Compatibility Assessment of Drip Irrigation Laterals

Emitters inserted in drip irrigation laterals cause local head loss, generally estimated as a product of a coefficient and the velocity head. This local head loss coefficient and the emitter discharge curve hydraulic parameters may exhibit considerable variability attributable to the manufacturing process. This paper provides a framework for assessing whether the variability in the hydraulic parameters could lead to significant differences in the performance of rolls of drip irrigation laterals from the same manufacturing batch. A system approach with inlet pressure as input, pressure distribution along the drip lateral and inlet discharge as outputs (or responses), and a drip lateral hydraulic model as the transfer function is explored. Within a Bayesian statistical framework of parameter uncertainty based on the Metropolis algorithm, the hydraulic parameters of pressure-compensating drip lateral rolls from the same manufacturing batch were inferred (calibrated). Overlapping of the space (region) of the hydraulic parameters of different drip laterals give an indication of compatibility (similarity) of the drip laterals. Results indicated that half of the drip lateral rolls tested were strongly compatible, a third were weakly compatible, and the remainder were not compatible with any other. This finding has significant ramifications in the design of drip irrigation lateral networks. Therefore, it is essential to closely examine the hydraulic properties of drip laterals for the design of drip irrigation networks to avoid poor performance of the system.     

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Wetlands are often considered as “economically unproductive”. In this paper it is shown that for the African floodplains this unjustly denies the actual and potential benefits of the traditional land use systems. Both in terms of water use and financial costs traditional African floodplain exploitation compares very well with modern irrigation schemes. Gross earnings of irrigation systems must figure at least three times as much as traditional floodplain production in order to attain the same net margin of profit. This reflects the shadow‐price of the work done by nature.     

初探水文地质工程勘察在开发地源热泵中作用

开发地源热泵,利用地下水作为地源热泵的冷热源,需要进行专门的水文地质勘察,勘察重点要取得冷热源井的出水量、回灌量、地下水温度、水位、流速、流向和水质资料,选择理想的供水含水层,评估地下水可开采量,初步确定抽灌井比等,本文结合工程实例对地源热泵水文地质勘察需要解决的问题做初步的探讨,说明水文地质勘察在开发地源热泵中具有十分重要的意义。     

屋顶绿化节水技术措施的探讨

本文结合屋顶绿化的具体特点,探讨屋顶绿化的节水灌溉技术的选择和屋顶花园种植区构造层中的疏水层改进,对解决屋顶绿化灌溉与排水设计过程中常遇见的问题提出了合理的设计思路。     

洪临灌区渠道防渗及处理措施

因肃州区洪临灌区处于干旱地区的多种农业土壤中,灌区的水渠和农田水分渗漏损失较大,以致大量水分无效消耗且灌溉水利用率不高,也不利于农作物生长。因此提高灌区输水渠道的防渗性和改进灌区灌溉措施,不仅缓解干旱地区水资源不足的问题还可提高灌溉水利用率,针对灌区渠道情况提出一些防渗措施。     

消防水泵的联动控制设计——解读《〈火灾自动报警系统设计规范〉图示》

以湿式自动喷水灭火系统和湿式消火栓系统的联动控制为例,介绍国家建筑标准设计14X505-1《〈火灾自动报警系统设计规范〉图示》中关于联动控制的部分内容。     

Effects of water-saving superabsorbent polymer on antioxidant enzyme activities and lipid peroxidation in corn (Zea mays L.) under drought stress

