Energy Profiles Across Constructed Riffles

Riffle reconstruction has become an important river rehabilitation technique in disturbed channels. However, design has often lacked sufficient hydraulic analysis to adequately assess the potential effects on flow resistance and flood levels. This paper describes the results of a hydraulic field study of four steep gravel–cobble bed rivers where it was found that the energy loss across natural and constructed riffle–pool sequences varied between 50 and 100% of the total energy loss over a range of high discharges up to, and including bankfull. This demonstrates that riffle reconstruction can influence postrehabilitation flood elevations, and that the additional flow resistance should be an important consideration in design. Importantly, the observed riffle energy loss is found to vary between 0.5 and 1 times the riffle amplitude, and it is proposed that this relationship can be used to account for the additional hydraulic resistance imparted by constructed riffles in the design and analysis of riffle–pool rehabilitation initiatives in steep gravel–cobble bed rivers.     

Flow and Velocity Distribution in Meandering Compound Channels

An investigation of flow and velocity distribution in meandering compound channels with over bank flow is described. Equations concerning the three-dimensional variation of longitudinal, transverse, and vertical velocity in the main channel and floodplain of compound section in terms of channel parameters are presented. The flow and velocity distributions in meandering compound channels are strongly governed by interaction between flow in the main channel and that in the floodplain. The proposed equations take adequate care of the interaction affect. Results from the formulations, simulating the three-dimensional velocity field in the main channel and in the floodplain of meandering compound channels are compared with their respective experimental channel data obtained from a series of symmetrical and unsymmetrical test channels with smooth and rough sections. The aspect ratio of the test channels varies from two to five. The equations are found to be in good agreement with the experimental data. The formulations are verified against the natural river and other meandering compound channel data. The power laws used for simulating the three-dimensional velocity structure are found to be quite adequate.     

“94.6”特大暴雨洪水初步分析

9403号台风后,华南地区6月上、中旬普降暴雨,大暴雨、局部特大暴雨,造成珠江流域西、北江中下游并发超50年一遇大洪水,两江洪峰几乎同时到达思贤滘,此时又处在潮水上涨期,西北江三角洲水位在洪湖共同作用下迅猛上涨,部分水位站达到50～100年一遇,给两广带来严重的灾害。本文在阐述流域概况基础上,分析了天气系统暴雨时空分布和暴雨洪水特点,分别论证北江洪水、西江洪水及西北江三角洲洪水情况,供有关部门参考。     

准噶尔盆地西北缘三叠—侏罗系沉积模式

本文根据584口探井资料结合现代沉积考察成果,对准噶尔盆地西北缘三叠—侏罗系沉积特征进行了研究,并在此基础上建立了各层相应的沉积模式:下三叠统百口泉组为旱地、半旱地—辫状河—曲流河—湖盆三角洲—湖沉积体系;中三叠统克拉玛依组为断崖扇—扇三角洲或辫状三角洲—湖沉积体系;上三叠统白碱滩组为扇三角洲—湖及湖底扇沉积体系;下侏罗统八道湾组为湿地扇—砾质网状河—网状河泛滥平原沉积体系。     

安阳河水情自动化遥测预报系统

安阳河坡陡流急,汇流特快,预见期短,防守困难.为了及时掌握上游水情和雨情、增长洪水有效预见期,尽可能及时采取防洪措施,减少下游洪水灾害损失,现已研制成水情自动化遥测、预报系统,经三年使用,运行可靠.本文详细介绍了该系统的设计思想、组成和工作方法,为其它中小流域采取非工程防洪措施提供了一个很好的范例.     

