Analysis of uniformity of sprinkle irrigation in a semi-arid area

One of the most appropriate sprinkler systems for arid or semi-arid areas – where a great deal of irrigating water is required – are the permanent set systems and the continuous-move laterals. To know the reality of water application in this type of areas, many field evaluations of solid set systems and centre pivot irrigation were conducted in Castilla-La Mancha region (Spain). The main factors affecting water application and evaporation and drift losses with these systems (pressure, wind speed, sprinkler type, etc.) were analysed. A set of performance guidelines and recommendations for the design and management of sprinkle irrigation is presented to attain the highest uniformity and efficiency in water application in semi-arid areas. To use working pressure as low as possible, but with sprinklers that produce a great deal of middle size water drops along with night irrigation for minimising evaporation and drift losses are important aspects.     

喷灌技术在干旱风沙区的应用研究

喷灌在灌溉技术中具有独特的优势而得到广泛的应用,但因其受风的影响大、蒸发损失多,在风沙区的应用受到了极大的制约。通过对风沙区蒸发和风速分布规律的分析以及风沙区喷灌灌溉试验和喷灌在大田中应用的案例调查,给出了喷灌灌溉水利用效率与风速之间的关系,指出只要很好的利用风沙区蒸发和风速分布规律,避开高蒸发时段和高风速时区,在风沙区进行喷灌仍可获得较高的灌溉水利用效率和灌水均匀度,喷灌在风沙区仍有广阔的应用是前景。     

Effects of a suspended shade cloth cover on water quality of an agricultural reservoir for irrigation

Water availability and quality are two fundamental factors for agriculture in arid and semi-arid regions. This study evaluates the effects of a water-permeable, Suspended Shade Cloth Cover (SSCC), on the quality of water stored in an on-farm Agricultural Water Reservoir (AWR). Water quality (water temperature, electrical conductivity, chlorophyll-a concentration, dissolved oxygen concentration and water turbidity) and environmental (evaporation, rainfall, wind speed and solar radiation) parameters were measured over a 2-year period in a typical AWR located in south-eastern Spain. In the first year, the AWR remained uncovered and the behaviour was quasi-isothermal. In the second year, installing a SSCC induced a thermal gradient in the water that reached a maximum temperature difference of 12 °C during summer. The lack of turbulence under the cover and the reduction in photosynthesis (95% reduction of chlorophyll-a) reduced the concentration of dissolved oxygen to 1.5 mg L⁻¹, and turbidity from 40 NTU at installation to less than 1 NTU. The positive balance between rainfall and evaporation during the second year reduced the electrical conductivity of the water by 8.2%. The improvement in water quality associated with the installation of a SSCC increases the efficiency of drip irrigation systems by reducing the water filtering requirements, the likelihood of emitter clogging, and the risk of irrigation-induced salinity.     

Soil salinity and sodicity effects of wastewater irrigation in South East Australia

Although ‘sewage farming’ or wastewater irrigation started in Australia in the latter parts of the 19th century, it was in the late 1960s that a considerable interest was revived in arid and semi-arid parts of the world due to scarcity of alternative water sources and the urgency to increase local food production. The practice has manifold benefits in the form of water conservation, nutrient recycling, surface and ground water pollution prevention. But for arid and semi-arid regions like many parts of Australia, while wastewater irrigation can be an attractive solution to irrigation water problems, it might not be the ideal solution for the common soil types encountered in these regions. Due to characteristic low rainfall, high evaporation and low leaching, these soils tend to have higher salt accumulations. This paper examines the soil salinity and sodicity effects of wastewater irrigation in soil types typical to South Eastern Australia and takes the soils of Western Treatment Plant (WTP) as a case study to highlight these issues.     

节水是维持西北干旱区水资源与生态平衡的关键

在开发大西北中,我们面临水资源短缺的挑战,本文针对西北干旱区水资源特征、水资源利用对环境影响的分析,提出通过制定流域合理开发模式、加强水利管理、建立合理灌溉制度、按方收费、推广先进灌水技术、控制潜水临界深度、整治河道、取缔病库、培育耐旱作物等措施,减少水体蒸发和渗漏的部分损失,提高水的利用率,增加单位水体的效益,这是维持西北干旱区水资源与生态平衡的关键。     

再生水灌溉对紫花苜蓿产量和品质的影响

[目的]探究再生水灌溉不同因素对紫花苜蓿产量和品质的影响.[方法]通过三因素三水平正交试验,利用极差分析和方差分析,研究了再生水灌溉不同因素的主次顺序、显著性、各因素影响趋势及最优组合.[结果]灌溉定额对紫花苜蓿株高、茎粗、一级分枝数、干草产量、粗脂肪、粗纤维、酸性洗涤纤维、中性洗涤纤维、相对饲喂价值、氮、磷、钾和钙影...     

