基于实测的军事地形图和Landsat遥感影像,重建了20世纪30年代至2015年的近百年长江荆江段河道演变空间数据集,并以此为基础使用计盒维数法在ArcGIS 10.2平台上测算得出河道分形维数近百年来的变化过程。研究表明：荆江河道具有明显的分形特征,河道分维数值在1.074 7~1.049 1之间变动,平均值为1.061 3。近百年来荆江河道演变可以划分为2个阶段：20世纪30~50年代和1976~2015年,其分维均值分别为1.074 3和1.052 6。近百年来荆江河道处于逐渐趋于稳定的过程中。各时间断面下荆江的分维值都高于上荆江,下荆江的河流复杂程度大于上荆江,且荆江河道分维的变化主要取决于下荆江。近百年来荆江河道分维下降的原因主要是1949年后荆江河道大规模治理和人工截弯取直。

Based on the historical military topographic maps and Landsat TM/ETM+ remote sensing images, the spatial data set of river course evolution in Jingjiang River section of the Yangtze River from 1930s to 2015 reconstructed in this study. On this basis, the evolutionary process of river fractal dimension over the last 100 years calculated on ArcGIS 10.2 platform by using box counting dimension method. The results show that the Jingjiang River section of the Yangtze River has obvious fractal characteristics, and the river fractal dimension varies from 1.074 7 to 1.049 1 with an average of 1.061 3. The evolution of Jingjiang River section of the Yangtze River in the past 100 years can be divided into two stages: 1930s-1950s and 1976-2015, with the average fractal dimension of 1.074 3 and 1.052 6 respectively. In the past 100 years, Jingjiang River section of the Yangtze River has been in the process of gradually stabilizing. The fractal dimension and complexity of down Jingjiang River section over the past 100 years is higher than that of up Jingjiang River section in each time, and the change of fractal dimension of whole Jingjiang River section mainly depends on that of down Jingjiang River section. The main reasons for the decline of river fractal dimension in the past 100 years are the large-scale governance of Jingjiang River section and river cut off projects after 1949.

湖泊是重要的国土资源，具有调节径流、繁衍水生生物和维持区域生态环境等多种功能，同时也是农业灌溉、工业和生活用水的重要来源。随着太湖流域社会经济的快速发展，城市化和工业化进程加速，该地区湖泊形态发生显著性变化。研究基于多源遥感影像，采用区域生长法结合人工目视解译交互提取湖泊水域信息，通过面积变化率、湖泊景观形状指数（LSI）和湖泊质心偏移度3个主要指标，分析了新中国成立初期（1960年）以来各时段内太湖、滆湖和长荡湖的时空演变规律及其成因。结果表明：通过同期高景1号和Landsat8影像数据对比分析，3个典型湖泊提取面积误差分别为0.1%，0.3%和0.3%，采用不同空间分辨率的遥感数据提取水域面积时，对湖泊等大型水体提取面积影响较小；3个典型湖泊水域面积整体呈现“减少-增加-再减少-增加”的波状起伏特征，其中1960年代-1980年代之间湖泊萎缩最严重，萎缩率分别为5.44%，26.11%和25.84%；3个典型湖泊景观形状指数（LSI）整体呈先减少后增加的变化趋势；不同湖泊的演变特征具有明显的空间差异；湖泊面积减少主要受圈圩养殖、围湖造田以及建筑建设等人类活动的影响。通过对3个典型湖泊形态演变的原因分析，可为太湖流域湖泊保护及演变驱动力机制研究提供基础。

