冰川亏损对哈拉湖流域湖泊水位波动的影响

青藏高原的内陆湖泊水位和冰川变化和其流域内冰川质量亏损对湖泊水位波动的影响及其贡献对水量平衡研究具有重要意义。以哈拉湖流域冰川为例,基于2000-2015年星载雷达测高资料和Landsat卫星多光谱遥感资料分别提取湖泊水位和面积变化;结合附近的托勒台站气象观测资料,进一步分析其水位波动变化原因和冰川亏损对湖泊水量贡献。结果表明:受年降水量和夏季降水量增加影响,哈拉湖水位呈增加趋势,但哈拉湖流域冰川亏损加速趋势不明显;与2000年相比,湖泊面积增加了(21.4±4.8)km~2,湖泊水位增加了(1.68±0.26)m,相应的湖泊水容量增加了(16.1±0.3)×10~8m~3水当量。流域冰川亏损量达对哈拉湖水量的贡献率为39.65%,降水量增加对湖泊水量贡献了22.82%。     

Mapping the spatial changes in Lake Volta using multitemporal remote sensing approach

Lake Volta is the world's largest man‐made lake by surface area, and the fourth largest by water volume. Located completely within Ghana, it has a surface area of about 8502 km² (3283 square miles). Like many other lakes on the African continent, Lake Volta is a major natural resource for Ghana, storing water for the operation of the hydroelectric dam, water supply for domestic, agricultural and industrial purposes, habitat for diverse aquatic species, an avenue for recreational activities, means of navigation between the north and south parts of the country, and a climate modulator for the tropical region. The lake has experienced variable water level and surface area changes attributable to climate change and excessive water abstractions. Using histogram thresholding techniques, this study produced binary images and vector maps of the lake. Spatial extent mapping of the lake using Landsat TM 1990, ETM + 2000 and ETM + 2007 images indicated the lake experienced both increased and decreased surface area changes during the study period. The lake's surface area varied by about 197 km² between 1990 and 2007, with the water level fluctuating between ±7 m. Factors thought to be contributing to these changes include human factors (regulated flows, deforestation, increased water abstractions and pollution) as well as natural phenomenon (climate change, water run‐off and subsequent sediment transport).     

联合Landsat影像和ICESat测高数据估计青海湖湖泊水量变化

湖泊既是陆地水资源的重要储蓄场所,也是区域和全球水文循环系统的重要组成部分,其水量波动对气候变化较为敏感。为了掌握湖泊面积、水位和水量的变化规律,借助1988-2018年Landsat TM/ETM/OLI影像和归一化差异水体指数NDWI（normalized difference water index）提取青海湖湖泊水域面积;利用ICESat-GLAS（ice, cloud, and land elevation satellite-geoscience laser altimeter system）测高数据提取青海湖湖泊水位变化,并结合观测资料检验陆地GLAS光斑脚点高程和湖泊水位的估测精度。根据湖泊面积与水位、水量与水位的关系,构建1988-2018年青海湖湖泊面积-水位-水量波动时变序列,并探讨湖泊水位、面积、水量的年内和年际变化特征。结果表明：GLAS光斑脚点高程与高程实测值的标准误差为0.14 m,与SRTM3高程标准误差为0.26 m;1988-2018年青海湖年均水位和水量总体上呈增加趋势,其中年均水位最低值出现于2004年,平均水位为(3 193.0±0.16) m,湖泊面积为(4 190±13) km²;与1988年年均水位相比,2018年青海湖年均水位上升了(1.93±0.22) m,湖泊年均面积扩张了(197.75±6.3) km²,湖泊水量增加了(8.93±0.12) km³。     

洪泽湖中低水位下泄流能力数值模拟

为研究淮河中下游发生中小洪水时洪泽湖的泄流能力,建立淮河蚌埠至洪泽湖出湖口三河闸段一二维耦合水动力模型,模拟分析了重点河段切滩对洪泽湖中低水位下泄流能力的影响及切滩前后的流域行洪过程。结果表明:在5年一遇洪水过程下,洪峰时刻淮河干流蚌埠、临淮关、香庙、浮山和洪山头等水文站水位较切滩前分别下降0.02m、0.07m、0.21m、0.55m和0.70m,漫滩时间分别减少1d、4d、9d、9d和17d;洪泽湖三河闸站水位最高值为13.33m,相比切滩之前升高 0.07m,湖泊对应的下泄流量为8300m³/s,较切滩前增大800m³/s,泄流能力提高11%。     

