环太湖江苏段入湖河道污染物通量与湖区水质的响应关系

基于2008-2018年环太湖江苏段入湖河道污染物通量及湖区水质数据,从时空变化及相关关系两个方面探讨了入湖污染物通量与湖区水质的响应关系,并分析了污染物进入湖体影响水质的主要因子.结果表明:太湖污染减排已见成效,氨氮、总氮、高锰酸盐指数和化学需氧量入湖污染物通量整体呈下降趋势,年均下降率分别为8.0%、2.0%、1.6%和2.2%,湖体氨氮和总氮时间格局响应较好,年均下降率分别为2.1%和2.3%.湖体氨氮、总氮、总磷、高锰酸盐指数和化学需氧量与入湖污染物通量整体由西北部、西部湖区向东南部、东部湖区递减,空间格局上响应基本一致.全湖区年尺度总氮、氨氮浓度与入湖河道污染物通量分别呈显著正相关、极显著正相关关系;影响湖区总氮、氨氮的主要因子为入湖河道的总氮、氨氮浓度,其次为入湖河道浓度与原湖区水质差值,因此亟需加强入湖河道水质浓度的控制.     

结合Landsat ETM与实测光谱估测太湖叶绿素及悬浮物含量

实地测试太湖水体的反射光谱,实验室分析水样,运用相关分析法探求叶绿素、悬浮物的光谱特征波段,估测叶绿素和悬浮物含量;对比LandsatETM波段,运用不同的函数曲线对相应的波段组合进行回归拟合,建立相应的估测模型,选取精度最好的两个分别对太湖的叶绿素和悬浮物含量进行估测.结果表明:(1)对多光谱遥感而言,LandsatTM/ETM是定量获取叶绿素和悬浮物的较好的数据源,但不是最适合的数据源;(2)通过ETM3与叶绿素建立一定的函数关系来估测叶绿素含量具有较高的精度,其中利用算术组合ETM3/ETM1估测叶绿素的精度最高;(3)ETM4与悬浮物具有较高的相关度,其中利用算术组合ETM4/ETM1估测悬浮物含量的精度最高;(4)LandsatETM卫星影像中,不同尺寸的像元窗口影响水质参数的估测精度;对叶绿素估测而青,7×7或者5×5窗口比较适合,对悬浮物估测而言,一般不超过3×3.     

太湖蓝藻爆发与水温的关系的MODIS遥感

利用MODIS高光谱遥感数据动态监测太湖地区蓝藻水华发展过程,并结合水温环境因子,探讨蓝藻爆发的环境条件.首先,通过简单的比值植被指数,实现蓝藻生物量的遥感估算;根据六期遥感估算结果,监测太湖蓝藻动态发展过程.然后,利用MODIS热红外波段(31和32),采用分裂窗算法,同步反演出的太湖表面水体温度,探讨蓝藻爆发的水温条件,及蓝藻生长与水-温度之间的关系.研究结果表明,在水体富营养化前提下,水体温度是影响蓝藻生长的重要环境因子;合适的水体温度(24-30℃)是蓝藻爆发的必要条件;大于30℃的高温,对蓝藻的生长有明显的抑制作用.     

东太湖CDOM吸收光谱的影响因素与参数确定

CDOM吸收特性是湖泊水色遥感的重要研究内容之一,影响着水体的遥感反射率;吸收光谱的形状一般符合波长的负指数关系,但不同水体的形态因子即S值是不同的.实地采集东太湖水样,实验室测量叶绿素、悬浮物质以及黄色物质的组份含量,室内测试计算水样的CDOM吸收光谱,根据光谱曲线形状,把样点分为三组,分别进行考察,结果发现对东太湖春季水体而言,浮游植物的降解对CDOM吸收具有重要甚至主导作用;水体中有机悬浮颗粒占有一定的比例,在测试或计算东太湖总的吸收或散射系数时,必须充分考虑有机悬浮颗粒的吸收与散射特性,否则会带来较大的误差;以500nm为分界点,把300—700nm的波段范围分为两个部分即300—500nm和500—700nm,分别定义CDOM吸收光谱的曲线斜率即S值,可以提高CDOM吸收光谱的估测精度,把S值定义为随波长线性变化的函数,可以进一步提高CDOM吸收光谱的估测精度,对东太湖春季水体而言,当:300≤λ<500nm时,S(μm-1)=-0.0193×λ 20.821,当500≤λ≤700nm时,S(μm-1)=-0.0121×λ 16.003.     

2009年环太湖入出湖河流水量及污染负荷通量

通过对2009年环太湖水文巡测及同步水质监测数据整理,得到2009年环太湖河流入出湖水量以及污染负荷,并将之与前期文献资料数据进行对比.结果表明,2009年环太湖河道入出湖水量分别为88.40×108 m3、93.27×108m3.入湖水量超过5×108m3的依次为陈东港、大浦港、梁溪河、太滆运河、望虞河.出湖水量最大...     

