基于多源遥感数据的黄河数字流域模型改进

山区河流水系众多，往往因地势险要难以现场量测获得河流基础信息，是典型的缺资料地区。本文结合多源遥感提取的68个河流断面及34个水文站实测断面，建立了黄河中游各级别河流的断面概化模型。融合传统线状DEM水系及河流表面、概化断面构建河道边界形态。针对黄河数字流域模型，基于不同级别河流的河道边界条件建立了断面判别模块，改进其汇流模型。以黄河一级支流皇甫川流域为例，以2010—2015年的资料率定模型，以2016年汛期日径流及年内3场典型洪水过程验证模拟效果。结果表明，改进后的模型输入参数均可由遥感观测获取，且日流量模拟的纳什效率系数高于0.8，流速及水深的模拟误差分别为7%、9%，全时期洪峰流量的模拟误差平均为15%、峰现时间误差约1.4 h，均较改进前明显提升。研究成果可为山区河流水文过程模拟及河流地貌演化等研究提供重要的基础数据和技术参考。     

基于DEM和HEC-GeoRAS软件的洪水模拟

传统的洪水模拟需要工程河段的实测河道地形或断面资料,消耗大量人力、物力。无实测地形资料情况下对工程河段设计洪水进行模拟计算,是工程设计需解决的关键技术问题之一。将HEC-GeoRAS模型应用到白龙江鸭浮岩河段,利用实测地形数据和30 m分辨率DEM数据分别建模,对比两种方法的计算结果。结果表明:基于30 m分辨率DEM数据的HEC-GeoRAS模拟结果与根据实测地形资料计算的结果相差较小(百年一遇洪水平均水位误差在0.3 m以内,平均流速误差在0.6 m/s以内),这一误差对于水位、流速变幅较大的山区河流工程可以接受,为无实测地形山区河段洪水模拟提供了一种新思路。     

珠江流域跨省河流管理基础空间数据库建设

从珠江流域跨省河流管理需求出发,阐述珠江流域跨省河流管理基础空间数据库建设的原则、依据、内容,设计其空间数据库的结构关系,建立了跨省河流管理基础空间数据库的一个原型。该原型以珠江流域1：250000基础地理信息、TM遥感数据及相关法律法规为基本依据,实现了基础水系、跨省河流、管理河段及相关管理河段的水事巡查、遥感动态监测、审批管理成果等的可视化、对象化、规范化整编和统一管理,不仅可以直接服务于珠江流域跨省河流的水行政管理,也为扩展以水系为核心的数字流域基础空间数据库建设奠定基础。     

拉萨河流域河宽与地形结构因子相互关系分析

利用Google Earth遥感影像,测量了拉萨河流域451个局部河段的河流水面宽度,得出了10个主要河段的平均河宽。研究中,分别点绘了10个主要河段的平均河宽与5种地形结构因子(河流纵比降、弯曲度、凹度、河流上游集水面积、流域平均坡度)的相关图,采用线性函数、指数函数、对数函数以及幂函数4种函数对其进行相关性分析。结果发现,在5种因子中,河流水面宽度与上游集水面积相关性最好,当用线性函数拟合时确定性系数达到了0.81;河流的纵比降与河宽的相关性也较好,当采用指数函数与幂函数拟合时,两者的确定性系数均为0.76。研究探讨拉萨河流域河宽和地形结构因子的相互关系对认识青藏高原河流地貌特征规律以及提高无资料流域河流流量和总水量预测的能力等均有重要意义。     

游荡型河流的洪水演算

本文依据黄河下游河道的河相关系和简化圣维南方程组，建立了游荡型河流洪水演进的对流一扩散模型，该模型将随机性和确定性相结合，用河相关系定义了洪水波的平移与衰减特性，只要在进口输入上游流域的来水来沙条件，可同步输出全河段所有断面的流量过程。经历史洪水验证表明，预报成果的精度和可靠性是比较满意的。     