Lakes are important territorial resources and have many functions such as regulating runoff， multiplying aquatic organisms and maintaining the regional ecological environment. They are also an important source of water for agricultural irrigation， industry and domestic use. With the rapid socio-economic development of the Taihu Lake Basin， and the acceleration of urbanization and industrialization， the lake morphology in the region has undergone significant changes. Based on multi-source remote sensing images， the research uses the regional growth method combined with the artificial visual interpretation method to interactively extract lake water information. Through the three main indicators of area change rate， lake landscape shape index （LSI） and lake centroid offset， this paper analyzes the temporal and spatial evolution laws and the causes of Taihu Lake， Gehu Lake and Changdang Lake from 1960s to 2020s. The results show that through a comparative analysis of SuperView-1 and Landsat8 image data during the same period， the errors of the extraction area of three typical lakes are 0.1%， 0.3% and 0.3% respectively. When remote sensing data of different spatial resolutions is used to extract water area， they have little effect on the extraction area of large water bodies such as lakes. The area of the three typical lakes shows the characteristics of decreasing- increasing-decreasing-increasing wave-like undulations. Among them， the lakes shrank the most seriously during the period from 1960s to 1980s， The shrinkage rates of Taihu Lake， Gehu Lake and Changdang Lake are 5.44%， 26.11% and 25.84% respectively. The three typical lake landscape indexes （LSI） show an overall trend of decreasing and then increasing. The evolution characteristics of different lakes have obvious spatial differences. The decrease in lake area is mainly affected by human activities such as polder farming， reclaiming farmland and building construction. An analysis of the reasons for the evolution of three typical lakes can provide a basis for the study of lake protection and the driving force mechanism of evolution in the Taihu Lake Basin.

河湖水系是水资源的载体，其演变将对自然生态环境和区域经济社会发展带来影响，研究河湖水系演变特征可为流域水资源的科学管理及河湖水系的均衡管控提供依据。本文以襄阳市为研究区，采用GIS和RS方法，基于河湖水系空间格局内涵，构建了包含水系数量、水系结构和水系连通三个方面的河湖水系空间格局演变评价指标体系，分析了全市建国以来河湖水系空间格局的变化特征。结果表明：自1950年以来，河湖水系无论在数量、结构还是连通方面都发生了一定变化，河网密度及河网发育系数呈增加的趋势，水面率及主干河流面积长度在1996年最大，节点连接率及水系连通度均呈减小的趋势；人类活动是近年来河湖水系空间格局变化的主导因素，且其变化与不同时期经济社会发展需求密不可分，人类活动程度越强，水系结构越趋于简单，连通性越趋于下降。

河湖水系是水资源的载体，其演变将对自然生态环境和区域经济社会发展带来影响，研究河湖水系演变特征可为流域水资源的科学管理及河湖水系的均衡管控提供依据。本文以襄阳市为研究区，采用GIS和RS方法，基于河湖水系空间格局内涵，构建了包含水系数量、水系结构和水系连通三个方面的河湖水系空间格局演变评价指标体系，分析了全市建国以来河湖水系空间格局的变化特征。结果表明：自1950年以来，河湖水系无论在数量、结构还是连通方面都发生了一定变化，河网密度及河网发育系数呈增加的趋势，水面率及主干河流面积长度在1996年最大，节点连接率及水系连通度均呈减小的趋势；人类活动是近年来河湖水系空间格局变化的主导因素，且其变化与不同时期经济社会发展需求密不可分，人类活动程度越强，水系结构越趋于简单，连通性越趋于下降。

