珠江河口悬浮泥沙遥感数据集

选择 1 995— 2 0 0 0年间NOAA系列卫星AVHRR遥感器获取的珠江口及其邻近海域可见光和近红外遥感数据 ,利用基于海面 遥感器光谱反射率斜率传递现象的悬浮泥沙遥感算法 ,建立珠江口及其邻近海域 1 5 2个时相的悬浮泥沙数据集 ,进行悬浮泥沙浓度分布和变动规律的特征累积频率悬浮泥沙浓度、均值与均方差统计。结果表明 ,珠江口河口浅滩是悬浮泥沙浓度的高值区。随着径流、潮流的相互关系的变动 ,珠江口的悬浮泥沙浓度具有明显的季节变化 ,内伶仃洋悬浮泥沙浓度季节变动幅度最大 ,而磨刀门外浑浊水体的延伸方向变动幅度最大。     

东海陆架北部泥质区悬浮体的絮凝沉积作用

1997年2月在东海北部取得悬浮体和底质样品，通过粒度分析和扫描电镜及能谱分析，探讨了陆架北部泥质区悬浮体的絮凝沉积作用，结果表明，生物因素是泥区悬浮体的发生絮凝的机制之一，可影响悬浮体在海水中的行为，生物活动产生的软组织，分泌物和粘膜等有机中将矿物矿屑和生物骨屑结构，吸附和捕集在一起形成絮凝体而迅速沉积，在悬浮体含量较低，水化学环境相对稳定的东海陆架，絮凝作用是泥质区得以形成的关键过程之一。     

Suspended sediment yield modeling in Mahanadi River,India by multi-objective optimization hybridizing artificial intelligence algorithms

River sediment produced through weathering is one of the principal landscape modification processes on earth.Rivers are an integral part of the hydrologic cycle and are the major geologic agents that erode the continents and transport water and sediments to the oceans.Estimation of suspended sediment yield is always a key parameter for planning and management of any river system.It is always challenging to model sediment yield using traditional mathematical models because they are incapable of handling the complex non-linearity and non-stationarity.The suspended sediment modeling of the river depends on the number of factors such as rock type,relief,rainfall,temperature,water discharge and catchment area.In this study,we proposed a hybrid genetic algorithm-based multi-objective optimization with artificial neural network(GA-MOO-ANN)with automated parameter tuning model using these factors to estimate the suspended sediment yield in the entire Mahanadi River basin.The model was validated by comparing statistically with other models,and it appeared that the GA-MOO-ANN model has the lowest root mean squared error(0.009)and highest coefficient of correlation(0.885)values among all comparative models(traditional neural network,multiple linear regression,and sediment rating curve)for all stations.It was also observed that the proposed model is the least biased(0.001)model.Thus,the proposed GA-MOOANN is the most capable model,compared to other studied models,for estimating the suspended sediment yield in the entire Mahanadi river basin,India.The results also suggested that the proposed GA-MOO-ANN model is unable to estimate suspended sediment yield satisfactorily at gauge stations having very small catchment areas whereas performing satisfactorily on locations having moderate to the large catchment area.The models provide the best result at Tikarapara,the gauge station location in the extreme downstream,having the largest catchment area.     

Size effects of suspended particles on gill damage in green-lipped mussel Perna viridis

The green-lipped mussels Perna viridis were exposed to <500 μm suspended solids (SS) with concentrations of 0 (control), 250, 500, 750 and 1000 mg/L for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significantly higher damages to the cilia on the frontal surface of the gill filaments than that on the abfrontal surface in both demibranchs. Percent ciliary depletion varied with SS concentrations and time. No sign of recovery of the gill filaments was observed after the mussels were transferred to clean seawater. In a second experiment, mussels were exposed to SS with size range from <63, >125–<250 and >250–<500 μm at 600 mg/L, together with a control (0 mg/L) for 14 days, followed by transferring to clean, filtered seawater for 28 days. Results of scanning microscopy showed significant ciliary damages in both the ascending and descending lamellae under the three particle size groups as compared with the control. Percent depletion of frontal cilia was most serious for the >250–<500 μm size group and least for the <63 μm size group. However, percent depletion of abfrontal cilia was most serious for the >125–<250 μm size group and least for the <63 μm size group. No recovery of ciliary damages was observed. The effects of particle size of suspended sediments on the morphological damages of gill filaments in the green-lipped mussels were discussed.     