澜沧江源扎那曲莫云段河型判别初步分析

澜沧江源地处青藏高原唐古拉山北麓,比邻长江南源当曲,人迹罕至。为了进一步认识澜沧江地貌特征、尤其是河流地貌,得出河流地貌演化、河床冲淤演变的一些基础资料,通过实地考察,采集数据与图像,结合现有河型判别方法,对澜沧江西源扎那曲莫云河段的河型进行判别。结果表明:莫云河段河道边界约束较弱、河床稳定性较差,在顺直-弯曲-分汊-游荡的河型分类体系中,各家判别式一致判定莫云河段为游荡河型;在顺直-弯曲-辫状的河型分类体系中,则一致判定为辫状河型;最后结合国内的河流特点和主流分类体系,可以确定莫云河段属于游荡河型。实地考察资料和河型的判别,可为进一步研究澜沧江源的河流地貌提供参考。     

全国不同区域河流生态基流达标现状与不达标原因EI北大核心CSCD

为系统认识我国不同区域河流生态基流达标现状,针对全国各大流域90个已确定生态基流目标的主要河流控制断面,基于2009—2018年实测流量资料,综合月均流量、日均流量2种不同达标评估方法,对断面生态基流达标现状进行了评估,并初步剖析了不同区域不达标原因,提出了调控保障建议。结果表明:按照月均流量达标评价,全国主要河流断面生态基流达标率为73.3%;采用日均流量达标评价方法,全国主要河流断面生态基流达标率显著下降,仅为26.7%。东北、西南地区生态基流达标率好于其他区域,黄淮海地区的淮河水系、沂沭泗水系及东南沿海地区的西江水系为本次评价中生态基流达标率最差的3个水系。全国层面,取用水总量高、取用水季节性冲突、水利工程不合理调度等人为因素是生态基流不达标的主要原因,占比62.3%。     

黄河上游河道水力几何形态关系分析

根据黄河上游干流10个水文断面的多年实测资料,分析了黄河上游不同断面及不同河段的水面宽、水深、流速与流量之间的关系,并探讨了水力几何形态关系中各相关参数的沿程变化特征。结果表明：在整个上游河段,水面宽随流量的变化速率较小,其中上游上段的水力几何形态主要通过流量对水深和流速的共同影响来实现,上游下段则主要通过流量对流速的影响来实现;黄河上游水力几何形态关系与黄河下游及国内外其他河流相比,有相似也有差异,这与该河段的地貌及河道边界条件有关,也与人类活动的影响有关。     

汾河下游王庄——柴庄河道特性及河床演变分析

通过对汾河下游王庄至柴庄段河道特征和来水来沙特性分析，得出汾河在该段的河相关系、纵横向稳定系数、床沙质沿程组成和汾河该段的三种不同的河型，即王庄至石滩及襄汾县城至柴庄为山区型河流；石滩至洪洞县城为山区向平原过渡型河流；洪洞县城至襄汾县城为平原冲积性婉蜒河流。给出了婉蜒型河段河床纵比降与床沙质的数学表达式。分析了三种不同类型的河段的河床演变特性及影响该段河床演变的因素，得出了过渡型河段和婉蜒型河段的河床演变在纵向上表现为泥沙堆积和淤积，从１９５３～１９８９年，过渡型河段年堆积速度为３．３ｃｍ／ａ，婉蜒型河段年淤积速度为２．６ｃｍ／ａ；在横向变化上过渡型河段河槽变化保持在３００～５００ｍ，婉蜒型河流主槽宽约１００ｍ，自由演变，其摆幅宽度可达１５００ｍ。     

时空维度拓展的河相关系研究进展

从时间和空间两个维度拓展河相关系理论是当前的研究热点.对多断面河相关系的地貌学意义与表达方式、影响因素和在资料缺乏地区流量估算的应用,以及多频率沿程河相关系的研究成果进行较系统的分析和总结,探讨了多断面河相关系、多频率沿程河相关系,以及山区河流广义河相关系的意义与内涵.多断面河相关系是断面河相关系在河网空间的延伸,多频...     

