临洮县:建设规模化农村饮水安全工程

<正>临洮县隶属于甘肃中部的定西市,是陇上历史文化名城,也是国家贫困县之一。全县总面积2851km2,辖18个乡镇351个村,总人口54.35万,其中农村人口49.54万。受自然地理条件限制,全县多年平均年降水量451.7mm,时空分布极不均匀,且80%以上集中在6—9月。由于干旱少雨,临洮县水资源短缺,广大农村群众饮水十分困难,长期靠取用窖水、塘坝水、山泉水和沟溪水生活。经2004年对全县农村群众饮水现状调查评估,临洮全县农村饮水不安全人口为35.64万,占全县农村人口的71.94%。     

内部制约与外部挤压下的北部湾港口发展策略研究

随着经济全球化和区域经济一体化的发展,港口已经成为带动区域经济发展的战略资源与重要增长点。广西北部湾经济区地处东盟、华南、西南三大经济圈的结合地带,是我国西部大开发区域中唯一的沿海地带,也是我国与东盟国家陆地接壤、海上相通的唯一西部港口。在此背景下,环北部湾港口的发展就显得尤为关键。但是与我国其他沿海港口相比,北部湾港的发展面临着内部制约与外部挤压的双重压力。这让北部湾港口的发展压力更为沉重。     

The Improvement in GWLF Model Simulation Performance in Watershed Hydrology by Changing the Transport Framework

The correct and reasonable delineation of actual hydrologic processes is a footstone for the effective simulation of pollutants in watershed models. In this study, a simple but comprehensive semidistributed modeling approach based on the generalized watershed loading function (GWLF) was modified to enable the accurate simulation of hydrology in watersheds. The frame of the original GWLF model (ORM), with a lumped hydrological parameter, was modified by adding channel routing processes, which made it possible to introduce the concept of subbasins. Then, the revised GWLF model was applied to the Luanhe watershed (30,000 km²) on a monthly bias in comparison with the ORM and the previously revised version. The sensitivity analysis and generalized likelihood uncertainty estimation (GLUE) uncertainty analysis were individually conducted to evaluate these modifications. Eventually, we compared four extreme conditions for the daily streamflow simulations of the three model versions in the Tunxi watershed but without calibration. All of the results indicated that the stability and accuracy of the model and the validity of the parameters were all enhanced and improved by the new revised version of the model, which provided reliable simulation results and indicated that it is a prospective tool to support watershed management.

     

基于Tennant方法的河流生态基流应用现状及改进思路

Tennant法作为国内外应用最为广泛的水文方法,在生态基流研究中起着重要作用。但是,作为一种经验方法,具有局限性,在参考或应用某种方法时应该对其进行合理性分析。系统总结了Tennant法普遍存在的时空变化大、流量适宜性较弱、普适条件较差的3个关键问题,基于3种改进形式的变量:特征流量、用水期、百分率,深化研究Tennant方法的改善战略,进而归纳出3种改进方法:年均值法、同期均值法、改进百分系数法。最后,对Tennant法进行展望,提出选取具有年内和年际丰枯变化性的低流量指标、建立基流百分比与水生生物栖息地之间的适应曲线簇、有针对性地修正具体河流中水生生物的生物和物理需求、确定生态基流阈值时需考虑到流量与河流生态系统之间的关系等发展趋势,以期拓宽Tennant法的使用范围、完善不同地区河流生态基流的技术支持。     

Approach of water–salt regulation using micro-sprinkler irrigation in two coastal saline soils

