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Estimation of suspended sediment concentration based on bio-optical mechanism and HJ-1 image in Chaohu Lake

Science china Earth Sciences 2010年第S1期53卷 58-66页

作者： WANG Qiao1,2,JIN Xin2,LI YunMei2,WU ChuanQing1,Lü Heng2,WANG YanFei2,ZHANG Hong2,YIN Bin2 & ZHU Li1 1Satellite environment Center,ministry of environmental Protection,Beijing 100029,china 2key laboratory of virtual geographic environment of education ministry,nanjing normal university,nanjing 210046,china 1. Satellite environment Center Ministry of Environmental Protection Beijing 100029 China2. Key Laboratory of Virtual Geographic Environment of Education Ministry Nanjing Normal University Nanjing 210046 China

Synchronization experiment was conducted in June,2009 to get Inherent Optical Properties(IOP) of water component in Chaohu *** bio-optical mechanism was studied combined with multispectral data of environmental Satellite 1(CCD),and then inversion models of total suspended matter(TSM),inorganic suspended matter(ISM) and organic suspended matter(OSM) concentration were *** data indicated that:the absorption ratio of suspended particulate matter and CDOM to total were almost no change from band 1 to band 2 with about 85% and 9%,*** ratio of pure water to total increased from 0.4% to 5.6%.Water reflectance in these two bands were influenced by absorption of three kinds of components:algae particles absorption surpassed non-algal particles in band 3,and so played an important role in total absorption with about 35.7%;the proportion of pure water absorption and particles matter backscattering both were 99% in band 4,so these two components decided the main inherent optical properties in band *** models of TSM and ISM concentration inversion based on band combination(band 3 + band 4)/(band 1 + band 2) were built,while OSM concentration was estimated by band 4/(band 1 + band 2) *** by image data,RE of TSM concentration between modeled and measured was 33.4%,and RMSE was 18.68 mg/*** of ISM and OSM concentration were 39.9% and 35.2% *** inversion was more accurate when satellite-ground data were just in the same *** this situation,RE of ISM concentration dropped to 25.4%,and that of TSM and OSM reduced to 26.5% and 26.8% as well.

关键词： HJ-1 Satellite bio-optical property Chaohu Lake suspended matter

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Research on the slope spectrum of the Loess Plateau

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Science china(Technological Sciences) 2008年第S1期51卷 175-185页

作者： TANG GuoAn,LI FaYuan,LIU XueJun,LONG Yi & YANG Xin key laboratory of virtual geographic environment,nanjing normal university,ministry of education,nanjing 210046,china nanjing normal Univ Key Lab Virtual Geog Environm Minist Educ Nanjing 210046 Peoples R China

A new concept dealing with digital analysis of loess terrain,slope spectrum,is presented and discussed in this paper,by introducing its characteristic,represen-tation and extracting method from DEMs. Using 48 geomorphological units in dif-ferent parts of the loess as test areas and 5 m-resolution DEMs as original test data,the quantitative depiction and spatial distribution of slope spectrum in china's Loess Plateau have been studied on the basis of a series of carefully-designed experiments. In addition,initial experiment indicates a strong relationship between the slope spectrum and the loess landform types,displaying a potential importance of the slope spectrum in geomorphological studies. Based on the slope spectrums derived from the 25 m-resolution DEM data in whole loess terrain in northern part of Shaanxi,13 slope spectrum indices were extracted and integrated into a compre-hensive layer with image integration method. Based on that,a series of unsuper-vised classifications was applied in order to make a landform classification in northern Shaanxi Loess Plateau. Experimental results show that the slope spec-trum analysis is an effective method in revealing the macro landform features. A continuous change of slope spectrum from south to north in northern Shaanxi Loess Plateau shows an obvious spatial distribution of different loess landforms. This also proves the great significance of the slope spectrum method in describing the terrain roughness and landform evolution as well as a further understanding on landform genesis and spatial distribution rule of different landforms in the Loess Plateau.

关键词： Loess Plateau slope spectrum slope DEM loess landform

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An extended time-dependent numerical model of the mild-slope equation with weakly nonlinear amplitude dispersion

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Acta Oceanologica Sinica 2010年第2期29卷 5-13页

作者： ZHAO Hongjun SONG Zhiyao XU Fumin LI Ruijie key laboratory of Coastal Disasters and Defence Ministry of Education Hohai University Nanjing 210098 China Ocean College Hohai University Nanjing 210098 China key laboratory of virtual geographic environment Ministry of Education Nanjing Normal University Nanjing 210097 China

In the present paper, by introducing the effective wave elevation, we transform the extended elliptic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. （2003）, the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. （2007）＇s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly varying topography and wave breaking, the present model is applied to study：（1） wave refraction and diffraction over a submerged elliptic shoal on a slope （Berkhoff et al., 1982）; （2） Bragg reflection of monochromatic waves from the sinusoidal ripples （Davies and Heathershaw, 1985）; （3） wave transformation near a shore attached breakwater （Watanabe and Maruyama, 1986）. Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models （REF/DIF model and FUNWAVE model） show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.

