Economic analysis of water temperature reduction practices in a large river floodplain: an exploratory study of the Willamette River,Oregon

This paper examines ecosystem restoration practices that focus on water temperature reductions in the upper mainstem Willamette River, Oregon, for the benefit of endangered salmonids and other native cold‐water species. The analysis integrates hydrologic, natural science and economic models to determine the cost‐effectiveness of alternative water temperature reduction strategies. A temperature model is used to simulate the effects of combinations of upstream riparian shading and flow augmentations on downstream water temperatures. Costs associated with these strategies are estimated and consist of the opportunity costs of lost agricultural production and recreation opportunities due to flow releases from an up‐stream reservoir. Temperature reductions from another strategy, hyporheic flow enhancement, are also examined. Restoration strategies associated with enhanced hyporheic cooling consist of removal/reconnection of current obstacles to the creation of dynamic river channel complexity. The observed reduction of summer water temperatures associated with enhanced channel complexity indicates that restoring hyporheic flow processes is more likely to achieve cost‐effective temperature reductions and meet the total maximum daily load (TMDL) target than conventional approaches that rely on increased riparian shading or/and combinations of flow augmentation. Although the costs associated with the hyporheic flow enhancement approach are substantial, the effects of such a long‐term ecological improvement of the floodplain are expected to assist the recovery of salmonid populations and provide ancillary benefits to society. Copyright © 2008 John Wiley & Sons, Ltd.     

天津海河磷的分布特征

采集海河干流重要断面、相应排污渠以及部分支流(北运河、子牙河、南运河)共29个监测断面的水样,对样品中的溶解性活性磷(SRP)、总溶解态磷(TDP)与总磷(TP)进行测定,并分析其分布特征。结果显示:海河干流各断面的TP质量浓度为0.4~3.5mg/L,已超出GB3838—2002《地表水环境质量标准》Ⅴ类水质标准,SRP质量浓度0.09~0.75 mg/L,TDP质量浓度0.24~1.42 mg/L;各排污渠(支流)TP质量浓度0.2~5.0 mg/L,SRP质量浓度0.01~3.63 mg/L,TDP质量浓度0.12~4.16 mg/L。排污渠(支流)多数断面的含磷量比相应干流的高。天津海河总磷以总溶解态磷为主要形态,这和海河悬浮颗粒物浓度较低有关。     

南水北调中线穿黄隧道盾构注浆浆材试验

为满足南水北调中线工程穿黄隧洞盾构施工工法要求,对研制开发的水泥-膨润土-水玻璃系双液塑性壁后注浆材料,通过室内模拟注浆试验,重点探讨了材料组分对注浆材料流动性、稳定性、凝胶特性、强度等性能的影响.结果表明:凝胶时间可控制在10 s左右;不同配比注浆材料1 h单轴抗压强度为0.08～0.12 MPa,28 d为7.81～8.52 MPa;渗透系数为2.0×10-8 cm/s;模拟注浆时浆液不被水稀释,充填良好;且不会对地层产生劈裂,也不会向开挖掌子面渗漏.     

基于灰色聚类的黄河防汛物资分类储备模型研究

对黄河防汛抢险物资进行分类是科学储备黄河防汛抢险物资的前提和基础。通过综合考虑物资的重要性、储备性、成本性和社会性,结合黄河防汛抢险的特殊性,建立了黄河防汛物资分类指标体系,采用灰色聚类的方法对防汛物资进行分类,针对各类防汛物资的特点和实际需求,提出相应的管理策略,提高防汛物资保障能力,为黄河防汛物资的科学储备提供依据。     