基于决策树的Landsat TM/ETM+图像中太湖蓝藻水华信息提取

以9期Landsat TM/ETM+影像为数据源,基于K-T变换和归一化植被指数(NDVI),建立了湖泊蓝藻水华信息提取的决策树模型.基于大气顶面反射率图像,选用2005年10月17日太湖图像进行了对比验证,表明决策树模型比单波段阈值法、多波段阈值法(RVI、DVI、NDVI)能够更有效地提取蓝藻水华信息,区分陆生植被、水生植物和水华,省去了水体掩膜的过程.使用太湖2002年10月25日和2011年7月22日图像、巢湖2005年8月12日的图像,验证决策树模型方法和工作流程的有效性.使用多期TM图像确定了阈值的取值范围,其中,亮度、绿度、NDVI的下限值依次为0.191、-0.007、-0.054,湿度下限范围为0.07~0.15;亮度阈值上限范围为0.3~0.7、绿度为0.2~0.5、湿度为0.1~0.3,这些结果可作为湖泊蓝藻水华遥感监测的参考.     

Monitoring wetland ditch water levels in the North Kent Marshes,UK, using Landsat TM imagery and ground-based measurements

Abstract

An understanding of hydrology is a prerequisite for ensuring the successful management, conservation and restoration of wetland environments. Frequently, however, little is known about historical hydrological conditions, such as water levels, within wetlands. Moreover, many channel and ditch systems in wetlands are not routinely monitored, except perhaps for research purposes. A methodology is presented herein which makes use of satellite imagery to indirectly provide remotely sensed observations of water levels within channels and ditches. Using multi-temporal Landsat Thematic Mapper (TM) imagery and simultaneous ground-based measurements of water levels, statistical relationships are established between satellite-derived effective wet ditch widths and measured water levels in the drainage system of the Elmley Marshes, southeast England. These relationships can be used subsequently to estimate historical ditch water levels and to monitor contemporary ditch water levels in the wetland. The study shows that satellite imagery has much to offer in monitoring changes in the hydrological regime of wetlands and in providing complimentary approaches to field monitoring.     

Remotely sensed assessment of water quality levels in the Pearl River Estuary, China

In this paper, a method of assessing water quality from satellite data is introduced. The composite pollution index (CPI) was calculated from measured chemical oxygen demand (COD) and nutrient concentration. The relationships between CPI and 240 band combinations of SeaWiFS water-leaving radiance were analyzed and the optimal band combination for estimating CPI was chosen from the 240 band combinations. An algorithm for retrieval of CPI was developed using the optimal band combination, (L₄₄₃ × L₅₁₀)/(L₄₁₂ + L₄₉₀). The CPI was estimated from atmospherically corrected SeaWiFS data by employing the algorithm. Furthermore, the CPI value range for each water quality level was determined based on data obtained from 850 samples taken in the Pearl River Estuary. The remotely sensed CPIs were then transferred to water quality levels and appropriate maps were derived. The remotely sensed water quality level maps displayed a similar distribution of levels based on in situ investigation issued by the State Ocean Administration, China. This study demonstrates that remote sensing can play an important role in water quality assessment.     

夏季短期调水对太湖贡湖湾湖区水质及藻类的影响

贡湖湾作为"引江济太"工程长江来水进入太湖的第一站,湖湾水体生态环境的变化是对调水工程净水效果的最好响应,因此本文针对贡湖湾一次夏季短期调水展开调查研究,分别取2013年7月24日(调水前)和2013年8月18日(短期调水后)两次监测水样的水体理化指标和浮游藻类群落数据进行了对比分析,并对浮游藻类群落与环境因子做了相关性分析.结果表明:受来水影响,短期调水后监测区水体的p H略有下降,溶解氧、浊度、硝态氮、总氮、总磷以及高锰酸盐指数等水体理化指标浓度均较调水前有所升高;其中受调水影响最为显著的区域为望虞河的入湖口区、湾心区.两次监测调水前后湖区水体优势藻种属未发生变化,仍以微囊藻为主,但蓝藻种属比例有所下降,绿藻和硅藻等种属比例则有所上升.望虞河入湖口区和贡湖湾湾心区的Shannon-Wiener多样性指数和Pielou均匀度指数受调水的影响升高.同时,浮游藻类群落结构与受水水体理化参数的冗余分析结果表明,此次监测的短期调水后,太湖贡湖湾监测湖区水体p H、溶解氧、硝态氮、总氮、总磷、高锰酸盐指数等环境因子与浮游藻类的群落分布呈显著相关,是影响受水水体中藻类群落的主要环境因子.     

