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1.
《Agricultural Water Management》1996,29(2):117-127
A field experiment was conducted on a red-brown earth (Natrixeralf) to find the effectiveness of spontaneously dispersed clay from sodic soils and mechanically dispersed clay (by puddling) from calcic and sodic soils in reducing the seepage loss of water from a series of small dams (pits). The effect of inoculating algae in the pits on reducing seepage was also investigated. A plastic lined pit was used for water balance control to measure incoming rainfall and evaporative loss.The results showed the effectiveness of dispersed soil clay in sealing the surface soil materials in the banks and beds of the pits. The dispersed clays from sodic soils were very effective in reducing the seepage to zero. When the clay concentration was above 8 g L−1 the sealing was complete, irrespective of spontaneous or mechanical dispersion from sodic soils. The mechanically dispersed clay from calcic soils were less effective in sealing because of the deposition of flocculated materials in the pore systems formed domains and generated microporosity. In calcic pits, the inoculation of algae reduced the seepage by 13 to 23% and increase in biopolymer (chlorophyll and polysaccharide) production was only small. 相似文献
2.
《Agricultural Water Management》1988,15(2):189-195
The measurement or prediction of percolation losses in field situations is of great practical significance for efficient irrigation and for determination of the leaching requirement, particularly of clayey soils where impeded percolation occurs. Hydraulic properties and water losses in packed Ashutia clay soil were determined under prevented-evaporation and free-evaporation conditions using lysimeter and tensiometric techniques. Hydraulic conductivity was determined as a function of soil moisture content using percolation flux computed. An exponential relationship between hydraulic conductivity and soil water content K = aebθ, was found. The percolation and evaporation-plus-percolation fluxes estimated from tensiometer readings under prevented-and free-evaporation conditions, respectively, matched with profile water losses from lysimeter measurements. The error ranged between 0.01 and 0.82 mm day−1 with high correlation coefficient indicating that water loss from a soil profile can be estimated from tensiometer readings. 相似文献
3.
Summary Several irrigation management experiments were conducted at different locations on sandy soils in Haryana State to overcome excessive permeability, poor soil moisture retention and storage in the root zone. Subsurface compaction to 30–40 cm depth created by 6 passes of a 1,500 kg tractor-driven iron roller, 24 to 48 h after irrigation, was found to be beneficial in reducing irrigation requirement. In general, yield of different crops was not affected significantly by surface rolling, except that of mustard which increased significantly. Slight increase in subsurface compaction, about 0.1 g cm–3, increased the soil moisture retention and reduced the infiltration rate and saturated hydraulic conductivity. Hydraulic conductivity was a better parameter than bulk density for evaluating the effect of rolling. The depth of irrigation water applied in rolling treatment was about 58–74% that of the no-rolling control. Compaction thus reduced water input to these sandy soils without adversely affecting the crop yield. 相似文献
4.
明渠输水系统由于着生藻类生长等因素,渠道糙率增加、渠道输水能力降低.现有的物理、化学、生物除藻方法因其各自的局限性而无法在灌区管理中广泛应用.水力除藻从水动力学角度出发,通过增大剪切层内水流对边界的剪应力,达到剥离水藻的目的.而研究水力除藻,水藻不能视为固定、静态的边界,因此需要建立藻类的生态系统模型.综合了以流速、温... 相似文献
5.
Hydraulic conductivity and clay dispersion as affected by application sequence of saline and simulated rain water 总被引：1，自引：0，他引：1
Summary Saturated hydraulic conductivity HC, and degree of clay dispersion DD, were determined for a sandy loam and a clay loam soil with waters of different combinations of sodium adsorption ratios SAR (5, 15, 30 and 45 mmol1/2l–1/2) and total electrolyte concentration TEC (15, 30, 60 and 90 me l–1) followed by distilled water to simulate rainwater. Increase in SAR and decrease in TEC of leaching water increased DD and decreased HC of soils. The HC values were more highly correlated with SAR than TEC. The critical ratio of TEC/SAR of water below which the relative HC is less than the hreshold value (i.e. 0.75) was 3.82 and 2.01 for clay loam and sandy loam, respectively taking the HC of initial soil with good quality water (SAR = 0.5, EC = 0.3dS m–1) as the reference. Drastic reductions in conductivity were observed even at SAR = 5 (60–83%) when saline water was displaced by rainwater, sensitivity being greater for the sandy loam than for the clay loam; recovery was negligible when the saline water was again applied. Data of EC and clay content of the effluent on application of distilled water suggested that clay dispersion, its movement and lodgement into conducting pores, may be the major cause of HC reduction in sandy loam, whereas in clay loam, surface sealing is the major cause. With distilled water application HC values were governed by SAR rather than TEC of initial water used. The study thus suggests that existing water quality criterion may underestimate the real soil permeability hazards from saline-sodic waters during rainfall infiltration in monsoon season. 相似文献
6.
