Albert J. Clemmens

Portable RBC Flumes for Furrows and Earthen Channels

ABSTRACT A new style of portable flow-measuring flume has been designed for furrows and unlined channels. These flumes are relatively easy to install and operate. Sensitivity to leveling has been decreased by placing the stilling well near the flume throat. They are long-throated flumes and require very little head loss for satisfactory operation. They are simple to construct since they consist of a short trapezoidal section with a contraction inserted in the flume bottom. Rating tables are provided for several standard sizes with capacities ranging from 1.5 to 50 L/s (0.05 to 1.8 ftVs).

Statistical methods for irrigation system water delivery performance evaluation

There are several different parameters that can be measured and used to describe the performance of water delivery service; flow rate, volume, duration, pressure, and frequency. The proper one(s) to consider depends on the project conditions and objectives. The overall performance of an irrigation water delivery system can be broken down into two components; the delivery schedule and operations. The performance of the delivery schedule can be evaluated by looking at the ratio of intended to required water (volume, rate, duration, etc.) and the performance of operations by the ratio of actual to intended water. The overall performance is expressed by the product of these two ratios; the actual divided by the required water. Statistical relations are provided to express equity, adequacy and reliability from measurement of these ratios.

Field calibration of submerged sluice gates in irrigation canals.

Four rectangular sluice gates were calibrated for submerged-flow conditions using nearly 16,000 field-measured data points on Canal B of the B-XII irrigation scheme in Lebrija, Spain. Water depth and gate opening values were measured using acoustic sensors at each of the gate structures, and the data were recorded on electronic data loggers. Several gate calibration equations were tested and it was found that the rectangular sluice gates can be used for accurate flow measurement. The Energy-Momentum (E-M) equations proved to be sound. The calibration of the contraction coefficient, to be used in the energy equation, allowed good estimations of the discharge for three of the four gates studied. The gate for which the E-M method did not perform satisfactorily was located at the head of the canal with a unique nonsymmetric approach flow condition. Alternatively, we investigated the performance of the conventional discharge equation. The variation of the discharge coefficient, Cd , with the head differential,...

Evaluation of infiltration measurements for border irrigation

Abstract A number of methods are discussed for obtaining a reasonable estimate of the infiltration function for irrigation borders. Data from ring infiltrometers are fit to power functions for infiltration rate and cumulative infiltration rate versus time and to a branch function where the infiltration rate is not allowed to go below some value (called the final infiltration rate). A volume balance within the border is used to adjust the data to give a better indication of the “average” infiltration conditions over the border. The results of Bouwers method, which uses a series of borders as infiltrometers, were compared to the results of ring data for actual field data. Bowers method was also analyzed by developing advance and recession curves with the zero-inertia border-irrigation model with a known infiltration rate. The zero-inertia model was also used to examine the effect of different infiltration functions for specific examples (resulting from different irrigations or different estimation methods) on the application of water by surface irrigation.

Real-time implementation of model predictive control on Maricopa-Stanfield Irrigation and Drainage District's WM Canal.

Water resources are limited in many agricultural areas. One method to improve the effective use of water is to improve delivery service from irrigation canals. This can be done by applying automatic control methods that control the gates in an irrigation canal. The model predictive control (MPC) is one such advanced control method. In this article, the MPC is used to deliver irrigation water to the WM Canal at the Maricopa-Stanfield Irrigation and Drainage District. The tests show that the water is efficiently delivered to the users and water level deviations at all locations are small. The control is compared to the results from an advanced Linear Quadratic Regulator control method, also tested on the actual canal.

Cotton response to high frequency surface irrigation

High frequency irrigation with surface irrigation methods has been proposed as a means to increase cotton productivity in cases where drip irrigation or other pressurized systems are not economically justifiable. Field studies were conducted in 1993 and 1994 to evaluate the effects of surface irrigation frequency on the growth, lint yield and water use for a semi-determinate cotton cultivar in central Arizona. Cotton was grown in level basins on a sandy loam under three irrigation treatments defined as low frequency irrigation for the whole season (L), high frequency irrigation for the whole season (H), and low frequency irrigation until the initiation of rapid fruiting, high frequency during rapid fruiting, and low frequency after rapid fruiting (LHL). The treatments were governed by the percentage of allowable soil water depletion within the effective root zone, and the allowable depletion targets for low and high frequency irrigation were 55 and 30%, respectively. An irrigation scheduling program calculated the soil water depletion within the estimated cotton root depth on a daily basis for each treatment and was used to project the dates and amounts for treatment irrigations. In 1993, seven, 14, and 11 irrigations and in 1994 eight, 13 and 10 irrigations were given to the L, H, and LHL treatments, respectively. The total amount of water applied including rainfall differed among the treatments by 4% in 1993 and by 1% in 1994. Soil water measurements indicated that actual soil water depletion within the estimated cotton root depth immediately before treatment irrigations was close to the intended treatment allowable depletion targets for the majority of the growing season. Cotton growth and lint yields were maximized under the H treatment, and yields in this treatment averaged 15 and 21% more lint than the L treatment for the first and second seasons, respectively. The LHL treatment, although not as effective in increasing crop productivity as the H treatment, out yielded the low frequency treatment by an average of 10% in the two seasons. Crop evapotranspiration determined from the soil water balance was 8 and 9% higher for the H than the L treatment and 3 and 5% higher for the LHL than the L treatment in 1993 and 1994, respectively.

