长三角“水乡客厅”水体透明度数值模型构建

“水乡客厅”作为长三角区域一体化的重要示范性工程,如何提升其水体透明度,改善水体感官仍然是一个亟待解决的难题。在相关水质监测及悬浮物沉降试验的基础上,分析研究了“水乡客厅”水体透明度的主要影响因素,并构建了其与水体透明度的多元回归方程,基于该方程,构建了水体透明度数值模型。结果显示：相较于圩内河道,圩外河道及湖荡的水体透明度相对较低;研究区域内水体透明度的主要影响因素为悬浮物浓度,其皮尔逊相关系数为-0.48,呈明显负相关关系,次要因素为叶绿素浓度;分圩内河道、圩外河道、湖荡区域分别构建悬浮物沉降系数与悬浮物浓度、水体流速的拟合方程,决定系数R²均>0.8,拟合效果较好;基于上述分析结果所构建的水体透明度数值模型能够较好地描述“水乡客厅”水体透明度的分布规律,可为后续区域水生态修复及富营养化治理提供技术支撑。     

1956—2011年青海湖变化特征及原因分析

基于卫星影像数据,从湖水位、水面面积、湖岸线三个方面分析了1956—2011年青海湖的变化特征,结果表明:56 a间水位累计下降3.28 m;2005年是青海湖由萎缩转为扩张的转折年份,2005—2011年湖水位累计涨幅1.01 m;水面面积与湖水位有很好的正相关关系,1956—2004年萎缩了397.5 km2,2005—2011年扩张了80.4 km2;1995年以来沙岛湖一直与大湖水体分离,湖岸线变化不均匀;水位变化的主要影响因素是降水径流的变化,气温、蒸发、冰川融水、人类活动等其他原因并非主导因素。     

人类活动对全球地表水储量变化的影响研究

正研究人类活动对全球水文循环的影响程度,对于淡水资源的可持续利用至关重要。然而,由于对湖泊、水塘以及水库水位的监测不足,相对于自然水体的自然变化,定量研究人工水库引起的地表水蓄水量的变化还不够。全球地表水体水量变化以及人类对其的影响程度仍然未知。本文研究发现,全球地表水量季节性变化的57%发生在人类管理运行的水库。     

新型简易透明度检测装置设计与研究

透明度作为水质监测重要指标之一,在藻类高发期能够直观快速地反映水体富营养化程度。然而,最常用的水质透明度检测方法塞式圆盘法受制于实际测量条件,具有其一定的检测局限性。通过设计一种简易透明度检测装置,解决了在坝前等有坡度的监测环境下,传统方法无法进行透明度测定的问题,并通过计算校正使测量结果更加准确,与传统船采法的测量结果相符。这种新方法能够更加方便、快捷地获取水体透明度指标,从而更好地为水体质量评估提供依据。     

云南典型高原湖泊富营养化及其生态修复研究

始于70年代末80年代初的湖泊富营养化问题,严重阻碍了云南社会经济发展,继而引起了人们极大地关注。已有的研究从富营养化特征、机制、演化以及生态、工程修复等方面进行了相关探究,其1980—2010年湖泊水体总磷、总氮、透明度、叶绿素、生化需氧量及营养状况指数等均指示和记录了近30年来云南典型高原湖泊富营养化特征及演化过程。在系统总结前人研究成果的基础上、基于云南高原湖泊富营养化的典型性与差异性、富营养化演化及其修复现状的背景下认为:近年来富营养化水体水质好转大多只是季节性或区域性迹象,云南高原湖泊整体上乃处于持续的富营养化和污染状态,部分湖泊因为周边农业用地和建设的扩展已经导致湖泊处于不可恢复状态,抚仙湖、阳宗海等湖泊周边因开发需水量大,导致湖泊水位出现快速下降和湖容大量减少。进一步对云南高原典型富营养化湖泊开展更大时间尺度的研究,特别是湖泊变化机理的研究和趋势预警的升级是今后努力的重点和方向。     

干旱区平原水库模拟蒸发量试验研究

干旱区平原水库水面蒸发是平原水库水量损失的重要组成部分,由于水库面积大,采用常规蒸发皿测定的蒸发量与水库实际蒸发量特征不相符。为了准确模拟干旱区平原水库蒸发量,开展了模拟水库的小面积水域蒸发试验,通过水位测针测量蒸发池的蒸发量,并与蒸发皿蒸发量进行比较。试验结果表明,在实际蒸发量中,蒸发池的蒸发量波动较大,蒸发皿蒸发速率比水面蒸发速率高9.1%。蒸发皿蒸发量与水面蒸发量的比值呈现先下降后上升的趋势;蒸发池水面蒸发量主要受到温度、净辐射、风速、饱和水汽压差影响;蒸发皿水体容量小,与蒸发池相比水体热容量较小,因此与大气交换更加快速,受净辐射和气温日较差影响较大。     

