Evaluation of various quick methods for estimating furrow and border infiltration parameters

For estimating infiltration properties of surface irrigation, some ‘quick’ and easy methods have been developed. The main objective of this study was to evaluate different ‘quick’ methods and to compare the obtained results with two new methods proposed based on the Shepard one-point approach. For this purpose, data sets measured in six borders and five furrows were used for evaluating different methods. Using the volume balance equation and estimated infiltration parameters, the total infiltrated volume and advance times were predicted to evaluate the accuracy of estimated infiltration parameters. The results showed that the modified Mailapalli and Elliott and Walker methods provided the lowest errors for both furrow and border irrigations. The Elliott and Walker method predicted advance times with highest accuracy. There was very small difference between the Shepard and new proposed one-point methods. The performance of the Elliott and Walker method was slightly better than the new proposed two-point method for the experimental furrows, while a minor difference was found for the experimental borders. The results also showed that the performance of the Elliot and Walker method would be improved using binomial approximation instead of Kiefer approximation.     

Simple mathematical model for water advance determination

The explicit volume balance model was modified and combined with the motion equation of the zero inertia to predict water advance in border irrigation. A system of dimensionless notation was used to obtain implicit and explicit solutions of the model. This model is simpler than previously used models, yet maintains a high degree of accuracy. The proposed model requires no programming and can easily be performed using a hand calculator. The outcomes of the proposed model were comparable to those of the more sophisticated zero inertia model. Using well-documented field examples, the proposed model provided acceptable results, implying that it could be used in practice to determine the advance distance with insignificant errors. In addition, the model is applicable to conditions under which the traditional volume balance model fails.     

Modeling and error analysis of kinematic-wave equations of furrow irrigation

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.     

Performance of three infiltration models under surge irrigation

Three models were developed to predict infiltration under a surge-flow irrigation regime. One model (2P) utilized the Kostiakov-Lewis infiltration equation. The other two models (2PF and 3P) utilized the modified Kostiakov-Lewis infiltration equation. All three models combined continuous-flow furrow irrigation volume-balance hydraulic models presented by Reddell and Latortue (1986, 1988) with a numerical variation of the Cycle Ratio-Time Model (CRTM) for surge irrigation presented by Blair and Smerdon (1987). The volume–balance component of the models estimated the soil's continuous-flow furrow irrigation infiltration function using first surge-cycle advance data. The numerical CRTM component used the estimated infiltration function in conjunction with the surge-flow irrigation infiltration opportunity-time to predict infiltration. An assessment of overall model accuracy was based upon an infiltrated volume root mean square error (RMSE) statistic. Overall, the 2PF model returned the lowest RMSE values and the 3P model was the next most accurate. The 2P model was the least accurate. While the 2PF model was the most accurate, this model has limited applicability since it requires inflow and outflow measurements throughout an irrigation event to evaluate the soil's basic infiltration constant. Despite its good overall performance, anomalous results from the 3P model suggest that further testing is needed. Although the 2P model was the least accurate of the three models evaluated here, and although it consistently underpredicted infiltration, it appears to be the most stable and effective of the three models evaluated. Received: 22 May 2000     

畦田灌溉水流演进计算简化模型研究

在对水量平衡模型进行修改的基础上,结合零惯量运动方程,以水量平衡方程为基础,对畦灌水流演进模型的结构进行了研究。应用无因次系统模型,求得了模型的显式和隐式解。该模型可以用来计算畦灌水流演进距离。对山东省陈垓引黄灌区畦灌水流演进计算结果表明,该模型比以往使用的模型简单,计算精度与较复杂的零惯量模型的计算精度相当。模型计算不需编程,可以用手算完成全部计算过程,解决了传统的水量平衡模型无法解决的问题。     

Accounting for temporal inflow variation in the inverse solution for infiltration in surface irrigation

A simple modification of the volume balance equation of the IPARM model is presented to facilitate the use of variable inflow. Traditional approaches for estimating infiltration from advance and/or runoff have merely considered the constant or step inflow case. Whenever this assumption is violated, significant uncertainty is introduced into the estimated infiltration parameters. Evaluation of the procedure with a number of data sets has demonstrated significant improvements in the estimates of infiltration parameters. Furthermore, the technique has shown that a portion of the apparent variability in estimated soil intake rates between furrows in the same field is a consequence of the constant inflow assumption. Accounting for the variable inflow to estimate infiltration functions, both standardised the shape of the infiltration curve and reduced the magnitude of the variation between curves. The proposed technique remains restricted by limitations similar to that of other volume balance models but offers greater performance under typical inflow variations often experienced in practice.     

