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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 17 (1997), S. 111-120 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A complete set of dependent furrow irrigation variables has been identified, for which empirical functions, of general applicability, have been developed. A one-dimensional sensitivity analysis technique coupled with dimensional analysis was employed to reduce the number of independent irrigation variables to a manageable size. Simulation experiments were carried out to generate the data used in developing the pertinent functional relationships. Regression analysis was used to ascertain the specific form of the equations. The predictive quality of the functions has been assessed by comparing their output with those of a zero-inertia model, and was found to be satisfactory.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 15 (1994), S. 123-136 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The design problem of furrow irrigation systems considering runoff and drainage water quality was formulated as an optimization problem, with maximization of net benefits as the objective. A power advance function with an empirically derived relationship between the furrow irrigation design variables and relative crop yield were used in the formulation. The generalized geometric programming technique was used to solve for the optimal values for the design variables that maximized the net benefits from a furrow irrigation system. The optimal efficiency for which the system must be designed under a given set of soil, crop, and economic conditions is not known in advance. In the design, the application efficiency was not specified a priori. It was an output from the optimal design. The analysis suggested that it might not be economical to design surface irrigation systems to achieve a high application efficiency that is specified a priori. In the absence of environmental degradation problems from irrigation, it may sometimes be profitable to design surface irrigation systems to operate at less than the standard application efficiency (55%–90%) that is routinely used in the design. Formulation of the design problem as an optimization problem would yield the optimal application efficiency that would maximize the net benefits to the farmer under any given set of conditions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 17 (1997), S. 121-126 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Significant advances have been made in the areas of mathematical modelling of surface irrigation processes; nevertheless, their impact on system design and management remains minimal. The main reasons for this are complexity, cost, and the level-of-expertise requirement of the existing models. Empirical functions of the type presented in a companion paper can help overcome these problems. This paper describes the use of those functions in the conventional design and management of furrow irrigation systems.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation science 15 (1994), S. 113-121 
    ISSN: 1432-1319
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A moving control volume approach was used to model the advance phase of a furrow irrigation system whereas a fixed control volume was used to model the nearly stationary phase and the runoff rate. The resulting finite-difference equations of the kinematic-wave model were linearized and explicit algebraic expressions were obtained for computation of advance and runoff rate. The solutions for the advance increment and the runoff rate were compared with the nonlinear scheme, the zero-inertia model, and a set of field data. A close agreement was found between the models and the field data. Assuming a constant infiltration rate, a differential equation was derived to estimate the error between the kinematic-wave model and the zero-inertia model in predicting the flow cross-sectional area along the field length. The differential equation and two dimensionless terms were used to define the limits for use of the kinematic-wave model in furrow irrigation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Water resources management 5 (1991), S. 217-231 
    ISSN: 1573-1650
    Keywords: Linear distribution model ; open-channel flow ; canal operation problem ; observer-controller ; irrigation canals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract Using a linear distributed model of open-channel flow, the canal operation problem was formulated as an optimal control problem, and an algorithm for the gate opening in the presence of unknown external disturbances (changes in flow rate demands) was derived by solving the algebraic Riccati equation. An observer was designed to estimate the values for depth of flow and flow rates at the intermediate nodes based upon measured values of depth at the upstream and downstream ends of a pool. Considering an example, the changes in depths and gate opening obtained from the linearized model were compared with the results obtained from the nonlinear hydrodynamic equations. For an external disturbance of 20% of the initial flow rate in the pool, the difference between the two models in predicting the variation in the upstream and downstream water surface elevations and the change in the upstream gate opening was insignificant.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation and drainage systems 5 (1991), S. 267-275 
    ISSN: 1573-0654
    Keywords: aquatic algae ; irrigation water ; trash screens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Floating trash in surface irrigation waters can block or reduce the flow of irrigation water and significantly increase irrigation costs. Dimensional analysis was applied to experimental data to develop equations for designing irrigation trash screens and for modifying a trash screen to compensate for variations in water flow. The equations were based on providing adequate horizontal flow across the screen to float aquatic algae off the screen and thereby prevent blockage.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Irrigation and drainage systems 9 (1995), S. 105-116 
    ISSN: 1573-0654
    Keywords: irrigation canals ; optimization ; scheduling ; turnouts ; zero-one programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An improved 0–1 programming model was presented for optimal flow regulation and optimal grouping and sequencing of outlets in irrigation distributaries, under restrictions of both the rotational period and the incoming flow rate into distributaries. The problem was solved using a commercially available 0–1 programming software package. The example computations indicated that this model could effectively provide a constant flow rate into the canal during most of the rotation period, and thus reduce the frequency of headgate operation. This formulation also minimized the accidental water wastage by appropriately sizing the canal cross-section.
    Type of Medium: Electronic Resource
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