Probabilistic modelling of long-term beach evolution near segmented shore-parallel breakwaters     

Baoxing Wang  Dominic Reeve 《Coastal Engineering》2010

This paper presents a new framework for probabilistic modelling of long-term beach evolution in the vicinity of detached breakwaters. The study focuses on the key physical processes contributing to beach variability over a range of spatial and temporal scales. Based on a one-line model, the framework is enhanced with sophisticated solutions for beach-wave-structure interaction, diffraction together with a treatment of varying tide level. The sediment transport rate is calibrated at regional and local levels using data from bespoke field campaigns and site-specific coefficients are proposed. Monte Carlo simulation is conducted for long-term shoreline simulation under a sequence of time varying sequence of waves, currents and tidal levels. The results of the Monte Carlo simulation give an insight into the statistical characteristics of beach behaviour within the defence system. In particular, regions within the scheme that are relatively stable and those that exhibit greater natural fluctuations are identified.  相似文献   

Distributed discharge and sediment concentration predictions in the sub‐humid Ethiopian highlands: the Debre Mawi watershed          下载免费PDF全文

Seifu A. Tilahun  Christian D. Guzman  Assefa D. Zegeye  Dessalegn C. Dagnew  Amy S. Collick  Birru Yitaferu  Tammo S. Steenhuis 《水文研究》2015,29(7):1817-1828

Experimental research in the Ethiopian highlands found that saturation excess induced runoff and erosion are common in the sub‐humid conditions. Because most erosion simulation models applied in the highlands are based on infiltration excess, we, as an alternative, developed the Parameter Efficient Distributed (PED) model, which can simulate water and sediment fluxes in landscapes with saturation excess runoff. The PED model has previously only been tested at the outlet of a watershed and not for distributed runoff and sediment concentration within the watershed. In this study, we compare the distributed storm runoff and sediment concentration of the PED model against collected data in the 95‐ha Debre Mawi watershed and three of its nested sub‐watersheds for the 2010 and 2011 rainy seasons. In the PED model framework, the hydrology of the watershed is divided between infiltrating and runoff zones, with erosion only taking place from two surface runoff zones. Daily storm runoff and sediment concentration values, ranging from 0.5 to over 30 mm and from 0.1 to 35 g l^?1, respectively, were well simulated. The Nash Sutcliffe efficiency values for the daily storm runoff for outlet and sub‐watersheds ranged from 0.66 to 0.82, and the Nash–Sutcliffe efficiency for daily sediment concentrations were greater than 0.78. Furthermore, the model uses realistic fractional areas for surface and subsurface flow contributions, for example between saturated areas (15%), degraded areas (30%) and permeable areas (55%) at the main outlet, while close similarity was found for the remaining hydrology and erosion parameter values. One exception occurred for the distinctly greater transport limited parameter at the actively gullying lower part of the watershed. The results suggest that the model based on saturation excess provides a good representation of the observed spatially distributed runoff and sediment concentrations within a watershed by modelling the bottom lands (as opposed to the uplands) as the dominant contributor of the runoff and sediment load. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Analysis of flood propagation changes in the Kienstock—Bratislava reach of the Danube River/Analyse des changements de propagation des crues dans le tronçon Kienstock—Bratislava du Fleuve Danube     

《水文科学杂志》2013,58(4)

Abstract

In the first part of this study, a flood wave transformation analysis for the largest historical floods in the Danube River reach Kienstock–Bratislava was carried out. For the simulation of the historical (1899 and 1954) flood propagation, the nonlinear river model NLN-Danube (calibrated on the recent river reach conditions) was used. It was shown that the simulated peak discharges were not changed significantly when compared to their historical counterparts. However, the simulated hydrographs exhibit a significant acceleration of the flood wave movement at discharges of between 5000 and 9000 m³ s^-1. In the second part, the travel time-water level relationships between Kienstock and Bratislava were analysed on a dataset of the flood peak water levels for the period 1991–2002. An empirical regression routing scheme for the Danube short-term water level forecast at Bratislava station was derived. This is based on the measured water level at Kienstock gauging station.  相似文献   

NUMERICAL SIMULATION OF THE KUROSHIO USING NESTED MODEL OF THREE-DIMENSIONAL BAROCLINIC CIRCULATION     

李毓湘  蔡怡 《中国海洋湖沼学报》1999,17(1):19-27

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＫｕｒｏｓｈｉｏｉｓｔｈｅｗｅｓｔｅｒｎｂｏｕｎｄａｒｙｃｕｒｒｅｎｔｉｎｔｈｅＮｏｒｔｈＰａｃｉｆｉｃａｎｄｉｓｔｈｅｃｏｕｎｔｅｒｐａｒｔｏｆｔｈｅＧｕｌｆＳｔｒｅａｍｉｎｔｈｅＮｏｒｔｈＡｔｌａｎｔｉｃ.ＴｈｅｏｒｉｇｉｎｏｆｔｈｅＫｕｒｏｓｈｉｏｉｓｔｈｅｎｏｒｔｈｗａｒｄｆｌｏｗｉｎｇｂｒａｎｃｈｏｆｔｈｅＮｏｒｔｈＥｑｕａｔｏｒｉａｌＣｕｒｒｅｎｔｗｈｉｃｈｉｓｄｉｖｉｄｅｄｉｎｔｏｔｗｏｃｕｒｒｅｎｔｓｏｎａｐｐｒｏａｃｈｉｎｇｔｈｅｗｅｓｔｅｒｎｂｏ…  相似文献   

