Journal of Irrigation and Drainage Engineering

This article reviews the method for allocating flow to irrigation plots proposed by Clément and Galand in (1979). Mention is made of its shortcomings, such as the lack of consideration given to the specific technical and economic factors governing current pressurized (drip or sprinkler) irrigation systems and how they provide water to plots. We propose a method for fixed irrigation systems, which takes into account the irrigation method on the plot and the existence of an optimum block area. The result is to allocate a constant flow of water to plots up to an established value of maximum surface area. From there on, we propose applying linear increases related to the total plot area. We also present a formula for calculating the maximum number of blocks based on variables that are easily obtainable during the project phase.

Moment analysis techniques are applied to describe the spatial and temporal subsurface wetting patterns resulting from furrow infiltration and redistribution. These techniques are adapted from previous work with drip irrigation. The water added is considered as a “plume” with the zeroth moment representing the total volume of water applied to the domain. The first moments lead to the location of the center of the plume, and the second moments relate to the amount of spreading about the mean position. Using moments, any fraction of the applied water and its spatial extent, defined by an ellipse, can be related to a “probability” curve. Remarkably, the probability curves are, for practical purposes, identical for all times and for all of the soils considered in this study. The same observation was made in relation to the distribution of water under a dripper. The consistency of the probability relationships can be exploited to pinpoint the distribution of irrigation water under a furrow in a compact and physically meaningful way. This approach is tested with numerically generated data for infiltration from furrows in three contrasting soils. The general conclusion is that moment analysis allows a straightforward, physically meaningful description of the general pattern of moisture distribution. Potential applications of the results of moment analyses include improved irrigation management, formulation of the infiltration and redistribution process from a furrow in a neural network setting, and parameter estimation of the soil hydraulic properties.

The modernization of irrigation districts in Spain is based on the construction of collective pressurized networks equipped with remote control systems. In this paper, a simulation approach is used to explore the benefits of introducing a collective solid-set irrigation control software. The controller works in combination with a district management database, real-time evapotranspiration and meteorology information, and a remote control system. Controller decisions are based on the simulation of sprinkler irrigation performance and on crop–water balance. The decision to irrigate a plot can be guided by the use of two simulation parameters: the estimated application efficiency of the irrigation event (heavily affected by wind speed) and a crop–water stress index. Simulation experiments were performed in a district located at the Ebro basin of Spain. The collective controller resulted in water conservation (with respect to the current situation) of 2,234 and $\mathrm{4,664}{\mathrm{m}}^3{\mathrm{ha}}^{-1}$ for corn and alfalfa, respectively, and in an increase in water productivity of up to 91%. Although additional research is needed to produce a reliable collective controller, these preliminary results are encouraging.

Automated site-specific sprinkler irrigation system can save water and maximize productivity, but implementing automated irrigation is challenging in system integration and decision making. A controllable irrigation system was integrated into a closed-loop control with a distributed wireless in-field sensor network for automated variable-rate irrigation. An experimental field was configured into five soil zones based on soil electrical conductivity. In-field soil water sensors were installed on each zone of the distributed wireless sensor network and remotely monitored by a base station for decision making. The soil water sensors were calibrated with a neutron probe and individually identified for their response ranges at each zone. Irrigation decisions were site-specifically made based on feedback of soil water conditions from distributed in-field sensor stations. Variable-rate water application was remotely controlled by the base station to actuate solenoids to regulate the amount of time an individual group of sprinkler nozzles was irrigating in a $60\text{-}\mathrm{s}$ time period. The performance of the system was evaluated with the measurement of water usage and soil water status throughout the growing season. Variable water distribution collected in catch cans highly matched to the rate assigned by computer with $r^2=0.96$ . User-friendly software provided real-time wireless irrigation control and monitoring during the irrigation operation without interruptions in wireless radio communication.