Laboratory flume test was conducted to investigate the effect of flowing water an soil-cement canal tiles. For this purpose, soil-cement tiles were constructed from different soils at various cement contents. A flume, 3 metre long and 100 mm wide, was lined with the tiles and the lined bed was subjected to flow velocities of around 2 m/s for a period of 7 days. The tiles made from coarse-textured soil (sandy loam and silt loam) aggregates of 5 mm and from fine textured soil (clay loam) aggregates of 2 mm size were found to be intact and smooth even when constructed at a cement contents lower than that needed to meet the durability requirements.Attempts were also made to measure seepage losses of soil-cement tile linings. A channel section of approximately 1 metre length with a side slope of 1:1 was constructed in the laboratory with the tiles and seepage losses measured by the ponding method were found to be in the range of 0.00123–0.00343 m3/m2/day.The results clearly suggest that soil-cement tiles (irrespective of type of soil) made with 2 mm or less size of soil aggregates are erosion resistant and due to very little or negligible rates of seepage losses, the soil-cement tile lining of irrigation canals is expected to be very promising especially in the areas where irrigation water is costly. 相似文献
7.
为揭示咸水灌溉对土壤水力特性的影响机制,探求西北内陆干旱地区的合理灌溉模式,对石羊河流域中游地区开展制种玉米咸水灌溉田间试验,通过设置4种灌溉水矿化度水平(0.71,3.00,6.00,9.00 g/L),研究土壤盐分对土壤容重、孔隙度、质地和饱和导水率的影响.研究结果表明:对土壤进行咸水灌溉会引起土壤容重、孔隙度的改变,从而改变土壤饱和导水率.随着灌水次数的增多,各个处理土壤容重都越来越大,孔隙度越来越小,从而使得饱和导水率越来越小.此外咸水灌溉还会引起土壤质地的改变,特别是黏粒含量的增大,会使土壤饱和导水率减小.研究成果对咸水资源的高效利用及农业的可持续发展,具有重要的理论意义和实用价值. 相似文献
8.
Summary Fine textured soils (> 40% clay) form a major proportion of irrigated soils in northeastern Australia. More than half these soils are irrigated with groundwater, some of which has high salinity (electrical conductivity > 2.9 mS cm–1). A simple prediction of salt leaching was sought to aid in land management decisions.An empirical model of leaching fraction is presented based on rainfall and easily measured soil properties related to hydraulic conductivity. The model is based on data from 766 soils. To account for the complexity of interactions between soil properties, the data was stratified into groups based on clay content and mineralogy (expressed here as CEC/clay ratio). This allowed simple linear regressions using ESP and rainfall to be developed to predict leaching fraction.When applied to irrigated soils, a salinity correction term (ECrain+irrigation/ECrain) was used to account for the flocculation effects of the increased salinity of irrigation waters. The model gave good predictions of leaching fraction for two irrigation regions with widely differing soil properties (Fig. 4). 相似文献
9.
《Agricultural Water Management》2006,85(3):272-278
Among traditional irrigation systems, pitcher irrigation is one of the most efficient. Water seeps out of a buried pitcher due to the pressure head gradient across the wall of the pitcher directly into the root zone of the irrigated crop. The pressure gradient results from positive pressure head inside pitcher and negative pressure head at the outer surface of the pitcher which is in contact with soil. Laboratory experiments were conducted to quantify the influence of evaporation, which controls the negative pressure condition in the soil, on the seepage rate of pitchers and to explore the auto-regulative capability of the pitcher irrigation system. Two groups of pitchers, group A with high hydraulic conductivity and group B with low hydraulic conductivity, were filled with water and placed in a closed chamber at varying temperature and humidity. The pan evaporation rate (Ep) inside chambers ranged from 1 mm/d when the temperature and relative humidity were kept around 20 °C and 97% to 16 mm/d at 45 °C and relative humidity of 40%. A positive and significant correlation was found between seepage rate of pitchers and Ep with an average R2 of 0.97. The average seepage rates of all pitchers at Ep values of 1 and 16 mm/d were 125 mL/d to as high as 1020 mL/d, respectively. Differences in the seepage rates in pitchers from group A and group B were high at low Ep and low at high Ep values. At low Ep, seepage rate was more affected by water pressure head inside pitchers and the hydraulic conductivity whereas at high Ep values the negative pressure head at the outer surface of pitchers were more important. The average seepage rate of type A pitchers was 200% higher than that of type B at Ep value of 1 mm/d but for the high Ep value of 16 mm/d the corresponding increase in the seepage rate of type A compared to type B was only 4%. Thus, evaporation rate controls seepage from the pitcher and the system is auto-regulative. 相似文献
10.