太湖水情特征

根据太湖湖区及环湖河道主要测站的历年水文气象资料,分析探讨了太湖的径流、水位、增减水现象和河湖流向等水情特征,为合理利用和保护湖泊水资源提供依据。     

2010-2011水文年浙江省环太湖河道水质水量及污染物通量

根据2010-2011水文年浙江省环太湖河道水质水量同步监测资料,分析了进出太湖的水量、水质及污染物通量的时空变化.监测期内,浙江省入湖水量为22.890×108m3,出湖水量为31.576×108m3,环湖河道水质总体上保持稳定,主要污染物指标基本处于Ⅱ～Ⅲ类标准.污染物通量的估算结果表明,环湖河道的高锰酸盐指数、氨氮、总磷和总氮通量均以出湖为主,入湖污染物通量的减少主要源于入太湖河流倒流流量的增加.     

2007年以来环太湖22条主要河流水质变化及其对太湖的影响

随着现代经济的迅速发展,太湖流域污染问题日益严重.为了解太湖湖区以及入湖河流的水质变化趋势,分析两者之间的关系,本文选取太湖湖区以及环太湖22条主要入湖河流2007-2014年水质监测资料,按行政区划分析22条主要入湖河流的氨氮、高锰酸盐指数、总磷和总氮浓度变化趋势以及其与太湖水质关系.结果显示,江苏省境内河流2007年以来污染物浓度普遍高于浙江省,但主要入湖河流总体上呈好转趋势,并且河流各指标的浓度变化与太湖的水质变化密切相关,验证了河道污染物输入作为太湖主要的污染物外源,直接影响太湖水质的变化,指出对入湖河流污染物的控制是缓解和治理太湖污染输入的重要途径.     

Estimating turbidity and total suspended matter in the Adour River plume (South Bay of Biscay) using MODIS 250-m imagery

The Basque coastal waters (South Bay of Biscay) are directly influenced by the Adour River freshwater plume. The Adour outflow leads to important variations of suspended matter concentrations and turbidity, which in turn may affect biological productivity and water quality. This study aims at both developing specific algorithms and testing the efficiency of atmospherically corrected MODIS-Aqua 250-m surface reflectance product (MYD09) to map total suspended matter concentrations and turbidity within the Adour coastal region. First, regional empirical algorithms based on in-situ data were tested to retrieve the concentration of total suspended matter and turbidity from the remote sensing reflectance. Then, the respective sensitivity of MODIS surface reflectance bands 1 and 2 for water quality application was investigated as well as the quality of atmospheric corrections. Finally, selected algorithms were applied to the MYD09 product. The resulting 250-m resolution maps were then compared to 1000-m maps produced by IFREMER and comparisons between satellite measurements and in-situ sampling points were performed. Results show that MODIS-Aqua band 1 (620–670 nm) is appropriate for predicting turbidity and total suspended matter concentrations using polynomial regression models, whilst band 2 is unadapted. Comparison between total suspended matter concentration 250-m resolution maps and mineral suspended matter 1000-m maps (generated by IFREMER) produced consistent results. A high correlation was obtained between turbidity measured in-situ and turbidity retrieved from MODIS-Aqua satellite data.     

基于反射光谱和模拟MERIS数据的太湖悬浮物遥感定量模型

利用地物光谱仪研究了太湖水体的反射光谱特征,通过对比分析,发现580nm反射率值和810nm的反射峰高是太湖悬浮物的敏感波段,并通过光谱微分的方法,发现840nm附近的一阶微分与悬浮物浓度相关性最好,基于上述结论,分别建立了太湖悬浮物的反射光谱和一阶微分遥感定量模型,并利用反射光谱数据,模拟MERIS数据的波段设置,结果表明MERIS第5、12、13波段可以很好的估测太湖的悬浮物浓度.     

Retrieval of suspended sediment concentrations in large turbid rivers using Landsat ETM+: an example from the Yangtze River,China

Suspended sediment concentration (SSC) is a critical parameter in the study of river sediment transport and water quality variation, but traditional measurement methods are costly and time‐consuming. This paper is focused on presenting a methodology that may be useful in estimating SSC which is of key importance in process geomorphology and hydrology. In previous studies, remote sensing has been applied to estimate the SSC of sea waters as well as low turbid inland waters like lakes, reservoirs and short river reaches visible within a single Landsat satellite image coverage. Rivers, especially highly turbid large rivers, have largely been ignored. The dataset used in this paper includes measured SSC and multi‐temporal Landsat ETM+ images covering most part of the Yangtze River. Using an effective easy‐to‐use atmospheric correction method that does not require in situ atmospheric conditions, retrieved water reflectance of Band 4 was found to be a good SSC indicator within the large SSC range 22–2610 mg l^–1. The newly developed regression relation between SSC and water reflectance of Band 4 appears to be able to provide a relatively accurate SSC estimate directly from Landsat ETM+ images for the Yangtze River from the upper, the middle to the lower reaches. With the relation it is possible to estimate or map out SSC dynamics of large rivers which lack SSC data due to constraints of conventional measurements. Copyright © 2009 John Wiley & Sons, Ltd.     