Soil salinity is a major environmental factor limiting the productivity of agricultural lands. To determine the effects of irrigation water salinity and leaching on soil salinity and consequently wheat yield, a field experiment was conducted on a silty clay soil, a typical soil of Rudasht region, Isfahan province, Iran, with three irrigation water salinity levels of 2, 8, and $12\mathrm{dS}∕\mathrm{m}$ with/without leaching levels of 4, 19, and 32% with two different irrigation water managements, using factorial design with four replications for each treatment. The results showed that as the irrigation water salinity and consequently soil salinity increases, the yield components such as grain yield, straw yield, 1,000-grain weight, crop height, spike length, and leaf area index decreases significantly. Leaching caused the yield components to increase significantly. An increase in seed protein percentage was noted as the salinity of irrigation water increased. The interaction effects of irrigation management and leaching on yield and yield components was significant. The results of best fit line to relative yield data versus soil ECe showed that the parameters of the above linear relation are site specific, and there is no significant difference between the parameters obtained in this study as compared to the other researchers’ results and the study validates the established relationships between wheat yield and salinity obtained by other researchers. The recycled drainage water could be used in combination with less saline river water as an alternative and less expensive irrigation water to grow salt-tolerant crops such as wheat, to produce profitable yield and to improve the agricultural economy of arid land regions.

The purpose of this study is to develop an integrating evaporation estimation model using a data mining process for the Lakes District in the southern part of Turkey. Lakes Eğirdir, Kovada, and Karacaören Dam are located in the Lakes District. The proposed data mining process is applied on these lakes for evaporation estimation. The daily pan evaporation data used in the data mining process are taken from State Hydraulic Works in southern Turkey. These data cover an $8\text{-}\text{year}$ period between 1998 and 2005 inclusively for daily pan evaporation of Lakes Eğirdir, Kovada, and Karacaören Dam. It is known that a developed integrated daily pan evaporation model is necessary for these lakes, which are so important to the Lakes District. Therefore, a data mining model having two inputs and one output is developed. Input parameters used in the developed models for Lakes Eğirdir, Kovada, and Karacaören Dam were daily pan evaporation values of Lakes Kovada + Karacaören Dam, Lakes Eğirdir + Karacaören Dam, and Lakes Eğirdir Kovada, respectively. As a result, in comparing the developed models with measured daily pan evaporation values, the REP tree model has better agreement with measured daily pan evaporation than other models. The results show the developed model was more accurate.

This work describes the cost efficiency of a solar photovoltaic (PV) pumping system for irrigation system in relation to the most effective traditional power system, a diesel engine. A mathematical model for optimal sizing of a solar PV pumping system is used to estimate the maximum area that can be economically irrigated by the solar PV pumping system. The proposed methodology and model have been applied in two different areas in Croatia Osijek and Split, as paradigms of continental and coastal Croatia as well as European Union. The obtained results show that maximum areas which can be economically irrigated in the Osijek region are greater than in the Split region. Such result indicates that PV irrigation systems can be equally economically applied in relatively cooler climates and with less solar radiation, as well as in a warmer Mediterranean climate.

This paper demonstrated how a modeling approach can be used to find the optimal mix of farmers’ water management practices to improve irrigation efficiency at the tertiary level in collective canal schemes. The approach is developed for the case of the Office du Niger and based on a field study of $3\text{years}$ . First, a simulation model is presented in which all relevant physical and social aspects of water management at the farmers’ level are considered. Next, simulations are performed to evaluate the impact on performance of different combinations of management practices and different external conditions. Finally, the combinations are selected that succeed in limiting seasonal water consumption to $\mathrm{1,400}\mathrm{mm}$ and avoiding irrigation problems, but which are also realistic from a farmer’s point of view. Results demonstrate that in the Office du Niger, where seasonal water consumption per hectare should be reduced by about 30%, a tight control of the tertiary intake in combination with a good maintenance of the tertiary canal should be proposed. Although the model software is built especially for the case of the Office du Niger, the concept of the model can be transferred to other irrigation schemes, as it uses only simple hydraulic principles and limited data input.

