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Fish stranding is a critical issue in rivers with peaking operations. The ability to accurately predict potential stranding areas can become a decisive factor to assess environmental impacts and to plan mitigation measures. The presented work shows that common procedures suggested in the literature in the use of one‐dimensional (1D) models for flood zone mapping are not always applicable to compute stranding areas. Specific and easy‐to‐understand guidance needs to be given for smaller‐scale issues. We provide specific guidelines to accurately predict potential stranding areas in a cost‐effective manner. By analysing four different river morphologies in detail in a peaking river, we find that the optimal geometry effort (number of cross sections) does not necessarily coincide with the maximum and it varies between channel types according to river physical characteristics such as sinuosity and channel complexity. The use of a 1D model can provide good estimates with an optimal geometry layout. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Sudden changes in water releases below hydropower facilities (hydropeaking) can dramatically affect benthic organisms. Aquatic gastropods are an ideal organism for studying such effects because they inhabit littoral areas that are frequently dewatered during hydropeaking and have a low dispersal ability making them highly susceptible. We explored mortality rates of Taylorconcha serpenticola, the threatened Bliss Rapids snail, in four laboratory experiments that simulated hydropeaking during varying seasons and varying hydropower operation scenarios. Experiments were conducted in a light and temperature controlled Conviron® and were designed to simulate conditions on the Middle Snake River, Idaho, USA, in reaches that are subjected to hydropeaking. Experiments examined the effects of three air temperatures (winter = ?7°C, spring = 17°C and summer = 37°C), three durations of exposure to air (2, 4 and 6 h), three dewatering rates (instantaneous, 0.3 and 0.15 m h?1), two substrate textures (smooth and vesicular) and consecutive daily exposures (1 to 15 days). With 2 h exposures >80% of gastropods survived under both the summer and winter condition, but with 6 h exposure only 60% survived under winter conditions and almost none survived under summer conditions. Survivorship of gastropods was always high under spring conditions (>90%) even when exposed for 6 h d?1for up to 15 days. When subjected to consecutive daily exposures, survivorship was lowest under winter conditions. Neither rate of dewatering nor substrate texture affected survivorship. Our data suggest that hydropower operations that include rapid stage fluctuations under extreme temperatures can cause high mortality of sensitive benthic species especially when exposure time is prolonged. Future water management policy decisions will need to consider these factors to manage for protection of aquatic species of conservation concern. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Research on hydropeaking in Austria started in the 1990s and the implementation of the WFD stipulated large research projects since the year 2009. The first research projects supported the process understanding and in a second investigation step, measures were evaluated. The mountains in the region of Tyrol create large heads and thus support the production of flexible energy. In this region, TIWAG is operating 9 large (>10 MW) and 27 small (<10 MW) hydropower plants, with an installed capacity of about 1,550 MW and a mean annual production of 3,000 GWh. As the governmental energy strategy foresees an extension of the hydropower production in Austria, suitable options were selected in 2004 by TIWAG and the water management framework plan for Western Tyrol was developed. This strategic planning instrument proposes five large power plants, with a generation of 1,800 GWh/year of renewable energy, which enables to reach the WFD targets, because the concept includes hydropeaking mitigation by combining buffer reservoirs (impoundments), diversion hydropower plants, and retention basins. We present our promising concept of hydropeaking mitigation and exemplify this based on the GKI, a hydropeaking diversion hydropower plants (HPP) at the Swiss/Austrian border as well as the Silz hydropeaking retention basin, with a volume of about 300,000 m3. As the presented case studies are the largest measures for hydropeaking mitigation being currently implemented in Central Europe, they have pilot-character. Thus, ongoing research and monitoring programs are expected to improve the knowledge about hydropeaking mitigation. 相似文献