大伙房水库暴雨洪水前后水体变化趋势分析

文章基于1995年特大洪水和2013年的"8.16"特大暴雨引发的洪水前后大伙房水库水体透明度监测数据,分析了两次洪水前后库区水体透明度变化趋势,并对两次洪水前后水体透明度变化差异性进行解析,对比分析结果表明,降水范围、持续时间和强度是影响库区洪水后水体透明度恢复到正常状态的关键因素。最后针对洪水所导致的水体浑浊,透明度降低所带来的饮用水安全问题,提出了相应的对策和建议。     

赣江尾闾碟形湖水体季节性分布特征

碟形湖是鄱阳湖湿地的一类重要组成部分。赣江尾闾(中支)碟形湖分布广泛,地形和鄱阳湖水位变化共同造就了水体空间分布的季节性差异。为进一步了解碟形湖的形态特征和水体的空间分布情况,基于湖区5 m分辨率的数字高程模型提取了碟形湖地形,构建了主要碟形湖的水位-面积-容积曲线,以汛后期潴水型典型年2014年为例,基于Landsat 8遥感影像分析了典型水文时期赣江中支三角洲的碟形湖水体分布变化。结果表明:三角洲上游和下游的碟形湖形态差异明显;碟形湖四周高、中间低、深度较浅的地形特征导致其可以容纳的水量不及2亿m~3;在秋季退水期和冬季枯水期,碟形湖水体占三角洲水体覆盖的70%～90%,是越冬候鸟栖息的重要湿生环境。     

大沙河水库富营养化限制性因子分析

运用回归统计法,研究了大沙河水库叶绿素a与环境因子间的相关性,同时分析了水库的富营养化状况以及叶绿素a的时间分布特征。研究表明,大沙河水库处于富营养化状态,且叶绿素a的季节性差异不显著;叶绿素a与水温、氮素无明显相关性,与pH呈显著正相关,与DO、CODMn和BOD,呈一定的正相关,与透明度呈明显负相关,且与透明度的自然对数呈线性关系,与pH、DO呈幂指数关系,与TP呈显著线性正相关,与TN／TP呈显著负相关;大沙河水库为磷限制性水体,TP是浮游植物的生长限制因子。     

基于Sentinel2-L1C的江汉平原水产养殖区水质参数反演

遥感技术已成为监测内陆水域水质的一种有效手段，为研究江汉平原水产养殖区域内水体总磷、总氮和化学需氧量浓度的变化规律，基于Sentinel2-L1C遥感数据建立水体透明度、悬浮物浓度、叶绿素a浓度3种光学活性物质浓度的反演模型，结合推算出的水体透明度、悬浮物浓度和叶绿素a浓度与拟合点水体实测总磷、总氮和化学需氧量浓度分别建立关联，构建江汉平原拟合点水体总磷、总氮和化学需氧量浓度3种非光学活性物质浓度的间接反演模型并进行模型的率定验证。结果表明：水体透明度与水体总磷浓度具有较好相关性，水体透明度越高，水质越好，水体总磷浓度越低；水体悬浮物浓度与水体总氮浓度具有较高相关性，水体悬浮物浓度越高，水质越差，对应水体总氮浓度越高；水体叶绿素a浓度越高，对应水体化学需氧量浓度越高。构建水体总磷浓度、总氮浓度和化学需氧量浓度的间接反演模型，确定性系数均>0.6,并对江汉平原监测点水体的总磷、总氮和化学需氧量浓度进行了模拟和分析，结论与水产养殖区内饲料投喂主要时期的影响规律基本保持一致。研究结果对于探测江汉平原水产养殖区大尺度范围水质参数的时空演变具有一定的实用价值。     

Understanding Seasonal Water Clarity Dynamics of Lake Dahuchi from In Situ and Remote Sensing Data

Obtaining, analyzing and understanding the seasonal dynamics of water clarity is of importance for understanding and managing lakes and sustaining their ecosystem services. This study aimed to explore the seasonal dynamics of water clarity and to analyze how water level, wind velocity and total precipitation influence this dynamics in Lake Dahuchi, China. The Secchi disk depths recorded in the field and derived from Moderate Resolution Imaging Spectroradiometer (MODIS) images together demonstrated a seasonal pattern of water clarity, which was lower in winter and spring, increased in April or May to reach the highest values in summer, upon which it gradually declined from September onward. Piecewise linear regression analysis between water clarity and water level showed that water level could explain 70% of the variation of the logarithm of Secchi disk depth. The water clarity of Lake Dahuchi was primarily controlled by suspended sediment, while the seasonal variation of water level induced different sediment resuspension, thus we concluded that the water clarity seasonal dynamics of Lake Dahuchi was mainly regulated by seasonal variation of water level.     

