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河道取水、水库蓄水、跨流域调水等水资源开发方式改变着河流自然水文情势,保留适宜的河道内生态需水能够维持河流所需的自净扩散能力,维系河势稳定,保护和维持河湖生态系统结构和功能的完整性。本文采用Qp法、田纳特法(Tennant Method)、逐月频率计算法、逐月最小生态径流计算方法、最小月平均实测径流法5种方法对资水河道内生态需水量进行计算分析和比较。结果表明逐月频率计算法结果较为合理,设定资水逐月河道内生态需水量,确定年生态需水量应为112.1×10~8m~3。为政府部门提供了更具操作性的分时段水量控制参考标准。 相似文献
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分析估算大汶河干流生态基流量是解决其生态环境恶化问题的基础。根据大汶口水文站历年径流资料,采用Tennant法、基流比例法等多种水文学法推求生态基流值,通过计算不同水平年的年际、年内不同水期和鱼类产卵育幼期生态基流量,在分析了各种方法应用区间和适用条件的基础上,综合考虑拦蓄引水工程和河道生态基流缺失等因素确定了大汶河干流生态基流。认为:基流量为1.1~14.1m~3·s~(-1)能更好地代表该区域不同水期的河道生态需水,经分析其生态基流保障程度基本达到90%以上,说明本文采取的方法在计算代表北方季节性、雨洪型河流的生态基流时是合理、可行性的,并进一步提出了生态基流的保障措施。 相似文献
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确定河流生态流量既是保护河流生态系统的根本举措,又是开展梯级水库生态调度的重要依据。基于逐月最小生态流量法、RVA法、DC法和逐月频率法,分别计算了清江水布垭和隔河岩水库坝址的生态流量过程,并采用Tennant法对结果进行合理性分析。结果表明:RVA法优于逐月最小生态流量法和DC法,计算得到的最小生态流量在一般用水期和产卵育肥期的评价结果分别为“好”、“中”等级;逐月频率法第3种情景计算的适宜生态流量,其评价结果均为“最佳”等级。研究成果为清江流域保护和梯级水库生态调度提供技术参考。 相似文献
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基于武江河道内的生物多样性和物种特征,提出适宜水力学指标法计算维持河道生态系统稳定性所需的生态流量。该方法以代表鱼类为生态保护目标,根据湿周、流速与流量的关系,求得鱼类不同生命周期的生态流量。结果表明:(1)越冬期鱼类所需流速下限为0.2m/s,产卵期平均流速为0.5～0.7m/s,肥育期流速范围为0.3～0.6m/s;(2)产卵期河道生态流量为116.3～150.3 m/s,越冬期与肥育期中后阶段生态流量为49.55 m~3/s;肥育期初期(8月)生态流量为71.97 m~3/s;(3)提出的适宜水力学指标法以维持鱼类良好的生境条件为生态保护目标,计算结果符合Tennant法河流生态用水标准,且更能反映河流的丰枯变化,可为流域水资源开发利用提供参考。 相似文献
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1981年8月,水利部水文局颁发了《地表水资源调查和统计分析技术细则》,其中关于径流资料还原计算的规定为:“还原计算应采用调查和分析相结合的方法,……应尽可能搜集历年逐月用水资料,如确有困难时,可按用水的不同发展阶段选择丰、平、枯典型年份,调查其年用水量及年内分配情况,推算其他年份还原水量。”由于目前时间紧,调查工作量大,对于调查搜集历年逐月用水资料确有困难的地区,我们根据上述规定,按用水的不同发展阶段,选择丰、平、枯三种代表年份进行调查,然后将 相似文献
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考虑径流年内分布影响的丰枯划分方法及其应用 总被引：1，自引：0，他引：1
在分析现有的考虑年内分布影响的径流丰枯划分方法不足之处的基础上,提出一种求取年内各月权重值的新方法--因子分析定权法,并将其应用于西江干流梧州水文站1946-2000年的年平均流量的丰枯划分;然后,应用Markov过程分析法,对该站年平均流量丰枯状态演化的概率特性进行了研究。结果表明：梧州站枯水、平水和丰水状态的自保守性依次减弱;无论径流处于何种初始状态,其向枯水、平水和丰水状态转移的概率依次减小;在其径流长期演化过程中,枯水、平水和丰水状态的出现频率依次降低。 相似文献
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为探究重要国际河流湄公河支流NamLik河在NamLik1-2水库建设后下游的生态水文情势变化,基于水库下游Hinheup水文站1980—2018年日平均流量数据、流域ERA5再分析气象数据以及NamLik流域地理信息数据,采用IHA＿RVA法定量分析水库运行后河流水文情势改变;基于SWAT模型分析了气候变化和水库调度对水库下游径流年内分配变化的贡献率。结果表明：（1）NamLik1-2水库建库后下游水文情势发生较大改变,整体水文改变度达79%,属于高度改变;下游河道流量年内分配变化显著,月均流量指标的水文改变度达到70.4%。（2）基于SWAT模型对无水库情景的天然径流还原结果,计算得到水库对径流汛期减少和枯季增加的贡献率分别为142%和71%,而气候变化的相应贡献率分别为-42%和29%,水库运行是引起下游径流年内分配变化的主要原因。 相似文献
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针对平原区多数河流缺乏有效的流量资料的情况,研究适用于平原区河流生态水量阈值的计算方法具有重要现实意义。本文对比分析7Q10法、保证率法、湿周法、基于Tennant改进的生态水位法等4种代表性生态水量计算方法与结果,以水文节律、生态水位满足度为判别原则,评价了上述方法的适用性。分析结果显示：（1）在水文节律相应性方面,7Q10法、Q90法、湿周法计算的生态水位值为单一的特定值,无法反映水文节律的天然变化过程;（2）在生态满足度方面,7Q10法的多年平均生态水位的满足度最小;（3）基于Tennant法改进的生态水位法的水文节律模拟效果最好、生态水位满足度最高。研究表明：在选择的4种计算方法中,相较于7Q10法、Q90法及湿周法,基于Tennant法改进的生态水位法能较好地满足水文节律相应性和生态水位满足度原则,对平原区河流生态水位（阈值）计算具有一定的适用性。该研究成果可为苏北平原河网区流量资料缺乏型河流生态需水的确定和管理提供有益的参考。 相似文献
