Modelling the impact and potential mitigation of cold water pollution on Murray cod populations downstream of Hume Dam,Australia

A one‐dimensional hydrodynamic reservoir model is coupled with a stochastic fish population model to examine the impacts of cold water pollution (CWP) on the Australian freshwater fish, Murray cod, downstream of Hume Dam, Australia. Mitigation of CWP through the introduction of selective withdrawal capabilities to access near‐surface water is predicted to increase discharge temperatures during the crucial spring‐early summer post‐spawning period by 4–6°C for normal operating conditions, that is, a full reservoir in early spring. No improvement in discharge temperature was predicted for drought conditions characterized by relatively low storage levels in early spring. The predicted temperature increase using selective withdrawal increased the predicted average minimum female population abundance by 30–300% depending on the assumed spawning behaviour. Increased discharge temperatures appear to be achievable and are expected to reduce the stress currently impacting Murray cod populations due to CWP during crucial post‐spawning periods. This provides evidence that mitigation of this problem may assist in rehabilitating Murray cod populations in the Murray River downstream of Hume Dam. Copyright © 2007 John Wiley & Sons, Ltd.     

橡胶坝蓄水工程对城市浅层地下水环境影响的评价

在查清浅层地下水含水层组合情况后，通过实测资料对比分析了南阳市白河第三橡胶坝蓄水前后地下水开采量、地下水动态变化规律、地下水降落漏斗演变趋势、地下水水质情况、环境地质现象等问题。指出蓄水前，地下水环境处于不断恶化的过程中；浅层地下水超采严重致使市中心城区缺水严重；地下水位持续下降，在白河南北形成了2个降落漏斗并不断扩大；水质恶化，局部地段出现地裂缝，膨胀土地区低层建筑物墙体开裂等。蓄水后，在库水范围内白河侧渗底渗量增大，增大了浅层地下水的补给量，地下水动储量增大，大大缓解了市中心城区的缺水现状；在地下水开采量不断增大的情况下，漏斗中心的地下水位回升，并趋于动平衡状态；除橡胶坝下游、白河左岸1000m及右岸600m等处外，漏斗内的其它部位水质变好，地下水环境明显得到改善。但同时地下水位上升使某些建筑物地下室进水及需对拟建建筑物深基坑降水，给工程建设带来了一些不利影响。     

考虑淤沙影响的高拱坝水库水温数值分析

本文考虑高拱坝水库淤沙的影响,采用热流耦合方法对水库立面二维水温数学模型进行数值分析,探讨高拱坝水库水温的分布规律。在此基础之上,分析了水库水温分层的形成过程及原因,并重点探讨了淤沙对高拱坝水库水温以及运行期应力的影响,对比分析了水温的规范算法、实测值和本文数值计算方法之间的差别,并对规范的水库水温计算方法进行了评价。二滩水库的数值计算结果表明,在1 060m高程以下,考虑淤沙的影响更接近实测的水温结果,而按照规范方法计算的水库水温边界条件,具有较大的安全裕度。     

大坝下游河道水温变化规律及其影响

以汉江凡口水库为例,讨论了河流上建坝以后下游河道的水温变化情况及其对周围环境正负两方面的影响。根据实测资料,以附近天然河道的水温为主要因子,建立了河道主要断面的水温预测方程。     

重力坝运行期年变化温度场引起的应力

气温和水温的年变化在重力坝内会引起相当大的拉应力,是重力坝在运行期产生裂缝的重要原因,但目前还缺乏一套实用的计算方法,笔者提出了一套计算公式,可用以计算不同表面保温条件下气温和水温年变化在重力坝内引起的应力并从而计算表面保温的效果。     

Sensitivity of water quality indicators in a large tropical reservoir to selected climate and land‐use changes