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The Orlu hydroelectric power plant on the River Oriège is managed by ‘hydropeaking’ and generates significant and frequent daily fluctuations in flow downstream. Observations at this site aimed to determine the impact of these variations on the aquatic environment. Surveys were carried out in June and October, upstream and about 2 km downstream of the plant, with a view to studying fish feeding habits and nutritive resources. In June, when the natural river flow was high, invertebrate populations differed very little between the two sectors. In October, after the low-water period, density and biomass were significantly lower in the downstream sector than they were upstream. Invertebrate drift was studied by taking samples every hour over a 24-hour cycle. Upstream, this drift showed a clear daily rhythm, dominated by nocturnal drift. Downstream in June, invertebrate drift was more abundant than upstream; a similar nychthemeral rhythm was apparent, but there were significant peaks during hydropeaking. In October, this daily rhythm disappeared, and drift was extremely low when river flow was low; on the other hand, a marked increase was observed during hydropeaking. Fish feeding habits were studied parallel to drift by capturing about 20 fish every four hours and analysing their stomach contents. No clear rhythm in the daily food uptake was observed. Stomach content was more abundant downstream. Lastly, the number of prey captured by fish at a given period of the day did not appear to be linked with the effective quantity of invertebrates simultaneously available in the river. 相似文献
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YAN Zhong-min ZHOU Chun-tian LU Shi-qiang 《水动力学研究与进展(B辑)》2006,18(6):723-726
1. INTRODUCTION Hydraulic jumps usually occur in the transition zone from supercritical flow to sub-critical flow, which have been widely used for energy dissipation and water purification[1]. So hydraulic jumps have been the subject of numerous researche… 相似文献
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管道泄漏检测的水力瞬变全频域数学模型 总被引：1，自引：3，他引：1
输水管道泄漏孔的存在及其位置直接影响着系统压力波形的畸变和衰减特性,通过分析有、无泄漏时任意位置处的压头频域特性可使泄漏检测成为可能.在考虑非恒定摩阻影响的基础上,提出基于水力瞬变全频域数学模型的泄漏检测反问题分析方法.用拉氏频域变换处理边界条件和实测数据,并将遗传算法用于频域反问题模型的求解,在寻优速度上比传统的瞬变时域分析的方法有了较大的改善.算例表明基于水力瞬变全频域数学模型分析的管道泄漏检测是一种有效的新方法. 相似文献
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传统的傅里叶频率测量算法,通过傅里叶算法求出相邻2个周期的相位,采用相位差对采样频率进行修正和迭代,计算量大而精度差。文中根据严格推导得到傅里叶算法计算值的准确数学形式,通过对相位差的三角函数进行分解展开,代入傅里叶算法计算值,即可在不需要计算相位的情况下得到相邻2个周期相位差的准确值,从而得到真实的信号频率。仿真分析结果表明,该算法精度高,计算量小,实现简单,完全适合于微机保护测控类装置的实际应用。 相似文献
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水利工程造价指的是水利工程项目在整个建设过程中所发生的全部费用支出。施工阶段是水利项目消耗资金的重要环节,并且较易受到工程项目中人、财、物、环境等各方面因素的影响,把握好施工操作步骤有助于降低成本。本文通过对水利工程施工阶段工程造价的分析,探讨了对工程造价控制的研究,以期为水利工程施工阶段工程造价控制措施更加到位。 相似文献
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采用Singhal空化模型和修改的κ-εRNG湍流模型,数值模拟了三维扭曲水翼非定常空泡流动及其云空泡的动态脱落,空泡形态、流场等定性结果与相应的试验结果进行了比较。预报的回射流和侧射流的流动特性,以及云空泡的动态脱落的主要特征与试验结果相一致。计算结果表明,对于外形为凸形的片状空泡,侧射流是片状空泡脱落的主要原因。 相似文献
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水工结构的三维阶谱有限元分析 总被引：15，自引：4，他引：15
根据p型有限单元法的阶谱特点,详细论述了三维阶谱单元法的基本的分析过程和具体的实现路径,包括基函数的构造、边界约束条件的处理、刚度矩阵和荷载列阵的形成、提高数值积分效率的途径等。引入了三维阶谱单元法的虚结点和广义结点的概念,并把三维阶谱单元法应用于水工结构计算。 相似文献
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基于Hung教授所做移动荷载作用下弹性半空间的振动分析,给出了频域内求解移动荷载作用下三维层状场地动力响应的理论推导,得到弹性半空间动力刚度矩阵和单层土动力刚度矩阵;根据相邻层连接处的平衡条件和变形协调条件,得到具有对称性精确分析、且不受土层厚度影响的整体刚度矩阵。本理论分析方法可用于求解三维层状场地在车辆移动荷载作用下的动力响应问题。 相似文献
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在中低电压等级的线路测控保护一体化装置中,可以较容易地实现手动同期功能,但两侧频率相差较大时,采用相同时间间隔采样会对模拟量有效值的计算带来很大误差。文中分析了频率偏离额定值较大时,利用傅里叶算法计算有效值的误差,提出了一种修正幅值的实用方法。通过理论分析和数字仿真表明该修正方法使有效值的计算精度大大提高,而且计算量增加不大,有很好的实用价值。 相似文献
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Isabel Boavida Maria João Costa Maria Manuela Portela Francisco Godinho Jeffrey Tuhtan António Pinheiro 《河流研究与利用》2023,39(3):554-560
Hydropeaking caused by small-scale hydropower plants creates rapid changes in the intensity, frequency, and persistence of river flows. These changes can induce stress in fish across all life-stages and, may negatively impact fish communities. Rapid increases in the flow velocity may cause fish to avoid unstable habitats, seeking out nearby refuges to reduce their energy expenditure. A lateral flow-refuge constructed from maritime plywood (0.4 m wide × 0.5 m long × 0.4 m high) was installed in the left river bank, 40 m downstream of the Bragado hydropower plant. A multispectral stereo underwater camera trap was installed inside the flow-refuge to monitor fish over one-month period. The camera recorded images continuously both during base and peak flow conditions. Two