东北半干旱抗旱灌溉区节水农业综合效益等级评价模型

建立了节水农业综合效益评价的投影寻踪模型,其利用基于实数编码的加速遗传算法(RAGA)优化其投影方向,将多维数据指标(样本评价指标)转换到低维子空间,根据投影函数值的大小做出评价,最大限度避免了权重矩阵取值的人为干扰。以东北干旱半干旱抗旱灌溉区为例,利用所建模型进行技术集成和单一技术(喷灌)综合效益等级评价,取得了满意的效果,为节水农业评价及其它评判问题提供一条新的方法与思路。     

A study of losses from field channels under arid region conditions

In arid regions, water losses from unlined small field channels are usually high due to seepage and evaporation from open surfaces. These losses are often neglected by many project planners and engineers. A theoretical analysis has been developed to modify the equation usually used to determine the water losses based on the ponding method, where the channel longitudinal slope was considered in the analysis. A field investigation has been carried out in sandy soil to determine and evaluate the water losses for three different types of channels. They are: earthen-uncompacted channel, compacted channel bed and channel lined by jute mats coated with bitumen emulsion on both faces. The last two cases are relatively low-cost, need less skillful labour than lining by cement and are more suitable for temporary field channels. Manning's coefficient was determined for each case. The results show that the process of compating the channel bed reduced the rate of seepage by a considerable value and that lining of field channels by prefabricated bitumen jute mats caused a significant reduction in the seepage rate. The results also show that the evaporation from open surfaces caused a considerable loss and should be considered when studying water losses from irrigation channels in arid regions. Abbreviations A = channel surface area ⋅ A_c = channel cross section-area ⋅ b = channel bed width ⋅ d = observed difference in Class-A pan ⋅ h₁ = original water depth in the canal ⋅ h₂ = canal water depth after a certain time ⋅ k = constant ⋅ L = canal length ⋅ n = Manning's coefficient ⋅ p = average wetted perimeter ⋅ q_evap = evaporation losses rate ⋅ q_s = canal seepage losses rate ⋅ q_t = total losses from the canal ⋅ Q = canal discharge ⋅ R = penetration resistance ⋅ R_h = hydraulic radius of the channel ⋅ s = channel longitudinal slope ⋅ t = time ⋅ V_e = volume of water lost by evaporation ⋅ v_m = channel mean velocity ⋅ v_s = channel surface velocity ⋅ V_s = volume of water lost by seepage ⋅ V_t = total volume of water lost ⋅ w = water surface width of the canal ⋅ y₁ = downstream water depth at time zero ⋅ y₂ = downstream water depth after a time t ⋅ z = canal side slope Received: 6 October 1995     

垂向混合产流模型在不同地区的应用与改进

基于垂向混合产流模型的结构特征,选择不同地区加以应用比较,率定了模型在西北干旱半干旱地区的参数,在此基础之上进行了洪水模拟计算,分析对比了模型在不同地区的应用和洪水模拟结果不合格的原因。通过分时段双源蒸散发计算和改进的格林-安普特下渗公式的应用计算,使模型在北方干旱地区和南方湿润地区也具有一定的适应性、成熟性和有效性。     

覆膜方式对不同生态区大豆产量和水分利用效率的影响

全膜微垄沟播种植技术是在全膜双垄沟播技术的基础上创新研发的一种集覆盖抑蒸、垄面集雨、垄沟种植为一体的新型地膜覆盖技术。【目的】明确西北半干旱雨养区地膜覆盖条件下旱地大豆在不同生态区产量的差异。【方法】于2014—2016年进行大田定位试验,以露地无覆盖(CK)为对照,设置了3种覆膜方式,分别为全膜微垄沟播(T1)、全膜双垄沟播(T2)、全膜覆土穴播(T3),研究半湿润偏旱区、半干旱区、半干旱偏旱区3种不同生态区地膜覆盖对大豆产量及水分利用效率的影响。【结果】与CK相比,在3个生态区均以T1处理产量最高,T2处理次之,T3处理最低;其中全膜微垄沟播不同生态区比较:半湿润偏旱区>半干旱区>半干旱偏旱区,分别较露地无覆盖CK增产58.5%、78.1%和95.3%;水分利用效率分别较CK提高65.9%、57.6%和56.1%。尤其在年降雨量500～600 mm生态区全膜微垄沟播增产效应最明显,平均产量达到4 318.2 kg/hm2,最高达到4 353.3 kg/hm2,较CK增产58.5%。【结论】大豆全膜微垄沟播种植技术在西北半干旱雨养区,增产效果明显,其推广应用可有效提高该区降水资源的高效利用,实现旱作雨养区大豆稳产高产。     

Development of evapotranspiration and water supply of clay-loamy soil on the East Slovak Lowland

With regard to optimization of the factors of field crop harvest formation in semi-arid areas the phenomenon of soil drought is of key importance. This article deals with the problem of soil water management in connection to soil fertility in the area of East Slovakian Lowland, characterized by the complexity of its agro-ecologic conditions. In clay-loamy soils of the corresponding area, soil water content at the level limited by the threshold point and field water capacity ensures that the average value of actual evapotranspiration intensity varies between 2.69 and 3.89 mm per day⁻¹. Time development of soil water storage and evaporation deficit depends on optimized system of soil water management necessary for plant production.     