关键词： time-dependent mild-slope equation varying topography bottom friction nonlinear amplitude dispersion steep or rapidly wave breaking

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A NEW IMPLICIT SCHEME FOR SOLVING 3-D SHALLOW WATER FLOWS

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Journal of Hydrodynamics 2009年第6期21卷 790-798页

作者： ZHANG Zhuo SONG Zhi-yao LV Guo-nian State key laboratory of Hydrology Water Resources and Hydraulic Engineering Ocean College Hohai University Nanjing 210098 China key laboratory of virtual geographic environment Ministry of Education Nanjing Normal University Nanjing 210097 China

Based on the improved ADI method, this article proposes an improved implicit finite difference scheme for solving 3-D shallow water flows. The main objective is to design a numerical relation between the horizontal velocity on each layer and the depth-averaged velocity for employing the improved ADI method. With the free surface elevation and the depth-averaged velocity obtained by using essentially 2-D depth-averaged mode, the velocity profiles can be obtained easily and simultaneously. The wind-induced flows, the open channel flows due to the pressure gradient and the tidal flows in coastal waters are simulated, and the results are consistent well with the analytical solution and the field data, which shows that the present implicit scheme is stable and effective, and the established model is practical. Moreover, when only one vertical layer is specified, the present 3-D numerical model is reducea to the 2-D depth-averaged model.

关键词： shallow water equation ADI method wind-induced flow gravity-drived flow tidal flow

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Predicting bioconcentration factor values of organic pollutants based on medv descriptors derived QSARs

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Science china Chemistry 2007年第5期50卷 587-592页

作者： CUI ShiHai1,2, YANG Jing1, LIU ShuShen2,3 & WANG LianSheng2 1 College of Chemistry and environment, nanjing normal university, nanjing 210097, china 2 State key laboratory of Pollution Control and Resources Reuse, School of the environment, nanjing university, nanjing 210093, china 3 key laboratory of Yangtze Aquatic environment, ministry of education, College of environmental Science and Engineering, Tongji university, Shanghai 200092, china 1. College of Chemistry and environment Nanjing Normal University Nanjing 210097 China 2. State key laboratory of Pollution Control and Resources Reuse School of the Environment Nanjing University Nanjing 210093 China 3. key laboratory of Yangtze Aquatic environment Ministry of Education College of Environmental Science and Engineering Tongji University Shanghai 200092 China

The molecular electronegativity-distance vector (MEDV) is employed todescribe the chemical structure of organic *** linear relationships between themolecular descriptors and BCF values are developed by best subset regression and partial leastsquare regression *** main structural factors influencing the bioactivities are -CH2,-X,-Cnot 2 and q2_(LOO) present good estimation ability and stabilityof *** prediction power for external samples is validated by the model developed from thetraining set.

关键词： POPs, BCF, MEDV, QSAR

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AN APPROACH TO SEPARATING THE CURRENT VELOCITY IN ESTUARINE AND COASTAL WATERS

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Journal of Hydrodynamics 2009年第4期21卷 512-519页

作者： NI Zhi-hui SONG Zhi-yao WU Li-chun State key laboratory of Hydrology-Water Resources and Hydraulic Engineering Ocean College Hohai University Nanj ing 210098 China key laboratory of virtual geographic environment Ministry of Education Nanjing Normal University Nanjing 210097 China Chongqing education College Chongqing 400067 China

In the near-shore waters, the actual flow is mainly induced by tide, wind and salinity, and the river water runoff should also be included as a component in the estuary waters. The interactions among these major components are very complicated. Many approaches were proposed to study isolated tide and wind-driven currents or run-off based on the measured velocity, with all its components taken as a whole. In this article, firstly, based on the actual hydrodynamic characteristics of estuarine and coastal waters, an approach is proposed to separate the measured velocity by considering the theoretical current velocity profiles and using the least squares method. The vertical structures of tidal, wind-driven currents, density current and runoff can be obtained as well as their proportions in the measured velocity. Then, this approach is applied to the analysis of velocity data obtained in the North Branch of Yangtze River estuary and of laboratory test data. The results are found to be satisfactory. Finally, this approach is used to separate the measured velocity in the South Branch of Yangtze River estuary, to determine not only the bed friction velocity and roughness height, but also the surface wind stress, and to estimate the wind velocity data above the water surface. The results show that this method is simple in principle, practical in use, and reasonable in obtained results. So it can be used to effectively analyze the field data.

