J. Mohan Reddy

Optimal operation schedule of irrigation distribution systems

Abstract The ‘constant frequency-variable depth’ method of water delivery is discussed. The problem of clustering and sequencing outlets on a distributary channel to deliver the required quantity of water is described and formulated as a zero-one linear programming problem. The optimal operation schedule of the outlets was obtained for distributary 3 of the Meena branch canal in the Kukadi Irrigation Project in Maharashtra, India.

Optimal Design of Furrow Irrigation Systems

ABSTRACT GENERALIZED geometric programming and the Soil Conservation Service design procedure were combined to optimize furrow irrigation systems design based on minimum costs. Water, labor, and ditch con-struction were the costs considered. The system decision variables were the inflow rate, time of inflow, length of run, number of lengths of run, number of sets, and number of furrows per set. An example field was design-ed considering the cost coefficients, design variables and system constraints. Recommendations for further im-proving the design procedure by basing the design on maximum profit and including additional decision variables were given.

Improved 0–1 programming model for optimal flow scheduling in irrigation canals

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.

Kalman filtering in the control of irrigation canals

Abstract The Saint-Venant equations of open-channel flow were linearized about an average operating condition of the canal. The concepts of linear optimal theory were applied to derive a feedback control algorithm for constant-level control of an irrigation canal. The performance of the state estimators designed using the pole-placement technique and the Kalman filtering technique (both time-varying and steady-state) were compared with the results obtained using a full state feedback controller. An example problem with a single pool was considered for evaluating the relative merits of the technique used to design an estimator for irrigation canals. Considering the computational complexity and the accuracy of the results obtained, the steady state Kalman filtering technique was found to be adequate for irrigation canals. The performance of the system under a sampling frequency that is less than the frequency of simulation was also evaluated.

Analysis of surface irrigation performance terms and indices

Abstract Performance terms measure how close an irrigation event is to an ideal one. An ideal or a reference irrigation is one that can apply the right amount of water over the entire region of interest (subject region) without loss. The key phrase, used in the description of a reference irrigation, has been used as the criterion for identifying the performance terms that constitute a complete set, corresponding to any given irrigation regime. Indices have been defined to quantify the performance terms. The interrelationship between performance indices as well as the relationship between each index and the system variables have been explored. The repercussions of those observations on system design and management have been discussed.

Optimizing Surface Irrigation System Design Parameters: Simplified Analysis

ABSTRACT THE geometric programming method was described. Simple techniques such as monotonicity analysis, constraint activity, and condensation were utilized to reduce the size of the problem. Example optimal designs for borders and furrows were solved on a hand calculator following the suggested methodology. Results were the same as previously obtained from generalized geometric programming and extensive use of a digital computer. Globally optimal solutions for minimum cost and max-imum profit designs were obtained by using this mathematically rigorous but simple optimization pro-cedure.

Evaluation of optimal constant-volume control for irrigation canals

Abstract A lumped-parameter model was used for stimulating the dynamics of an irrigation canal using the concepts of optimal control theory. Using the state-space approach presented by Corriga , the problem was formulated as a discrete optimal control problem, and the solutions for gate opening in the presence of known variations in water withdrawal rates were obtained by solving the algebraic Riccati equation. An example problem was considered, and the variations in the depth of flow obtained by using the optimal control theory were compared with the results obtained from an unsteady open-channel flow model. For small and slow changes in the flow rates, the difference between the two models in predicting the changes in water surface elevation was not significant. However, as the variations in withdrawal rates increased, the accuracy of the optimal control model (which is based upon small perturbations around the uniform flow) in predicting the water surface elevations decreased.

Optimizing Furrow Irrigation Runoff Recovery Systems

ABSTRACT THE design parameters of a furrow irrigation runoff recovery system were optimized using the generalized geometric programming technique. The cost of pumping water from the well and the sump, the cost of labor, and the cost of constructing the sump were considered in the objective function. The major constraints specified for the system were required depth of application and volume of water remaining in the sump at the end of irrigation. The cost of the system using the optimization technique was 67% of the cost using a trial and error solution. The difference in the cost of system design between the two techniques—the trial and error and the optimization—was mainly due to the maximum volume of runoff collected during irrigation..

Design of a combined observer-controller for irrigation canals

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.

Design of Level Basin Irrigation Systems for Robust Performance

AbstractA well-designed level basin irrigation system is easy to manage and has significant potential for achieving high application efficiency and improved salinity control, particularly when the field is laser-leveled. Over the years, three different criteria have arisen to design level basin irrigation systems. These are the volume-balance design criterion proposed by the Soil Conservation Service of the USDA, the limiting length design criterion, and the completion-of-advance design criterion. For achieving a performance that is close to the design performance, in addition to proper design, a well-defined irrigation schedule must be followed such that the soil moisture deficit at the time of irrigation is close to the design depth. The actual overall performance of a level basin irrigation system will otherwise be lower than the design performance. Using a mathematical simulation model, the performance of a level basin designed using the completion-of-advance design approach was found to be robust rel...