Sediment transport in furrow irrigation

Irrigation-induced erosion in furrow irrigation causes loss of fertile soil and water quality degradation. Hence, quantification of irrigation-induced erosion is essential for efficient management of furrow irrigation. In this study, sediment transport was studied under bare and cropped field conditions for a furrow plot consisting of three parabolic shaped furrows of 40 m long and 0.5% slope. The inflow rates of 0.2, 0.3, 0.4 and 0.5 L s⁻¹; and 0.3, 0.4, 0.5, 0.6 and 0.7 L s⁻¹ were used for bare and cropped field conditions, respectively. The furrow cross section measured at every 5 m distance from the head end (before and after the irrigation event) was used to study the erosion pattern (erosion/deposition) along the furrow. The runoff collected at regular intervals of 10 min was used to study the sediment load. The total sediment export for an irrigation event was estimated using furrow cross-section data (FCD) and the sediment rate data (SRD), and compared with the total sediments collected at the tail end. For both bare and cropped conditions, soil erosion took place at the head and tail ends (free drain system), while the deposition occurred at the middle. The sediment transport increased initially and slightly decreased with time. A power relationship was obtained between the total sediment export and the inflow rate for bare furrow condition, whereas a linear relationship between these parameters was obtained for cropped field condition. The relative percentage errors suggested that both SRD and FCD methods can be used to estimate total sediment export from the field. The analysis (PSD) of the total sediments revealed that the geometric mean diameter of the sediment particle was 0.18 and 0.20 mm for bare and cropped field conditions, respectively.     

Forecasting and optimizing furrow irrigation management decision variables

Furrow irrigation can be better managed if the management decision variables (irrigation time and amount; inflow rate and cutoff) can be determined ahead of time. In this study, these decision variables were forecast and optimized using 1 day ahead grass reference crop evapotranspiration (ET₀) forecasts, based on the ARMA (1,1) time-series model, with a seasonal furrow irrigation model for both homogeneous and heterogeneous infiltration conditions. Heterogeneity in infiltration characteristics was restricted to variations along the furrow length as opposed to variations between furrows. The results obtained were compared with their counterparts using the observed ET₀ for the same period during the 1992 cropping season. Seasonal performance (application efficiency, inflow, runoff and deep percolation volumes) and economic return to water (yield benefits minus seasonal water related and labor costs) were affected by infiltration conditions, while irrigation requirement and bean yield were unchanged. In a given infiltration case, seasonal performance, irrigation schedules, bean yield and economic return to water were comparable (lower than 4% difference) for the two ET₀ conditions. For each ET₀ condition, individual irrigation events resulted in different irrigation designs (inflow rate and cutoff time) except inflow rates with heterogeneous infiltration. Differences in inflow volume were less than 2% and 5%, respectively, for homogeneous infiltration and heterogeneous infiltration. For the conditions studied, furrow irrigation management decision variables can be forecast and optimized to better manage the irrigation system, because irrigation performance was the same for both (forecast and observed) ET₀ cases. Received: 9 October 1999     

Soil water in relation to irrigation, water uptake and potato yield in a humid climate

Efficiently controlling soil water content with irrigation is essential for water conservation and often improves potato yield. Volumetric soil water content (θ_v) in relation to irrigation, plant uptake, and yield in potato hills and replicated plots was studied to evaluate four water management options. Measurements of θ_v using a hammer driven probe were used to derive a θ_v index representing the relative θ_v status of replicated plots positioned along a hill slope. Time series for θ_v were determined using time domain reflectometry (TDR) probes at 5 and 15 cm depths at the center, shoulder, and furrow locations in potato hills. Sap flow was determined using flow collars in replicated field plots for four treatments: un-irrigated, sprinkler, surface drip, and sub-surface drip irrigation (40 cm depth). Irrigated yields were high/low as the θ_v index was low/high suggesting θ_v excess was a production problem in the wetter portions of the study area. The diurnal pattern of sap flow was reflected in the θ_v fluctuation it induces at hill locations with appreciable uptake. Hill locations with higher plant uptake were drier as was the case for the 5 cm (dry) depth relative to the 15 cm (wet) depth and for locations in the hill (dry) relative to the furrow (wet). The surface drip system had the lowest water use requirement because it delivers water directly to the hill locations where uptake is greatest. The sub-surface drip system wetted the hill gradually (1-2 days). Measurement of the θ_v index prior to experimental establishment could improve future experimental design for treatment comparisons.     