3-D BAROCLINIC NUMERICAL SIMULATION OF THE SOUTH CHINA SEA I. UPPER CIRCULATION     

蔡树群甘子钧  刘秦玉 《中国海洋湖沼学报》2001,19(3):208-216

A three-dimensional baroclinic shelf sea model was employed to simulate the seasonal characteristics of the South China Sea (SCS) upper circulation. The results showed that: in summer, an anticyclonic eddy, after its formation between the Bashi Channel and Dongsha Islands in the northeastern SCS, moves southwestward until it disperses slowly. There exists a northward western boundary current along the east shore of the Indo-China Peninsula in the western SCS and an anticyclonic gyre in the southern SCS. But at the end of summer and beginning of autumn, a weak local cyclonic eddy forms in the Nansha Trough, then grows slowly and moves westward till it becomes a cyclonic gyre in the southern SCS in autumn. At the beginning of winter, there exists a cyclonic gyre in the northern and southern SCS, and there is a southward western boundary current along the east shore of the Indo-China Peninsula. But at the end of winter, an anticyclonic eddy grows and moves toward the western boundary after forming in the Nansha Trough. The eddy‘s movement induces a new opposite sign eddy on its eastern side, while the strength of the southward western boundary current gets weakened. This phenomenon continues till spring and causes eddies in the southern SCS.  相似文献   

SOFTWARE REVIEWS     

《The Professional geographer》1991,43(3):362-363

ATLAS*GIS , Version 1.0. ATLAS*MapMaker , Version 4.0. FIVFIV-SINSIN , Release 9.0. Geo-EAS , Version 1.2.1. Evan Englund Sim City , Version 1.0 Statistix , Version 3.1.  相似文献   

辽河油田曙一区杜84块兴隆台油层构造应力场研究     

苏生瑞  张靖宇  毛彦龙 《地球科学与环境学报》2001,23(1):11-15

根据辽河油田已有地层、构造资料，研究了杜84块构造格架、主要断裂特点，在此基础上,建立了构造应力场模拟的三维地质模型，用3D-σ软件进行了构造应力场三维有限元模拟研究。其结果表明，杜84块油层受构造应力状态为最大和中间主应力近水平，最小主应力垂直。在此应力场作用下，区内断层运动方式为正断兼水平扭动。三维有限元模拟计算结果表明，沿断层带均发生压应力和剪应力集中现象,从而有利于断层发生扭张性运动。位移分析表明，有明显的呈阶梯状组合的正断位移。据破坏率分析，在现有应力场作用下，油层所在岩体局部会产生裂缝。  相似文献   

Advances in Numerical Modeling of Astrophysical and Space Plasmas     

Anthony L. Peratt 《Astrophysics and Space Science》1997,256(1-2):51-75

Advances in the simulation of astrophysical and cosmic plasmas are the direct result of advances in computational capabilities, today consisting of new techniques such as multilevel concurrent simulation, multi-teraflop computational platforms and experimental facilities for producing and diagnosing plasmas under extreme conditions for the benchmarking of simulations. Examples of these are the treatment of mesoscalic plasma and the scaling to astrophysical and cosmic dimensions and the Accelerated Strategic Computing Initiative whose goal is to construct petaflop (10¹⁵ floating operations per second) computers, and pulsed power and laser inertial confinement plasmas where megajoules of energy are delivered to highly-diagnosed plasmas. This paper concentrates on the achievements to date in simulating and experimentally producing plasmas scaled to both astrophysical and cosmic plasma dimensions. A previous paper (Part I, Peratt, 1997) outlines the algorithms and computational growth.  相似文献   

On the Possibility of Directional Analysis for Geo-neutrinos     

Mikhail Batygov 《Earth, Moon, and Planets》2006,99(1-4):183-192

The possibility of terrestrial antineutrino directionality studies is considered for future unloaded liquid scintillator detectors. Monte-Carlo simulations suggest that the measurable displacement between prompt and delayed antineutrino signals makes such studies possible. However, it is estimated that on the order of 1000 terrestrial antineutrino events are required to test the simplest models, demanding detectors of 100 kt size to collect sufficient data in a reasonable period of time.  相似文献   

Development and application of simulation technique for hydrokinetic hammer     

Tianye ZHU  Qingyan WANG  Kun YIN  Siyi WANG 《世界地质(英文版)》2007,10(2)

The computer simulation is an important method for hydrokinetic hammer design. Various kinds of simulation measures with their technical characters and applications being taken during the computer aided design are enumerated. Computer simulation supports plenty of valuable references to the designer. Each type of simulation process is used to explore the exact aspect of the performance of hydrokinetic hammer and each type of simulation method has its own excellences and deficiencies. Thus the integrative simulation methods based on modern computational technology are brought forward to obtain the perfect capability of the whole product. Along with the development of computer hardware and software, various kinds of platforms have been provided to different simulation methods that can be carried out with distinct working flows. The jet flow element is the core part of the hydrokinetic hammer. We can build the ideal simulation model of it by means of CFD (computational fluid dynamics) technology. On the other hand, to set up the digital model of piston and hammer, the best way is to build the virtual prototype using automatic dynamic analysis of mechanical system. As a result of the argumentation, we think the technique of Virtual Prototype and CFD are the prime way to process the combined computer simulation for hydrokinetic hammer.  相似文献