城市发展对水体多方面要素产生了巨大影响,尤其是对水资源丰富的城市,迫切需要开展相关监测研究。研究以武汉市为例,通过梳理国内外相关研究以及武汉水体保护政策,提出融合水体面积、水质、水体景观、滨水区生态环境4个方面要素的分析技术路线以更为全面的反映城市尺度的水体时空演变特征,具体的,利用随机森林模型基于1979—2019年遥感影像获取武汉67个重点水体信息,并以此获取水体面积和水体景观的变化特征;同时,通过梳理多年水质监测数据分析水质变化特征;另外,基于遥感生态指数（Remote Sensing Ecological Index, RSEI）分析滨水区生态环境变化;最后,采用多尺度地理加权回归模型（Multi-scale Geographically Weighted Regression, MGWR）对重点水体面积变化的影响因素研究,希冀为政府制定差异化的水体保护政策提供科学支撑,并为其他地区水体的多要素分析提供有益借鉴。结果表明：① 武汉市水体面积呈下降趋势,水体总面积、重点水体面积分别减少10.75%及13.12%,中心城区及郊区水体变化存在显著差异;② 水体景观呈退化趋势,周长面积分维数、平均斑块面积、聚合指数及结合指数分别减少了6.43%,79.35%,1.55%及10.94%;③ 重点水体水质总体呈恶化趋势,其中江河及水库多数常年为III类及以上水体,中心城区湖泊多为V类及以下水体,郊区湖泊多为IV类及V类水体;④ 中心城区及郊区滨水区遥感生态指数（RSEI）分析表明滨水区生态环境呈恢复态势,其中中心城区滨水区平均RSEI增长了14.29%;⑤ MGWR分析表明,自然气象因素中,相对湿度的增加对江夏区湖泊恢复影响更为显著,降水对水面较小的水体恢复影响更为显著;社会经济因素中,各行政区GDP的增加有助于水体恢复,对中心城区、黄陂及新洲的水体保护影响更为显著;滨水缓冲区内不透水面占比（IS）的增加导致大多数水体面积的减少,然而,对于少数重点修复水体,IS增加是受相关保护政策影响,IS增加有助于这些水体恢复。

干旱区河流变迁与绿洲演变和沙漠进退密切相关，是近年来干旱区环境变化研究的焦点之一。玛纳斯河贯穿山地—绿洲—荒漠系统，是新疆准噶尔盆地环境演变的典型区域。文章利用遥感影像，结合实地测量的地貌与沉积记录、室内沉积分析和测年等资料，研究了玛纳斯河下游冲积平原河道演变过程，即近4 000多年来玛斯河在下游冲积平原发生了3次可识别的迁移事件及方向，河道变迁在空间上总体表现为一个自西南向东北迁移的过程。在此基础上，进一步讨论了玛纳斯河下游冲积平原河道的变迁原因及发展趋势，指出区域构造活动是影响玛纳斯河下游河道近4 000年来定向迁移的主要原因，并预测在没有异常气候波动和构造活动的影响下，今后一段时间内玛纳斯河不会发生大规模的迁移。

利用历史图件、地形图及遥感数据监测塔里木河下游诸多湖泊水域面积并分析近一百多年的变化情况。根据湖泊水域及其变化,该区湖泊在100多年内变化过程可以分为3个时间段：① 20世纪60年代以前,该区水文条件较好,19世纪末20世纪初湖泊总面积超过2000 km²;20世纪60-70年代至20世纪末,随着水利设施的陆续兴建,湖泊水域缩小,甚至某些湖泊彻底干涸;21世纪随着塔里木河流域综合治理与下游生态输水工程的实施,该区水文条件有所好转,干涸多年的一些湖泊重新形成水域,2013年湖泊水域总面积达760 km²。② 根据湖盆成因及水域变化把该区湖泊分为：河道西侧的风成湖,河道网之间及东侧的河成湖及河道末端的构造湖等三类。③ 初步总结风成湖演变过程,发现该区风成湖与河成湖在形状、深度、水质、形成时间等方面有较大差异。④ 近代人为因素对湖泊水域变化的影响高于自然因素。

利用ICESat-1、CryoSat-2测高数据与水文站实测数据,分析了1970—2020年巴尔喀什湖水位变化特征,结合MOD09A1数据及相关资料分析了巴尔喀什湖长时间序列面积和水量变化状况,并利用巴尔喀什湖流域灌溉数据及Climatic Research Unit（CRU）气象数据,简要探究了气候变化及人类活动对湖泊长期变化的影响。结果表明：巴尔喀什湖水位在研究时段内总体呈现先下降后波动上升的趋势,1987年水位值达到最低（340.64 m）,年内水位增长主要发生在2月底至6月初,且暖季（4—10月）水位波动比冷季（11月—次年3月）更剧烈;1970—2020年巴尔喀什湖面积从19996 km²减少到16641.93 km²,湖面缩小约16.77%;在此期间巴尔喀什湖水量损失约为12.33 km³。湖泊动态变化为多种因素共同作用的结果,1970—1987年湖泊动态变化主要由卡普恰盖水库蓄水和哈萨克斯坦境内灌区耕地扩张等人类活动引起;气温与降水在总体趋势上与湖泊的动态变化并无明显相关性,定量讨论各因素对湖泊动态变化的影响,还需进一步研究。