Water-Level Difference Controller for Main Canals

The operation of main irrigation canals is complicated in situations in which the operator does not have full control over the canal inflow, or in which there are very long transmission distances from the point of supply, or both. Experienced operators are able to control the canal, but often supply errors are simply passed downstream, thus creating problems further down the system. In previous work, the writer showed that it is important to contain such errors and not let them pass downstream. With automatic upstream-level control, all flow errors are passed to the downstream end of the canal. Distant downstream water-level control requires full control of canal inflow. Without this, errors will occur at the upstream-most canal pool. An alternative scheme is offered here in which the canal check gates are controlled on the basis of the relative water-level error between adjacent pools. The scheme uses a simple linear model for canal pool response. The scheme is imple- mented as a multiple-input, multiple-output scheme and is solved as a linear quadratic regulator (LQR). Thus, all gates respond to relative deviations from water-level set point. The scheme works to keep the relative deviations in all pools the same. If inflow and outflow do not match, it effectively treats the canal as a storage reservoir. When in equilibrium, operators will be able to judge the actual flow rate mismatch by the rate of change of water levels. The scheme acts like a combination of upstream-level and distant downstream-level control. It was tested on a simulation model of the Central Main Canal at the Central Arizona Irrigation and Drainage District (CAIDD), Eloy, AZ. DOI: 10.1061/ (ASCE)IR.1943-4774.0000367.

ASSESSING THE POTENTIAL FOR MODERN SURFACE IRRIGATION IN EGYPT

Over the past decade, there has been a gradual shift in Egypt towards development of farm mechanization systems. Efficient use of equipment requires tilling basins and furrows in long strips. However, for irrigation, these strips are typically broken up into small basins; this requires considerable labor and results in nonuniform and inefficient irrigation. Irrigation of long strips on very flat, nearly level fields is difficult with the current degree of land-grading precision. Use of laser-controlled land-grading equipment is increasing in Egypt, but this has not led to irrigation of long strips. A project was undertaken to examine the potential performance of modern level basins in Egypt. Field studies were conducted to verify that these modern surface irrigation methods would be viable. These field studies were also used to determine infiltration and roughness conditions which might be typical of soils in the Nile Delta. Simulation studies were also performed to determine the influence of land-grading precision on level-basin performance. This article summarizes the studies that have been performed and provides an introduction to the application of this technology to improving surface-irrigation performance.

SURFACE-IRRIGATION EVALUATION MODELS: APPLICATION TO LEVEL BASINS IN EGYPT

Models for simulating flow in surface irrigation are helpful in evaluating irrigation performance, both as observed in a given field, and in hypothetical, what-if scenarios. However, the use of surface-irrigation simulation and design software is often hindered by the lack of appropriate field values for the infiltration and roughness parameters required as input. Moreover, in various places around the globe, for example, Egypt, as a consequence of local soils and cropping and cultural practices, the field conditions encountered can be quite different from those common in the U.S. Interactive field-parameter-evaluation software, EVALUE, was developed as an aid for estimating these parameters from extensive field measurements. In the interactive process, the engineer-user is provided with information to assist in making his/her choices, but retains full control over the selection of parameter values in the empirical formulas used to describe infiltration and roughness. Parameter estimates made in Egypt were validated by entry into the general surface-irrigation simulation program, SRFR, and subsequent comparison of the predicted and measured results. The procedure verifies both the parameter-estimation techniques and the simulation program. The techniques and models described are presented in terms of Egyptian data, but are sufficiently general to be applicable anywhere.

Estimation of Soil and Crop Hydraulic Properties

Some two dozen methods for estimating infiltration and roughness parameters from field measurements of test irrigations are reviewed in this paper. They differ in their assumptions, ease of analysis, quantity of field data required, and accuracy. They are divided into two broad categories, depending upon the basic approach to determine infiltration. One features direct application of mass conservation, expressed in terms of the infiltration parameters and then inverted in some way in order to extract those parameters. The other involves repeated simulation with a sequence of values of the infiltration parameters, coupled to some kind of search procedure—an optimization—to minimize differences between simulation and measurement. A new one-point technique is proposed, along with suggestions for extending existing methods.