Changes in mid-summer water temperature and clarity across the Great Lakes between 1968 and 2002

In recent decades, three important events have likely played a role in changing the water temperature and clarity of the Laurentian Great Lakes: 1) warmer climate, 2) reduced phosphorus loading, and 3) invasion by European Dreissenid mussels. This paper compiled environmental data from government agencies monitoring the middle and lower portions of the Great Lakes basin (lakes Huron, Erie and Ontario) to document changes in aquatic environments between 1968 and 2002. Over this 34-year period, mean annual air temperature increased at an average rate of 0.037 °C/y, resulting in a 1.3 °C increase. Surface water temperature during August has been rising at annual rates of 0.084 °C (Lake Huron) and 0.048 °C (Lake Ontario) resulting in increases of 2.9 °C and 1.6 °C, respectively. In Lake Erie, the trend was also positive, but it was smaller and not significant. Water clarity, measured here by August Secchi depth, increased in all lakes. Secchi depth increased 1.7 m in Lake Huron, 3.1 m in Lake Ontario and 2.4 m in Lake Erie. Prior to the invasion of Dreissenid mussels, increases in Secchi depth were significant (p < 0.05) in lakes Erie and Ontario, suggesting that phosphorus abatement aided water clarity. After Dreissenid mussel invasion, significant increases in Secchi depth were detected in lakes Ontario and Huron.     

Trends in Water Clarity of the Lower Great Lakes from Remotely Sensed Aquatic Color

Satellite observations of aquatic colour enable environmental monitoring of the Great Lakes at spatial and temporal scales not obtainable through ground-based monitoring. By merging data from the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly binned images of water-leaving radiance over the Great Lakes have been produced for the periods 1979–1985 and 1998–2006. This time-series can be interpreted in terms of changes in water clarity, showing seasonal and inter-annual variability of bright-water episodes such as phytoplankton blooms, re-suspension of bottom sediments, and whiting events. Variations in Secchi disk depth over Lakes Erie and Ontario are predicted using empirical relationships from coincident measurements of water transparency and remotely-sensed water-leaving radiance. Satellite observations document the extent to which the water clarity of the lower Great Lakes has changed over the last three decades in response to significant events including the invasion of zebra mussels. Results confirm dramatic reductions in Lake Ontario turbidity in the years following mussel colonization, with a doubling of estimated Secchi depths. Evidence confirms a reduction in the frequency/intensity of whiting events in agreement with suggestions of the role of calcium uptake by mussels on lake water clarity. Increased spring-time water clarity in the eastern basin of Lake Erie also corroborates previous observations in the region. Despite historical reports of localised increases in transparency in the western basin immediately following the mussel invasion, image analysis shows a significant increase in turbidity between the two study periods, in agreement with more recent reports of longer term trends in water clarity. Through its capacity to provide regular and readily interpretable synoptic views of regions undergoing significant environmental change, this work illustrates the value of remotely sensing water colour to water clarity monitoring in the lower Great Lakes.     

Monitoring Lake Simcoe Water Clarity Using Landsat-5 TM Images

This study focuses on utilizing satellite remote sensing to monitor the water clarity of Lake Simcoe, Ontario, Canada, which has been suffering from the overload of phosphorus (TP) and therefore eutrophication for decades. The dataset includes 22 cloud-free Landsat-5 Thematic Mapper (TM) images, as well as the nearly simultaneous in-situ observations from 15 stations on the lake. Compared to the general model used to estimate the Secchi Disk Transparency (SDT), a parameter for water clarity measurements, an improved model is developed, from the TM images. The results of these estimations are validated using the in-situ data by linear regression, and the accuracies are measured by the coefficient of determination R ². The results reveal an indication of high model fit between the majority of SDT predictions and the in-situ observations. Also, the improved SDT model provides higher prediction accuracies than the general one when applied to 68.2% (15 out of 22) of the images. The estimated clarity maps indicate that the turbid water is normally distributed at the nearshore areas and the northeastern region. Meanwhile, the southwestern lake has much clearer water than the other regions. In addition, the southern bay has always been suffering from a serious water quality problem even till now. The water clarity of Lake Simcoe shows strong seasonal patterns, that it is at its worst in August and September annually and much better in the other sampling seasons. On an overall scale, the lake water clarity kept relatively stable from 1987 until the fall of 1992, followed by a gradual increase until 2000, after a slight decrease, and lastly stayed consistent until the summer of 2008.     