Due to climate change and anthropogenic activities, water resource issues are challenging and have attracted significant attention worldwide. Lake level variation is an essential indicator of regional and global climate and environment. For the past few decades, the development of remote sensing has enabled long-term dynamic monitoring of lake levels and areas. In this work, the water level change of Balkhash Lake during the period of 1970—2020 was derived from ICESat-1, CryoSat-2, and the hydro-meteorological stations. Moreover, combined with MOD09A1 data and related literature, the area and water volume change of Balkhash Lake in a long time series were analyzed. The results indicated that during the study period, the water level of Lake Balkhash first showed a downward trend, and reached its lowest point (340.64 m) in 1987, and then began to fluctuate upward. Generally, the water level growth during the year mainly occurred from the end of February to the beginning of June. The water level fluctuates more dramatically in the warm season (from April to October) than in the cold season (from November to March of the following year). The multi-year average water level is the highest in spring and lowest in autumn. From 1970 to 2020, the area of the Balkhash Lake decreased from 19996 km² to 16641.93 km², and the lake area decreased by about 16.77%. Meanwhile, the water volume of the Balkhash Lake undergone a total loss of approximately 12.33 km³. The analysis revealed that the dynamic changes of the lake from 1970 to 1987 were mainly caused by human activities, such as the impoundment of the Kapchagay Reservoir and the expansion of arable land in the irrigation area in Kazakhstan. However, the overall trend of temperature and precipitation has no obvious correlation with the dynamic changes of the lake. Owing to the complexity and uncertainty of environmental changes, quantitative discussion of the impact of various factors on lake dynamics requires further research. Multi-mission altimetry satellite provides a powerful tool for the long-term and large-scale monitoring of lake level variations, which is of great significance to the study of lake level change and its response to climate and environment.

基于卫星遥感数据,提取近60 a伊塞克湖面积、水位变化信息,反演伊塞克湖水量变化时间序列,结合1960—2020年CRU气象数据、1960—2000年乔尔蓬阿塔气象站气温降水观测数据和入湖水量观测数据,建立湖泊水量平衡模型,分析水量平衡各分量的变化特征,并探讨其影响因素。结果表明：（1） 1960年以来伊塞克湖水量变化经历了持续减少-波动增加的过程,1998年为变化的时间拐点;20世纪60—80年代中期,入湖水量主要受灌溉引水影响持续减少,1986年后随灌溉水量减少、降水和冰川融水的增加而转为上升趋势;湖区降水以9.1 mm·(10a)^-1的速率增加,蒸发量随湖区升温和湖体面积增加总体呈显著增加趋势。（2） 20世纪80年代中期以前伊塞克湖大部分年份湖泊水量呈负平衡,地下水持续补给湖泊,1986年起湖泊的水量收支亏损逐渐减小,1998年以来以正平衡为主。（3） 入湖径流、降水、蒸发等水量平衡分量的互动关系决定了湖泊水量的变化,而产流区气候变化和灌区灌溉引水通过改变入湖径流间接驱动湖泊水量的变化;1960—1986年,以灌溉引水为主的人类活动是驱动伊塞克湖水量变化的主导因素,贡献率达71.6%,1987年以来,气候变化因子对湖泊水量变化的累计贡献超过80%。