A prototype raster geographic information system (GIS) coupled with a decision support submodel for agricultural nitrogen nonpoint source pollution analysis is presented herein. This analysis is an extension of the one-dimensional approach used to simulate and analyze farm production systems and their impact on the environment. The farm system was rasterized into an aggregation of spatial units with homogeneous physical and management characteristics. A crop model to simulate the farm and the environmental response to management alternatives was integrated with this prototype GIS. The system coordinates the running of the crop model on each homogeneous unit and results are passed to a maximum expected utility decision analysis submodel. Only the crop yield and chemical leaching are considered in the decision model. Based on the utility of these two parameters and the probability of realization, the management alternative that potentially leads to the highest yield and lowest nitrogen leaching will be recommended. This prototype model was evaluated with field data from a controlled lettuce production with intense nitrogen application in Arizona. The results achieved compared well with the actual field data including the best management practice recommended for this farm production system.

Regulations for mitigating nonpoint source pollution from small catchments often include requirements for treating a first-flush depth of runoff, either by storing the storm water until it can be treated and released, or by passing it through a filtering device. In either case, the structural measure used to improve water quality needs to be designed or selected to accommodate a flow rate that corresponds to the first-flush runoff depth. An uncomplicated graphical procedure for calculating first-flush design flow rates is presented that is based on standard National Resource Conservation Service rainfall–runoff computation methods in which excess precipitation obtained by applying the runoff curve-number approach to $24\text{-}\mathrm{h}$ design storm storms is transformed to runoff using triangular unit hydrographs. The solution is made dimensionless by grouping parameters, and, as a result, can be condensed into a single graph that provides highly accurate flow rate estimates.

Two methods are developed to estimate rainfall erosivity indices produced by four standard design storms developed by the National Resource Conservation Service (NRCS), which are used widely throughout the United States. The first method is based on regression analysis of erosivity indices calculated from the actual $24\text{-}\mathrm{h}$ duration rainfall distributions and is presented in an uncomplicated form. The second method is founded on fits of an exponential distribution to the ordered rainfall intensities obtained for $6\text{-}\min$ $\left(0.1\text{-}\mathrm{h}\right)$ intervals for each of the design storm types. Subsequent integration of the unit kinetic energy equation used over the storm durations, which makes use of the exponential expression for rainfall intensity, leads to an analytical approximation of the rainfall erosivity index. Although the regression equations estimate erosivity design storms accurately and are easy to apply, they are limited to durations of $24\mathrm{h}$ . The analytical solution, on the other hand, can be used to estimate erosivity indices from the four storm types for any duration of $24\mathrm{h}$ or less.

Researchers used column and flume experiments with uniform silica sand with and without suspended solids to examine the extent and longevity of hydraulic conductivity reduction (HCR) resulting from three anionic polyacrylamide (PAM) application methods, liquid injection, slurry surface, and granular surface application. Low turbidity (0.4 NTU) liquid injection column tests showed 20–65% HCR, likely caused by an extensional viscosity mechanism. HCR increased as turbidity increased, especially at low PAM concentrations. High turbidity (100 NTU) liquid injection column tests showed 66–77% HCR, likely through surficial PAM–clay aggregate filtration. Column and adsorption tests strongly suggest PAM–sand adsorption does not cause substantial HCR. In low turbidity flume tests, PAM slurry application to the sand surface produced up to 100% HCR, likely through a viscosity mechanism, and granular application to the media surface produced up to 100% HCR, likely through fixed surficial polymer gel formation. Hydraulic conductivity returned to control-adjusted pretreatment levels following PAM application in all tests except granular surface application at high mass loads or with high turbidity.

Pivoting was incorporated in the process of solving the linear system of equations that results after discretizing the Saint- Venant equations using the four-point implicit scheme, and applying the Newton–Raphson algorithm to the resulting set of nonlinear equations. Both exchange of rows only (partial pivoting) and exchange of rows and columns (full pivoting) were investigated using the CanalMan hydraulic model. Partial pivoting was used with the LU (lower and upper) decomposition linear equation solver, whereas full pivoting was used with the Gauss–Jordan elimination algorithm. It was demonstrated that the application of partial and full pivoting to the solution of the linear set of equations during Newton–Raphson iterations can make the difference between convergence and divergence of the solution, and should be applied as needed. However, full pivoting should be used only when needed because it slows the simulation considerably.