This study compared the sensitivity of water quality in tropical Aguamilpa Reservoir, as represented by normalized algae mass and dissolved oxygen, to selected projected changes from global climate change and development. The sensitivity of reservoir stratification as an indicator of reservoir sensitivity also was analysed. Model simulations indicated the reservoir was more sensitive to changes during the warm‐dry season than at other times. Both indexes (normalized algal mass and dissolved oxygen mass) were more sensitive to changes in air temperature (climate change) and nitrogen loading (development) than to changes in flow. The sensitivity to air temperature was similar to, but generally less than, the sensitivity to nutrient inflow. At the bounding values for change (3 °C for temperature; 50% increase in nitrogen loading), the algae mass sensitivities were 0.15 mg L^?1 per 3 °C and 0.2 mg L^?1 per 50% nitrogen load increase, and the dissolved oxygen mass sensitivities were 0.7 mg L^?1 per 3 °C and 2.0 mg L^?1 per 50% load increase. Changes in air temperature and nitrogen loadings affect the reservoir in different ways, air temperature mostly changing the timing of the algal growth with little change in peak values, while nutrient loadings change the peak values with little change in the timing. While the sensitivities are similar, the total algal mass change is significantly larger for nitrogen loading, compared to air temperature changes. These results imply global climate change effects can be partially mitigated by implementing management measures in the surrounding watersheds to minimize nutrient inflows, especially nitrogen in the case of Aguamilpa Reservoir.     

大王滩水库水污染现状分析

根据大王滩水库的水质监测数据 ,利用内梅罗综合污染指数法对水库水质现状进行评价分析 ,得出大王滩水库的水质污染类型、主要污染物和主要污染源污染成因     

黏土心墙坝库水位骤降联合降雨上下游坝坡渗透稳定性数值模拟

为研究库水位骤降联合降雨情况下某黏土心墙坝的渗流特性以及稳定性规律,利用Geo-studio软件,对库水位骤降、不同强度降雨以及降雨发生在库水位骤降的不同时刻下的某黏土心墙坝的渗流特性以及上下游坝坡的稳定性规律进行了数值模拟。计算结果表明:(1)库水位骤降工况下孔压降低152%,上游坝坡安全系数先减小12.8%,后略有增大,下游坝坡则增大0.5%,库水位下降速率越大,孔压下降越快,上游坝坡安全系数下降越快,最小安全系数越小,下游坝坡安全系数上升越快;(2)降雨工况下孔压先平均增大2.1%后降低至初始水平,安全系数则先减小0.3%后增大至初始水平,降雨强度越大,孔压上升的幅度越大,最小安全系数越小;(3)降雨发生在库水位骤降不同时刻下,孔压呈现先减小后保持不变,在降雨时刻呈现突然上升的趋势,上游坝坡安全系数先减小后维持不变,下游坝坡安全系数先增大后保持不变,在降雨时刻突然下降,降雨发生在库水位下降结束时刻安全系数最小。     

重污染河流闸坝防污限制水位研究

重污染河流上的闸坝过量蓄水是导致污染团集中下泄造成水污染事件的主要诱因之一。针对这一问题,本文提出和定义了防污限制水位的概念,并以兴利和防污为目标,构建了重污染河流闸坝防污限制水位模型,以研究预防因污染团集中下泄造成水污染事件的闸坝防污限制水位,规范重污染河流闸坝的蓄水量。将该方法应用到淮河流域沙颍河的多个闸坝,计算结果表明,该模型能够有效地求解重污染河流的闸坝防污限制水位,具有一定的实用性。这对重污染河流开展闸坝防污调度研究提供重要的技术支撑。     

坝体变位和内水压力对坝后背管结构应力的影响

用三维接触单元模拟背管与坝体接触面，分析坝体变形和内水压力对李家峡坝后背管结构应力的影响。坝体变位对背管结构轴向应力的影响表现为上部为拉应力下部为压应力，并且拉应力由背管的上弯段向下弯段逐渐减小，部分轴向拉应力值大于混凝土设计抗拉强度；背管内水压力对背管结构环向应力的影响表现为环向拉应力，并且管腰外缘和管顶内缘混凝土环向拉应力是混凝土设计抗拉强度的2．4倍。根据应力的大小分布可以确定，坝体变形是背管产生较大轴向拉应力的主要因素，是产生环向拉应力的次要因素；内水压力是使背管产生较大环向拉应力的主要因素，是产生轴向拉应力的次要因素。     