Comparison of surge and continuous furrow methods for cotton in the Harran plain

This study compares surge flow with conventional steady flow irrigation in 130–160 m field lengths in order to analyze the potential of the former for reducing deep percolation and tailwater runoff together with the improvement of irrigation efficiency. The field experiment comprises of four surge treatments with two inflow rates of 0.0498 and 0.12 m³/min (Q₁ and Q₂), and two cycle ratios of 0.33 and 0.50 (CR₁ and CR₂), respectively, with 30 min on-times, along with two steady flow treatments with the same inflow rates. Surge flow irrigation of the level furrows was successfully managed under the field conditions with decreases in the total water applications (2–22%) and the water intake (14–25%), except in the treatments of surge S₁₁ (Q₁ CR₁) with 9% increase in the latter together with 21–38% decrease in the tailwater runoff and 19–70% decrease in the calculated deep percolation below the root zone of 1.20 m depending on inflow rates and cycle ratios of the permeable Harran soils. Surge flow reduced the water intake of a surface soil loosened by tillage by 13–23% as compared to continuous flow, thus manifesting an incomparable advantage to the level furrow systems.     

贺兰山东麓砂质酿酒葡萄园土壤水分分布研究

针对贺兰山东麓砂质酿酒葡萄园漏水漏肥,水分利用率低等问题,采用田间试验,分别设置沟灌、单管滴灌和双管滴灌的方式,研究土壤水分分布及葡萄需水规律,从而制定适宜的灌溉制度。结果表明,沟灌水分下渗基本在70cm内的根系分布层,灌溉后期含水率低,灌溉周期为13d;双管滴灌水平侧渗区域主要集中在20～45cm的葡萄毛根活动区域,垂直入渗在在60cm根系分布区内,灌溉周期为9d;单管滴灌垂直下渗速率高于侧渗速率,灌溉周期为7d。单管滴灌方式便于大规模的葡萄机械化管理,最佳水分管理方式为增加单次灌溉时间让单次灌水量达到450m3/hm2。     

Simulation of furrow irrigation practices (SOFIP): a field-scale modelling of water management and crop yield for furrow irrigation

Because of the spatial and temporal variabilities of the advance infiltration process, furrow irrigation investigations should not be limited to a single furrow irrigation event when using a modelling approach. The paper deals with the development and application of simulation of furrow irrigation practices (SOFIP), a model used to analyse furrow irrigation practices that take into account spatial and temporal variabilities of the advance infiltration process. SOFIP can be used to compare alternative furrow irrigation management strategies and find options that mitigate local deep-percolation risks while ensuring a crop yield level that is acceptable to the farmer. The model is comprised of three distinct modelling elements. The first element is RAIEOPT, a hydraulic model that predicts the advance infiltration process. Infiltration prediction in RAIEOPT depends on a soil moisture deficit parameter. PILOTE, a crop model, which is designed to simulate soil water balance and predict yield values, updates the soil moisture parameter. This parameter is an input of a parameter generator (PG), the third model component, which in turn provides RAIEOPT with the data required to simulate irrigation at the scale of an N-furrow set. The study of sources of variability and their impact on irrigation advance, based on field observations, allowed us to build a robust PG. Model applications show that irrigation practices must account for inter-furrow advance variability when optimising furrow irrigation systems. The impact of advance variability on deep percolation and crop yield losses depends on both climatic conditions and irrigation practices.     

Optimization of furrow irrigation schedules,designs and net return to water

A seasonal furrow irrigation model consisting of irrigation scheduling and kinematic-wave-based hydraulic submodels was modified to incorporate an economic optimization submodel. The model used a systematic simulation technique to optimize furrow irrigation schedules and designs assuming 80% irrigation adequacy at cutoff time. The irrigation schedules and designs were optimized for the homogeneous and heterogeneous infiltration under the mean and observed ET_o (grass reference crop ET) conditions. The optimal management allowable depletion (MAD) level changed with the variation in ET_o condition, and with the consideration of spatial and temporal (seasonal) variability in infiltration characteristics. Irrigation design changed with both infiltration conditions and MAD level. Infiltration variability did not influence the bean yield. However, the return to water decreased when spatial variability in infiltration conditions was considered. Using mean ET_o resulted in slightly higher yield and net return to water as compared to using observed ET_o. A small variation in daily mean ET_o values with respect to daily observed ET_o values caused a change in both irrigation schedules and designs. Therefore, mean ET_o cannot be used to forecast irrigation schedules and designs at the beginning of crop season. The net return to water increased (1.7 to 3.6%), and the seasonal inflow, losses, and bean yield decreased in the case of variable interval scheduling (holding MAD constant) as compared to the fixed interval scheduling (MAD varies).     