different peak-flow conditions were detected: peak and high peak-flow conditions. The peak flow conditions correspond to a turbine discharge of 0.67 m3/s (peak), and 2.1 m3/s (high peak) at full load. The base-flow condition corresponded to a discharge of 0.064 m3/s. The fish presence inside the refuge was observed to be significantly higher during the peak condition when compared with the base and high peak conditions. These findings strongly indicate that the flow during the high peak condition prevented fish from using the flow-refuge due to the increase in the current. We hypothesize that this may be due to the increase in the current velocity and increased levels of ambient turbulence near the refuge. An alternate hypothesis is that the spatial distribution of velocities and depths during the high peak condition induced fish to inhabit areas with poor access to the refuge. The results of this study indicate that fish refuges can be used to successfully mitigate hydropeaking, and that their use by fish can depend on the flow regime. 相似文献
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Hydropeaking due to hydropower production can have negative impacts on aquatic fauna. One of the mechanisms for causing impacts on fish and aquatic macroinvertebrates is linked to the rapid dewatering of habitats, which can result in stranding or trapping. The magnitude of these impacts depends both on the characteristics of the flow variations and of the river morphology, as well as biological parameters (species, behavior, etc). When discharge is rapidly reduced, the risk of impacts on fishes (and notably the risk of fish stranding in dewatered zones along the riverbank) is frequently assessed by calculations of vertical ramping velocity among other methods. However, to assess fish stranding risks, the lateral ramping velocity calculated as a horizontal ramping rate (HRR) appears to be a more relevant indicator as it directly measures shoreline drawdown rates. HRR has the advantage of integrating river morphology, but it remains challenging to calculate HRRs in complex situations such as braided rivers. Using hydraulic simulations of the Durance, a gravel bed braided river, we have developed an innovative approach for HRR calculation. Considering two simulated flows, the algorithms for the calculations require partitioning the finite elements into wet and drying meshes. To recommend rates of lowering discharges during hydropeaking events, further studies are required to evaluate more precisely HRR limits for fish stranding regarding biotic and abiotic parameters: species, sizes, nychthemeral cycles, temperature, substrate, and so forth. 相似文献
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Anthropogenic factors such as dam construction and hydropower generation can dramatically alter the flow regime of rivers and may impact growth of aquatic organisms. Using incremental growth techniques, annual growth of Alabama bass Micropterus henshalli and redeye bass M. coosae in the Tallapoosa River, Alabama, USA, was evaluated in response to variation in flow regime. Fish were collected from the Tallapoosa River above Harris Dam (unregulated site) and at two sites downstream of the dam (regulated sites), as well as Hillabee Creek (unregulated tributary). Flow variables were calculated for each growth year, and the best model that described growth for each species at each location was determined using Akaike's Information Criterion. Additionally, growth increments of each species at ages 1, 2, and 3 were compared between years characterized by low and high flow variability. Age was the best explanatory variable that described growth in all models, although flow variables were included in more than half the models. In all cases, annual and seasonal flow variables had low predictive power and explained <2% of the variation in growth. Growth was higher for age‐1 fish in years with less flow variation but was similar among years for age‐2 and age‐3 fish. Overall, this study provided little evidence that annual growth of either species was heavily influenced by flow in this regulated river. 相似文献
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水力机械运行中的拍振和共振问题探讨 总被引：1，自引：0，他引：1
拍振和共振是常见的自然现象,对水力机械稳定运行危害很大,但在对其研究中存在将二者混淆和对部分虚假拍振信号辨识不清等问题,需深入探讨。本文首先介绍了拍振波的基本原理,通过对几种特殊情况的分析说明了拍振波的拍振频率和幅值范围,并在分析拍振波本质特征、共振基本特征、扰动频率和固有频率差别的基础上进一步论述了拍振和共振的区别,提出了扰动频率和系统固有频率接近不会产生拍振、两个不同的扰动波即使频率相同也不可能产生共振等新见解;其次,本文还分析了采集信号不健全和高频载波两种虚假\"类拍振波\"的产生原因,提出了提高信号采集频率避免类拍振波和依据拍振波本质特征辨识拍振波的简单方法。 相似文献
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为了深入研究水轮机接力器的响应速度,本文对其固有频率进行了理论分析。结果表明:接力器响应速度与接力器活塞面积、油液有效体积弹性模量成正比,与总压缩容积、负载总质量成反比。最后,结合工程实际应用,提出了提高接力器响应速度的具体措施。 相似文献