11.
Spatial characterization of soil physical properties could improve the estimation of surface irrigation performance. The
aim of this research was to characterize the spatial and time variability of a set of irrigation-related soil properties.
The small-scale experimental level-basin (729 m2) was located on an alluvial loam soil. A corn crop was established in the basin and irrigated five times during the season.
A detailed survey of the soil properties (generally using a 3 × 3 m network) was performed. Classic statistical and geostatistical
tools were used to characterize the variables and their interactions. Semivariograms were validated for the studied variables,
except for the clay fraction, the saturated hydraulic conductivity and the infiltration parameters. The resulting geostatistical
range was often in the interval of 6–10 m. For the three surveys of soil surface elevation the range was smaller, about 4 m.
No correlation was found between saturated hydraulic conductivity and the other soil physical properties. Soil surface elevation
showed a high correlation between surveys. After the first irrigation, the standard deviation of elevation increased from
an initial 9.6 mm to 20.8 mm. The soil physical parameters were used to map the soil water management allowable depletion.
In a companion paper these results are used to explain the spatial variability of corn yield and soil water recharge due to
irrigation.
Received: 24 February 1998 相似文献
12.
Hydraulic conductivity (K) and soil water diffusivity (D) characterizing water flow under saturated and unsaturated conditions, respectively, were determined for a sandy loam and a clay loam soil, using water with different combinations of total electrolyte concentrations, C (i.e., 20, 40, 80, 125 and 250 meq 1?1) and sodium adsorption ratios, SAR (i.e., 0, 20, 30, 40, 80 and ∞ mmole ). Both K and D were found to increase with C and decrease with SAR. In low sodium adsorption ratio ranges (i.e., up to 20) the requirement of electrolyte concentration to maintain relative hydraulic conductivity = 0.5 was relatively more for sandy loam than for clay loam soil. However, the trend for electrolyte concentration requirements for the two soils was reversed at high sodium adsorption ratios (i.e. > 20). A spline function was used to draw the best fitting line through the data points of horizontal absorption experiments. 相似文献
13.
High levels of soil sodicity, resulting from intensive irrigation with saline-sodic waters, lead to an increased soil susceptibility to seal formation and to severe problems of runoff and soil erosion. The objective of this study was to investigate the efficacy of the addition of small amounts of an anionic polyacrylamide (PAM) to the irrigation water in controlling seal formation, runoff and soil erosion. Two predominantly montmorillonitic soils were studied, a grumusol (Typic Haploxerert) and a loess (Calcic Haploxeralf), having naturally occurring exchangeable sodium percentage (ESP)>12. The soils were exposed to 60 mm of simulated irrigation with commonly used tap water (TW, electrical conductivity=0.8 dS m–1; sodium adsorption ratio (SAR)=2), or saline water (SW, electrical conductivity=5.0 dS m–1; SAR>12). PAM effectiveness in controlling runoff and erosion from the sodic soils was compared with runoff and erosion levels obtained from untreated soils having low ESPs (<4). For both soils and for both water qualities and polymer concentrations in the irrigation water, PAM was efficient in controlling runoff at low ESP levels and inefficient at high ESP levels. At moderate ESP levels, PAM's efficacy in controlling runoff was inconsistent and varied with water quality and polymer concentration. Conversely, in general, soil loss originating from rill erosion, was significantly and effectively reduced in moderate and high ESP soils by addition of PAM to the irrigation water, irrespective of water quality and polymer concentration. PAM was more effective in reducing rill erosion than in reducing runoff in the moderate and high ESP samples, because the energy involved in generating runoff is much higher than that involved in rill erosion. PAM treated surface aggregates were not stable against the distructive forces leading to seal formation and runoff production; but they were stable enough to resist the hydraulic shear exerted by the runoff flow. 相似文献
14.
15.