This study aimed to investigate whether saline silt and sandy loam coastal soils could be reclaimed by micro-sprinkler irrigation. The experiments were run using moderately salt-tolerant tall fescue grass. Micro-sprinkler irrigation in three stages was used to regulate soil matric potential at a 20-cm soil depth. Continued regulation of soil water and salt through micro-sprinkler irrigation consistently resulted in an increasingly large low-salinity region. The application of the three stages of soil water–salt regulation resulted in an absence of salt accumulation throughout the soil profile and the conversion of highly saline soils into moderately saline soils. There were increases in the plant height, leaf width, leaf length, and tiller numbers of tall fescue throughout the leaching process. The results showed that micro-sprinkler irrigation in three soil water and salt regulation stages can be used to successfully cultivate tall festuca in highly saline coastal soil. This approach achieved better effects in sandy loam soil than in silt soil. Tall fescue showed greater survival rates in sandy loam soil due to the rapid reclamation process, whereas plant growth was higher in silt soil because of effective water conservation. In sandy loam, soil moisture should be maintained during soil reclamation, and in silt soil, soil root-zone environments optimal for the emergence of plants should be quickly established. Micro-sprinkler irrigation can be successfully applied to the cultivation of tall fescue in coastal heavy saline soils under a three-stage soil water–salt regulation regime.     

不同尺寸混凝土三点弯曲梁试件断裂过程试验研究

为探讨不同尺寸混凝土三点弯曲梁试件断裂过程的差异性及其尺寸效应,设计了高度为0.25 m、0.30 m、0.40 m、0.50 m的4组16根不同尺寸混凝土三点弯曲梁试件,对其进行全过程断裂试验,并分析了荷载~张口位移曲线、起裂和失稳荷载、起裂和失稳韧度等断裂参数的变化。结合双K断裂韧度计算方法,得到不同尺寸混凝土三点弯曲梁试件的起裂韧度和失稳韧度。结果表明:不同尺寸混凝土试件断裂过程具有差异性;起裂韧度不随试件高度的增加而变化,失稳断裂韧度随试件高度的增加而增大。试件高度从0.25 m增加到0.50 m时,失稳韧度增加了0.40 MPa·m1/2。     

加压液化输沙技术不同孔径对“浑水水力分离清水装置”流场影响的数值模拟

为探究加压液化输沙技术运用于浑水水力分离清水装置的最佳孔径,运用FLUENT软件,采用RNG k-ε紊流模型和多相流混合模型,对不同加压液化渗水孔孔径作用下,浑水水力分离清水装置的水沙两相三维流场进行了数值模拟。根据模型计算结果,分析对比了不同加压液化渗水孔孔径作用下,装置内部流场泥沙分布的变化。研究表明:加压液化渗水孔孔径为2mm时,装置内部浓度分层明显,锥体底部水沙扰动剧烈,没有出现泥沙淤积,清水溢流出口含沙浓度较小,水沙分离作用效果明显,是装置运用加压液化输沙技术的理想状态。研究成果为优化加压液化输沙技术与装置的结合奠定了理论基础。     

版权保护对美国出口影响的实证分析

本文采用引力模型,对美国与不同国家的贸易截面数据进行实证分析显示,美国核心版权产品由于版权保护水平的的提高,对强模仿威胁国家(低保护高模仿)会带来显著的市场扩张效应;增加美国核心版权产品的出口,对弱模仿威胁国家(高保护低模仿)会带来显著的市场力量效应,会使美国出口下降。     

山秀水电站二期截流围堰优化设计与施工

山秀水电站二期截流围堰施工措施优化是根据地形、河床覆盖层及水流情况,采用下游围堰作为截流戗堤,龙口留在下游围堰及围堰内闭气方案.科学地利用一、二期围堰拆、填平衡,在水深13.3 m,导流量486 m3/s,下游围堰轴线长151m的条件下,边抽水边加固闭气体,围堰闭气成功,保证了二期工程的施工按期圆满完成,顺利通过验收.     

多沙粗沙区不同水土保持措施组合对径流影响分析

在对多沙粗沙区不同类型区水土保持措施组合的调查、评价的基础上,分析了《黄河近期重点治理开发规划》中皇甫川、三川河和马莲河3条支流不同措施组合对径流的影响。结果表明,水土保持措施规划实施后,对径流的影响在枯水年分别为3278万m^3和2159万m^3,占河龙区间多年平均实测径流量的20．9％,若是丰水年或平水年将分别占到58．8％和38．9％。可见,水土保持措施对径流的影响作用是很大的。