Infiltration parameters from optimisation on furrow irrigation advance data

Knowledge of the soil infiltration parameters is necessary for efficient furrow irrigation. A method is proposed for the determination of the parameters in the Kostiakov-Lewis infiltration equation from measurements of the furrow irrigation advance and inflow. The method employs a volume balance model using optimisation to minimise the error between the predicted and measured advance and differs from existing approaches in that only advance data and inflow rates are required. The average cross sectional area of the furrow and the final infiltration rate are treated as fitted parameters and need not be measured. A simple but effective optimisation algorithm is developed which allows for the solution of the four parameters without user input. The speed and simplicity of the optimisation may lead to application in real-time control of furrow irrigation. Received: 16 August 1995     

基于非恒定渐变流-急变流方程的变流量畦灌数值模型

传统畦灌模型多是基于非恒定渐变流方程建立的,在模拟变流量畦灌水流运动时的精度难以保障。本文综合分析了变流量畦灌过程中田面水流的运动状况,将其按照边界条件的不同划分为恒定流量进水阶段、变流量进水阶段、畦首消退阶段、田面消退第1阶段、田面消退第2阶段等5个阶段,基于非恒定渐变流方程和非恒定急变流方程构建了适用于变流量畦灌系统的渐变流-急变流数值模型,通过2组恒定流量畦灌、4组变流量畦灌的田间试验以及2组文献资料中的畦灌试验数据对模型进行了验证。结果表明,渐变流-急变流畦灌模型模拟值与现场实测结果吻合较好,模拟推进时间决定系数R2均大于0.96、模拟消退时间R2大于0.90。与目前常用的WinSRFR模型相比,渐变流-急变流畦灌数值模型在模拟恒定流量畦灌方面具有相似的精度,且在模拟变流量畦灌方面精度更高。渐变流-急变流畦灌模型可以较精准地模拟变流量畦灌的水流运动状况,可为分析变流量畦灌系统、优化变流量畦灌方案提供支撑。     

Furrow infiltration estimation from time to a single advance point

A simple and quick method to determine the Soil Conservation Service (SCS) intake function in furrow irrigation is presented. The time of advance at only one location of the field, inflow rate, and average flow area are the only field data required to estimate the two parameters of the SCS infiltration equation. The dependence of the two intake parameters, k and α, of the SCS intake function was expressed analytically and then the single unknown intake parameter of the SCS function, α, could be determined by applying a volume–balance (VB) equation using a power advance assumption. Estimates of infiltration by the proposed method were compared with measured furrow infiltration data and a recently developed one-point method which uses the two parameter Philip infiltration equation, but is restricted by an assumption that the advance trajectory follows the power function with the exponent of 1/2. It is shown that the proposed one-point method can give more accurate results than the previous one-point method.     

Infiltration parameters from surface irrigation advance and run-off data

A computer model was developed to employ runoff data in the calculation of the infiltration parameters of the modified Kostiakov equation. The model (IPARM) uses a simple volume balance approach to estimate the parameters from commonly collected field data. Several data sets have been used to verify the procedure. Infiltration parameters were calculated using both advance and runoff data combined and advance data alone. Simulations of each example using SIRMOD were compared to the measured data to identify the possible benefits of the procedure. The inclusion of runoff did not compromise the ability to reproduce the advance curve however the simulations are more capable of reproducing the measured runoff rates and volumes and therefore offer better estimations of the total volume applied to the soil (in one case a reduction in error of the total infiltration from 22% to 1%). This procedure will be of most benefit where the infiltration parameters are expected to represent soil hydraulic characteristics for times greater than the completion of the advance phase. Further analysis has shown that the infiltration parameters are more sensitive to runoff than the advance highlighting the requirement for accurate field measurement and a weighting factor between the advance and runoff errors.     

