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1.
本文利用全球陆面数据同化系统与降雨观测数据,以陕西半湿润区陈河流域为研究对象,驱动WRF-Hydro模型,研究该模型的表现和适用性,并在结构、参数、输入输出和模拟结果方面与新安江模型对比.考虑到次表面层与实际包气带的区别,引入土层厚度乘子ZSOILFAC对前者进行等比缩放,发现其与新安江模型反推包气带的厚度有较好的一致性.研究表明:在陈河流域中WRF-Hydro计算步长须在建议值的基础上缩小; WRF-Hydro模型善于模拟洪水细节,新安江模型表现好且稳定;前者的径流深和洪峰合格率平于或略低于后者;在两个指标均合格的洪水中,前者平均均方根误差比后者小21.5%,但对于其他洪水,前者平均均方根误差比后者大56.2%; WRF-Hydro在洪水起涨时刻模拟较好,表现出其在中小流域应用的潜力.  相似文献   
2.
中国物理海洋学研究70年:发展历程、学术成就概览   总被引:2,自引:2,他引:0  
本文概略评述新中国成立70年来物理海洋学各分支研究领域的发展历程和若干学术成就。中国物理海洋学研究起步于海浪、潮汐、近海环流与水团,以及以风暴潮为主的海洋气象灾害的研究。随着国力的增强,研究领域不断拓展,涌现了大量具有广泛影响力的研究成果,其中包括:提出了被国际广泛采用的“普遍风浪谱”和“涌浪谱”,发展了第三代海浪数值模式;提出了“准调和分析方法”和“潮汐潮流永久预报”等潮汐潮流的分析和预报方法;发现并命名了“棉兰老潜流”,揭示了东海黑潮的多核结构及其多尺度变异机理等,系统描述了太平洋西边界流系;提出了印度尼西亚贯穿流的南海分支(或称南海贯穿流);不断完善了中国近海陆架环流系统,在南海环流、黑潮及其分支、台湾暖流、闽浙沿岸流、黄海冷水团环流、黄海暖流、渤海环流,以及陆架波方面均取得了深刻的认识;从大气桥和海洋桥两个方面对太平洋–印度洋–大西洋洋际相互作用进行了系统的总结;发展了浅海水团的研究方法,基本摸清了中国近海水团的分布和消长特征与机制,在大洋和极地水团分布及运动研究方面也做出了重要贡献;阐明了南海中尺度涡的宏观特征和生成机制,揭示了中尺度涡的三维结构,定量评估了其全球物质与能量输运能力;基本摸清了中国近海海洋锋的空间分布和季节变化特征,提出了地形、正压不稳定和斜压不稳定等锋面动力学机制;构建了“南海内波潜标观测网”,实现了对内波生成–演变–消亡全过程机理的系统认识;发展了湍流的剪切不稳定理论,提出了海流“边缘不稳定”的概念,开发了海洋湍流模式,提出了湍流混合参数化的新方法等;在海洋内部混合机制和能量来源方面取得了新的认识,并阐述了混合对海洋深层环流、营养物质输运等过程的影响;研发了全球浪–潮–流耦合模式,推出一系列海洋与气候模式;发展了可同化主要海洋观测数据的海洋数据同化系统和用于ENSO预报的耦合同化系统;建立了达到国际水准的非地转(水槽/水池)和地转(旋转平台)物理模 型实验平台;发展了ENSO预报的误差分析方法,建立了海洋和气候系统年代际变化的理论体系,揭示了中深层海洋对全球气候变化的响应;初步建成了中国近海海洋观测网;持续开展南北极调查研究;建立了台风、风暴潮、巨浪和海啸的业务化预报系统,为中国气象减灾提供保障;突破了国外的海洋技术封锁,研发了万米水深的深水水听器和海洋光学特性系列测量仪器;建立了溢油、危险化学品漂移扩散等预测模型,为伴随海洋资源开发所带来的风险事故的应急处理和预警预报提供科学支撑。文中引用的大量学术成果文献(每位第一作者优选不超过3篇)显示,经过70年的发展,中国物理海洋学研究培养了一支实力雄厚的科研队伍,这是最宝贵的成果。这支队伍必将成为中国物理海洋学研究攀登新高峰的主力军。  相似文献   
3.