River scale model of a training dam using lightweight granulates

Replacing existing river groynes with longitudinal training dams is considered as a promising flood mitigation measure in the main Dutch rivers, which can also serve to guarantee navigability during low flows and to create conditions favourable for ecological development. Whereas the bed response in the streamwise uniform part of a river trained by a longitudinal dam can be readily predicted, the bed response at the transition zones is unclear. In the present study, we investigate the local morphological effects resulting at the intake section of a longitudinal training dam, where the flow is distributed over the main channel and a side channel in between the dam and the river shore. A sediment recirculating model with a nearly undistorted geometry with respect to the prototype was setup. Lightweight polystyrene granulates were used as a surrogate for sediment, to properly scale the Shields parameter without compromising Froude scaling, and reach dynamical similarity. A laser scanner allowed collecting high-resolution bed elevation data. Results obtained under typical low flow and high flow conditions show a general deepening of the bed in the area adjacent to the training dam, in response to narrowing of the main channel. Scour at an upstream river groyne embedded in the model showed a scour hole which was deeper than realistic. Throughout the entire domain, bedforms developed featuring geometrical properties that reproduced the prototype conditions appropriately. Based on a comparison with characteristics from the River Waal, regarded as the prototype without a longitudinal dam, lightweight sediments were considered to be a proper choice for this study, in which bedload is the main sediment transport mode. The main conclusion regards the absence of significant morphodynamic developments at the intake section, both during the high flow experiment and during the low flow experiment, which can be attributed to the alignment of the dam with the local streamlines.     

黄河内蒙古河段冲淤量评估

通过实测断面资料、来沙量资料和同流量水位的变化等,对黄河内蒙古河段的冲淤量分别进行了估算,其结果基本一致。综合分析表明,1986-2004年内蒙古三盛公—头道拐河段年均淤积量为0.616亿t是基本可靠的,而主槽的淤积量占全断面的80%以上。总体看,这一数值可以反映1986年龙羊峡水库运用以来内蒙古河道的淤积情况。     

丁坝在三屯河河道整治中的成功经验

三屯河渠首以下3km范围内的河道，东西两岸毗邻三屯河东西干渠及耕地，河道两岸多年遭受洪水的严重侵蚀破坏，直接危及到了下游东、西引水干渠的安全。2000年，对该段河道采用丁坝型式进行了总体整治设计，当年秋季竣工。经过近3a的运行，整治效果较明显，彻底根治了水患，确保了东、西引水干渠的安全，取得了巨大的防洪效益。     

The effects on fish spawning and management implications of impoundment water releases in an intermittent South African river

The potamodromous smallscale redfin minnow (Pseudobarbus asper) spawned in the riffle areas of the regulated Groot River, the major tributary of the Gamtoos River system, during controlled releases of water from Beervlei Dam. Water had been released at irregular intervals from this flood control dam solely for irrigating agricultural lands. Flushing flows removed accumulated salts from riverine pools and were followed by reduced flows which initiated spawning of the minnow species. Developing embryos of P. asper were found in the riffle zone of the main river channel during the water releases. Ripe-running males were located under the boulders in the riffles. Several developing embryos of Labeo umbratus were found with the P. asper eggs. Very little is known about the effects of man-made alterations to the river flow regime on the reproductive activity of fishes in the majority of South African river systems. The agriculturally based flooding regime at Beervlei may have increased the recruitment of the redfin minnow species. Water management must give cognizance to the biological and environmental requirements within the regulated river systems. Water release strategies from Beervlei Dam should include instream flow decisions based on the requirements of the aquatic environment as well as for agriculture.     

钱塘江北岸老海塘塘脚防冲工程技术

介绍钱塘江北岸明清老海塘概况和工程自然条件 .提出运用板桩防冲墙技术解决塘脚防冲技术难题 ,并研制出可以遥控操作的多功能打桩机 .该技术在海宁明清海塘塘脚防冲工程中应用9 9km ,节省投资 5 2 0 0万元 ,并已在类似工程中推广应用 .     

Comparison of macrobenthos in braided and channelized sectors of the Drôme River,France

The influence of braided pattern on macrobenthic communities was studied in the Lower Drǒme River (France). The qualitative differences between embanked and braided sections are weak. The sessile species (for example Psychomyia pusilla) are more frequent in the embanked section whereas the drifting species (for example Baetis fuscatus) are more frequent in the braided section. The density of macroinvertebrates in the latter, especially in the secondary channels, is higher than in the embanked section, but the diversity remains low because the location of the channels changes at each extreme flood.