At-a-station hydraulic geometry for reaches with bridge collapse events

This study explores the at-a-station hydraulic geometry (AHG) for reaches with bridge collapse events. Eighteen reaches in Eastern United States, thirteen reaches in Appalachian Highland, and five reaches in Coastal Plain are examined. The methodology applied for retrieving AHG uses LiDAR (Light detection and ranging) data, and the study results are checked for both hydraulic and geomorphic consistency. The resulting data set is composed of five to thirty-five measurements of water surface width, mean depth, and mean velocity at each of the 181 cross-sections. The exponents of the AHG relationships vary considerably. Nonetheless, for most of the cross-sections, width responds more rapidly to changing discharge, and velocity exponents are less than the width and depth exponents combined. Wide shallow channels with highly erodible beds and/or banks, the ability to transport large bed materials, and the ability to attain a super-critical condition—are the common profile extracted for most of the cross-sections across all sites. A definitive AHG configuration is found for the sites with the least human interference. Comparatively low variation of bank-full geometry is also found for the sites with the least human interference. The prevalence of low flows and/or lower return periods of heavy-tail flows are also exhibited for most of the sites. The study results suggest that the stream channel instability can be reasonably understood and predicted from AHG particularly if human interference is limited within the watershed. These findings have implications not only for the study of the risk of bridge collapse and bridge design but also to characterize instability in a more rigorous and practical way.     

河岸与河底相对粗糙度对河道平衡形态的影响研究

边界条件对河流地貌形态具有重要影响,基于河道边界阻力水力半径分割方法,利用变分方法研究河岸与河底相对粗糙度对冲积河流平衡河道形态的影响。结果表明,河岸与河底相对粗糙度对河流达到平衡时的最大输沙率有一定的影响,但对河道平衡形态的影响非常显著。在临界和平均水力几何形态关系式中,随着河岸与河底相对粗糙度的增大,河宽关系式的系数逐渐减小,水深关系式的系数逐渐增大,但控制变量,特别是流量的指数变幅很小。     

Relationship between downstream hydraulic geometry and suspended sediment concentration characteristics

The downstream hydraulic geometry relationships, i.e., the downstream variation of the water surface width W, the hydraulic depth H, and the mean velocity V at a constant flow frequency, represent the adaptation of channel geometry and flow dynamics to a given hydrological regime. It has been reported that W, H, and V all tend to increase in the downstream direction for most natural rivers but their increasing rates show relative differences. It is widely known that most natural rivers exhibit W increasing at a greater rate compared to H, indicating the formation of wide and shallow rivers. Nevertheless, rivers showing the opposite to this trend, i.e., H increases at a rate greater than that of W, have also been observed. We investigated four rivers in this study where two of them (the Kansas River and the Tennessee River) show greater increasing rate of W than that of H and the other two (the Mississippi River and the Nakdong River) show the opposite. We found that the two types of rivers show different spatial patterns in their relationships between suspended sediment concentration (C) and flow discharge (Q). Essentially, rivers with a greater increasing rate of W (i.e., the Kansas and the Tennessee) show C-Q relationships lagged in the downstream direction. On the other hand, rivers with a smaller increasing rate of W (i.e., the Mississippi and the Nakdong) show C-Q relationships that are aligned along the downstream direction. Considering that the flow discharge increases downstream in general, the rivers showing the aligned C-Q relationships are exposed to greater imbalance of spatial distribution of sediment fluxes, and hence supposed to be less stable compared to the other type of rivers.     