ABSTRACT

Characterizing, understanding and better estimating uncertainties are key concerns for drawing robust conclusions when analyzing changing socio-hydrological systems. Here we suggest developing a perceptual model of uncertainty that is complementary to the perceptual model of the socio-hydrological system and we provide an example application to flood risk change analysis. Such a perceptual model aims to make all relevant uncertainty sources – and different perceptions thereof – explicit in a structured way. It is a first step to assessing uncertainty in system outcomes that can help to prioritize research efforts and to structure dialogue and communication about uncertainty in interdisciplinary work.  相似文献   
4.
The extent to which forests, relative to shorter vegetation, mitigate flood peak discharges remains controversial and relatively poorly researched, with only a few significant field studies. Considering the effect purely of change of vegetation cover, peak flow magnitude comparisons for paired catchments have suggested that forests do not mitigate large floods, whereas flood frequency comparisons have shown that forests mitigate frequencies over all magnitudes of flood. This study investigates the apparent inconsistency using field-based evidence from four contrasting field programmes at scales of 0.34–3.1 km2. Repeated patterns are identified that provide strong evidence of real effects with physical explanations. Magnitude and frequency comparisons are both relevant to the impact of forests on peak discharges but address different questions. Both can show a convergence of response between forested and grassland/logged states at the highest recorded flows but the associated return periods may be quite variable and are subject to estimation uncertainty. For low to moderate events, the forested catchments have a lower peak magnitude for a given frequency than the grassland/logged catchments. Depending on antecedent soil saturation, a given storm may nevertheless generate peak discharges of the same magnitude for both catchment states but these peaks will have different return periods. The effect purely of change in vegetation cover may be modified by additional forestry interventions, such as road networks and drainage ditches which, by effectively increasing the drainage density, may increase peak flows for all event magnitudes. For all the sites, forest cover substantially reduces annual runoff.  相似文献   
5.
以解决挑流消能工在泄洪期间为提高消能率而加重下游雾化问题为目标,探究不同体型挑坎的下游雾化特性。通过水力学模型试验,对典型的非对称舌型坎、标准舌型坎、扭面贴坎和连续坎的下游水舌风分布、下游溅水雨强和不同液滴体积分布以及挑流水舌水力特性与冲刷特性进行了研究。研究表明:①各种工况下,非对称舌型坎、标准舌型坎、扭面贴坎的下游水舌风风速均大于连续坎。②对于非对称舌型坎,其溢洪道轴线左侧溅水强度大于右侧,其雨强左右两侧峰值差值最大为5.625 g/(m 2·min);对于扭面贴坎,其溢洪道轴线右侧溅水强度更大,其雨强左右两侧峰值差值最大为45.125 g/(m 2·min)。③随着距离水舌入水点长度增大,大粒径水滴数量和体积占比均剧烈下降;连续坎和舌型坎的挑宽均随着角度的增加而增加;冲坑深度随着角度的减小而增大。④在挑坎合适边墙侧设置扭面贴角能改善下游雾化危害,同时适当增加挑角可以减弱下游冲刷破坏。  相似文献   
6.
山区阶梯式河道水流阻力研究   总被引:1,自引:0,他引:1       下载免费PDF全文
罗铭  张焕  丁锐  黄尔  杨奉广 《水科学进展》2019,30(5):719-726
山区阶梯式河道是自然界来水来沙和山区大比降河床相互作用所形成的,其水力特性、河道阻力较为复杂。为了深入研究其阻力机理,从河床结构阻水的角度提出阶梯式结构糙率尺度的概念,得到了适用于阶梯式河道跌落水流的形体阻力系数表达式,并由不同来源的阻力分量构成了新的山区阶梯式河道水流总阻力系数公式。新公式结果表明,通过不同类型河段的野外试验数据,表面泥沙、阶梯形状以及漂石产生的阻力系数分量之和与试验测量总阻力系数数据的误差较小。随着雷诺数和阶梯单元尺寸的增加,河床表面的泥沙肤面阻力系数基本不变,阶梯式结构形成的跌落水流过渡到滑行水流,阶梯形体阻力系数逐渐变小,而较大粒径松散漂石产生的水流阻力系数只随着雷诺数的增大而减小。  相似文献   
7.