Dynamics of Stream Water Quality during Snowmelt and Rainfall – Runoff Events in a Small Agricultural Catchment

Surface water quality can vary a lot with fluctuating discharge during a Rainfall – runoff event. This paper uses a set of hydrological and hydrochemical variables to explain concentration–discharge loops and hysteresis of ${\rm NO}_{3}^{- } $ , ${\rm NH}_{4}^{ + } $ and total suspended solids in a brook dewatering a small upland agricultural catchment in the Czech Republic. Our study is based on data collected by a continuous monitoring approach provided by an automatic ISCO sampler both from snow thawing and rainfall – runoff events. Methods of correlation, regression and principal component analysis (PCA) were employed to reveal possible relationships among the variables. For ${\rm NO}_{3}^{- } $ and ${\rm NH}_{4}^{ + } $ , we found several types of concentration–discharge loops due to the loop rotation direction and also the loop curvature shape, in mutual combinations, no matter which type of a hydrological event it was related to. PCA indicated that ${\rm NO}_{3}^{- } $ loops correlated mostly with the length of a rising hydrograph limb and with the slope of the initial phase of a falling hydrograph limb, 5‐day amount of precipitation and runoff coefficient. In case of ${\rm NH}_{4}^{ + } $ , the concentrations usually increased with elevated discharge, whereas PCA did not detect any closer linkages. For suspended solids, an unambiguous positive monotonic relationship was discovered. Although no definite pattern was found, this study showed the necessity of a continuous water quality monitoring system as an approach for capturing and understanding relationships between solute concentrations and runoff formation for tracing and modelling catchment pollution sources and describing transport processes.     

一种基于NAMPD的快速边界提取算法

The nonsymmetry and antipacking pattern representation model(NAM) ,inspired by the concept of the packing problem,uses a set of subpatterns to represent an original pattern.The NAM is a promising method for image representation because of its ability to focus on the interesting subsets of an image.In this paper,we develop a new method for gray-scale image representation based on NAM,called NAM-structured plane decomposition(NAMPD) ,in which each subpattern is associated with a rectangular region in the imag...     

Estimation of discharges at river mouth with MODIS image

The transport of the sediment, carried in suspension by water, is central to hydrology and the ecological functioning of river floodplains and deltas. River discharge estimation is useful for demonstrating this information. In this study, we extracted MODIS reflectance values from a pixel near the river mouth after carrying out the simple atmospheric correction method, then applied single regression analysis to reflectance values and the in situ discharge of Naka River in Tokushima prefecture and Monobe River in Kochi prefecture, Japan. MODIS images and in situ data were taken from January through December, 2004. As a result, both in Naka River and Monobe River, robustly positive relationships between the discharges observed in situ and remotely sensed MODIS reflectance data in the region of river mouth were found throughout the year. In addition, we estimated monthly and annual average discharge from the MODIS reflectance with the regression formula. As a result, in situ average discharge was well estimated.     

江苏近岸海域HJ CCD影像悬浮泥沙遥感反演

基于2012~2014年期间江苏近岸海域实测遥感反射率、悬浮泥沙浓度及HJ CCD数据,建立该海域HJ CCD影像悬浮泥沙遥感反演模型。通过研究水体实测反射光谱特征,确定对悬浮泥沙浓度变化的敏感波段,并与悬浮泥沙浓度进行函数拟合分析。结果表明:将HJ CCD Band3的等效遥感反射率、HJ CCD Band3与Band2等效遥感反射率的比值分别作为敏感因子,并采用对数函数模拟低值区、指数函数模拟高值区获得的叠加模型表现最为突出。通过卫星应用发现,第2、3波段比值模型的遥感反演结果与实际情况相符,可有效削弱大气校正、表观反射率到遥感反射率的转换方法以及HJ CCD辐射分辨率较低等一系列问题的干扰,为江苏近岸海域HJ CCD悬浮泥沙遥感反演的最优模型。     

香港能见度、大气悬浮粒子浓度与气象条件的关系

利用2005年赤鱲角能见度及东涌悬浮粒子 (PM2.5) 浓度的每小时数据,发现PM2.5 浓度与能见度 (撇除雨雾及相对湿度≥95%的个例) 呈倒数关系,相关系数约为0.8。此外,出现低能见度 (能见度低于8 km,而雨雾及相对湿度≥95%的个例不计) 的每月总时数与月平均PM2.5浓度都呈现相类似的季节趋势,即冬季较高,夏季较低。利用HYSPLIT作反轨迹图分析显示这现象跟影响香港的空气来源有关。来自内陆的轨迹中,出现低能见度的日平均时数及日平均PM2.5的浓度,分别远高于来自海洋的轨迹。文中还分析了一个有热带气旋接近本港的个例,论证气象条件对能见度及PM2.5浓度的重要性。