生态水文学:生态需水及其与流速因素的相互作用

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。     

滦河下游河道生态需水量

为量化水库下游河道生态修复所需水量,以滦河下游潘家口水库—滦河口为研究样区,采用逐月频率法和生态水力学法估算河道生态需水量,既具有水文学方法的简便,又考虑生物学特性,强调了水文-生态的联系。通过对研究区河道1956~2000年生态、水文及水力资料的分析计算,结果表明:①逐月频率法和生态水力学法在计算滦河下游河道生态需水中均合理;②最小、适宜、理想等级年生态需水量分别为4.29亿,8.93亿和16.29亿m3,分别占河道天然径流量的10.18%、21.21%和38.68%;③年内汛期8月份及生物繁殖期(4~6月)需水量分别达到年度总量的33.5%和11.5%。     

河流生态需水计算及空间满足率分析——以济南市为例

随着经济社会发展,用水量增大,导致河流生态需水常常得不到满足。生态需水作为河流生态系统的重要指标,对维持生态系统可持续具有关键作用。充分考虑河流生态系统的生物需求,采用食物网模型(Ecopath)识别了鱼类关键物种,在此基础上确定生态流速,结合无人机反演河段大断面,采用改进的生态水力半径法(AEHRA)计算生态需水,在生态需水计算结果的基础上采用River2D模型模拟河段流量,进而计算河段的生态需水满足率。计算结果表明汛期各河段生态需水基本能够得到满足,非汛期绝大多数河段生态需水不能得到满足,并且满足率极低,导致生态系统健康无法维持。因此,应加强非汛期的河流生态调度以满足河流生态需水。研究提出的计算河段生态需水的新方法可为水生态修复提供方法基础,研究结果可为济南市河流水生态修复与管理提供重要的科学依据。     

基于生态保护目标的武江流域生态流量定值研究

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。     

基于栖息地突变分析的春汛期生态需水阈值模型

根据春汛期水生态系统的特点,应用河道内流量增量法,选用二维河流模型River2D,建立栖息地与流量变化的动态关系,进而应用Mann-Kendall方法,开发基于栖息地突变分析的生态需水阈值模型。以第二松花江支流辉发河五道沟断面附近河段为例,选择松花江流域分布较为广泛的鲤鱼作为对象物种,以流速和水深两个因素表征鱼类栖息地,利用1956～2000年45年的春汛期月径流资料,判定鱼类栖息地在1970年开始发生了突变。在突变前加权可用面积95%的置信区间范围为275.5～915.7m2/km,对应的流量范围为58.8～121.1m3/s,并将其作为研究区春汛期间的生态需水阈值。春汛发生在冰封期刚刚结束的时段,适宜的春汛期生态需水能够提高生态系统多样性,对于鱼类等水生生物乃至于整个生态系统都有重要的生态意义。     

基于多种水文学法分析大汶河干流生态基流

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。     

河口生态需水研究进展

针对陆海交互作用下河口生态需水影响因素多且时空差异性显著的特点,在系统分析淡水输入对河口生态系统水环境过程和生物过程影响的基础上,按生态需水目标的差异,将河口生态需水分析方法划分为基于典型生物资源保护目标、基于生境保护目标以及基于多目标整合分析3种类型。从生态需水目标筛选、生态需水目标对淡水输入响应关系以及生态需水计算方法实用性方面探讨了河口生态需水研究中面临的主要问题。结论认为生态系统健康综合表征指标的确定应成为分析河口生态需水的关键科学基础,筛选控制性生态要素构建河口关键生态水文过程模型可成为有效提高生态需水计算方法实用性的主要技术手段。     

生态需水的概念及其计算方法

论述了生态需水的概念,从生态需水量的基本原理出发,探讨了各类生态需水量计算的框架。以渭河为例,估算其多年平均河道内生态需水为3980亿m3。并对未来生态需水研究趋势进行了展望。     

河道内生态需水估算方法及其评述

针对目前常用的水文指标法、水力学法、整体分析法和栖息地法,4大类河道内生态需水估算方法就其适用条件和范围作了相关评述。认为不同的估算方法有其不同的适用条件和范围,在实际应用中需根据已有资料条件和研究的目的,选用不同的计算方法。     

北方平原区河道生态需水量计算初探

河道生态需水量的确定对保持河道的生态功能具有重要意义。在现有河道生态环境需水理论的基础上,以聊城市徒骇河为例,结合北方平原河网地区河道的特点,分析了河道生态需水量的计算。河道生态需水包括河道内生态基流和敏感生态需水,其中生态基流分非汛期和汛期两个水期分别确定,非汛期生态基流按多年平均天然径流量的10％;汛期生态基流可按多年平均天然径流量20％确定;敏感生态需水选择了两处水利风景区确定。     

流量监测软在线架构与实践

聚焦新形势下水资源监测预警、生态流量监测等"水利行业强监管"的要求,以及实时流量监测的迫切需要,基于影响流量的内在水力要素关联,利用已有的实时要素监测信息,架构流量实时监测的通用算法,实现流量"软在线",成果在安徽普遍应用。与既有以流速传感为基础的流量在线监测"硬在线"方法互为补充,探索结果提示新一轮规划应拓宽视野,必要时设置水力控制断面或增加控制河段的辅助站,为流量在线监测提供基础条件。     

水库调度的新阶段——生态调度

现行水库调度方式以防洪调度与兴利调度为主,从保护河流生态系统的观点看,没有涉及生态因素,调度应兼顾河流生态系统需求.分析了生态调度的内涵,介绍了国内外大型水利工程生态调度的进展情况,分析了生态调度包含的内容.在此基础上,提出了生态调度的专项调度:生态需水量调度、生态洪水调度、泥沙调度、水质调度、其他生态因子调度和涉及几个专项的综合调度.     