解决重力坝加高时温度应力的新思路和技术

重力坝加高时，老坝块已充分冷却，由于水泥水化热及浇筑温度等原因，新浇坝块的温度将超过老坝块，新老坝块之间将形成温差。这一温差不但将在新坝块中引起拉应力，还将在老坝块的坝踵部位引起拉应力，使坝体应力恶化，甚至引起裂缝。为此，提出一套新思路和新技术，综合应用弹性力学圣维南原理、水管超冷和强力保温措施。解决了重力坝加高的温度应力难题。分析结果表明，这一套新的思路和技术是有效的。     

Simulating effects of hydro‐dam alteration on thermal regime and wild steelhead recruitment in a stable‐flow Lake Michigan tributary

Hydroelectric dams may affect anadromous fish survival and recruitment by limiting access to upstream habitats and adversely affecting quality of downstream habitats. In the Manistee River, a tributary to Lake Michigan, two hydroelectric dams potentially limit recruitment of anadromous rainbow trout (steelhead) by increasing tailrace water temperatures to levels that significantly reduce survival of young‐of‐year (YOY) fish. The objectives of this study were to determine whether proposed restoration scenarios (dam removals or a bottom withdrawal retrofit) would alter the Manistee River thermal regime and, consequently, improve wild steelhead survival and recruitment. Physical process models were used to predict Manistee River thermal regimes following each dam alteration scenario. Empirical relationships were derived from historical field surveys to quantify the effect of temperature on YOY production and potential recruitment of Manistee River steelhead. Both dam alteration scenarios lowered summer temperatures and increased steelhead recruitment by between 59% and 129%, but total recruitments were still low compared to other Great Lakes tributaries. Considering only temperature effects, bottom withdrawal provides the greatest promise for increasing natural steelhead recruitment by decreasing the likelihood of year‐class failures in the warmest summers. Results of this study may allow managers to evaluate mitigation alternatives for Manistee River dams during future relicensing negotiations, and illustrate the utility of physical process temperature models in groundwater‐fed rivers. Copyright © 2004 John Wiley & Sons, Ltd.     

高混凝土拱坝一期水冷温度对水管周边混凝土的影响

混凝土拱坝一期水管冷却一般在刚浇筑完混凝土后采用通水冷却10-20d,目的是起到消峰控温的作用,然而在实际的工程操作中,施工方有时为了控制最高温度而大限度地降低一期冷却水温。本文以锦屏一级高拱坝为例,借助于有限元计算,建立了水管冷却的精细模型,从理论上解决了三个方面的问题,一是是否冷却水温越低对最高温度的控制就越好,二是不同冷却温度对混凝土周边温度应力的影响,三是不同管材(包括塑料管和铁管)对混凝土温度应力的影响,从而为工程实践提供了一定的依据。     

控制幕运行方式改善下泄水温及其成因研究

控制幕取水方式能够有效地减缓温度分层型水库下泄低温水对下游生态环境的不利影响,但目前缺乏控制幕运行方式下泄水温规律的试验研究以及对下泄水温成因的分析。本文基于某水库水温资料,首先通过试验探讨不同控制幕运行方式对下泄水温的改善效果,总结下泄水温规律。其次,利用三维数学模型进行精细模拟,分析控制幕表层和底层同时过流运行方式的流动规律,探讨下泄水温成因。结果表明:控制幕表层过流运行方式能够显著提高下泄水温;采用控制幕表层底层同时过流运行方式时,主流区位于控制幕顶部和底部,下泄水体主要由表层高温水与底层低温水掺混而成,下泄水温取决于所取表层高温水和底层低温水的掺混比例。研究成果对温度分层型水库控制幕取水的运行调度具有重要意义。     

溧水水库型饮用水水源地水环境现状及污染源分析

为研究溧水方便水库的污染情况与环境现状,分析了COD、TN、TP、叶绿素量等指标,发现以农田径流为主的面源污染是最主要的水源地污染源,水源地主要超标污染物为TP及TN,总体属于Ⅳ类水。通过对大量数据进行指数分析发现:方便水库平水期水质最优,基本处于贫-中营养等级;丰水期的水质最差,基本处于中度富营养化状态,水体富营养化严重;枯水期水质良好,存在轻度富营养化趋势。方便水库的底泥重金属污染等级为低风险等级,整个方便水库的底泥属于营养盐污染底泥,有机污染严重,亟需进行适当的清淤处理。本研究对预防和控制水体污染及富营养化有一定的参考作用。     