Development of an adaptive surface irrigation system

Cablegation is a simple system for automating surface irrigation in small- and medium-sized fields using a gated pipe. In this work, a Programmable Logic Control, PLC, was used to develop an adaptive cablegation system capable of establishing the infiltration equation in real time and then adjusting the irrigation times to the infiltration rate and field geometry. A controlling program was developed for the on-field determination of the infiltration equation, simulation of advance in each furrow, and the optimization and management of the irrigation event. The equipment was tested in three experimental stations, including a Luvissol field organized in contour terraces with furrows of various lengths. The results demonstrate the capability of the system to adapt the application times to the different furrow lengths and the gradual decrease in the soil infiltration and to recommend an application depth that optimizes the Application Efficiency. Various improvements were made to this solar-powered cablegation, resulting in a reliable surface irrigation system capable of unsupervised operation.     

Operative irrigation modelling for real-time applications on closed-end furrows

The complexity of physical phenomena in furrow irrigation,where numerous parameters vary with time and space, makeempirical models more operative than mechanistic models forimproving irrigation efficiency. In addition, when theseempirical models are well adapted for real-time calibration onadvance trajectory, they can be considered an efficient toolto predict irrigation performance.In the first section of this paper, the selection of operativefurrow irrigation modelling for real-time applications isdiscussed. Models derived from Horton and linear infiltrationequations through the water balance equation (WBE) arepreferred to those derived from the 2-term Philips equationand to the solution of WBE involving both the power advancefunction and Kostiakovs extended equation.The second section shows that simplified analytical modellingoptions can be added to the basic advance-infiltration modelfor improving irrigation efficiency. The modelling optiondeveloped in this paper concerns the prediction of cutoff timeand irrigation performance for closed-end furrows (CEF).The simplified analytical model for CEF based on the massconservation principle is successfully compared to field testsand numerical simulations.     

Prediction of surface irrigation advance using soil intake properties

A simple method for predicting surface irrigation advance trajectories using infiltration parameters and inflow rate as inputs was developed. The difference between the inflow rate and the sum of infiltration rates over the wetted portion of the field equals the flow rate available for advance. An average (characteristic) infiltration rate ahead of the wet portion is computed using a fixed time step. An advance step (for a fixed time step) is calculated from the ratio of the flow rate available for advance and characteristic infiltration rate. Predictions of advance by the proposed method were compared with field observations, with the kinematic wave model, and with analytical solutions of Philip and Farrell (1964). In all cases, the method provided predictions that were in good agreement with field observations, and performed similarly to the kinematic wave model. The method offers a simple and efficient tool for prediction and evaluation of surface irrigation systems under various soil types and variable inflow rates. The method is particularly useful for predictions in fields with spatially and temporally variable intake properties.     

Estimation of advance and infiltration equations in furrow irrigation for untested discharges

The exponents of the advance and infiltration power laws have been shown to remain practically constant for different furrow irrigation discharges. Under this hypothesis, a procedure to estimate the advance and infiltration equations corresponding to untested discharges was developed. The proposed procedure was validated with different field experiments, obtaining satisfactory results for non-erosive discharges. However, significant deviations were obtained when erosive discharges were used. This behavior corroborates the hypothesis presented by some authors that the erosion and sedimentation processes occurring in furrow irrigation as a consequence of high surface velocities can reduce—and even suppress—the effect of the wetted perimeter on the infiltration rate. Finally, an equation was derived to predict the effect of the wetted perimeter on the infiltration parameters.     

