渠道生态衬砌技术及其应用前景

渠道衬砌是灌区节水的重要途径之一,生态型渠道形态和功能构建关键技术的研究对于灌区的生态建设意义重大.针对传统灌区沟渠日益突出的生态环境条件恶化、生物多样性下降等问题,对灌区生态型沟渠空间形态构建、水体自净能力提高和水质改善、适宜生境条件构建等关键技术进行研究和实践是非常有必要的.生态衬砌是一种能够弥补传统渠道衬砌的负面影响,改善现有渠道中的生态环境,同时也保持传统渠道衬砌的防渗优势的工程技术措施.为此,进行渠道生态衬砌可以获得节水和生态环保的双重效果.在分析传统渠道衬砌引起生态问题的基础上,对现行的三种渠道生态衬砌方法作了简要的介绍,并对其应用前景进行了分析.     

渠道衬砌对农田水土环境的影响研究——以隆胜节水示范区为例北大核心

在引黄水量大幅减少且河套灌区大范围实施节水改造工程的背景下,为研究河套灌区渠道衬砌前后对农田水土环境的影响,通过对隆盛节水改造典型示范区的环境效应进行监测分析研究,结果显示示范区环境变化主要与灌水量有关,渠道衬砌有效提高了灌溉水利用系数,对地下水埋深及土壤盐碱化有一定影响。为控制灌区土壤盐碱化,示范区地下水埋深阈值为1.6~1.8 m,西济支渠区域适宜引水量为1 645~1 850万m^3。渠道衬砌后灌区具有535万m^3节水潜力,研究结果将为灌区节水改造提供理论基础。     

渠道衬砌对农田水土环境的影响研究——以隆胜节水示范区为例

在引黄水量大幅减少且河套灌区大范围实施节水改造工程的背景下,为研究河套灌区渠道衬砌前后对农田水土环境的影响,通过对隆盛节水改造典型示范区的环境效应进行监测分析研究,结果显示示范区环境变化主要与灌水量有关,渠道衬砌有效提高了灌溉水利用系数,对地下水埋深及土壤盐碱化有一定影响。为控制灌区土壤盐碱化,示范区地下水埋深阈值为1.6~1.8 m,西济支渠区域适宜引水量为1 645~1 850万m~3。渠道衬砌后灌区具有535万m~3节水潜力,研究结果将为灌区节水改造提供理论基础。     

内蒙古河套灌区节水改造工程综合节水技术研究

河套灌区属季节性冻土地区,针对渠道冻胀破坏与渗漏严重、灌溉用水量大、灌区管理粗放等问题,开展了6个方面的专题研究,简要总结了不同级别渠道适宜的衬砌结构型式,聚苯乙烯保温与风积沙换填防冻措施,土壤固化剂新材料应用,渠道防渗效果监测,田间节水改造技术和节水改造工程实施后对灌区环境的影响等诸多方面,并对大型灌区节水改造工程建...     

影响衬砌渠道冻胀破坏严重的关键因素

衬砌渠道冻胀破坏多年来一直影响着宁夏引黄灌区渠道的使用年限和安全运行,制约着灌区发展。通过大量的试验数据对引起灌区混凝土衬砌渠道冻胀破坏的渠床土质、土体密度、气温、地温、冻土深度、冻胀量、基土水份、地下水位等因素进行研究分析,研究衬砌渠道冻胀破坏机理、各影响因素与冻胀破坏的关系,为灌区续建配套和节水工程改造设计与建设提供技术依据。     

混凝土渠道衬砌形式防渗效果试验与分析

通过对河北省石津灌区混凝土渠道的衬砌形式、结构形式、伸缩缝填充形式等采用动水法测量渠道输水损失分析,从防渗效果与投资二方面综合考虑,确定"现浇混凝土+保温板,树脂油膏砂浆填缝"形式是适合石津灌区的渠道防渗形式,为灌区节水改造工程提供理论依据。     

内蒙古河套灌区隆胜节水农业示范区水盐动态分析

通过水管部门组织科技人员对河套灌区调研为基础,以农业综合节水为目的,在灌区的中游永济灌域隆胜乡境内建设了节水农业示范区,面积为0.28万hm2.节水农业改造工程主要措施:渠道防渗衬砌、平地缩块.节水农业改造工程2002年竣工后,在运行中监测了3年,得出灌溉水量平均减少了12.3%;对示范区水盐动态进行了分析.     

应用方差分析方法研究内蒙古河套灌区用水量影响因素

运用方差分析方法研究了河套灌区1990-2000年单位面积灌溉用水量变化的影响因素.结果表明:渠道衬砌、渠系配套建设等工程节水措施和用水管理措施对减少灌区用水量产生显著影响,而种植结构调整因素和降雨对灌区用水量产生的影响并不显著.在将来的节水改造中,应继续加强种植结构调整以增强节水效果.本研究所建立的模型拟合优度好,能准确地解释和评价灌区用水量的影响因素.     

四川红层地区渠道加固整治实用技术研究与应用

【目的】在四川红层地区修建的渠道等水工建筑物,因衬砌材料特性、水流冲刷磨损、风化剥蚀、植物根系侵蚀以及长期运行,造成渗漏、阻水等病害现象十分严重,且边坡崩塌等地质病害问题逐年加剧,因此病害治理是灌区节水改造工程的重点。【方法】在研究都江堰灌区节水改造工程渠道整治技术的基础上,提出了采用电焊网为增强材料、铺设锚固后以水泥砂浆覆盖的施工技术作为红层地区渠道加固整治实用技术。【结果】通过运行效果分析,既达到渠道边坡稳定、防渗减糙、满足过流能力等功能保障,又能节约国家投资、少占耕地、节约工期、保护生态。【结论】渠道加固整治实用技术是费省效宏、节能减排的研究技术,在都江堰灌区应用广泛。     

大中型灌区技术改造规划中的几个问题

1　编制好以节水为中心的灌区整体规划这次大型灌区技术改造 ,绝非是原有灌区简单地进行修修补补 ,不是缺渠道简单地补挖渠道 ;建筑物不全 ,补修建筑物 ;没衬砌的渠道 ,进行衬砌等修补。而是应根据中央制定的节水农业发展规划和近期实施方案 ,按照以节水为中心进行灌区全面整体规划。对原有渠系布局 ,灌溉方法 ,耕作方式 ,灌溉制度和种植结构进行重新规划和调整。这次灌区技术改造是以节水为中心的 ,其规划应紧紧围绕节水为出发点 ,提高灌溉水的利用率和水分生产率 ,实现水资源的可持续利用和灌区的可持续发展。要有利于保护和改善灌区的生…     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。