Based on the satellite data, the water level and area information of Lake Issyk-Kul was extracted, and the water volume was reconstruct; combined with CRU meteorological data from 1960-2020, the temperature and precipitation observation data from 1960-2000 at the Cholpon-Ata meteorological station and the water volume observation data into the lake, the lake water balance model was established to analyze the changing characteristics of each element of the water balance and to explore its influencing factors. The results indicated that: (1) Since 1960, the water volume of Issyk-Kul Lake has undergone a process of continuous decrease and fluctuating increase, with 1998 being the inflection point of the change; from the 1960s to the mid-1980s, the water volume into the lake decreased continuously mainly due to the influence of irrigation diversions, and then turned to an increasing trend after 1986 with the decrease of irrigation water and the increase of precipitation and glacial meltwater; precipitation in the lake area increased at a rate of 9.1 mm·(10a)^-1, and the evapotranspiration tends to increase significantly with increasing temperature and lake area. (2) Before the mid-1980s, Issyk-Kul had a negative water balance in most years, and groundwater continued to recharge the lake; since 1986, the water balance deficit of the lake gradually decreased, and since 1998, the positive balance has been dominated. (3) The interaction of water balance components such as runoff, precipitation and evaporation determines the changes in lake water volume, while climate change in the flow-producing areas and irrigation diversions in irrigation areas indirectly drive the changes in lake water volume by changing runoff; from 1960 to 1986, human activities, mainly irrigation diversions, were the dominant factor driving the changes in Issyk-Kul water volume, with a contribution of 71.6%, and since 1987 the cumulative contribution of climate change factors to changes in lake water volume exceeds 80%.

为了研究小浪底水库运行后黄河下游游荡段河势演变情况，选取黄河下游游荡段2001-2020年近20年的Landsat卫星遥感影像图片，基于ARCGIS和ENVI软件采用边缘提取算法提取河道水边线及修正归一化差异水体指数（MNDWI）法提取水体，分析汛期河道水面宽度、汛后主流位置、汛后心滩数量等特征指标。结果表明：①小浪底水库运行后，经过20年的冲淤调整，黄河下游游荡段河势在汛期得到明显改善，主流基本归顺；②该河段河型没有明显变化，汛期水面宽度随流量同增同减，总体上逐年变宽，但夹河滩-高村河段水面宽度由于河道整治工程的控制较为稳定；③采用MNDWI法对水体的智能化提取，发现主流摆幅呈现3种规律：①主流位置基本不变②主流位置向同一个方向移动③主流位置迁徙不定；④心滩数量与流量呈负相关，总体上在2001-2007年逐年减少，2007年达到最小值13个，2007-2015年逐年增多，2015年达到最大值58个，2015-2020年又逐年减少，同时在河道河型突变位置也会发生变化。河势调整会改变河道整治工程的有效性，同时也会对滩区群众的生产生活造成影响，因此需要加强黄河下游游荡段河势的监测并对心滩的变化予以足够的重视，提升对黄河下游河势调整规律及心滩演变的认识。

In order to study the river regime evolution of the braided reach in Lower Yellow River after the operation of the Xiaolangdi Reservoir， the Landsat satellite remote sensing images of the braided reach in Lower Yellow River during the past 20 years from 2001 to 2020 are selected， and the edge extraction algorithm is used based on ARCGIS and ENVI software to extract water edge and correct the normalized differences. The water body index method （MNDWI） is used to extract the water body and analyze the characteristic indicators such as the water surface width of the river channel during the flood season， the position of the mainstream after the flood season， and the number of central banks after the flood season. The results show that： ①After the operation of Xiaolangdi Reservoir， after 20 years of dredging adjustment， the river conditions in the braided reach in Lower Yellow River have been significantly improved during the flood season， and the mainstream has basically returned.②There is no obvious change in the river shape of this reach， and the width of the water surface increases and decreases with the amount of water during the flood season， and generally widens year by year. However， the width of the water surface of the Jiahetan-Gaocun section is relatively stable due to the control of the river channel improvement project. ③Using the MNDWI method to intelligently extract the water body， it is found that the swing of the mainstream presents three rules： ①The position of the mainstream is basically unchanged. ②Mainstream position moves in the same direction. ③ Mainstream locations are migratory. ④The number of the mid-channel beaches is negatively correlated with the water volume， generally decreasing year by year from 2001 to 2007， reaching a minimum of 13 in 2007， increasing year by year from 2007 to 2015， reaching a maximum of 58 in 2015， and decreasing year by year from 2015 to 2020， and at the same time， the location of the river-shaped abrupt change in the channel will also change. The adjustment of river regime will change the effectiveness of the river improvement project， and will also affect the production and life of the people in the beach area. Therefore， it is necessary to strengthen the monitoring of the river regime in the wandering section of the Lower Yellow River and pay enough attention to the changes of the heart beach to enhance the understanding of the law of river situation adjustment and the evolution of the heart beach in the Lower Yellow River.