Changes in hydraulic conductivity of soils varying in calcite content under cycles of irrigation with saline-sodic and simulated rain water 总被引：1，自引：0，他引：1
Soil infiltration problems occur as a result of alternating irrigation with saline-sodic waters and monsoon rainfall. Hydraulic
conductivity (K) and related soil properties of a non-calcareous (CaCO3 0.8%) and a calcareous soil (25.7%) having similar textural constituents were monitored. The soils were subjected to six
consecutive cycles of irrigation with saline waters (SW) of sodium adsorption ratio (SAR), 10, 20 or 30 (mmol/l)1/2, but of similar electrolyte concentration (EC; 80 mEq/l), and each followed by simulated rain water (SRW) (electrical conductivity
<0.02 dS/m). Results are presented in terms of relative K i.e. K
r=K
sw/K
tw where K
tw is steady state K measured separately under application with tap water (ECw 0.54 dS/m, SAR 0.9). For irrigation with SW alone, K
r values were reduced to 0.95, 0.79 and 0.70 at SAR of 10, 20 and 30, respectively, in non-calcareous soil. The corresponding
values of 0.95, 0.87 and 0.79 were slightly higher in calcareous soil. Severe reductions in K
r were observed in both the soils when subjected to alternate use of SW and SRW (K
r=0.22, 0.03 and 0.02 in non-calcareous, and 0.57, 0.17 and 0.07 in calcareous soil). About half of the reductions in K
r were reversible when SW was subsequently applied. Depth distributions of salinity, pH, dispersible clay and hydraulic head
indicate that disaggregation and dispersion of surface soil was the cause of reduced K with SRW, whereas “washed in” sub-soil became restrictive and controlled the K values with SW under alternations of SW and SRW. Salt release (<1 mEq/l) was insufficient to avoid dispersion and sustain
K even in the calcareous soil. For evaluating the infiltration hazard of saline-sodic water, measurements of stabilized K values after consecutive cycles of SW and SRW should serve as a better diagnostic criteria under monsoonal climates than
threshold EC–SAR combinations.
Received: 8 June 1998 相似文献
16.
Measured and simulated soil wetting patterns under porous clay pipe sub-surface irrigation 总被引：1，自引：0，他引：1
Sub-surface irrigation with porous clay pipe can be an efficient, water saving method of irrigation for many less developed arid and semi-arid regions. Maximizing the efficiency of clay pipe irrigation requires guidelines and criteria for system design and operation. In this study, experimental and simulated (with HYDRUS (2D/3D)) soil wetting patterns were investigated for sub-surface pipe systems operating at different water pressures. Predictions of the soil water content made with HYDRUS were found to be in good agreement (R2 = 0.98) with the observed data. Additional simulations with HYDRUS were used to study the effects of various design parameters on soil wetting. Increasing the system pressure increased the size of the wetted zone. The installation depth affects the recommended lateral spacing as well as the amount of evaporative water loss. For a given water application, the potential rate of surface evaporation affected the shape of the wetted region only minimally. Soil texture, due to its connection to soil hydraulic conductivity and water retention, has a larger impact on the wetting geometry. In general, greater horizontal spreading occurs in fine texture soils, or in the case of layered soils, in the finer textured layers. 相似文献
17.
地表滴灌条件下土壤湿润体运移量化表征 总被引：2，自引：0，他引：2
基于非饱和土壤水分运动的Richards方程,采用HYDRUS-2D/3D模拟软件对11种典型土质(美国制土壤质地分类系统)中滴灌湿润体的运动过程进行了数值模拟。结果表明,湿润体平均含水率的增量与滴灌流量正相关,与饱和导水率负相关;湿润体垂向迁移距离与滴头流量、饱和导水率和时间呈幂函数关系;湿润体径向迁移距离可用滴头流量、平均含水率的增量、垂向迁移距离和时间来定量表征。据此建立了描述不同土质中湿润体动态变化规律的经验公式,通过与数值模拟结果、文献试验数据等进行对比,表明此经验公式对不同土质中湿润体运移规律的预测效果较好,可为农业生产中地表滴灌设计提供简便实用的计算工具。 相似文献
18.
