库区泥沙来源研究进展

河流泥沙时空变化与流域内自然因素和人类活动密切相关,随着全球范围内大量水库的兴建,阻断了河流连通性,水库泥沙淤积问题被普遍关注,导致库容损失、淹没区范围增大,对航运和下游河道河床等带来不利影响。水库泥沙淤积防治措施不断发展,但只能暂时减轻对库容的影响,并没有从源头上解决问题。对国内外水库泥沙来源的研究状况进行了全面的综述,主要包括径流小区观测法、水文资料分析法、大面积调查法、理化分析法、指纹识别法等的研究成果、利弊和进展,在此基础上浅析泥沙来源研究。     

泥沙来源确定方法述评

对解析泥沙来源的径流小区观测法、大面积调查法、水文资料分析法和理化分析法等4类方法进行了阐述,并介绍了从理化分析法发展而来的"指纹"识别技术。各种解析方法的适用条件和应用效果差别较大,缺乏详细的可信度分析;探索新的单一沙源解析方法以及通过多种解析方法组合来分析复杂沙源是以后研究的趋势。     

流域产输沙模型中考虑泥沙来源的动态粒径计算方法

为准确反映泥沙粒径分布特征在不同时间尺度上的变化过程,提高流域产输沙模型的模拟精度,以黄河干流玛曲水文站以上区域为研究对象,根据不同季节的泥沙来源不同这一特点,采用坡面、谷沟、河道各来源的泥沙量作为权重,基于WEP-SED分布式流域产输沙模型对流域产输沙过程中的综合泥沙中值粒径进行加权平均计算,并对采用泥沙固定粒径计算方法和不同来源的泥沙动态粒径计算方法的模型模拟的玛曲水文站输沙率进行比较。结果表明：与采用泥沙固定粒径计算方法相比,采用泥沙动态粒径计算方法可有效提高模型模拟精度,其NSE值从0.601提升至0.706;采用泥沙动态粒径计算方法模拟的泥沙中值粒径呈现汛期小、非汛期大的动态变化规律,其年内分布规律与实测资料一致。     

近30年土壤侵蚀模型研究进展

土壤侵蚀模型是定量预测土壤侵蚀程度的一种重要方法，对“山水林田湖草沙冰”系统治理具有重要意义。为进一步认识国内外土壤侵蚀模型研究进展，了解前沿方向，运用CiteSpace与VOSviewer软件，分析1991-2020年国内外土壤侵蚀模型的研究进展。以中国知网核心期刊和WoS数据库核心馆藏为数据源。分析结果显示，目前国内该领域的研究前沿方向是：优化不同土壤种类条件下的土壤侵蚀模型；将遥感技术与模型改进相结合，提高预测精度；以解决实际应用问题。国际的研究前沿方向是通过指纹识别技术示踪河道泥沙来源，逆推不同地区的侵蚀泥沙产出占比；解决黄土高原易侵蚀引起的高产沙问题。     

三维泥沙数学模型的研究进展

对国内外近年来在三维水流泥沙数学模型的研究应用情况进行总结和评述，指出三维泥沙数学模型研究的必要性和重要性，对数学模型的基本方程、边界条件，泥沙扩散系数，泥沙沉降速度，数值计算方法等进行讨论，介绍模型的验证和应用情况，最后提出改进和完善三维泥沙数学模型研究、应用的途径。     

退耕还林背景下的小流域侵蚀产沙研究

以退耕还林实施效果的显现期(2003-2011年)为背景,采用指纹识别技术反演淤地坝泥沙来源及小流域侵蚀产沙演变。结果显示,9年间,沟道、人工林、灌木地和缓坡耕地的平均泥沙贡献率分别为40%、25.9%、20.3%和13.8%,淤地坝泥沙主要来自沟道。根据各源地泥沙贡献率及其与面积占比的关系,确定小流域中不同土地利用类型的平均侵蚀强度由大到小依次为沟道缓坡耕地人工林灌木地。随着退耕年限的增加,人工林泥沙贡献率出现小幅增长,沟道侵蚀有下降趋势,但沟道仍为黄土高原丘陵区侵蚀泥沙的主要来源地。退耕还林时期栽植的灌木有效减少了侵蚀作用,缓坡耕地则仍需辅以相应的水土保持措施。     