秋季太湖悬浮物高光谱估算模型

2004年10月,在太湖设置67个采样点,现场测量了水体遥感反射比、后向散射系数和辅助参数,实验室分析了水体的悬浮物浓度和水色要素吸收系数.本文在对遥感反射比光谱分析的基础上,比较了几种水体遥感反射比光谱估算悬浮物浓度的方法,结果发现广泛应用的带比值项的算法,虽然可以应用于太湖总悬浮物浓度估算,但是普遍存在相对误差较高的弱点.通过对光谱的分析,确定了750hm单波段算法的参数,并提出了利用近红外812nm波峰高度来估算水体悬浮物的方法.文中还详细阐述了为什么比值算法等在太湖水体悬浮物浓度估算中相对误差比较高,并解释了利用近红外估算精度高的原因,并指明以上算法在遥感应用中的优点和不足,以及现实水体(水质)遥感对现有遥感器配置和遥感算法的需求.     

东太湖水环境现状及保护对策

根据2002年4月至2003年4月东太湖的水质监测结果,分析了东太湖的水质现状、空间分布特征及变化趋势．其中TN变化范围0．57-3．91mg／L,平均值1．61 mg／L,NH4 -N变化范围0．01-0．42mg／L,平均值0．14mg／L,NO3--N 变化范围0．044-0．549mg／L,平均值0．16mg／L,而TP平均值为0.103mg／L,与以前的调查结果相比,TN、TP和NH4 -N 均明显增加,CODMn有所下降,水质状况总体较差,但不同水域因其影响因子不同,水质亦有明显差别,湖心区水质最好．目前,东太湖水体总体上处于中富营养状态,部分湖区已达到富营养状态．最后根据东太湖水环境的现状,提出一些措施和建议．     

Monitoring the impact of backflow and dredging on water clarity using MODIS images of Poyang Lake,China

Backflow from the Yangtze River to Poyang Lake occurs frequently due to their different flood seasons. Based on the reasons for and time period of backflow, this study estimated the spatial‐temporal extent and the change of water clarity influenced by sediments within the backflow and northern Poyang Lake using time‐series Moderate Resolution Imaging Spectroradiometer (MODIS) images. The results revealed that the sediments from backflows together with dredging activities in the northern Poyang Lake not only affected the northern Poyang Lake, but also influenced the central and southern Poyang Lake and the Poyang Lake national nature reserve, and resulted in great decline of water clarity in the regions influenced, which could seriously affect the lake ecosystem. The results indicated that MODIS images have potential for monitoring the distribution of sediments from backflows and dredging activities. However, the potential is limited because of the frequent cloud cover in the study area and the characteristics of backflow itself. The dredging activity combined with backflows might have great negative impacts on the Poyang Lake ecosystem, and it would be worthwhile to explore the possible impacts in order to develop scientific knowledge to support the decisions, which need to be made by the responsible authorities for deciding how to rationally manage this unique lake ecosystem Copyright © 2008 John Wiley & Sons, Ltd.     

基于热红外遥感影像的河流水温反演方法比较——以长江上游流域为例

水温是影响河流生态环境的重要因素.传统水温观测手段受限于测站的地理位置,数据分布稀疏.近20年来随着热红外卫星传感器在空间分辨率上的革新,热红外遥感影像逐步被应用于反演河流水温,但目前相关研究聚焦于利用单颗卫星数据并使用单一水温反演方法而忽略与其他卫星以及处理方法做对比.本文以长江上游流域为例,分别评估了水文反演流程中...     

太湖秋季水体遥感反射比的简单经验估测模型

2004年10月现场测量了太湖水体的遥感反射比、后向散射系数以及其他必要参数,实验室测量了水体的悬浮颗粒物质浓度.首先把太湖划分为3个大区,即遥感反射比受湖底影响的区域(影响区)、不受湖底影响的区域(非影响区)以及可能受湖底影响的区域(可能影响区),然后再把太湖分为高混浊、中混浊、低清澈以及高清澈等4类水体类型,分别列出了各种水体区域类型的相关属性数据.在整个太湖区域范围内,建立了后向散射和悬浮颗粒物质浓度的经验回归模型;仅在非影响区内,建立了遥感反射比和后向散射的经验回归模型,并可以利用悬浮颗粒物质浓度直接估测遥感反射比.最后详细分析了模型的精度.