An open-book watershed model for prototyping space-borne flood monitoring systems in International River Basins

A new era involving both simple and complex hydrologic modeling of un-gauged river basins may now emerge with the anticipated global availability of high resolution satellite rainfall data from the proposed Global Precipitation Measurement (GPM) mission. This era of application pertains to rapid prototyping of GPM-based flood monitoring systems for downstream nations in International River Basins (IRBs) where basin-wide in-situ rainfall data is unavailable due to lack of either an infrastructure or a treaty for real-time data sharing with upstream riparian nations. In this paper, we develop, verify and apply an open-book watershed model for demonstrating the value of a parsimonious modeling scheme in quick prototyping of satellite rainfall-based flood monitoring systems for lowermost nations in flood-prone IRBs. The open-book watershed modeling concept was first formulated by Yen and Chow [1969. A laboratory study of surface runoff due to moving rainstorms. Water Resources Research 5(5), 989–1006] more than 30 years ago as a convenient and pragmatic framework to understand the underlying physics behind surface hydrologic phenomena. Our developed model is based on first principles of conservation of mass and momentum that parsimoniously represents the static geophysical features of a basin with minimum calibration. Such a generic and parsimonious representation has the added potential to supplement complex hydrologic models for stakeholder involvement and conflict management in transboundary river basins, among many additional applications. We first demonstrate the physical consistency of our model through sensitivity analysis of some geophysical basin parameters pertinent to the rainfall-runoff transformation. Next, we simulate the stream-flow hydrograph for a 4-month long period using basin-wide radar (WSR-88D) rainfall data over Oklahoma assuming an open-book river basin configuration. Finally, using the radar-simulated hydrograph as the benchmark, and assuming a two-nation hypothetical IRB over Oklahoma, we explored the impact of assimilating NASA's real-time satellite rainfall data (IR-3B41RT) over the upstream nation on the flow monitoring accuracy for the downstream nation. We developed a relationship defining the improvement in flow monitoring that can be expected from assimilating IR-3B41RT over transboundary regions as a function of the relative area occupied by the downstream nation for a semi-arid region. The relative improvement in flow monitoring accuracy for the downstream nation was found to be clearly high (over 35% reduction in root mean squared error) when more than 90% of the basin is transboundary. However, flow monitoring accuracy reduces considerably and even becomes negative when 60% or less of the basin area is transboundary to the downstream nation. Our findings, although hypothetical and very regime-specific, illustrate very clearly the feasibility of utilizing anticipated GPM data to alleviate the current flood monitoring limitations experienced by many nations in IRBs through the application of a generic and parsimonious model.     

湘江流域水情遥测数据采集系统通信原理

湖南湘江水情信息采集系统是由法国政府贷款的建设项目，系统设备均由法方提供，除计算机网络设备外，遥测终端均由法国公司生产研制。本文介绍了该系统的基本情况和工作原理，并重点介绍了超短波TDMA（时分多址）通信方式在水情信息采集系统中首次运用情况，对系统功能和可靠性作了全面描述，其有关技术和工作制式值得有关专家同行关注探讨。     

大广坝流域台风期洪水预报方法的研究

大广坝流域洪水由台风雨形成,台风登陆路径的不同造成台风期降雨中心位置分布的差异,另外流域上游的友谊水库对下游大广坝水库天然入流方式的改变,直接导致洪水预报方案的改变,即从全流域产汇流计算改为"上下库区间汇流计算和库区产汇流计算".通过分析大广坝流域台风雨洪成因及其特点,按降雨类型分别设计了相应的洪水预报方案,经检验,方案预报精度达到甲等水平,可为大广坝电站防洪度汛提供更加准确及时的雨洪信息.     

Flood Damage Reduction

Abstract

A fundamental conflict occurs when a floodplain, fluvio-morphologically formed by the river for draining its high flows, is occupied and developed by humanity. Consequently, damages are experienced that are the inevitable costs of occupancy of the floodplain. A systematic methodology is suggested for formulating an optimal scheme for addressing any flood situation with its own unique characteristics. This methodology embraces all available measures, structural and non-structural, traditional and modern, in evolving the best scheme. Diverse flood situations in New Brunswick (Canada), the Nile River Basin and Bangladesh exemplify three flooding situations radically different in origin and character. Finally, some important conclusions are drawn and recommendations are made for approaching solutions to major flood problems     

浅谈城市防洪与水土保持的关系

针对城市防洪与水土保持的关系作了阐述.对城市水土保持进行了分析,阐述了城市防洪和水土保持的特点.最后从硬、软两方面给出了自己的一些粗浅的想法.