珠江口潮流泥沙数学模型关键问题探讨

河口潮流、波浪、泥沙、盐度构成了一个极其复杂的耦合系统,将波浪、盐度作为影响泥沙运动的重要因子,与波浪模型和盐度模型耦合,提出了珠江口潮流泥沙模型构架。分析了珠江口泥沙絮凝、泥沙起动、波浪作用下的挟沙力等泥沙数学模型关键问题。以盐度对河口泥沙絮凝的影响分析为基础,根据计算得到的不同径、潮动力作用下河口盐度分布,实现了泥沙絮凝沉速进行实时修正;通过影响河口滩、槽挟沙能力主导因子的识别,提出了一套水流挟沙能力实测资料筛选的方法,建立了波、流共同作用下河口水流挟沙力公式,并以此计算潮波作用下的挟沙力。研究完善了模型的辅助方程,为珠江口泥沙精细模拟奠定了基础。     

葛洲坝枢纽三江引航道冲沙时泥沙输移特性

本文根据原型实测资料、模型试验以及分析计算,对葛洲坝三江引航道冲沙期泥沙输移特性进行了研究,揭示了水流和泥沙的相互关系,并提出进一步改进的措施,以提高引航道的冲沙效率。     

深埋长隧洞TBM施工的风险识别

深埋长大隧洞施工过程中存在大量不确定性,如何识别其中的风险成为目前研究的热点之一.结合南水北调西线工程深埋长大隧洞TBM施工,系统分析了施工过程中不确定性因素的来源,提出了基于故障树(FrA)-层次分析(AHP)的风险识别模型.该模型以故障树方法辨识出系统所有风险因子.以层次分析法确定各风险因子权重并对其排序,可较准确、全面地识别工程中所遇风险.通过工程实例计算,结果表明该方法与实际符合较好,为以后进一步风险分析提供了依据.     

流域侵蚀产沙平衡研究进展

介绍了国内外流域侵蚀产沙平衡研究的主要成果。分析了流域泥沙的主要来源及国内外泥沙来源的主要研究方法；介绍了侵蚀泥沙的坡面～河道运移过程、坡面～河道耦合关系的研究现状；提出了当前河道泥沙存蓄与输移研究的主要问题，并分析了该领域目前研究的现状；对比分析了目前流域侵蚀产沙平衡研究中几个主要模型的适用范围与优缺点；提出了我国未来流域侵蚀产沙平衡研究中应注重发展的主要问题。     

Fingerprinting the contribution of quarrying to fine‐grained bed sediment in a mountainous catchment,Iran

The contribution of quarrying in the context of multiple catchment sources of fine‐grained sediment has rarely been investigated. This study assessed the relative importance of quarrying as a sediment source alongside rangeland surface soils and channel banks in a mountainous catchment in northern Tehran, Iran, using fingerprinting. Eight geochemical tracers were measured on 24 potential sediment source samples and four fine‐grained sediment samples. Statistical analysis to select three different composite fingerprints for discriminating the potential sediment sources comprised: (a) the Kruskal–Wallis H test (KW‐H), (b) a combination of KW‐H and discriminant function analysis (DFA), and (c) a combination of KW‐H and principal components and classification analysis (PCCA). A Bayesian unmixing model was used to apportion sediment source contributions using the three composite fingerprints. Using the KW‐H composite signature, the respective relative contributions (with uncertainty ranges) from channel banks, rangeland surface soils, and quarrying were estimated as 28.4% (10.9–46.8), 15.1% (6.6–22.7), and 56.6% (38.3–74.2), compared with 35.4% (11.9–60.1), 13.4% (4.1–22.2), and 51.3% (26.5–74.3) using a composite signature selected using a combination of KW‐H and DFA, or 20.7% (3.9–41.7), 17.2% (4.4–29.9), and 61.4% (44–78.8) using a fingerprint selected using KW‐H and PCCA. The different composite signatures therefore all consistently suggested that quarrying is the dominant source of the fine‐grained sediment samples. Potential mitigation measures targeting this land use include closure to permit revegetation to reduce exposure of bare surfaces to sediment mobilization. Limitations and uncertainties associated with this preliminary investigation are briefly discussed.     

Tributary contributions to sediment deposited in the Jacuí Delta,Southern Brazil

The Jacuí Delta drains into Lake Guaíba which is the main source of water for more than two million people in South Brazil and has suffered from pollution with heavy metals and phosphorus. The objective of the current research is to demonstrate how the use of sediment source tracing techniques, in combination with sediment flux monitoring, can improve understanding of the sediment source contributions to one of the largest lakes in South America. The sediment flux monitoring results were based on data obtained from 12-years of records of water flow and suspended sediment concentrations. The sediment source fingerprinting approach was based on the use of geochemical tracers. Based on the study, the respective contributions of the tributaries to the sediment in Lake Guaíba were estimated to be as follows: the Jacuí River (median of 54% - interquartile range (IQR) 34–71%), the Caí River (12%, IQR 7–16%), the Sinos River (5%, IQR 1–20%), and the Gravataí River (16%, IQR 10–30%). These results are similar to those derived from the sediment flux monitoring, namely: the Jacuí River (70%), the Caí River (19%), the Gravataí River (4%), and the Sinos River (7%). These results demonstrate that the sediment source fingerprinting approach combined with sediment flux monitoring can provide a useful means of estimating the respective sediment contributions from individual tributaries in large and complex delta systems and may provide a powerful tool to guide water resource management.     

