上海市水权交易的潜力分析—从产

随着城市经济的发展，农业、工业、生活和生态环境用水之间竞争加剧，运用市场机制和经济手段来合理分配水资源是目前国际社会所采取的战略举措。基于不同产业的用水效率和效益的差异分析，说明在产业间开展水权交易可优化水资源配置。现以工业化程度最高的上海为例，对上海的用水结构与产业结构进行对比分析，揭示水权交易的内在去驱动力，并提出了推动水权交易实践的政策建议。     

Effect of timing of first and last irrigation on the yield and water use efficiency in cotton

With increasing concern about declining water resources, there is increasing thrust in improving water management in farming systems to improve water use efficiency. The present investigation was undertaken to determine the optimum timing for the first and last irrigation of cotton on the basis of meteorological approach for scheduling irrigations. The experiment was conducted in a split plot design with three timings of first irrigation as main-plots and three timing of last irrigation as sub-plots. Delay of first irrigation from 28 days after sowing (DAS) to 42 DAS, irrespective of last irrigation, resulted in an increase of 8, 14 and 17% in seed cotton yield during first, second and third year, respectively. The corresponding increases due to delay in the last irrigation from 130 to 170 DAS were 14, 32 and 8%, respectively. On the basis of 3 years average, application of first and last irrigation at optimum time (after 42 and 170 days after sowing) resulted in an increase of 36% in seed cotton yield without involving any additional cost. Water expense efficiency (WEE) increased by 54%.     

灌溉水利用系数综合测定法实例分析

灌溉水利用系数是衡量农业节水效果的关键指标。目前各地区统计出的灌溉水利用系数差异极大。很多数据明显的存在错误，难以作为比较与衡量的标准。影响灌溉水利用系数正常测定的主要原因是传统测定方法存在测定工作量巨大、测定条件难以保证等。通过开展对灌溉水利用系数资料的搜集、整理并对灌区进行实地调研，在了解目前灌区灌溉水利用系数测量中存在问题及原因的基础上，对灌区灌溉水利用系数测量计算方法进行了分析研究，提出了测定灌溉水利用系数的综合测定计算方法。该方法既克服了传统测量方法中工作量大，需要大量人力、物力才能完成的缺点，又弥补了只测量典型渠段而引起较大误差的不足，而且能反映出灌区渠系用水情况、灌溉工程质量及灌溉用水管理水平等。以漳河灌区为例进行了应用分析。     

水分亏缺对覆膜玉米生长发育及产量的影响

通过系统的覆膜玉米亏水灌溉试验 ,研究了不同生育期内不同程度的水分亏缺对覆膜玉米生长发育、光合作用、产量及水分利用效率等的影响。结果表明 ,拔节期受旱对玉米株高及叶面积指数影响最大 ,抽雄后的水分亏缺对玉米生长发育影响不明显。各处理产量资料表明 ,覆膜春玉米的需水临界期为抽雄开花期 ,此期轻度的水分亏缺可造成产量大幅度下降 :灌浆期较抽雄开花期玉米产量对水分亏缺敏感程度低 ,但在这个阶段的水分亏缺也可使玉米减产 ;拔节期玉米产量对水分胁迫敏感程度较差 ,该阶段为对玉米进行水分亏缺处理的适宜时期     

Irrigation and food security in the 21st century

Global food projections indicate that food prices in the next threedecades will likely be stable or decline, but progress inreducing malnutrition in developing countries will be slow. Smallshortfalls in crop productivity growth would lead to rising foodprices and worsening malnutrition. Increased food production fromirrigation is essential, and will require expansion of irrigatedarea and water supplies, and improved efficiency of use of existingwater supplies. Neither of these growth factors will prove easy, andboth will require complex institutional and policy reforms. Failureto meet food production needs through efficient expansion andintensification of irrigated agriculture would increase pressure onland resources and hasten the process of environmental degradation.Irrigation and water development strategies have been hampered bya lack of understanding of the links between water scarcity, foodproduction, food security, and environmental sustainability.Research to improve this understanding would have high payoffs.     

灌溉渠系水利用系数的分析与计算

灌溉渠系的布置形式一般可分为串联渠系、等效并联渠系和非等效并联渠系 ,对这 3种灌溉渠系水利用系数进行了理论研究。用实例验证了上述的理论分析。研究成果可应用于实际灌溉工程     

Modelling carbon dynamics in mixed grass–red clover swards

Growth and carbon dynamics in mixed grass–red clover leys were simulated using a growth model for pure stands based on radiation use, allocation within plant and loss of biomass. The model and its parameter values were taken from previous applications of the model to pure swards of grass and red clover grown in the same experiment at the same sites and years.     

热泵式节能烘干机的设计

热泵是一种使热量从低温介质流向高温介质,以对高温物体进行供热的装置.为此,利用热泵原理研究设计了一种小型高效节能烘干机,并介绍了该机的主要特点、总体结构等,尤其对热泵、烘干床进行了详细介绍.该机具有结构简单新颖、造价低廉、使用寿命长、高效节能等优点,不仅可以烘干多种农产品,还可以烘干茶叶、蘑菇等多种农副产品.     

The value of performance studies of irrigation projects for lending agencies

This paper looks at the World Bank's experience with irrigation and drainage projects and compares their performance expected at appraisal stage with the performance re-assessed at completion and at the time of impact evaluation, typically 3 to 5 years later when projects have reached their full potential. This review confirms the over-optimistic assumptions of project performance at appraisal and completion stages. The deficiencies in water distribution are far greater than suspected, affecting cropping intensity and crop yields much more than originally thought. An important lesson from this memo is the need to adopt more realistic values of key parameters in the preparation of irrigation projects.     

The rehabilitation of an irrigation system along the Yellow River

The People's Victory Irrigation System which diverts water from the Yellow River of China covers a total irrigable area of 59 000 ha. The system encountered some serious problems in the first decade of its operation — salinity and waterlogging of irrigated land, siltation of irrigation and drainage channels, as well as a low efficiency of water use. This paper describes a series of structural and functional measures which have been adopted in the past 24 years for the rehabilitation of the system, including: improvement of the existing drainage system and construction of new drainage system on agricultural land, conjunctive use of surface and groundwater supplies, a comprehensive programme to reduce the levels of siltation as well as the implementation of improved water management practices. A model for the optimal operation of the system by using system analysis theory as an aid in reducing the operation and maintenance (O & M) costs has been developed in recent years. The results are that the soil salinity has been controlled and the agricultural production has increased whilst the efficiency of water use has improved and the siltation levels reduced. Experience gained on this system has been successfully used in developing and managing other irrigation projects along the lower reaches of the Yellow River. The proposed procedure of solving the said optimal model has also embodied some benefits from reducing O & M costs in operation.