An assessment of water quality in two Great Lakes connecting channels

Compared to the Great Lakes, their connecting channels are relatively understudied and infrequently assessed. To address this gap, we conducted a spatially-explicit water quality assessment of two connecting channels, the St. Marys River and the Lake Huron-Lake Erie Corridor (HEC) in 2014–2016. We compared the condition of the channels to each other and to the up- and downriver Great Lakes with data from an assessment of the Great Lakes nearshore. In the absence of channel-specific thresholds, we assessed the condition of the area of each channel as good, fair, or poor by applying the most protective water quality thresholds for the downriver lake. Condition of the St. Marys River was rated mostly fair for total phosphorus (TP, 56% of the area) and mostly good (61% of the area) for chlorophyll a. Area-weighted mean concentrations of these parameters were intermediate to Lake Superior and Lake Huron. Unlike Lake Superior and Lake Huron, a large proportion (97%) of the area of the St. Marys River was in poor condition for water clarity based on Secchi depth. Area-weighted mean concentrations of TP and chlorophyll a in the HEC were more like Lake Huron than Lake Erie. For these indicators, most of the area of the HEC was rated good (81% and 86%, respectively). Interpretation of assessment results is complicated by variation in thresholds among and within lakes. Appropriate thresholds should align with assessment objectives and in the case of connecting channels be at least as protective as thresholds for the downriver lake.     

鄱阳湖水环境演变特征研究

鄱阳湖水质安全是鄱阳湖生态经济区规划实施的重要物质基础,也是长江流域生态安全的重要组成。本文通过收集湖区主要水质监测断面2003-2008年逐月监测资料,采用单因子评价、湖泊富营养化评价、季节性肯达尔检验等分析主要河流、湖泊水环境演变特征。研究表明,鄱阳湖区现状水质较好,全年、汛期、非汛期的I-Ⅲ类水面积比例分别为63．9％、99．3％、40．8％,水体处于中营养一轻度富营养化状态。赣江、抚河、修河等人湖控制断面I一Ⅲ类水比例高于90％,乐安河、长江等控制断面I-Ⅲ类水质比例高于70％,湖口断面现状水质较差,Ⅳ类及以下水质比例高于30％。随着鄱阳湖流域社会、经济的发展,部分水质断面污染物浓度增加,湖泊I-Ⅱ类水面积比例呈下降趋势,需要采取有效措施,减少流域污染物排放量和人湖量,实现一湖清水的目标,为水利枢纽工程实施提供良好的水环境条件。     

淮安市地表水水质变化趋势分析

应用季节性kendall检验法,对2000—2009年淮安市主要水系河流的地表水水质指标变化趋势进行分析评价。结果表明:随着近年来淮河流域水污染防治力度的加大,以及对洪泽湖作为南水北调东线工程输水主干线自身的治理,淮安市境内的主要河流湖泊总体水质略有好转,由于淮河入海水道水功能区划的调整,入海水道总体水质有所下降,而洪泽湖水体TP含量呈逐年上升趋势,其他水体水质总体变化不大。     

滇池水质状况综合评价及变化趋势分析

滇池是国家进行重点环境治理的河湖之一。在对滇池8个监测点采样监测的基础上,评价了2010年滇池水质现状。用均值型综合污染指数法对各监测点主要污染项目作了水体污染程度评价。以2001~2010年监测资料为基础,选取影响滇池水质的主要指标：氨氮、总氮、高锰酸盐指数、5 d生化需氧量、总磷,采用季节性Kendall检验法进行水质变化趋势分析。结果表明,各监测站点水质均为劣Ⅴ类,其中氨氮、总磷污染严重,总氮、5 d生化需氧量指标趋于恶化,高锰酸盐指数无明显变化趋势。     

基于SPOT-VGT数据的洞庭湖水体面积变化分析

监测洞庭湖水体变化、全面了解其变化规律和演化趋势对于湖区治理和防洪减灾具有重要的现实意义.本文基于SPOT-VGT NDVI数据,采用动态阈值法提取了洞庭湖1998-2010年间逐旬水体信息,并结合历史数据分析了水体面积变化特征.主要结论如下:①动态阈值方法在长时间序列、大数据量的遥感信息提取中具有显著优越性.②洞庭湖水体面积在年内呈现明显季节性变化;在年际呈缩减趋势(丰水期);1825-2010年水体缩减呈现四个阶段,当前处于新一轮的锐减期.③基于累积降雨量数据建立的水面积预测经验模型,精度较为理想.     

大型水生植物与水中氮 磷等含量关系的研究

为探讨大型湖泊上覆水生植物与水中氮、磷等元素的关系,对骆马湖中大型水生植物生长区氮（N）、磷（P）、铁（Fe）、锰（Mn）元素含量进行了现场采样和研究,探讨其含量、季节性动态变化及与水生植物的相互关系。结果表明：大型水生植物生长区水中N、P、Fe、Mn元素含量均显著低于无草对照区的含量;总氮和锰元素季节性含量大小排序为：6月,10月,4月,总磷和铁则是10月,4月,6月,差异显著（P<0.05）;在大型水生植物作用下,铁、锰与磷的摩尔比季节性变化规律明显,微量元素对水体富营养化具有一定的调控作用。