Yield and quality of two tomato (Solanum lycopersicum L.) cultivars as influenced by drip and furrow irrigation using waters having high residual sodium carbonate

Performance of tomato when irrigated with sodic waters particularly under drip irrigation is not well known. A field experiment was conducted for 3 years to study the response of tomato crop to sodic water irrigation on a sandy loam soil. Irrigation waters having 0, 5 and 10 mmol_c L⁻¹ residual sodium carbonate (RSC) were applied through drip and furrow irrigation to two tomato cultivars, Edkawi (a salt tolerant cultivar) and Punjab Chhuhara (PC). High RSC of irrigation water significantly increased soil pH, ECe and exchangeable sodium percentage progressively; the increases were higher in furrow compared to drip irrigation. Effect of high RSC on increasing bulk density and decreasing infiltration rate of soil was also pronounced in furrow-irrigated plots. Higher soil moisture and lower salinity near the plant was maintained under drip irrigation than under furrow irrigation. Performance of the two cultivars was significantly different; pooled over 2002–03 and 2003–04 seasons, PC yielded 38.8 and 30.0 Mg ha⁻¹ and Edkawi yielded 31.8 and 22.9 Mg ha⁻¹ under drip and furrow irrigation, respectively. At RSC10, cultivar PC produced 38 and 46% higher fruit yield than cultivar Edkawi under drip and furrow irrigation, respectively. Reduction in fruit yield at higher RSC was due to lower fruit weight under drip irrigation and due to reduced fruit number as well as fruit weight under furrow irrigation. Decrease in fruit weight was more pronounced in cultivar Edkawi than in cultivar PC. Increase in RSC lowered quality of the fruits except the ascorbic acid content. High RSC under drip irrigation, in general, had lesser deteriorating effect on the fruit quality particularly for cultivar PC than under furrow irrigation. For obtaining high tomato yield and better-quality fruits using high RSC sodic waters, drip irrigation should be preferred over furrow irrigation. Better performance of local cultivar PC compared to Edkawi at medium and high RSC suggests that cultivars categorized as tolerant to salinity should be evaluated in the sodic environment particularly when irrigated with high RSC sodic waters.     

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.     

Effects of water infiltration and storage in cultivated soil on surface irrigation

Surface irrigation analysis and design require the knowledge of the variation of the cumulative infiltration water Z (L) (per unit area) into the soil as a function of the infiltration time t (T). The purpose of this study is to evaluate water infiltration and storage under surface irrigation in an alluvial clay soil cultivated with grape yield, and to determine if partially wetted furrow irrigation has more efficient water storage and infiltration than traditional border irrigation. The two irrigation components considered were wet (WT) and dry (DT) treatments, at which water applied when available soil water reached 65% and 50%, and the traditional border irrigation control. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. The infiltration (cumulative depth, Z and rate, I) was functioned to opportunity time (t_o) in minute for WT and DT treatments as: Z_WT = 0.528 t_o^0.6, Z_DT = 1.2 t_o^0.501, I_WT = 19 t_o^−0.4, and I_DT = 36 t_o^−0.498. The irrigation efficiency and soil water distribution have been evaluated using linear distribution and relative schedule depth. Coefficient of variation (CV) was 5.2 and 9.5% for WT and DT under furrow irrigation system comparing with 7.8% in border, respectively. Water was deeply percolated as 11.88 and 19.2% for wet and dry furrow treatments, respectively, compared with 12.8% for control, with no deficit in the irrigated area. Partially wetted furrow irrigation had greater water-efficiency and grape yield than both dry furrow and traditional border irrigations, where application efficiency achieved as 88.1% for wet furrow irrigation that achieved high grape fruit yield (30.71 Mg/ha) and water use efficiency 11.9 kg/m³.     

扶埂开沟膜下灌对土壤水分分布的影响

为探明扶埂开沟膜下灌条件对作物土壤水分分布以及经济效益的影响,以温室番茄为研究对象,采用完全随机试验设计方法,通过时域反射仪进行水分观测,研究扶埂开沟膜下灌条件下土壤水分分布规律,以及该灌溉方式对温室番茄经济效益的影响.结果表明:扶埂开沟膜下灌,垄背的土壤剖面达到最大含水量时间迟于垄沟以及垄坡,垄背剖面观测点在灌水后184 h;在扶埂开沟膜下灌条件下,温室番茄在苗期内进行缺水灌溉的IWUE最大达到34.925 kg/(hm²·mm^-1), 产量与商果率均较高,综合产生的净收入最高,经济效益达到最大值.     