Large wood (LW) transport can increase greatly during floods, leading to accumulations at river infrastructures. To mitigate the potential flood hazard, racks are a common method to retain LW upstream of endangered settlements or infrastructures. The majority of LW retention racks consist of vertical bars and, therefore, disrupt bedload transport. It can be hypothesized that inclined racks reduce backwater rise and local scour, as wood will block the upper part of the rack, thereby increasing the open flow cross-section below the accumulation. Flume experiments were conducted under clear water conditions to analyse backwater rise and local scour as a function of (1) rack inclination, (2) hydraulic inflow condition, (3) uniform bed material, and (4) LW volume. In addition, the first experiments were performed under live bed scour conditions to study the effect of bedload transport on local scour and backwater rise. Based on the experiments, backwater rise and local scour decrease with decreasing rack angle to the horizontal. LW predominantly accumulated at the upper part of the rack, leading to an open flow cross-section below the accumulation. The effect of rack angle was included in existing design equations for backwater rise and local scour depth. In addition, the first experiments with bedload transport resulted in smaller backwater rise and local scour depth. This study contributes to an enhanced process understanding of wood retention and bedload transport at rack structures and an improved design of LW retention racks. © 2020 John Wiley & Sons, Ltd.  相似文献   
8.
Abstract

The hydrology of water-dependent ecosystems around the world has been altered as a result of flow regulation and extraction for a variety of purposes including agricultural and urban water supply. The flow regime of the Murray-Darling Basin in Australia is no exception, with attendant impacts on the health of the environment. Restoration of parts of the flow regime is a key feature of environmental flow delivery. However, environmental flow delivery in a system that is managed primarily to provide a secure and stable supply for irrigation presents challenges for managers seeking to return more natural flow variability in line with ecosystem requirements. The institutional arrangements governing releases of water from storage can influence the ability of managers to respond to natural cues, such as naturally rising flows in a river. As such, the legal and governance aspects of environmental flow delivery are likely to be important influences on the outcomes achieved.
Editor Z.W. Kundzewicz; Guest editor M. Acreman

Citation Banks, S.A. and Docker, B.B., 2014. Delivering environmental flows in the Murray-Darling Basin (Australia)—legal and governance aspects. Hydrological Sciences Journal, 59 (3–4), 688–699.  相似文献   
9.
The peak of river floods usually decreases in the downstream direction unless it is compensated by freshwater inflow from tributaries. In the Yellow River (China) the opposite is regularly observed, where the peak discharge of river floods increases in the downstream direction (at a rate far exceeding the contribution from tributaries). This flood peak discharge increase is probably related to rapid morphological changes, to a modified bed friction, or to a combination of both. Yet the relative role of these processes is still poorly understood. This paper aims to analyze the relative contribution of bed erosion and friction change to the peak discharge increase, based on available data and a recently developed numerical model. Using this high-resolution, fully coupled morphodynamic model of non-capacity sediment transport, two hyperconcentrated floods characterized by downstream peak discharge increase are numerically reproduced and analyzed in detail. The results reveal that although erosion effects may contribute to the downstream discharge increase (especially in case of extreme erosion), for most cases the increase must be mainly due to a reduction in bed friction during peak discharge conditions. Additionally, based on the concept of channel storage reduction, the effects of decreasing bed friction and (very strong) bed erosion can be integrated in explaining the peak discharge increase.  相似文献   
10.
Predicting spatial and temporal variations in bank erosion due to extreme floods presents a long‐standing challenge in geomorphology. We develop two methodologies for rapid, regional‐scale assessments of stream reaches susceptible to channel widening. The first proposes that channel widening occurs when unit stream power exceeds a critical threshold (300 W/m2). The second is motivated by the observation that widening often occurs at channel bends. We introduce a new metric, the bend stress parameter, which is proportional to the centripetal force exerted on a concave bank. We propose that high centripetal forces generate locally high bank shear forces and enhance channel bank erosion. We test both metrics using the geomorphic signature of Tropical Storm Irene (2011) on the White and the Saxtons Rivers, Vermont. Specifically, we test if reaches where significant channel widening occurred during Irene required one or both metrics to exceed threshold values. We observe two distinct styles of channel widening. Where unit stream power and bend stress parameter are high, widening is usually due to bank retreat. Elsewhere widening is usually due to the stripping of the upstream end of mid‐channel islands. Excluding widening associated with the stripping of the heads of mid‐channel islands, almost all the widening (> 98%) occurred along reaches identified as susceptible to widening. The combined metrics identify up to one‐quarter of the reaches lacking susceptibility to channel widening. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
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