大型分层型水库下泄水温对取水高程敏感性分析研究

为分析下泄水温随取水高程变化规律,探讨分层型水库下泄水温的敏感性,结合丰满水电站,建立了全三维水动力-水温耦合数学模型,并同时开展了物理模型实验,计算结果与实验结果进行了相互验证。对取水水头16.0~25.0 m下取水水温进行预测研究,结果表明:大型分层型水库下泄水温不仅与上游取水高程有关,还取决于坝前库区取水层水温垂向分布;随着取水水头的降低,下泄水温逐渐升高,而增幅表现出逐渐减小,且该变化规律与坝前取水层水温垂向梯度无关;当老坝缺口拆除高程大于240.0 m时,下泄水温受老坝缺口拆除高程影响有限;大型分层型水库取水水头建议取16.0~18.0 m,但该结论仅根据单一工程研究得出,其通用性尚需要根据其他工程进一步研究验证。     

Use of spatial surrogates to assess the potential for non‐point source pollution in large watersheds

Sediment represents a major non‐point source pollutant throughout the world. In addition to reduced agricultural productivity as the result of the loss of fertile soil, soil erosion also can have significant water‐quality impacts in downstream waterbodies, reducing water transparency, degrading aquatic habitats and reducing the operational life and water storage capacity of reservoirs producing hydroelectric power. Various other pollutants also can absorb to sediment particles, creating additional downstream water‐quality concerns for humans and the natural environment. In view of its human and environmental significance, two indices (an erosion index and runoff index) were developed to identify areas within the US portion of the Rio Grande Basin exhibiting physical characteristics conducive to producing significant non‐point source pollution loads, focusing on land erosion as a sediment source. The erosion index is an adaptation of the Universal Soil Loss Equation, being the product of rainfall erosivity (R factor), soil erodibility (K factor), and a topographic factor (LS factor). The erosion index correlated well with measurements of sediment yields from runoff plots. The Curve Number was used as the runoff index. In conjunction with identified pollutant‐generating land uses, or source landscapes, these indices were used to identify sub‐watersheds within the US portion of the Rio Grande Basin that merit further investigation for non‐point source pollution prevention and control via the use of hydrologic modelling techniques.     

基于立面二维水动力-水温耦合模型的水库水温分布

建立了考虑浮力影响的立面二维水动力-水温耦合数学模型,对温差异重流进行了研究,分析了浮力流的水流结构和温度分层的形成、发展过程,利用水库物理模型的试验数据对模型进行了验证,再将该模型应用于一拟建水库,模拟预测了该水库建成后夏季典型条件下库区的流场及温度场分布,研究了不同高程放流洞放水对库区流场、温度场及下泄水温的影响。     

Prediction of sediment inflows to Angereb dam reservoir using the SRH‐1D sediment transport model

Angereb Dam, located in Ethiopia, was constructed in early 1994 as a water supply for the town of Gondar up to the year 2020. The reservoir could not achieve this objective, however, because of significant sedimentation problems. Accordingly, one objective of this study was to simulate the historical reservoir sedimentation pattern, as well as predict the near future (until 2015) sedimentation pattern of Angereb Reservoir. The Sedimentation and River Hydraulics one‐dimensional model (SRH‐1D), version 2.6, was used for this purpose. Another objective was to propose possible mitigation measures to reduce the quantity and rate of sedimentation in the reservoir. There was generally good agreement between measurements and model simulations, with the observed trends being well simulated. The exception was that the model tended to overpredict the sediment deposition volumes in the upstream reaches of the reservoir. The two mitigation alternatives for addressing the sedimentation problem, namely managing sediments in the watershed and flushing sediment through the dam bottom outlet, appear to be technically feasibility, with a predicted reduction of the volume of deposited sediment between 63 and 80% be achievable.     

应用LINGO求解水污染控制系统规划中的费用函数问题

利用LINGO软件,对新疆水磨河水污染控制系统规划的费用函数进行求解,获得全局最优解:以碳化生化需氧量为水质指标时的最低费用为1496.61万元,以氨氮为水质指标时最低费用为924.12万元,该计算结果均优于模拟退火法(SA)、动态规划(DP)和遗传算法(GA)得到的结果,表明LINGO软件在求解水污染控制系统规划中的费用函数问题具有一定的优越性。