Sewer model development under minimum data requirements

Planning, design and operation of urban drainage systems is often based on hydraulic sewer modelling. Sewer models are also increasingly used to quantify pollution loads discharged to aquatic ecosystems (e.g. via combined sewer overflows), which ultimately allows an estimation of the ecological impact emanating from urban drainage systems. The establishment of such network models, however, requires detailed and accurate information about the sewer network structure and the connected surface area. This infrastructure data is often unavailable, confidential or available in ‘paper’ format only. The present paper outlines a novel approach to develop a hydraulic sewer model constrained by a minimum amount of data. The approach combines the application of a surface flow accumulation algorithm to a selectively manipulated Digital Elevation Model (DEM) with a routine for hydraulic network dimensioning to generate a close-to-reality sewer network ready to be implemented in a hydraulic modelling platform. The method is tested for three real-life catchments of which characteristics vary in scale, topography, state of development and network complexity. For all cases the generated network is implemented on the EPA-SWMM platform to allow hydrodynamic simulations. Model performance is assessed by (1) evaluating the spatial match of existing and generated network layout, (2) comparing the estimated hydraulic dimension with real-life infrastructure data and (3) benchmarking simulated runoff with measured data for a defined validation period. The analysis shows that the presented method is capable of reproducing the original network layout, network length and corresponding discharge rates based on little, freely available information. Further research potential is identified to improve the hydraulic dimensioning and the application to complex systems that include control structures. The presented approach is useful to estimate the scope of drainage networks including layout and design (e.g. for preliminary planning in emerging areas) to screen existing networks and to identify critical spots where more precise information is required.     

基于生态水力学法的金沙电站最小下泄流量计算

最小下泄流量的确定是环境影响评价工作的重点,以金沙水电站为例,采用生态水力学法,在综合评判河段水深、流速、水面宽、湿周率、过水断面面积等水力参数以及水力形态要素的基础上,确定金沙水电站最小下泄流量,以满足下游河道鱼类生产繁衍的必要条件。     

The Impact of Biased Sampling on the Estimation of the Semivariogram Within Fractured Media Containing Multiple Fracture Sets

Monte Carlo simulation was used to examine the error (statistical bias) introduced in estimating a sample semivariogram through application of oriented sampling patterns to variables which are correlated with fracture orientation. Sample semivariograms of the directional components of the water velocity were used to illustrate that oriented sampling schemes can provide biased data sets which result in error in the estimation of the semivariogram, particularly in the estimation of the sill (or variance). Three sampling patterns were used to analyze directional semivariograms of the components of the fluid velocity: sampling along lines parallel to the mean regional hydraulic gradient, sampling among lines perpendicular to the mean regional hydraulic gradient, and sampling along fracture segments. The first two sampling patterns were shown to introduce substantial error in the sills of the velocity variograms. It is argued that this error is due to the combination of unequal sampling of fractures with different orientations (i.e., sampling bias) and the systematic variation in the magnitude of the velocity components with orientation of the fracture. As a consequence, it is suggested that correction factors developed to correct fracture frequency statistics need to be extended to improve estimation of spatial moments of variables which are correlated with fracture orientation.     

Introducing a new method to determine rivers’ ecological water requirement in comparison with hydrological and hydraulic methods

The absence of a rational, comprehensive, flexible and easy to use method with minimum data requirement to determine rivers’ environmental flow requirements is the main motivation for this research. Based on the microhabitat preferences of index species, hydrological (the Tennant and Q ₉₅) and hydraulic methods for determining the environmental flow requirement (EFR) are compared. Using an ad hoc procedure, the important species of a river at the southern part of the Caspian Sea in Iran were distinguished, and the discharges to maintain the microhabitat (depth and velocity) in critical months were calculated. The observed differences between the index species’ required velocity and depth and those suggested by the Tennant method emphasize the importance of the rivers morphological properties for this method application. Allocating EFR by the Tennant and Q ₉₅ methods would degrade the aquatic life. The EFR determined by the hydraulic method is equal to 95 % of the average annual discharge, which could maintain the ecological habitat in good situation, but may provoke a conflict in the region. The Tennant, Q ₉₅ and hydraulic methods allocate EFR as 14, 36 and 79 % of the annual flow volume, respectively. Developing a new combined method based on using the hydraulic method’s discharge for critical months and the Tennant method suggestion for the excellent condition in other months allocates 50 % of the average annual discharge. This new method is a compromise between protecting environment and considering the water rights of rivers’ flow consumers and is suggested specially for dry regions of the world.     

Ensemble-Based Assimilation of Nonlinearly Related Dynamic Data in Reservoir Models Exhibiting Non-Gaussian Characteristics

Mathematical Geosciences - Inverse modeling techniques for estimating reservoir parameters (e.g., transmissivity, permeability) utilize some dynamic (secondary) information (e.g., hydraulic head or...     

大汶河蜿蜒河段的演变分析

分析了大汶河蜿蜒性河段的水流特性.从主流平面位置变化(或称水流动力轴线变化)断面平均流速,平均水深和纵向水面比降的变化,弯道环流的变化等三个方面分析了蜿蜒性河段各水力因素在洪、中、枯水时期的变化趋势.从物理角度分析了弯道凹岸的冲刷和坍塌过程.     

水环境健康风险评价模型

简要介绍了水环境健康风险评价模型及其应用。实例说明,通过水环境健康风险评价,一方面可以定量地描述环境污染对公众健康的危害,使评价指标落实到人体健康上;另一方面,可以直接得出环境污染物的主次,从而为环境风险管理提供科学依据。在我国,环境健康风险评价暂时还没有包括在常规环境评价工作中,在今后的评价工作中应该逐步开展这方面的工作。