关键词： tide wind-driven current density current river water runoff friction velocity roughness height velocity separation

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Atmospheric correction of HJ-1A/B CCD images over Chinese coastal waters using MODIS-Terra aerosol data

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Science china(Technological Sciences) 2010年第S1期53卷 191-195页

作者： TIAN LiQiao 1,LU JianZhong 1,CHEN XiaoLing 1,2,3,YU ZhiFeng 1,XIAO JingJing 1,QIU Feng 1 & ZHAO Xi 1 1 State key laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan university,Wuhan 430079,china 2key laboratory of Poyang Lake Wetland and Watershed Research,ministry of education,Jiangxi normal university,Nanchang 330022,china 3 The key laboratory of Poyang Lake environment and Resource Utilization,ministry of education,Nanchang university,Nanchang 330031,china 1. State key laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Wuhan 430079 China 2. key laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education Jiangxi Normal University Nanchang 330022 China 3. The key laboratory of Poyang Lake environment and Resource Utilization Ministry of Education Nanchang University Nanchang 330031 China

This paper demonstrates an atmospheric correction method to process HJ-1A/B CCD images over Chinese coastal waters with the aid of MODIS-Terra aerosol *** on the assumption of zero water-leaving radiance at the two near-infrared (NIR)bands or the shortwave infrared(SWIR)bands,the atmospheric aerosol optical depth(AOD)is firstly retrieved from MODIS-Terra with a simple extension of the NIR-SWIR combined atmospheric correction approach embedded in SeaDAS (SeaWiFS data analysis system).Then the"turbid"and"non-turbid"waters are separated by the turbid water *** probability of AOD at 551 nm band is derived based on the NIR information over"non-turbid"waters and FLAASH model is selected to do the atmospheric correction of the HJ-1A/B CCD imagery using the AOD values of highest probabilities as ***,according to the histogram of the AOD distribution at 551 nm band,the studied turbid water area is divided into several blocks and HJ-1A/B CCD imagery is corrected with the corresponding AOD values displayed with the highest frequency in each *** method has been applied to several HJ-1A/B images over Chinese coastal waters and validated by synchronous in-situ *** results have shown that this method is effective in the atmospheric correction process of HJ-1A/B CCD images for ocean color remote sensing study and application in the coastal waters.

关键词： ocean color remote sensing atmospheric correction turbid coastal waters HJ-1A/B MODIS

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Study on the double-logarithmic profile of tidal flow velocity in the near-bed layers

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Acta Oceanologica Sinica 2009年第6期28卷 84-92页

作者： NI Zhihui SONG Zhiyao WU Lichun Southwestern Research Institute of Water Transport Engineering Chongqing Jiaotong UniversityChongqing 400016 China key laboratory of virtual geographic environment （ministry of education） Nanjing NormMUniversity Nanjing 210097 China State key laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098 China Chongqing education College Chongqing 400067 China

Tidal current velocity profile in the near-bed layers has been widely studied. The results showed that velocity profile in the near-bed layer obviously departure from the traditional logarithmic profile, due to the acceleration or deceleration. Although the logarithmic linear profile can reduce the rate of deviation from this, only it is a lower-order approximate solution. In this paper, considering the unsteady and non-linear features of tidal motion, the double logarithmic profile near-bed layers in estuarine and coastal waters is established on the assumption that the turbulent shear stress along the water depth was parabolic distribution, and on the basis of Prandtl＇s mixing length theory and yon Karman＇s self-similar theory. Having been verified the data observed at the West Solent in the south of England, and comparison of the logarithmic linear profile, it found that the double logarithmic profile is more precious than the latter. At last, the discussed results showed that：（1） The parabolic distribution of the tidal shear stresses verified good by the field data and experimental data, can be better reflected the basic features of the tidal shear stress deviating from linear distribution that is downward when to accelerate, upward when to decelerate. （2） The traditional logarithmic velocity profile is the zero-order approximation solution of the double logarithmic profile, the logarithmic linear profile is the first order, and the logarithmic parabolic profile is the second order. （3） Ignoring the conditions of diffusion and convection in the tida movement, the double logarithmic profile can reflect the tidal properties of acceleration or deceleration, so that the calculation of the friction velocity and roughness length are more reasonable. When the acceleration or the deceleration is about zero, the double logarithmic profile becomes the logarithmic profile.