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海河流域天然河川径流持续衰减,水文丰枯情势显著变化,亟需研究适用于非一致性水文序列的丰枯概率计算方法。基于标准化径流指数、GAMLSS模型等方法,提出一种不同等级丰枯水事件期望发生次数和期望等待时间的计算方法,研究变化环境下海河流域天然河川径流丰枯概率的演变规律。结果表明：(1)径流丰枯概率呈现出显著的枯增丰减趋势;(2)同传统的一致性分布等多类概率分布相比,以时间t为协变量的LOGNO分布拟合流域径流系列的效果最优,且基于该分布计算的期望发生次数更接近于历史实际;(3)非一致性最优模型不同情景条件下计算的流域极端枯水和极端丰水事件的期望等待时间分别为4.9～9.4 a、14.5～36.0 a,说明海河流域近期发生极端枯水的概率远大于极端丰水。 相似文献
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S. Shaeri Karimi M. Yasi S. Eslamian 《International Journal of Environmental Science and Technology》2012,9(3):549-558
Environmental flow assessment and maintenance are relatively new practices, especially in developing countries. This paper describes the desktop assessment of environmental flows in a river with insufficient data on ecological features and values. In this study, the potential environmental flows in a typical river reach of the Shahr Chai River in Iran were investigated using a newly developed hydrological method (flow duration curve (FDC) shifting) and Global Environmental Flow Calculator software. This approach uses monthly flow data to develop an environmental FDC and to generate flow requirements corresponding to different features of the river ecosystem. Results were compared with those from four alternative hydrological methods: the desktop reserve model (DRM), Tennant, low-flow index, and flow duration curve analysis (FDCA). Comparisons of these methods indicated that to maintain the basic function of the river ecosystem, the river flows should be managed within an acceptable environmental level. The predictions from the Tennant method and the low-flow index (7-day low flow with a 10-year return period), and from the FDCA (for flows exceeding 90?% of occurrence) are not as reliable as those from the FDC shifting technique and DRM. Comparative results indicate that a minimum flow rate of 1.2?m3/s (equivalent to 23?% of the natural mean annual runoff, or flow with 80?% occurrence depicted from the FDC) is required for the Shahr Chai River to run toward the internationally recognized Urmia Lake in Iran. 相似文献
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M. R. Majdzadeh Tabatabai R. Mousavi Nadushan S. Hashemi 《International Journal of Environmental Science and Technology》2017,14(8):1757-1770
In recent decades, due to river regulations and their impact on river morphology, brown trout populations have been declining along Lar River downstream of Lar Dam located near Tehran, Iran. Considering the recent water scarcity in the country, development of river habitat assessment models seems necessary. Therefore, in this research, an analytically applied approach is adopted to evaluate brown trout habitat by creating a relation among the hydrologic, hydraulic, geomorphic and ecologic processes. After field survey, dimensionless shear stress of the stream flow thresholds including environmental flow, bankfull flow, surface and subsurface sediment flow thresholds was calculated for Lar, Dalichay and Sefidab Rivers using Shields formula. Then, by considering the dimensionless shear stress ranges of the stream flow thresholds, functional flows ranges and duration were calculated together with ecological