A computationally simple semianalytical model is proposed for calculating the drawdown due to pumping a well tapping two aquifers separated by an aquiclude with no cross flow. The new model can take into account the transient pumping discharge. Equations are proposed for calculating the transient contributions of the aquifers to the pumped discharge and drawdowns in aquifers. The residual drawdowns in the aquifers and the aquifer contributions during recovery period can also be obtained using the proposed model. Based upon a similar principle, another model is also developed that can consider the effect of the well storage. The proposed models can be used to calculate drawdowns neglecting or considering the well storage, in the case of transient pumping from two aquifers having different values of transmissivity and storage coefficient. It is hoped that the new models would be of help to the field engineers and practitioners.

A zero-pressure isobar is reconstructed in a potential Laplacian field generated by a sink–source pair that models steady-state Darcian seepage from a ponded soil surface to a cavity draining a homogeneous isotropic half-plane. At sufficiently small flow rates (cavity depths under the soil surface) the obtained contour is almost spherical. For a given “sphere” its depth under a constant-head plane is found providing minimal inflow rate.

The economic design of microirrigation and sprinkler laterals requires the use of a combination of diameters of different lengths. The present practice is to solve the basic hydraulic equations using a trial-and-error method for a given allowable head loss. This requires an iterative process that consumes time and limits the accuracy of the solution. Herein is presented a direct analytical approach that gives an exact solution. The method is compared with the trial-and-error approach and found to give the same result.

The flow of water over a trapezoidal, broad-crested, or embankment weir with varying upstream and downstream slopes has been investigated. Data are presented comparing the effect of slopes of $2H:1V$ , $1H:1V$ and vertical in various combinations on the upstream and downstream faces of the weir. Pressure and surface profiles were self-similar for all cases tested. Increasing the upstream slope to the vertical decreased the height of the surface profile and, hence, the static pressure of the crest. It also reduced the discharge coefficient. The variation in downstream static pressures was negligible though. Varying the downstream slope had a negligible effect on the surface and pressure profiles over the weir. Changes in flow were constrained to the region downstream of the crest. Cavitation could occur at the downstream corner of the weir if the upstream head was sufficiently high and a sloped face was used. This paper presents data that will be of use in the design of hydraulic structures for flow control and measurement.

Event hydrologic modeling reveals how a basin responds to an individual rainfall event (e.g., quantity of surface runoff, peak, timing of the peak, detention). In contrast, continuous hydrologic modeling synthesizes hydrologic processes and phenomena (i.e., synthetic responses of the basin to a number of rain events and their cumulative effects) over a longer time period that includes both wet and dry conditions. Thus, fine-scale event hydrologic modeling is particularly useful for understanding detailed hydrologic processes and identifying the relevant parameters that can be further used for coarse-scale continuous modeling, especially when long-term intensive monitoring data are not available or the data are incomplete. Joint event and continuous hydrologic modeling with the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) is discussed in this technical note and an application to the Mona Lake watershed in west Michigan is presented. Specifically, four rainfall events were selected for calibrating/verifying the event model and identifying model parameters. The calibrated parameters were then used in the continuous hydrologic model. The Soil Conservation Service curve number and soil moisture accounting methods in HEC-HMS were used for simulating surface runoff in the event and continuous models, respectively, and the relationship between the two rainfall-runoff models was analyzed. The simulations provided hydrologic details about quantity, variability, and sources of runoff in the watershed. The model output suggests that the fine-scale ( $5\min$ time step) event hydrologic modeling, supported by intensive field data, is useful for improving the coarse-scale (hourly time step) continuous modeling by providing more accurate and well-calibrated parameters.