Bank‐derived material dominates fluvial sediment in a suburban Chesapeake Bay watershed

Excess fine sediment is a leading cause of ecological degradation within the Chesapeake Bay watershed. To effectively target sediment mitigation measures, it is necessary to identify and quantify the delivery of sediment sources to local waterbodies. This study examines the contributions of sediment sources within Upper Difficult Run, a suburbanized watershed in Fairfax County, Virginia. A source sediment library was constructed from stream banks, forest soils, and road dust. Target sediments were collected from fine channel deposits and suspended sediment during 16 storm events from 2008 to 2012. Apportionment of targets to sources was performed using Sed_SAT, a publicly available toolkit for sediment fingerprinting. Bed sediment was dominated by stream bank material (mean: 98%), with minor contributions from forests (2%). Suspended fine sediments were also dominated by stream banks (suspended sediment concentration‐weighted mean: 91%), with minor contributions from roads (8%) and forests (<1%). Stream banks dominated at all discharges, and on the rising limb and at peak flow, sediment concentrations increased due to bank material rather than surface erosion. Sediment budget data indicated that direct bank erosion was insufficient to account for the suspended load derived from stream banks. However, bank‐derived sediment re‐mobilized from in‐channel storage could account for this difference and, combined, resulted in a sediment delivery ratio of 0.847 for all bank‐derived sediments. Results demonstrate that stream bank erosion is responsible for the majority of fine sediment in this suburban watershed of the Chesapeake Bay drainage area. Thus, management actions to control upland sources of sediment may have limited effect on the sediment conditions of Upper Difficult Run, whereas efforts focusing on bank stabilization, channel restoration, and/or stormwater management to reduce bank erosion may improve the ecological condition of these waterbodies.     

模型试验含沙量量测技术研究

含沙量是河工、港工物理模型试验主要测量要素之一,现有的模型试验含沙量测量仪具有测量范围窄、相对误差大、重复性低等缺点,制约着物理模型试验含沙量的测量范围和试验准确性。介绍了一种自主研制的无线实时含沙量测量仪,该测量仪采用光电测量原理,将光信号转换成电信号,实现含沙量的实时在线测量。通过分析光电法含沙量测量仪的基本原理、硬件系统设计,分别研究了含沙量与透射光强、散射光强、透射光功率之间的变化关系,提出采用透射光与90°散射光相结合方法测量含沙量。经多组试验研究获得含沙量算法及其实现方式,确保含沙量测量的相对误差小于5%。本研究采用不确定度分析方法,分析新研制的含沙量测量仪的可靠性,试验表明仪器的不确定度小于0.4。     

Estimation of Suspended Sediment Yield in Natural Rivers Using Machine-coded Linear Genetic Programming

Estimation of suspended sediment yield is subject to uncertainty and bias. Many methods have been developed for estimating sediment yield but they still lack accuracy and robustness. This paper investigates the use of a machine-coded linear genetic programming (LGP) in daily suspended sediment estimation. The accuracy of LGP is compared with those of the Gene-expression programming (GEP), which is another branch of GP, and artificial neural network (ANN) technique. Daily streamflow and suspended sediment data from two stations on the Tongue River in Montana, USA, are used as case studies. Root mean square error (RMSE) and determination coefficient (R²) statistics are used for evaluating the accuracy of the models. Based on the comparison of the results, it is found that the LGP performs better than the GEP and ANN techniques. The GEP was also found to be better than the ANN. For the upstream and downstream stations, it is found that the LGP models with RMSE = 175 ton/day, R² = 0.941 and RMSE = 254 ton/day, R² = 0.959 in test period is superior in estimating daily suspended sediments than the best accurate GEP model with RMSE = 231 ton/day, R² = 0.941 and RMSE = 331 ton/day, R² = 0.934, respectively.     

