganges river basin, India: conservation implications

Mammalia ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Shakti Prajapati
Keyword(s):  
River Basin ◽  
Local Population ◽  
Uttar Pradesh ◽  
Ganges River ◽  
Population Declines ◽  
Irrigation Canals ◽  
Indus River ◽  
River Dolphin ◽  
Conservation Implications ◽  
Media Reports

AbstractPopulations of endangered Ganges and Indus river dolphins have been under severe threat from diversion of river water by dams, barrages, and canal networks across the Indus and Ganges–Brahmaputra river basins. River dolphins prefer deep water and might enter irrigation canals in the dry-season, getting stranded there. Stranding can cause mortality and local population declines, and poses an emerging challenge to river dolphin conservation efforts. In Pakistan’s Indus river basin, stranding rates of Indus dolphins in irrigation canals are high, and well-coordinated rescue-release operations are undertaken. Despite commendable river dolphin rescue efforts in some parts of India, stranding cases are not always reported. From open-access media reports (2007–08 to 2017–18), I found 26 stranding cases of Ganges river dolphins from the Ghaghara–Sharada canal network across seven districts of Uttar Pradesh, India. Of these, 62% reports were from 2015 to 2016. Most cases occurred in secondary and tertiary canal branches. Interviews with fishers, farmers, and government officials revealed low awareness of stranding cases. Stranded dolphins might have no chance of returning to their source habitat, unless rescued. From my results, I discuss how current barrage-canal operations could influence dolphin stranding risk, and their implications for flow management in the Ghaghara–Sharada river basin.

scholarly journals On Modeling and Constrained Model Predictive Control of Open Irrigation Canals

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Lihui Cen ◽  
Ziqiang Wu ◽  
Xiaofang Chen ◽  
Yanggui Zou ◽  
Shaohui Zhang
Keyword(s):  
Model Predictive Control ◽  
Prediction Model ◽  
Predictive Control ◽  
Hyperbolic Partial Differential Equations ◽  
Irrigation Canal ◽  
Irrigation Canals ◽  
Optimal Control Algorithms ◽  
Saint Venant Equations ◽  
Constrained Model ◽  
Constrained Model Predictive Control

This paper proposes a model predictive control of open irrigation canals with constraints. The Saint-Venant equations are widely used in hydraulics to model an open canal. As a set of hyperbolic partial differential equations, they are not solved explicitly and difficult to design optimal control algorithms. In this work, a prediction model of an open canal is developed by discretizing the Saint-Venant equations in both space and time. Based on the prediction model, a constrained model predictive control was firstly investigated for the case of one single-pool canal and then generalized to the case of a cascaded canal with multipools. The hydraulic software SICC was used to simulate the canal and test the algorithms with application to a real-world irrigation canal of Yehe irrigation area located in Hebei province.

FRACTIONAL ROBUST CONTROL TO DELAY CHANGES IN MAIN IRRIGATION CANALS

2005 ◽  
Vol 38 (1) ◽  
pp. 28-33 ◽  
Author(s):  
V. Feliu Batlle ◽  
Rivas R. Pérez ◽  
F Castillo
Keyword(s):  
Robust Control ◽  
Irrigation Canals

Levels and Levelers: Surveying Irrigation Canals in Medieval Valencia

1968 ◽  
Vol 9 (2) ◽  
pp. 165 ◽  
Author(s):  
Thomas F. Glick
Keyword(s):  
Irrigation Canals

A control tool for irrigation canals with scheduled demands

2008 ◽  
Vol 46 (sup1) ◽  
pp. 152-167 ◽  
Author(s):  
J. Soler Guitart ◽  
M. Gomez Valentín ◽  
J. Rodellar Benedé
Keyword(s):  
Irrigation Canals ◽  
Control Tool
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