黄河下游游荡性河段素以调整速度快与幅度大著称,河道心滩复杂多变,探究心滩形态特征与水沙过程之间的响应关系对于解析下游游荡性河段的河床演变机制具有重要的意义。围绕黄河下游铁谢至高村游荡性河段的心滩面积与数量等形态特征指标,结合下游水沙及冲淤特性,采用遥感影像和数值模拟相结合的研究方法厘清游荡性河段水沙过程与心滩面积及数量之间的响应关系,揭示水沙变化对心滩形态特征的影响机制。结果表明:自小浪底水库运用以来,下游河道发生剧烈冲刷,游荡性河段累计冲刷量15.37亿m³,占下游累计冲刷量的68%;在小浪底水库运用以前,游荡性河段的心滩面积与数量年际变化剧烈,存在着明显的增长与降低变化过程,而小浪底水库运用以后,该河段的心滩面积与数量呈现先减小后增大再减小的变化趋势;随着4 a滑动汛期平均流量和4 a滑动汛期平均来沙系数的增加,游荡性河段的心滩面积及数量分别呈现出减小和增大的变化趋势。数值模拟方法不仅可以较好地再现心滩发育及演变过程,还可以定性地表征特定水动力学因素对心滩形态特征塑造的影响,为阐明游荡性河段的心滩演变理论提供了一种新的研究方法。研究成果不仅有助于阐明河流平面形态的调整过程,还可为今后河道整治工程的布局提供理论支撑。

海岸线对海平面上升、海岸侵蚀、港湾淤积、湿地生态资源、近海海域环境等具有重要的指示作用。利用遥感和GIS技术获取了珠江河口区1973-2015年8期海岸线数据,分析了海岸线长度、类型、空间位置的时空演化特征,提出岸线利用程度指数并定量分析人类活动对岸线的影响,最后对海岸线变化驱动力进行了探讨。结果表明：① 珠江河口区海岸线长度总体持续增加,岸线变化强度具有阶段性,1990年以前变化缓慢,1990-2000年为变化高峰期,2000年后变化强度减弱;② 1973-1990年珠江河口区以自然岸线为主,之后人工岸线成为主导岸线类型,建设围堤岸线1973年占总长度的7.09%,2015年所占比例增加到46.49%,在所有岸线类型中变化最大、比例最高;③ 研究期内,珠江河口区海岸线以向海域推进为主,年均速率达到39.10 m/a,鸡啼门-虎跳门段、磨刀门-鸡啼门段和蕉门-洪奇门段为向海延伸的热点区域;④ 40年来岸线利用程度指数稳定上升,1995年前增速较快,之后相对平缓。伶仃洋东岸岸线利用程度增幅最大;⑤ 口门整治、开发建设和围海养殖等人为活动是珠江口海岸线发生变化的主要原因,自然环境条件、人口和经济的增长以及政策因素是岸线演变的重要驱动力。