efficiency of the cross sections. In addition, effects of annual water yield and entrenchment ratio of the cross sections on habitat functionality were also worked out as a result of which an exponential interaction was developed between the dimensionless shear stress and discharge. Results show that an increase in functional flows ranges and duration, together with rising of ecological efficiency, is directly proportional to an increase in median bed sediment size, entrenchment ratio and annual water yield. Therefore, flow regime, cross-sectional geometry, water-surface slope and bed sediment size could be effective on the ecological functions of the brown trout’s life cycle and functionality of river flow. 相似文献
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By following a simple set of rules, a flow net can be manually constructed to obtain a graphical solution to the Laplace equation for simple two‐dimensional (2‐D) flow problems. With the advent of numerical solutions such as the finite difference and finite element methods, it is more common to generate a flow net automatically using the nodal head and flow values output by the computer program. Two methods have been published for automatically generating flow nets from finite element solutions: the stream‐function method and the particle‐tracking method. The stream‐function method works well for many cases, but it does not work for problems with holes in the mesh or internal sources or sinks. The particle‐tracking method works for all cases, but previously published algorithms that utilize this method do not result in the properly sized flow channels. A new approach is presented in this paper that is a hybrid of the stream‐function and particle‐tracking approaches. This method works for all cases and generates the properly sized flow channels. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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本文研究涉及生态水文学中生态需水问题的一般认知。探讨了生态系统动态变化与水流驱动力因素之间的关系，重点探讨水流驱动因素中的关键指标—流速，通过分析流速与生态系统相互作用，从生态水文学动力因素出发估算生态需水；基于生态流速和水力半径，提出考虑河道内生态需水与水力因素关系的生态水力半径法，充分利用水生生物信息（鱼类产卵洄游流速）与河道信息（水位、流速、糙率等）估算河道内生态需水；归纳生态水力半径法在生态需水计算中的初步应用:考虑污染物降解耦合水量水质的生态需水计算、考虑鱼类等生物对流速要求的生态需水计算、考虑河道冲淤平衡的输沙需水量计算等方面。本文提出的生态流速研究既包括生物生长发育适宜的流速，又包括流速大小变化所涉及的许多动力因素，旨在延伸与扩展生态水文学的内涵与应用。 相似文献
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本文研究涉及生态水文学中生态需水问题的一般认知。探讨了生态系统动态变化与水流驱动力因素之间的关系，重点探讨水流驱动因素中的关键指标——流速，通过分析流速与生态系统相互作用，从生态水文学动力因素出发估算生态需水；基于生态流速和水力半径，提出考虑河道内生态需水与水力因素关系的生态水力半径法，充分利用水生生物信息（鱼类产卵洄游流速）与河道信息（水位、流速、糙率等）估算河道内生态需水；归纳生态水力半径法在生态需水计算中的初步应用：考虑污染物降解耦合水量水质的生态需水计算、考虑鱼类等生物对流速要求的生态需水计算、考虑河道冲淤平衡的输沙需水量计算等方面。本文提出的生态流速研究既包括生物生长发育适宜的流速，又包括流速大小变化所涉及的许多动力因素，旨在延伸与扩展生态水文学的内涵与应用。 相似文献
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泥石流空间易发程度调查是开展地质灾害防范和制定生态修复计划的基础之一。目前单纯依靠野外调查并结合遥感观测,或以小流域为单元的泥石流模拟,均难以在大空间范围内高效、准确地识别潜在泥石流沟。鉴于泥石流是一种高能重力流,此次研究以金沙江流域为例,在假定物源供给无差异条件下,提出通过求算河流功率梯度（ω）来实现地表外动力活动强度定量刻画和泥石流空间易发程度调查的新方案,并将泥石流沟验证点数与ω值关系曲线的比降趋势突变位置作为阈值（1×10?4 W/m2）,提取出大约3.2万条长度超过200 m的高能河谷或泥石流易发沟谷。这些沟谷基本位于金沙江和雅砻江干流中下游,在大约30 km距离的缓冲区范围内密集分布,其数量与缓冲区宽度存在乘幂函数关系。在全球变暖背景下,未来发生极端气象事件可能性趋于增加,这些地带,尤其是梯级库区河段应做为泥石流灾害的重点防范区。研究的最终结果提供了金沙江流域泥石流易发沟谷的空间位置及ω值的点阵数据集,可供检索高能河谷的准确位置,也可作为相关地质灾害与地表过程研究的基础数据和资料。 相似文献