关键词： turbulence shear stress tidal current double logarithmic profile near-bed layers friction velocity roughness length

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Sediment transport capacity of hyperconcentrated flow

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 961-975页

作者： SHU AnPing1,2 & FEI XiangJun2 1 School of environment & key laboratory of Water and Sediment Sciences,ministry of education,Beijing normal university,Beijing 100875,china 2 State key laboratory of Hydroscience and Engineering,Tsinghua university,Beijing 100084,china School of environment & key laboratory of Water and Sediment Sciences Ministry of Education Beijing Normal University Beijing 100875 China State key laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

As one of the most important components of river mechanics,sediment transport capacity of sediment-laden flows has attracted much attention from many researchers working on river mechanics and hydraulic engineering. Based on the time-averaged equation for a turbulent energy equilibrium in solid and liquid two-phase flow,an expression for the efficiency coefficient of suspended load movement was derived for the two-dimensional,steady,uniform,fully-developed turbulent flow. A new structural expression of sediment transport capacity was achieved. Using 115 runs of flume experimental data,which were obtained through two kinds of sediment transport experiments in the state of equilibrium,in combination with the basic rheological and sediment transporting characteristics of hyperconcentrated flow,the main parameters in the structural expression of sediment transport capacity were calibrated,and a new formula of sediment transport capacity for hyperconcentrated flow was developed. A large amount of field data from the Yellow River,Wuding River,and Yangtze River,etc. were adopted to verify the new formula and good agreement was obtained. These results above contribute to an improved theoretical system of river mechanics and a reliable tool for management of rivers carrying high concentration of sediments.

关键词： hyperconcentrated flow turbulent energy equilibrium efficiency coefficient sediment transport capacity

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Miocene Bahean stratigraphy in the Longzhong Basin, northern central china and its implications in environmental change

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Science china Earth Sciences 2006年第12期49卷 1270-1279页

作者： LI Jijun1,2, ZHANG Jun1, SONG Chunhui1, ZHAO Zhijun2, ZHANG Yong1, WANG Xiuxi 1, ZHANG Jianming1 & CUI Qiaoyu1 1. key laboratory of Western china’s environmental Systems (ministry of education) & College of Earth and environment Sciences, Lanzhou university, Lanzhou 730000, china 2. Jiangsu key laboratory of environmental Change and Ecological Construction & College of Geography, nanjing normal university, nanjing 210097, china 1. key laboratory of Western china’s environmental Systems (ministry of education) & College of Earth and environment Sciences Lanzhou University Lanzhou 730000 China 2. Jiangsu key laboratory of environmental Change and Ecological Construction & College of Geography Nanjing Normal University Nanjing 210097 China

Fossil mammal-riched Neogene strata are widely distributed in the southeast corner of the huge Longzhong Basin at Tianshui, Gansu Province, northern central china. Hipparion weihoense, a typical member of late Middle Miocene Bahean stage, was recently excavated at Yaodian along a well-exposed outcrop. Owing to the importance of the Bahean stage in the mammalian evolution and its potential for environmental change, we suggested a name of Yaodian Formation for the stratigra- phy, which is correlated to the Bahe Formation at Lantian, Shaanxi. High resolution paleomagnetic dating of the section shows that the Yaodian Formation covers the period between 11.67 Ma and 7.43 Ma, with the site bearing Hipparion weihoense being estimated at about 10.54―10.30 Ma, providing first magnetostratigraphic chronology for the Bahean Stage. The Yaodian Formation consists of fluvial channel deposits (11.67―10.40 Ma) at the bottom, floodplain deposits in the middle (10.40―9.23 Ma) and shallow lake sediments at the top (9.23―7.43 Ma). This upward fining sequence suggests that the relief in nearby mountain ranges such as West Qinling to the south and Huajia Ling to the north was greatly reduced after long-term denudation, fluvial transport capacity was low, and finally the drainage system was disintegrated, replaced with broad-shallow lakes in which only fine sediments like mud and marlite were deposited, indicating an old stage of development of a planation surface. A remarkable shift in ecology and climatic environment was found at 7.4―7.7 Ma when paleoclimate changed from early warm humid to late dry as indicated by sedimentary facies changed from early shallow lake sequence to late eolian red clays and a former coniferous-deciduous mixed forest was replaced by grassland, leading to great growth of Hipparion Fauna of Baodean stage in the region. Therefore, it is estimated that the present high relief of Qinling and drainage pattern did not come into being until Late Pliocene in response

关键词： Bahean stage,magnetostratigraphy,Yaodian Formation,Neogene,Longzhong Basin.

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