砂石覆盖厚度和粒径对土壤蒸发的影响

在干旱半干旱地区,砂石覆盖作为一项传统的覆盖技术,可以明显减少土壤蒸发,为作物生长提供良好的水分条件。为研究不同粒径和厚度砂石覆盖对土壤蒸发的影响,进行了室内模拟试验,对3种粒径(2.5~10、10~25和25~40 mm)和2种覆盖厚度(8 cm和14 cm)以及不同粒径砂石配比条件下土壤水分蒸发进行了研究。结果表明,砂石覆盖能有效地抑制土壤蒸发,在土壤含水量较高的阶段,这种抑制作用更加明显。砂石覆盖对土壤蒸发的抑制作用与粒径和覆盖厚度密切相关,在2.5~40 mm粒径范围内,随着砂石粒径的增大,砂石覆盖对蒸发的抑制作用降低,对蒸发过程的影响减弱,覆盖厚度越大,蒸发量越小。有效的砂石配比应选择细砂石处理,不宜过粗。     

树枝覆盖与保水剂对土壤水分的影响

通过野外定位试验,研究了树枝覆盖和保水剂对土壤水分的影响。结果表明,树枝覆盖抑制土壤蒸发的效果明显,在土壤含水量大于16%时,可抑制2/3左右的土壤蒸发,树枝覆盖可提高表层土壤含水量达30%;滴灌条件下保水剂穴施可明显减少土壤水分的垂直入渗,提高湿润体的平均土壤含水量;滴灌条件下树枝覆盖结合保水剂穴施节水效果明显,使0~70 cm深度的土壤含水量增加了24%。     

山区灌溉技术及应用研究

解决干旱、半干旱山地的农用灌溉用水问题，是帮助干旱山区农民脱贫致富的关键。采用YD型移动式高扬程灌溉及SYD型移动式滴灌技术，具有投资少、转移快捷方便、灌溉效率高及增产增效等优势，通过典型干旱山区的应用研究，该灌溉技术具有推广使用价值。     

Cover crop evapotranspiration under semi-arid conditions using FAO dual crop coefficient method with water stress compensation

Cover cropping is a common agro-environmental tool for soil and groundwater protection. In water limited environments, knowledge about additional water extraction by cover crop plants compared to a bare soil is required for a sustainable management strategy. Estimates obtained by the FAO dual crop coefficient method, compared to water balance-based data of actual evapotranspiration, were used to assess the risk of soil water depletion by four cover crop species (phacelia, hairy vetch, rye, mustard) compared to a fallow control. A water stress compensation function was developed for this model to account for additional water uptake from deeper soil layers under dry conditions. The average deviation of modelled cumulative evapotranspiration from the measured values was 1.4% under wet conditions in 2004 and 6.7% under dry conditions in 2005. Water stress compensation was suggested for rye and mustard, improving substantially the model estimates. Dry conditions during full cover crop growth resulted in water losses exceeding fallow by a maximum of +15.8% for rye, while no substantially higher water losses to the atmosphere were found in case of evenly distributed rainfall during the plant vegetation period with evaporation and transpiration concentrated in the upper soil layer. Generally the potential of cover crop induced water storage depletion was limited due to the low evaporative demand when plants achieved maximum growth. These results in a transpiration efficiency being highest for phacelia (5.1 g m⁻² mm⁻¹) and vetch (5.4 g m⁻² mm⁻¹) and substantially lower for rye (2.9 g m⁻² mm⁻¹) and mustard (2.8 g m⁻² mm⁻¹). Taking into account total evapotranspiration losses, mustard performed substantially better. The integration of stress compensation into the FAO crop coefficient approach provided reliable estimates of water losses under dry conditions. Cover crop species reducing the high evaporation potential from a bare soil surface in late summer by a fast canopy coverage during early development stages were considered most suitable in a sustainable cover crop management for water limited environments.     