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Stream–aquifer relationships in mountain basins are of great relevance because they control the water balance and, with it, the amount of resources (whether surface water or ground water) available for ecological and human demands. In this paper, this relationship is studied using environmental isotopes (δ18O and δD) to identify the occurrence of stream recharge in the Arbúcies River basin (NE Spain). Isotopic data from 51 natural springs define the local altitudinal gradient. This function is weighted by the proportional area above each point, given by the hypsometric curve, in order to estimate the isotopic stream water content as the contribution of runoff from incremental elevations. Stream water isotopes from two surveys are compared with hypsometrically averaged isotopic values to check for the appropriateness of this approach. Results show that it is more suitable when subsurface flows from surface formations, such as alluvial deposits, are the main contributors to stream discharge than when it derives from a single rainfall event. The characterization of stream isotope values is used as a key factor in identifying stream leakage to an unconfined alluvial aquifer in the lower reach of the Arbúcies River. 相似文献
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A new method to calculate the transport of dissolved species in aquifers is presented. This approach is an extension of the stream tubes which are used for flow computation. The flux tubes defined here are conservative for solutes, but not for water mass. The flux tubes are first defined in a general domain and then calculated in a two-dimensional uniform flow field. The tubes?? computation is based on a parametric solution. The method is extended further in order to deal with heterogeneous media. A particle-tracking algorithm is used where the deviation of the flux-tube boundaries due to dispersion is accounted for. The approximate solution obtained by this approach is compared to classical numerical solutions given by a finite difference code (RT3D) and a finite element code (FEFLOW). This comparison was performed for several test cases with increasing complexity. The differences between the flux-tube approach and the other methods always remain small, even regarding mass conservation. The major advantage of the flux-tube approach is the ability to reach a solution quickly, as the method is hundreds to thousands of times faster than classical finite difference or finite element models. 相似文献
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定量评价三峡蓄水后长江中游流域水文情势的时空变化,为长江中游生态保护和区域水资源管理提供科学依据。采用变化范围法分析了长江干流5个水文站的流量、含沙量日均数据,定量评估了三峡工程蓄水后,长江中游水沙变化度最大的江段和水文指标类别,及其对应的生态影响。研究结果表明三峡蓄水后,下游河道含沙量的变化度远大于流量,除城陵矶站外,含沙量较蓄水前有了大幅度下降,宜昌站的含沙量下降幅度达到了一个数量级,洞庭湖对长江干流含沙量有明显的调蓄作用。流量的变化度随着与大坝距离的增加而减小,且在7~11月流量下降幅度明显。这些水文节律的变化将影响下游鱼类产卵栖息地以及滞洪区水生生物与周边植被的生长。 相似文献