桥墩阻水比是确定涉河桥梁工程方案主要考量指标之一.为研究桥墩阻水比对弯道河流流速分布的影响,建立有机玻璃弯道水槽模型,针对不同阻水比桥墩对弯道河流流速分布影响开展试验研究.使用声学多普勒流速仪(acoustic doppler velocimeter,ADV)采集弯道试验段内的纵向和横向流速并进行分析,结果表明:随阻水比的增大,桥墩附近上下游主流位置趋于集中在水槽中间.在弗劳德数Fr=0.21和Fr=0.28两组工况下,墩前断面纵向流速方差均减小,其流速分布更加均匀;墩后断面纵向流速方差均增大,其流速分布更加紊乱;横向流速在墩前与墩后分布均更加紊乱.桥墩阻水比对纵向流速和横向流速分布的影响均随Fr增大而减小.

采用模型试验与数值模拟相结合的方法研究了弯道河流中桥梁布设对上游水位壅高的影响,确定弯道水流中桥墩上游水位变化由两部分组成,即桥墩导致河道过流能力降低,壅高了上游水位;受桥墩绕流阻力作用,弯道水流上游横向水位超高减小,促使水面线重新分布.进而在传统经验公式的基础上,基于物理试验、数值模拟结果和水力学理论,建立了弯道水流条件下桥墩上游最大水位壅高修正算法.结果对弯道河流涉河桥梁工程规划、设计、建设具有一定的指导价值.

为探讨适于南方岩溶地区的湿地生态系统健康评价方法,以会仙岩溶湿地为研究对象,针对岩溶地区湿地的独特特点,基于压力-状态-响应(pressure-state-response,PSR)模型构建会仙湿地生态系统健康评价体系.运用二元对比定权法确定指标权重,通过综合评价指数(comprehensive evaluation index,CEI)对会仙湿地生态系统健康状况进行评价.评价结果显示,会仙岩溶湿地健康指数为2.992,处于"亚健康"状态.研究结果表明:会仙湿地资源受到了一定程度的破坏,生态恢复能力退化,生态系统不稳定.应及时采取相应措施进行生态系统保护,从而促进会仙湿地生态系统的健康和可持续发展.研究结果对探寻会仙岩溶湿地退化原因、开展湿地保护与生态修复具有重要的应用价值.

以会仙岩溶湿地的核心区域为研究对象,基于研究区的地质条件和水文地质条件,概化出水文地质概念模型,运用Visual MODFLOW软件对会仙湿地地下水的分布特征进行数值模拟,经模型识别与验证,其模拟水位与观测水位取得较好的拟合效果.结果 表明:研究区地下水总体呈自北向南递减趋势流动,北部补给区地下水位最高,西南部排泄区地下水位最低,南北地下水位平均差值为7.34 m;水位动态变化受降雨强度影响较大,呈现出明显的季节性变化规律;南部分水塘、睦洞湖等排泄带水源补给充足,地下水位变幅不超过1 m,北部补给区的水位变幅在3m以上;经水均衡计算,模拟期的地下水总补给量为44 272.92万m3/a,其中降雨入渗补给量占76.85％,地下水的总排泄量为42 723.06万m3/a,地下水开采量与蒸发量分别占33.86％、36.63％;研究区在模拟期内总体处于正均衡状态,但处于负均衡的枯水月份占到2/3,湿地的退化直接影响其防洪调蓄和保水、蓄水能力,使“早期过旱、涝期过涝”现象极为显著.

Focusing on lake underwater terrain unknown and dynamic storage that is difficult to obtain by the traditional methods ,a new method is proposed for l ake dynamic storage estimation by multi‐source and multi‐temporal remote sensing without underwater terrain data .The details are as follows .Firstly ,extrac‐tion dynamic lake boundary through steps by steps adaptive iteration water body detection algorithmfrom multi‐temporal remote sensing imagery .And then ,retrieve water level information fromICESat GLAS laser point data .Thirdly ,comprehensive utilizing lake area and elevation data ,the lake boundary is converted to contour of water by the water level is assigned to the lake boundary line ,according to the time and water level information .Fourthly ,through the contour line construction TIN (triangulated irregular network) model and Kriging interpolation ,it is gotten that the simulated three‐dimensional lake digital elevation model .Finally ,on the basis of simulated DEM ,it is calculated that the dynamic lake volume ,lake area distribution and water level information .The Bosten lake is selected as a case studying to verify the algorithm .The area and dynamic water storage variations of Bosten lake are detected since 2000 .The results show that ,the maximum error is 2 2.1 × 108 m3 ,the minimum error is 0 0.0002 × 108 m3 ,the average error is 0 0.44 × 108 m3 ,the root mean square is 0 5.9 and the correlation coefficient reached 0 9.9 .

流域不透水面能直接影响非点源污染的转移模式,降低受纳水体质量,对生态环境造成巨大压力,是流域生态水文模型的一个重要参数.针对流域不透水面遥感信息提取及尺度依赖性问题,从像元、亚像元两个尺度进行了研究,论述了流域初始分类与样本获取、局部不透水面信息提取和亚像元级不透水面覆盖率计算的技术方法.以福建省九龙江流域为例,对2010年不透水面空间格局进行了提取,其总体精度达到82.81％,验证了本文研究成果的实用性.

The turbulent flow in open channel with smooth surface and artificially made rough surface is tested,in which the longitudinal mean-flow velocity and fluctuated mean flow velocity of the turbulent flow on smooth,transitional and rough surfaces with various water depths are measured by laser Doppler velocimeter(LDV).Based on the measured data,the effect from the artificial roughness on the turbulence intensity of the flow is analyzed,and then the developing and changing laws of the turbulence intensity for the smooth,transitional and rough surfaces of open channel are obtained.

利用激光测速仪,对壁面自水力粗糙面突减至水力过渡面时过渡段内的明渠紊流进行了试验研究,测量了糙率突减不同水深情况下明渠紊流的纵向时均流速和脉动流速。通过实测资料,分析水深和糙率改变后内边界层发展变化规律、粗糙度及水深对内边界层厚度的影响以及糙率突减后从一种均匀紊流到形成新的充分发展紊流所需要的纵向长度。

This paper makes experimental study on the turbulence under roughness coefficient mutation on bottom wall of open channel,measures the mean velocity and fluctuating velocity of turbulence at different water depth by using LDV,and based on a lot of experimental results,analyzes the evolving rules and thickness of boundary layer at different water depth and with different roughness coefficient,and studies on the necessary longitudinal length when flow changes from homogeneous flow to new turbulence.

The turbulent flow in open channel is tested with laser-Doppler anemometer, in which the longitudinal time average velocity and fluctuating velocity of turbulent flow in open channel under the conditions of the sudden changes of roughnesses at different water depths are measured. Based on the measured data, the change of the friction velocity of turbulent flow and the characteristics of the wall shear stress under different sudden roughnesses and different water depths are analyzed herein.

Three methods of turbulent numerical simulation are summarized in paper:Direct Numerical Simulation(DNS),Reynolds Averaged Navier-Stokes(RANS) and Large Eddy Simulation(LES).Their characteristics and applicability are analyzed and compared mainly in basic conceptions and theories according to the researchers studies in the last years.The conclusions will be helpful for study of turbulence.The methods of turbulent numerical simulation are still being groped now, so the research directions that will obtain salient developments of turbulence in the future are given in the end.

The use of underwater concrete to build a cut-off wall and some special problems encountered in its construction are described. Care must be taken to the construction technology of underwater concreting and scientific and rational technology would enable to avoid various accidents, to accelerate construction speed, to improve construction quality, to reduce the cost, and to ensure good economical benefits.