Using a furrow system for surface drainage under unsteady rain

Water excess during winter limits crop development on heavy clay soil conditions of the Gharb valley (Morocco). The furrow system to eliminate these negative effects is the adopted solution. This article focuses on the development of a water transfer model through a furrow system during unsteady rainfall event to evaluate the runoff volume resulting from a reference rainy event. This model contains a production function associated to a transfer function. The production function is based on the Green-Ampt infiltration equation. The latter has been adapted to account for unsteady rain conditions and rainfall intermittence. The transfer function is based on the kinematic wave model, the explicit solution of which is coupled with the water excess generated by the production function. Simulated runoff in the furrows is collected by a drainage ditch evacuating the flow outside a plot of 1.3 ha. The similarity between parameters of a furrow irrigation model and those of the production function is advantageously used for model calibration.The proposed modelling approach shows capabilities to predict water amount and peak discharges evacuated from a plot of around 1 ha by a furrow system under unsteady rainfall events. As an application, it is used to evaluate the ability of the surface drainage system to evacuate the excessive volumes of water under typical rainfalls.     

A spreadsheet model to evaluate sloping furrow irrigation accounting for infiltration variability

A spreadsheet model was developed to evaluate the performance of furrow irrigation that accounts for soil variability and requires few field measurements. The model adjusts an advance trajectory to three (advance distance, advance time) points and, similarly, it adjusts a recession trajectory to three (recession distance, recession time) points. The head of the furrow (distance = 0) is one of the points used to adjust both trajectories. It then calculates the parameters of the infiltration equation using the two-point method (based on the volume balance equation with assumed surface shape parameters). The model gives the option to enter an estimate of the soil infiltration variability in order to account for this variation when calculating irrigation performance indicators. The combination of variance technique was used for this purpose. A set of irrigation performance indicators (distribution uniformity, application efficiency, tail water ratio, deep percolation ratio and deficit coefficient) is calculated, assuming that the infiltrated water follows a normal frequency distribution. To illustrate the evaluation method, it was applied to three irrigation events conducted on a sunflower field, with 234 m long furrows spaced 0.75 m apart. The evaluations were performed in two 3-furrow sets. The application efficiency was satisfactory in the first irrigation, but low in the other two. Uniformity was high in all three irrigations. The performance indicator that was most affected by soil variability was distribution uniformity. Considering soil spatial variability was important for more realistic determination of the infiltrated water distribution, and therefore of the deep percolation, but it had less importance for the determination of the application efficiency, due to the relevance of runoff in our field application.     

Effects of sand column, furrow and supplemental irrigation on agricultural production in an arid environment

The effects of supplemental irrigation, sand columns and blocked furrows on soil water distribution and barley yield were studied on arid soils affected by surface crusts. The sand columns were 50 mm diameter, 600 mm deep, and filled with sand of 0.375 mm mean diameter. The blocked furrows were trenches about 250 mm deep, 300 mm wide, and 6 m long established perpendicular to the slope direction. Sand column and furrow treatments significantly increased soil water storage compared with natural or control treatments. Soil water storage significantly increased by about 210% and 230% near the center of the sand column and the furrow treatments, respectively, relative to the control treatment. For sand column treatments, soil water storage decreased linearly with distance from the center of the sand column to about 2.5 m, while for the furrow treatment soil water storage decreased logarithmically to a distance of about 1.0 m, beyond which the soil water storage was not significantly different from the natural or control treatments. The furrow and sand column treatments significantly increased the water application efficiency, seasonal consumptive use and barley grain and straw yields compared with natural and control treatments. Increasing furrow spacing increased the catchment area and consequently crop production per furrow, but decreased crop production per unit total (cultivated and catchment) area. Decreasing sand column spacing reduced surface runoff and increased soil water storage and consequently barley grain and straw yields. Supplemental irrigation is essential for grain production in limited rainfall areas. Soil management is also required to overcome the problems of the soil surface crusting and the low permeability of subsurface soil layers for maximum rainwater efficiency, and for optimal crop production with minimum supplemental irrigation water. Where agricultural land is not limited, furrowed soil surfaces appear to be the most suitable technique for barley grain production. Sand columns with sprinkler irrigation might be more suitable for growing barley as forage crop where agricultural land is limited. Received: 19 October 1998     

Performance Evaluation of Border Irrigation Models for South-East Australia: Part 2, Overall Suitability for Field Applications