Water use of spring wheat to raise water productivity

In semi-arid environments with a shortage of water resources and a risk of overexplotation of water supplies, spring wheat (Triticum aestivum L.) is a crop that can reduce water use and increase water productivity, because it takes advantage of spring rainfall and is harvested before the evaporative demands of summer. We carried out an experiment in 2003 at “Las Tiesas” farm, located between Barrax and Albacete (Central Spain), to improve accuracy in the estimation of wheat evapotranspiration (ETc) by using a weighing lysimeter. The measured seasonal ETc averages (5.63 mm day⁻¹) measured in the lysimeter was 417 mm compared to the calculated ETc values (5.31 mm day⁻¹) calculated with the standard FAO methodology of 393 mm. The evapotranspiration crop coefficient (Kc) derived from lysimetric measurements was Kc-mid: 1.20 and Kc-end: 0.15. The daily lysimeter Kc values were fit to the evolution linearly related to the green cover fraction (fc), which follows the crop development pattern. Seasonal soil evaporation was estimated as 135 mm and the basal crop coefficient approach was calculated in this study, Kcb which separates crop transpiration from soil evaporation (evaporation coefficient, Ke) was calculated and related to the green cover fraction (fc) and the Normalized Difference Vegetation Index (NDVI) obtained by field radiometry in case of wheat. The results obtained by this research will permit the reduction of water use and improvement of water productivity for wheat, which is of vital importance in areas of limited water resources.     

雨水利用,微灌技术与庭院经济

干旱半干旱地区缺水导致人们生活饮用水困难，更制约着工农业经济的发展。建集蓄雨水工程－集流场，蓄水水窑，可解决当地群众的生活用水，还可用剩余的水发展庭院经济，脱贫致富。在这类地区微灌技术成为利用集蓄的雨水发展庭院经济的纽带。但目前雨水利用与微灌技术的结合尚处较低水平，有待进一步研究适用于这类地区的设备和技术，使微灌给干旱半干旱地区人民带去福音。     

A model for regional optimal allocation of irrigation water resources under deficit irrigation and its applications

It is important to promote efficient use of water through better management of water resources, for social and economical sustainability in arid and semi-arid areas, under the conditions of severe water shortage. Based on the developments in deficit irrigation research, a recurrence control model for regional optimal allocation of irrigation water resources, aiming at overall maximum efficiency, is presented, with decomposition-harmonization principles of large systems. The model consists of three levels (layers). The first level involves dynamic programming (DP) for optimization of crop irrigation scheduling. The second level deals with optimal allocation of water resources among various crops. The last level concerns optimal allocation of water resources among different sub-regions. As a test, this model was applied to the combined optimal allocation of multiple water resources (surface, ground and in-take from the Weihe river) of Yangling, a semi-arid region on the Loess Plateau, China. Exemplary computation showed that not only are the results rational, but the method can also effectively overcome possible “dimensional obstacles” in dynamic programming of multiple dimensions. Furthermore, each sub-model is relatively independent by using various optimization methods. The model represents a new approach for improving irrigation efficiency, implementing water-saving irrigation, and solving the problem of water shortage in the region studied. The model can be extended in arid and semi-arid areas for better water management.     

牧草抗旱机理与节水灌溉技术研究

在干旱、半干旱地区，牧草因长期处于亏水环境中，形成了一定的抗性，存在一个较宽的对水分利用相对较高的生理耗水阈值。木文从这一水分生理角度出发，在充分研究牧草生理生态适旱系列变化过程的基础上，确定了几种干旱半干旱草地的经济耗水量，并制定出相应的经济灌溉制度。     

Effect of different drip irrigation regimes on sugar beet (Beta vulgaris L.) yield, quality and water use efficiency in Middle Anatolian, Turkey

Agricultural production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant plant varieties or water management for arid and semi-arid areas under water shortage conditions. A field study was conducted to determine effects of seasonal deficit irrigation on plant root yield, quality and water use efficiency (WUE) of sugar beet for a 2-year period in the semi-arid region. Irrigations were applied when approximately 50–55% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation (FI) treatment. In deficit irrigation treatments, irrigations were applied at the rates of 75, 50 and 25% of full irrigation treatment on the same day. Irrigation water was applied by a drip irrigation system. Increasing water deficits resulted in a relatively lower root and white sugar yields. The linear relationship between evapotranspiration and root yield was obtained. Similarly, WUE was the highest in DI25 irrigation conditions and the lowest in full irrigation conditions. According to the averaged values of 2 years, yield response factor (k _y ) was 0.93 for sugar beet. Sugar beet root quality parameters were influenced by drip irrigation levels in both years. The results revealed that irrigation of sugar beet with drip irrigation method at 75% level (DI25) had significant benefits in terms of saved irrigation water and large WUE, indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25% saving of irrigation water (DI25) caused 6.1% reduction in the net income.