冲积河流稳定平衡条件与断面几何形态的数理分析

冲积河流稳定平衡条件长期以来被认为无闭合解,致使众多经验假说得以应用。本文通过将两个无量纲断面形态参数宽深比和边坡角度引入到冲积河流三大基本运动方程中,详细分析了推移质输沙率与这两个变量之间的复杂关系,从数学上推导得出冲积河流达到稳定平衡的水动力学条件是推移质输沙率最大。河流达到稳定平衡时的过水断面形态数学表达式表明,天然冲积河流在平滩水位时所展现的水力几何关系是河流通过调整过水断面形态达到的稳定平衡的结果。     

A study of the stochastic evolution of hydraulic geometry relationships

Uncertainty resulting from climatic and environmental changes creates barriers to the accurate acquisition of information about rivers. In this study, a set of stable stochastic differential equations is developed to simulate the dynamic probability distributions of typical hydraulic geometry variables represented by slope, width, depth, and velocity with variations in bankfull discharge over time for a river system. Random parts of the equations are modelled based on single Gaussian white noise and further on combined Gaussian/fractional white noise with Poisson noise. Consistent estimates of the equation parameters are made using a composite nonparametric maximum likelihood estimation (MLE) method. The proposed models are examined through a Monte Carlo simulation of the lower Yellow River, and the results successfully reveal the potential responses of hydraulic geometries to stochastic disturbance and that average trends largely synchronize with the measured values. Comparisons of the three different models confirm the advantages of fractional jump‐diffusion model, and according to further discussion, stream power on the basis of such a model is concluded to serve as the better systematic measure of river dynamics. The proposed stochastic approach is new to the field of fluvial relationships, and its application could help to design and monitor river systems with specified accuracy requirements.     

Interbasin Consistency of Hydraulic Geometry and Its Relationships with Basin Morphology and Hydrology

Abstract

The width, mean depth, and mean velocity of a stream are typically power functions of discharge, whose exponents are unit-sum constrained. The appropriate methodology for testing statistical hypotheses involving such data is compositional data analysis (CDA). Prior to the advent of CDA, the Illinois State Water Survey (ISWS) undertook statewide and national studies of hydraulic geometry in which they developed an index called proportional stream order, which uses rational numbers to quantify the variation within a stream segment of a given order. The current investigation applies CDA to that data and to other hydrologic and morphologic parameters that are potential covariates of hydraulic geometry. Logratio linear modeling demonstrated that at-a-station hydraulic geometry was unrelated to proportional stream order in the Sangamon basin in central Illinois. The downstream hydraulic geometry of twelve basins in the humid region of the U.S. had atypicality indices consistent with a single, logistic normal population. There was no significant difference in the compositional mean or variability of the downstream exponents of the steep and shallow basins. Logratio linear models of the downstream hydraulic geometry of all twelve basins using runoff and drainage area as covariates resulted in random relationships. More localized channel factors probably control hydraulic geometry. These findings are consistent with the theory that channels adjust to a numerically consistent downstream hydraulic geometry and are pertinent to the derivation and application of models involving the impacts of point-source pollution on biological oxygen demand and of stream power on the evolution of drainage networks.     

河相关系的随机微分方程建模与研究

由气候变化等环境突变引起的水沙输入条件和边界条件的不确定性给河流地形特征的考察与模拟增加了困难。本文通过建立随机微分方程,研究了典型的河相关系特征变量(包括比降、河宽、水深、流速)随时间变化的概率分布演化规律。随机方程的随机输入项分别由3种噪声模型进行模拟,包括单独的高斯白噪声、组合的高斯白噪声加泊松噪声,和组合的分数白噪声加泊松噪声模型。方程中的未知参数使用一种复合型的极大似然非参数估计法进行估计。使用蒙特卡洛方法将方程应用于黄河下游高村-孙口段,结果较好地展示了河相关系对随机扰动的潜在响应,特别是,计算的随机平均值与测量值有较好的同步度。通过模型比较发现,既能反映非线性又能反映突变性特征的分数-泊松扩散模型是较适合模拟河相关系随机演化的模型,以此为基础的河流功率可作为系统性评估河流动态演化特征的优选指标。本文提出的分析河相关系的新方法,可根据指定精度用于设计和监测河流系统,既有理论价值又有实际意义。     