水文模型参数敏感性分析方法评述

针对水文模型敏感性分析中存在的诸多问题,分析水文模型参数敏感性分析在模型构建及应用过程中的主要作用及其与不确定性分析和参数优化之间的联系,总结敏感性分析方法的3种分类,并探讨水文模型中常用的筛选法、回归分析法、基于方差的分析方法及基于代理模型技术的分析方法等4种关键技术方法,剖析水文模型参数敏感性分析方法的适用条件及优缺点,回顾各种方法在水文模型中的研究现状,提出水文模型参数敏感性分析的研究框架与步骤,指出水文模型参数敏感性分析的计算效率、可靠性和参数的相关性是未来的主要研究方向。     

Assessment of uncertainty in Great Barrier Reef catchment models.

This paper addresses uncertainty in socio-economic and sediment-nutrient models that are being developed for the assessment of change in the Great Barrier Reef (GBR) area. The catchments draining into the GBR lagoon are sources of pollutants. The Reef Water Quality Management Plan of the Queensland Government identified sediments and nutrients transported to the GBR lagoon as the major long-term threats to the reef and inshore ecosystems and the wellbeing of the human communities. The plan clearly indicates that changes in land management are required by 2013 to reduce pollutant inputs and, at the same time, maintain or enhance the benefits from using the inland waters. Science that provides decision tools for natural resource management and improves socio-economic and biophysical understanding is required to enable managers to make better decisions. A major research activity (the Water for a Healthy Country Flagship) aims to address social, economic and biophysical outcomes of land management change in the GBR. It contains research activities that provide information for integrated model development. Currently, however, these models lack the ability to estimate the uncertainty associated with prediction. This project aims to provide statistical methods for assessing uncertainty in models of sediment transportation to the GBR. Furthermore, it provides a link between the models and the decision-making process that allows assessment of uncertainty, a step pertinent to the risk analysis of policy options. This paper describes current and ongoing approaches for assessing uncertainty using a sediment modelling example and provides a way forward for the integration of applied socio-economic and biophysical models used in the decision-making process.     

黄河流域水土保持减沙计算方法存在问题及改进途径探讨

水文法保法是分析计算汉域治理减水减沙效益常用的两种方法，但都存在一些问题。水文法计算的基础是帮雨沙资料建立的产沙模型，该模型很难准确地反映降雨产沙的自然规律；水保法计算的基础是制定的水土保持措施减沙定额，很难完全符合客观实际。本文从不同途径提出了三种经过改进的计算方法，即小流域天然产流量对比法、坡面综合措施减少沙系统数法和最大可能产沙量法。试算结果表明，在具有必要的前提下，应用这三咱方法分析计算流     

河流动床阻力影响参数分析及其计算研究

动床阻力计算对河流研究和工程问题解决十分重要。自20世纪中叶起利用现代水力学知识计算动床阻力的方法陆续出现，本文对现有成果进行了分析评述，并对经典的Einstein和钱宁等阻力计算方法进行剖析，发现基于水力半径分割假说建立的动床阻力算法，不适用于研究主要由悬移质输沙强度决定床面形态的水流阻力问题。为此，本文首先选取有代表性的基本物理量，同实测糙率值进行相关性分析，确定出主参数;通过数据分析确定水深和能坡的指数后，运用造床流量下床沙中值粒径公式计算河床比降;基于能坡I计算需体现河床比降主导影响的同时应考虑边岸局部水头损失作用的认识，给出能坡修正式，再引入能体现沙粒和含沙量对动床摩阻的影响的因子，建立了动床阻力计算新方法。大量实测资料验证结果表明，本文公式计算精度高，适用性强。     

Improved Wavelet Modeling Framework for Hydrologic Time Series Forecasting

The combination of wavelet analysis with black-box models presently is a prevalent approach to conduct hydrologic time series forecasting, but the results are impacted by wavelet decomposition of series, and uncertainty cannot be evaluated. In this paper, the method for discrete wavelet decomposition of series was developed, and an improved wavelet modeling framework, WMF for short, was proposed for hydrologic time series forecasting. It is to first separate different deterministic components and remove noise in original series by discrete wavelet decomposition; then, forecast the former and quantitatively describe noise’s random characters; at last, add them up and obtain the final forecasting result. Forecasting of deterministic components is to obtain deterministic forecasting results, and noise analysis is to estimate uncertainty. Results of four hydrologic cases indicate the better performance of the proposed WMF compared with those black-box models without series decomposition. Because of having reliable hydrologic basis, showing high effectiveness in accuracy, eligible rate and forecasting period, and being capable of uncertainty evaluation, the proposed WMF can improve the results of hydrologic time series forecasting.