Effect of temporal variability in soil hydraulic properties on simulated water transfer under high-frequency drip irrigation 总被引：2，自引：0，他引：2
Ibrahim Mubarak Jean Claude Mailhol Rafael Angulo-Jaramillo Sami Bouarfa Pierre Ruelle 《Agricultural Water Management》2009,96(11):1547-1559
The effect of changes in the hydraulic properties of a loamy topsoil on water transfer under daily drip irrigation was studied over a cropping cycle. Soil water contents were measured continuously with neutron probes and capacitance sensors placed in access tubes (EnviroSMART) and were compared to predications made by the Hydrus-2D model. Three different sets of hydraulic parameters measured before and after irrigation started, were used.Our results demonstrated that, based on the assumptions used in this study, the accuracy of the Hydrus predictions is good. Graphical and statistical comparisons of simulated and measured soil water contents and consequently the total water storage revealed a similar trend throughout the monitoring period for the all three different sets of parameters. The soil hydraulic properties determined after irrigation started were found to be much more representative of the majority of the irrigation season, as confirmed by the accuracy of the simulation results with high values of the index of agreement and with values of RMSE similar in magnitude to the error associated with field measurements (0.020 cm3 cm−3). The highest RMSE values (about 0.04 cm3 cm−3) were found when the model used input soil parameters measured before irrigation started.Generally, changes in topsoil hydraulic properties over time had no significant effect on soil moisture distribution in our agro-pedo-climatic context. One possible explanation is that daily water application was conducted at the same time as maximal root water uptake. This meant the soil did not need to store total daily crop water requirements and consequently that the water redistribution phase represented a very short stage in the irrigation cycle. It is probable that irrigating in the daytime when crop evapotranspiration is highest could prevent the effects of a temporal change and other problems connected with the soil. Moreover, water will be always available for the crop. Further experiments are needed to justify the results and to study the effects of low frequency drip irrigation on soil hydraulic characterization and consequently on soil water transfer in order to improve irrigation scheduling practices. 相似文献
19.
《Agricultural Water Management》2001,51(1):29-51
In this work we tested the influence of different solutions of a hydrophobic polymer named Guilspare®, applied to the soil surface to reduce soil evaporation, on the soil water status, soil temperature, crop performance and weed emergence. Two tests were carried out on a farm of the Guadalquivir river valley, southwest Spain, one with a maize crop and the other with bare soil. In the test with maize, we evaluated the effect of applying a solution of 2% v/v of Guilspare® in water, at the rate of 3 l m−2, on the crop performance and weed emergence. On both the treated and the untreated control plots, three rates of irrigation were applied, namely 100, 75 and 50% of the locally determined optimal irrigation depth to cover the crop needs for an optimum development and yield. For the case of 50% of the irrigation dose, the performance of the crop treated with the polymer (T50) was much better than that of the untreated control plot (C50). The crop height and green leaf area index for T50 were nearly as good as for the C100 control plants receiving 100% of the irrigation dose. The T50 crop was 73% of the yield of the treated and fully irrigated T100 crop, while the C50 yield was only 38% of the C100 yield. The treated crop reached the different phenological stages quicker than the untreated crop. The polymer was effective in reducing weed emergence. In the test with bare soil, 0.8% v/v of Guilspare® in water, at the rate of 1 l m−2, kept levels of water content in the soil as high as other solutions with greater amounts both of polymer and water. The average soil water content during the irrigation period in this lower treatment was 34 and 53% higher at depths of 0.15 and 0.25 m, respectively, than in the untreated plots. No influence of the polymer on soil temperature was observed. Results from additional measurements on weed emergence and hydraulic conductivity of the soil surface showed that the polymer was still effective 7 months after application. In fact, the hydraulic conductivity in the range near saturation was 44% greater in the treated plots than in the untreated ones, and the number of weeds was 27% lower. 相似文献
20.
《灌溉排水学报》2019,(1)
【目的】探究渠道水深对渠床土壤入渗特性的影响及其变化规律。【方法】以河套灌区典型斗渠规模的渠道水深对渠床土壤入渗特性的影响为对象,采用水位下降静水法入渗试验,分析了渠道水深对累积入渗量、入渗率、渗漏强度的影响。【结果】(1)在同一渠道水深条件下,土壤累积入渗量随着渗漏用时的延长而增加;土壤入渗率和渠道渗漏强度均随渗漏用时逐渐减小并最终趋于稳定。(2)不同渠道水深条件下土壤累积入渗量、土壤入渗率和渠道渗漏强度均呈现出随水深的增加而增大的趋势。(3)在渠道水深作用下渠床土壤含水率动态分布受基质势梯度、土壤导水率及湿周的影响较大。【结论】渠道水深对渠床土壤入渗特性中的累积入渗量、入渗率、渗漏强度及渠床土壤含水率动态分布均有较大影响,且前三者均随水深的增加而呈现指数规律增大,并且在不同渠道水深的相近入渗特性下最优水深为70 cm。 相似文献