Assessing impacts of surge-flow irrigation on water saving and productivity of cotton

To improve water saving and conservation in irrigated agriculture, a range of field evaluation experiments was carried out with various furrow irrigation treatments in cotton fields to estimate the possibilities of improving furrow irrigation performances under conditions of Central Fergana Valley, Uzbekistan. The research consisted in comparing surge and continuous-flow in long furrows and adopting alternate-furrow irrigation. The best results were achieved with surge-flow irrigation applied to alternate furrows. Field data allowed the calibration of a surface irrigation model that was used to identify alternative management issues. Results identified the need to better adjust inflow rates to soil infiltration conditions, cut-off times to the soil water deficits and improving irrigation scheduling. The best irrigation water productivity (0.61 kg m⁻³) was achieved with surge-flow on alternate furrows, which reduced irrigation water use by 44% (390 mm) and led to high application efficiency, near 85%. Results demonstrated the possibility for applying deficit irrigation in this region.     

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     

Cotton yields under different furrow irrigation management techniques in the Southeastern Anatolia Project (GAP) area,Turkey

The continuous flow furrow irrigation (COFFI), surge flow furrow irrigation (SUFFI), cutback flow furrow irrigation (CUFFI), variable alternate flow furrow irrigation (VAFFI), and tail water reuse system furrow (TWRSF) techniques with the same inflow rate of 0.072 m³ min⁻¹ were compared in relation to the cotton yield and water use efficiency at a 3-year field study conducted on cotton (Gossypium spp.) in the Southeastern Anatolia Project (GAP) area of Turkey. Yields revealed significant statistical differences between the furrow management techniques (P < 0.05). The maximum yield was obtained from the COFFI treatment (2,630 and 2,920 kg ha⁻¹) in the first 2 years, and from SUFFI and CUFFI treatments (3,690 and 3,780 kg ha⁻¹, respectively) in the last year. There were significant yield reductions, which varied from 10 to 35% in TWRSF and from 11 to 19% in VAFFI treatments although 43 and 28% more water was applied to the TWRSF than to CUFFI and SUFFI treatments, respectively. The average total water use efficiencies (WUE_ET) varied from 4.14 (VAFFI) to 2.59 (COFFI). The corresponding values were 0.37 and 0.36 kg ha⁻¹ m⁻³ for CUFFI and SUFFI, respectively. The average irrigation water use efficiency (WUE_IR) for CUFFI and SUFFI treatments were 0.30 and 0.23 kg ha⁻¹ m⁻³, respectively.     

Evaluation of surface irrigation as a function of water infiltration in cultivated soils in the Nile Delta

As sources of irrigation water are decreasing, efficient use of surface irrigation is essential. The purpose of this study is to determine if partially-wetted furrow irrigation has more efficient water storage and infiltration than traditional border irrigation in an alluvial clay soil under cultivated grape production. The two irrigation components considered were wet (WT) and dry (DT) treatments, at which water was applied when available soil water reached 65 % and 50 %, and the traditional border irrigation control. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. Coefficient of variation (CV) was 5.2 and 9.5 % for WT and DT under furrow irrigation system comparing with 7.8 % in border, respectively. Water was deeply percolated as 11.9 and 19.2 % for wet and dry furrow treatments respectively, compared with 12.8 % for control, with no deficit in the irrigated area. Partially-wetted furrow irrigation had greater water-efficiency and grape yield than dry furrow and traditional border irrigation, where application efficiency achieved as 88.1 % for wet furrow irrigation that achieved high grape fruit yield (30.71 Mg /ha). The infiltration (cumulative depth, Z and rate, I) was functioned to opportunity time (t ₀ ) in minute for WT and DT treatments as: Z _WT ?=?0.528?t ₀ ^0.6, Z _DT ?=?1.2?t ₀ ^0.501, I _WT ?=?19?t ₀ ^?0.4, I _DT ?=?36?t ₀ ^?0.498. Empirical power form equations were obtained for measured advance and recession times along the furrow length during the irrigation stages of advance, storage, depletion and recession. The irrigation parameters and coefficients, and soil water distribution have been also evaluated.     