The first paper in this two part paper provided details of six border irrigation models, namely Jobling-Turner, Strelkoff, Walker, Jaynes, Schmitz and Ross, field experiments and the procedure for evaluating the models as well as their performance for predicting advance and recession characteristics. In this paper, depending on their output details, some or all of these models are further examined for infiltration and runoff predictions, computational time and volume balance error. Also, the Strelkoff and Ross models are examined for the discharge-depth equation as an alternative to the Manning equation for describing overland flow in surface irrigation. Considering the overall accuracy of the model predictions, output details and user-friendliness, the Strelkoff model is concluded to be the most satisfactory for the field conditions of south-east Australia.     

基于轻量级无锚点深度卷积神经网络的树上苹果检测模型

为提高现有苹果目标检测模型在硬件资源受限制条件下的性能和适应性,实现在保持较高检测精度的同时,减轻模型计算量,降低检测耗时,减少模型计算和存储资源占用的目的,本研究通过改进轻量级的MobileNetV3网络,结合关键点预测的目标检测网络（CenterNet）,构建了用于苹果检测的轻量级无锚点深度学习网络模型（M-CenterNet）,并通过与CenterNet和单次多重检测器（Single Shot Multibox Detector,SSD）网络比较了模型的检测精度、模型容量和运行速度等方面的综合性能。对模型的测试结果表明,本研究模型的平均精度、误检率和漏检率分别为88.9%、10.9%和5.8%;模型体积和帧率分别为14.2MB和8.1fps;在不同光照方向、不同远近距离、不同受遮挡程度和不同果实数量等条件下有较好的果实检测效果和适应能力。在检测精度相当的情况下,所提网络模型体积仅为CenterNet网络的1/4;相比于SSD网络,所提网络模型的AP提升了3.9%,模型体积降低了84.3%;本网络模型在CPU环境中的运行速度比CenterNet和SSD网络提高了近1倍。研究结果可为非结构环境下果园作业平台的轻量化果实目标检测模型研究提供新的思路。     

Irrigation management in arid areas affected by surface crust

The effects of supplemental irrigation and irrigation practices on soil water storage and barley crop yield were studied for a crust-forming soil at the University of Jordan Research Station near Al-Muwaqqar village during the 1996/97 growing season. An amount of 0.0, 48.9, 73.3, 122.2 and 167 mm supplemental irrigation water were applied. The 48.9, 73.3 and 122.2 mm applications were applied through surface irrigation into furrows with blocked ends, and the 0.0 and 167 mm applications via sprinkler irrigation. The greatest water infiltration and subsequent soil storage was achieved with the 122.2 mm application followed by the 73.3 mm irrigation, both surface applied. Application efficiency (the fraction of applied water that infiltrated into the soil and stored in the 600 mm soil profile) and soil water storage associated with supplemental blocked furrow irrigation was significantly greater than with supplemental sprinkler irrigation. For arid zone soil, which has little or no structural stability, application of supplemental irrigation water via short, blocked-end furrows prevents runoff and increases the opportunity time for infiltration, thereby increasing the amount of applied water that is infiltrated into the soil and stored in the soil profile. Supplemental irrigation, applied by a low-rate sprinkler system, was not as effective because of the low infiltration rates that resulted from the development of a surface throttle due to dispersion of soil aggregates at the soil surface. The differences in stored water had a significant effect on grain and straw yields of barley. Without supplemental irrigation, barley grain and straw yields were zero in natural rainfall cultivation with a total rainfall of 136.5 mm. Barley yields in the control treatment, with a 167 mm supplemental sprinkler irrigation were low being 0.19 and 1.09 ton/ha of barley grain and straw, respectively. Supplemental irrigation through blocked-end furrows increased barley grain and straw yields significantly compared with supplemental sprinkler irrigation to a maximum of 0.59 and 1.8 ton/ha, respectively. The improvement coming from the increased water storage associated with furrows. Since irrigation water is very limited if available, farmers are encouraged to form such furrows for reducing runoff from rainfall thereby increasing the amount of water available for forage and field crop production.