BACKGROUND: Drought is the most important abiotic stress factor limiting corn (Zea mays L.) growth and productivity. Therefore efficient management of soil moisture and study of metabolic changes in response to drought are important for improved production of corn. The objective of the present study was to gain a better understanding of drought tolerance mechanisms and improve soil water management strategies using a water‐saving superabsorbent polymer (SAP) at 30 kg ha^?1 under three irrigation levels (adequate, moderate and deficit) using a new type of hydraulic pressure‐controlled auto‐irrigator. RESULTS: The results showed that relative water content and leaf water potential were much higher in corn treated with SAP. Although application of SAP reduced biomass accumulation by 11.1% under adequate irrigation, it increased the biomass markedly by 39.0% under moderate irrigation and 98.7% under deficit irrigation. Plants treated with SAP under deficit irrigation showed a significant decrease in superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase activities in leaves compared with control plants. CONCLUSION: The results of this study suggest that drought stress causes the production of oxygen radicals, leading to increased lipid peroxidation and oxidative stress in plants, and the application of a superabsorbent polymer could conserve soil water, making it available to plants for quenching oxidative stress and increasing biomass accumulation, especially under severe water stress. Copyright © 2010 Society of Chemical Industry     

不同灌水条件下烤烟耗水特征和用水效率的研究

１９９１～１９９２年连续两年采用地栽和大田试验相结合的方法研究了不同灌水条件下烤烟的耗水特征和用水效率，结果表明，大田期烤烟的耗水具有前期少、中期多、后期又少的规律性，伸根期烟田耗水量约占全生育期总耗水量的１６％～２０％，旺长期约为４４％～４６％，成熟期约占３５％～３７％。随灌水量增大，烟田耗水量增加，而烟草对水分利用率降低。主题词     

农业灌溉系统的现场控制设计

介绍了农业灌溉系统的现场控制设计。其硬件系统包括PLC系统、传感器系统、人机界面系统3部分,软件部分实现PLC系统和人机界面系统对现场的控制和报警。通过软、硬件的整体调试使系统达到设计要求。     

Effect of drought and irrigation on the fate of nitrogen applied to cut permanent grass swards in lysimeters: Experimental design and crop uptake

The effect of drought and irrigation on the yield and fertiliser nitrogen uptake by cut permanent grass swards was investigated using lysimeters containing monoliths (80 cm diam., 135 cm deep) of two soil types (Salop series, clay loam and Bromyard series, silt loam). Over the five summers 1977–81 swards were treated with four dressings of calcium nitrate at rates of 0 and 100 kg N ha^?1 after each cut; in the first year, the nitrogen was labelled with ¹⁵N. Rainfall equivalent to the long-term average gave mean yields of 12.9 t dry matter ha^?1 for Salop and 14.3 t dry matter ha^?1 for Bromyard. Irrigation (to 120% of average summer rainfall) gave a non-significant increase of 8–9% in herbage yield on both soils. When the average rainfall distribution was modified to create periods of drought for 4 weeks duration immediately before each cut and fertiliser application, yields were significantly depressed, by 12% on Salop soil and 20% on Bromyard soil. Adjustment of the drought so that cutting and nitrogen application fell mid-way in the dry period resulted in only a small non-significant depression of yield on both soils (yield 95–96% of average rainfall treatment). The recovery of applied ¹⁵N labelled fertiliser in herbage during the first year of the experiment was in the range 45–47% for the Salop soil and 39–52% for the Bromyard soil. In the Salop soil the recovery of the labelled nitrogen was not significantly affected by imposition of drought conditions or by irrigation. However, in the Bromyard soil the drought treatment resulted in a significant reduction in the recovery of fertiliser nitrogen to 79% of that of the average rainfall treatment and irrigation increased the recovery to 106%. The contrasting results from the two soils was due to the imposed drought treatments which were more effective in creating differing soil water status in the Bromyard soil. This was due to its good drainage and lower water holding capacity. On both soils, fertiliser nitrogen constituted 53–60% of the total nitrogen content of the herbage. This experiment indicates that on clay soils with poor drainage status, the pattern of rainfall distribution has relatively little impact on the productivity of the sward and its utilisation of fertiliser nitrogen. On freely-draining soils, however, heavy rainfall after drought following cutting and nitrogen application can substantially depress yield and fertiliser use.