利用中分辨率成像光谱仪(moderate resolution imaging spectroradiometer, MODIS)一级产品并结合航次数据, 反演2003—2015年间珠江河口表层悬浮泥沙浓度(suspended sediment concentration, SSC), 分析其分位数长期变化趋势并探讨其影响因素。结果表明, 珠江河口SSC呈总体下降趋势, 平均下降速率约为1.03mg·L ^-1·yr ^-1。口门外以及河口东北部区域平均SSC下降更快, 最高可达约4.0mg·L ^-1·yr ^-1。总体上, 珠江河口SSC高值下降速率大于低值, 且存在空间差异性。低值下降趋势显著地区主要分布在淇澳岛北部的口门外区域, 其SSC大小值之间的差异逐年增加; 而高值下降速率快的地区主要分布在虎门口、龙穴岛东南岸以及东航道附近水域, SSC每年大小值差异呈减小趋势。珠江河口SSC分位数趋势受径流输沙量、河口地形变化以及风的影响。由水库修建所致的上游输沙量减少导致淇澳岛北部口门外区域SSC的低值部分显著下降。虎门口、龙穴岛东南岸以及东航道附近水域的加深使得这些区域SSC高值部分下降显著, 而西滩区域的变浅使得冬季潮汐混合减弱, 导致SSC高值部分下降趋势显著。此外, 由风速下降引起的表层风混合减弱也是导致西滩南部SSC高值下降趋势显著的原因之一。

Suspended sediment concentration (SSC) in the Pearl River Estuary (PRE) during 2003-2015 was studied based on Moderate Resolution Imaging Spectroradiometer (MODIS) Level-1B product and in-situ measurements. The data were further used to analyze quantile trends and corresponding influence factors. The results showed that the SSC in the PRE displayed a decreasing trend, with an averaged SSC reduction rate of about1.03 mg·L ^-1·yr ^-1. The SSC in the regions near the river outlets and northeast part of the estuary suffered from much stronger decreases, which could be up to 4.0 mg·L ^-1·yr ^-1 during 2003-2015. Decreasing rate in high SSC were generally larger than those in low SSC, with a marked spatial difference. Low percentile of the SSC suffered from a stronger decline in the regions north of Qiao Island, with an increase in the variance of the distribution, while remarkable trends of high percentile of SSC occurred in the Humen outlet, northeastern coast of Longxue Island and regions near the East Channel, with corresponding decreases in the variance of the distribution. The quantile trends in the PRE were influenced by many factors. The seasonal variation of dam-induced reduction of the sediment load into the PRE contributed to most of the low-percentile SSC decreases north of Qiao Island. The subaqueous topographic change in the PRE induced by human activities dominated the high-percentile SSC trends in the Humen outlet, northeastern coast of Longxue Island, southern West Shoal, and regions near the East Channel. The decrease of the wind speed over the PRE also affected the high-percentile SSC trend in the southern West Shoal by weakening wind mixing in the boundary layer.

南四湖是南水北调东线工程的重要输水储蓄枢纽，监测其水体面积变化可服务于当地环境保护治理和合理开发利用。收集南四湖地区2006-2020年的Landsat遥感影像数据，利用新型水体指数（NWI）方法进行水体面积的提取，与Sentinal-2数据的计算结果进行对比验证，对年际、年内变化规律及影响因素进行分析。分析表明：2006-2015年南四湖水体面积年均减少33.854 km²，2015-2020年年均增长14.488 km²；受南水北调东线一期工程影响，降雨只在2013年以前对年内水体面积的影响较为显著。15年间南四湖水体面积呈现先减少后增加的趋势，水域生态环境得到好转。

Monitoring the water change of Nansihu， an important water conveyance and storage hub for the east route of South-to-North Water Diversion Project， can serve for local environmental protection and management and rational development and utilization. This paper collects Landsat data of Nansihu from 2006 to 2020 and utilizes New Water Index （ NWI） to extract the water area for Analysis of the interannual and interannual variation rules and influencing factors. The results are validated against Sentinal-2 data. The annual average water area of Nansihu Lake decreased by 33.854 km² from 2006 to 2015， and increased by 14.488 km² from 2015 to 2020. Under the influence of artificial water diversion， rainfall only had a significant influence on the water area of the year before 2013. From 2006 to 2015， the water area of Nansihu Lake decreased first and then increased，showing an improvement of local ecological environment.