河道束窄段对上游洪水过程特性的影响

为了研究束窄河段对洪水演进过程特征的影响,采用二维全水动力模型GAST模拟了束窄段河道洪水过程,通过理想河道和灞河上游实际河道分析了河道束窄程度与洪水特性间的定量关系。结果表明：束窄断面形状对洪水过程特征中水深、流速影响的大小依次为V形>U形>梯形>矩形。断面形状相同时,束窄程度越大对水深和流速影响越大。河道束窄段上游水位壅高,下游水位相对降低但流速更大。扩宽河道束窄段可以降低上游水位及上下游流速差。在“8·19”洪水下,灞河束窄河段束窄程度降低时（原河道束窄程度为64.4%,河道疏浚后束窄程度分别为55.6%、46.7%、37.8%）,上游最大水深分别减小0.669、0.985和1.066 m,上下游流速差分别减小0.702、1.592、2.550 m/s。洪量越大则河道水位越高、流速越大,束窄程度变化对水位和流速变化的影响也越大。将“8·19”洪水进行缩放入流情况下,原始河道最大水深分别为2.177、2.778、3.618 m,束窄程度为37.8%时最大水深减小至1.866、2.367、3.175 m。通过分析不同束窄程度的束窄段河道洪水过程特性,可为束窄段河道防洪提供参考。     

The Selwyn River of New Zealand: a benchmark system for alluvial plain rivers

Most of the world's alluvial plain rivers have undergone hydrological and geomorphical modifications due to water abstraction, dam and levee construction, gravel mining and other human activities. Some of these rivers function as benchmark systems for identifying and quantifying the ecological responses to hydrological and geomorphological changes. Benchmark systems are critical for understanding these responses, for predicting the effects of future changes, and for trialling restoration and mitigation measures. The Selwyn River of New Zealand is a benchmark system for undammed alluvial rivers that are under intense pressure for water abstraction, and are subject to large flow fluctuations. The Selwyn is a remarkably complex river, and increased understanding of this system will provide insight for understanding and managing other rivers in its class. Hydrological properties that characterize the Selwyn include strong surface water–groundwater interactions, contiguous ephemeral, intermittent, perennial‐losing and perennial‐gaining reaches and an expanding and contracting dry segment that persists for most of the year. The dry segment, in combination with broad spatial variation in aquifer structure and rainfall, cause the upstream (runoff‐fed) and downstream (groundwater‐fed) river sections to function very differently. These sections are also dissimilar in channel morphology; the upstream section has a braided planform, with mobile bars, and abundant islands and remnant channels, and the downstream section has a single, meandering channel, stable bars and no islands. As in many alluvial plain rivers, large floods drive reach‐scale channel evolution. This paper introduces a long‐term research program that is underway at the Selwyn River, and explores the hydrological and morphological dynamics that characterize the river. We focus on groundwater–surface water interactions, flow‐permanence patterns and flood‐dependent geomorphology. Hydrological and meteorological data are summarized in a conceptual model of relationships between prevailing weather systems, runoff, aquifer recharge and river flow. The physical template described in this paper governs ecological processes such as dispersal, succession and nutrient cycling. A conceptual model is proposed to organize predictions about dispersal in response to changes in hydrological connectivity. Copyright © 2007 John Wiley & Sons, Ltd.     

以水流挟沙力和河床演变规律研究调水调沙的主要水沙指标

冲积性河流的河床在输水输沙过程中,调节流量及含沙量和泥沙组成(调水调沙)可以调节河床水力几何形态和水流挟沙力,追求水沙输运和河床演变的相对平衡。在分析水流挟沙力和河槽水力形态规律的基础上,研究调水调沙的流量、含沙量等主要水沙指标,可以解决河道输沙减淤和河槽相对稳定问题。