Estimating the furrow infiltration characteristic from a single advance point

Management and control of surface irrigation, in particular furrow irrigation, is limited by spatio-temporal soil infiltration variability as well as the high cost and time associated with collecting intensive field data for estimation of the infiltration characteristics. Recent work has proposed scaling the commonly used infiltration function by using a model infiltration curve and a single advance point for every other furrow in an irrigation event. Scaling factors were calculated for a series of furrows at two sites and at four points down the length of the field (0.25 L, 0.5 L, 0.75 L and L). Differences in the value of the scaling factor with distance were found to be a function of the shape of the advance curves. It is concluded that use of points early in the advance results in a substantial loss of accuracy and should be avoided. The scaling factor was also strongly correlated with the furrow-wetted perimeter suggesting that the scaling is an appropriate way of both predicting and accommodating the effect of the hydraulic variability.     

宽垄沟灌覆膜条件下土壤水分侧向入渗特性

在大棚内模拟宽垄沟灌垄上覆膜栽培条件以及灌水方案,采用中子仪进行水分观测,研究宽垄沟灌模式下灌水前后水分在垄沟间侧向入渗特性。试验结果表明,在本试验条件下,水平向及垄背垂直向含水量梯度的存在导致水分侧向及向垄背的补给明显,垄背剖面的2个观测点表层,灌水前其含水量不足田间持水量的70%,灌水后垄沟水分的侧向入渗,使该二测点表层土壤含水量呈上升趋势,17d后其平均含水量能达到田间持水量的75%~80%之间。     

宽垄沟灌覆膜条件下土壤水分运移初探

宽垄沟灌作为一种大田作物栽培灌水方式已逐步受到关注.为研究灌水前后水分在垄沟间的运移及再分布,本试验在大棚内模拟宽垄沟灌垄上覆膜栽培条件以及灌水方案,采用中子仪进行水分观测.试验数据显示,在本试验条件下,垄背剖面的两个观测点表层,灌水前其含水量仅为田间持水量的65%和66%,灌水后垄沟水分的侧向入渗,144 h(6 d)分别达到田间持水量的73%和80%,408 h(17 d)达到田间持水量的78%和79%.试验结果表明,在宽垄沟灌覆膜条件下,水平向及垄背垂直向含水量梯度的存在导致水分侧向及向垄背的补给明显,且在覆膜条件下,垄背蒸散发损失少,起到减少土壤水分无效损耗、高效利用之效果.     

Soil water storage and surface runoff as influenced by irrigation method in arid soils with surface crust

The effects of irrigation methods, application rates and initial moisture content on soil water storage and surface runoff were studied in soils liable to surface crust formation during 1995–1996 at the University of Jordan Research Station near Al-Muwaqqar village. Four irrigation methods were tested (sprinkler, furrow, basin and trickle) and four application rates (6.2, 14.4, 24.4 and 28.4 mm/h). Two runs were performed (soil initially dry and soil initially wet). Basin irrigation provided the highest application efficiency followed by trickle, sprinkler and furrow irrigation methods. Entrapping water by the basin borders increased soil water storage by allowing more water to infiltrate through the surface crust. Decreasing the application rate from 28.4 to 6.2 mm/h increased soil water storage significantly in all 150 mm layers to a depth of 600 mm. If the soil was already wet, soil moisture storage decreased owing to siltation during the prewetting and formation of a surface crust and low soil water storage capacity. A sedimentary crust formed at the bottom of the furrows in the furrow irrigation treatment, which reduced soil water storage and increased surface runoff significantly owing to the reduction in infiltration. Increasing the application rate from 6.2 to 28.4 mm/h in the furrow surface irrigation treatment increased the runoff discharge 10-fold. Even with the lowest application rate the runoff coefficient under sprinkler irrigation was 20.3% indicating high susceptibility of Al-Muwaqqar soils to surface crust formation.     

沟灌条件下灌水沟入渗特性研究

为探明沟灌时灌水沟的水分入渗规律,从沟灌二维入渗过程、入渗湿润锋运移特性、累计入渗水量变化过程、土壤含水量分布等方面研究了沟灌的入渗特征及其影响,研究表明：灌水沟中水深、沟底宽、湿周对沟灌入渗过程均有明显影响。沟中水深增大,有利于加大侧向入渗,垂向入渗减少,而水深减小,会加大垂向入渗,增加深层渗漏。灌水沟底宽不影响灌水沟的侧向入渗,仅影响垂向入渗,底宽减小,垂向入渗深度相应减小,且土壤表面以下40 cm深以内水平向入渗深度平均值与最大垂向入渗深度的比值在沟底宽小时均大于沟底宽大时。合理的断面形式和大小有利于减小垂向入渗,加大水平侧向入渗,灌水沟断面形式为梯形断面时,宽深比近似为2效果最优。研究结果可为改进沟灌灌水技术提供参考。