扩大入江、入海泄量对洪泽湖及其上游淮干水位影响分析

为探究洪泽湖的出湖流量变化对洪泽湖的泄流能力以及淮河中下游水位的影响,建立淮河中下游一维、洪泽湖二维水动力数学模型,通过实测水文资料对模型进行率定及验证。基于数学模型,分析了扩大入江水道以及入海水道泄量对洪泽湖及淮河干流水位的影响。结果表明: 提高淮河入江水道泄流能力使其达到设计泄量,能使洪泽湖湖区内各个位置水位有所降低,其中蒋坝水位降幅最大,1991 年洪水时下降 0. 7 m,2003 年洪水时下降 0. 62 m,同时使淮河干流沿程水位均有不同程度的降低,从上游至下游沿程水位降幅呈逐渐增加的趋势。实施淮河入海水道工程对 1991 年型洪水洪泽湖湖区水位降低效果明显,其中蒋坝水位降幅最大,为 0. 06 m。淮河入海水道二期工程的启用能够使洪泽湖内水位有明显的降低,其中蒋坝水位降低幅度最大,1991 年洪水蒋坝水位降低 0. 3 m,溧河洼地区以及淮北淮南处降幅比蒋坝小,对淮干入湖河段水位的降幅相对比较小,到吴家渡水位降幅不明显。     

基于Landsat及ICESat和Hydroweb的太湖容积变化监测

为得到太湖长期动态变化过程,利用1975—2015年Landsat数据,基于归一化差异水体指数法(NDWI)和改进型归一化差异水体指数法(MNDWI)提取湖泊面积数据,并基于ICESat和Hydroweb数据提取太湖水位数据。将两者相结合,得到了太湖容积变化和水量平衡数据。据此,分析了太湖水位、面积和容积变化的规律和趋势,并对其影响因素进行了研究。结果表明,太湖面积和容积变化近40年来呈缓慢增长趋势,分别从1975年的2 320.07 km~2和-0.047 0 km~3增长到了2015年的2 341.06 km~2和0.275 9 km3,增长趋势不明显;太湖水位总体上呈波动变化趋势,水位从1975年的0.982 6 m变为2015年的1.135 9 m。因此,太湖水位与面积相关性中等(R2≈0.65),容积变化与面积和水位变化的相关性较高(R~20.85)。太湖水量平衡为正平衡且变化不大,为0.009 2 km~3。入湖水量的增加、年降雨量和年蒸发量的变化及政府"退地还湖"政策是导致太湖发生变化的主要原因。     

基于星载雷达测高资料估计博斯腾湖水位-水量变化研究

为了理解气候变化背景下的内陆湖泊水位、面积、水量波动变化规律,科学合理地指导湖泊水资源利用与开发。利用1990-2015年Landsat TM/ETM/OLI影像和2002-2015年多源星载雷达测高资料,借助归一化水体指数(Normalized Difference Water Index,NDWI)提取博斯腾湖湖泊水域面积,结合湖泊水位观测数据,对星载雷达测高数据提取的湖面瞬时水位估计值进行对比与分析;根据湖泊面积与水位、水量与水位的关系式,构建湖泊面积-水位-水量波动时变序列,并探讨湖泊水位和水量变化的年际特征。结果表明:ICESat-GLAS、ENVISatERS、Jason-12的当日水位估计值与附近扬水站的水位观测值绝对误差分别小于0. 21、0. 18、0. 15 m,而且具有较强的相关性和一致性。1990-2002年湖泊水位持续增长阶段; 2002-2015年期间,湖泊水位持续下降。2015年湖泊水域面积比1990年减少了(32. 20±3. 5) km2,年均水位下降了(0. 81±0. 19) m,湖泊水量减少了(9. 49±0. 022)×108m3。因此,湖泊水量变化为气候系统和人类活动的影响机制的理解提供了参考依据。     

洪泽湖洪水调蓄能力研究

洪泽湖在淮河流域防洪中发挥着巨大的作用,当前针对洪泽湖调蓄能力的研究较少,且不够全面。梳理了洪泽湖对洪水的调蓄过程,将洪泽湖对洪水的调蓄作用分为蓄滞作用和调节作用进行综合分析。结合1991、2003和2007年的暴雨洪水资料,对洪泽湖的调蓄能力进行了分析。洪泽湖对洪水的一次调蓄量变化不大,均为30×108m~3左右,表现出增长趋势。基于调蓄量无法充分表示洪泽湖的蓄滞作用,提出了能更准确表示湖泊对洪水蓄滞作用的参数——调节系数。洪泽湖对洪水的调节系数由0. 19提高至0. 21增长到0. 38,表明洪泽湖对洪水的蓄滞作用逐步增强。洪泽湖对"高瘦型"和"矮胖型"洪水的调节作用明显不同,对"矮胖型"洪水的调节作用更强。提出了出湖河道的泄流能力也是洪泽湖调蓄能力的一部分,人工河道的投入使用在防洪中发挥了重要作用。泥沙淤积和人工围垦是洪泽湖调蓄能力变化的决定性影响因素。研究结果为洪泽湖调蓄能力的分析提供了理论指导和技术支持。     

洞庭湖湖区最低生态水位的确定

为确定洞庭湖湖区最低生态水位,针对洞庭湖湖区复杂、不同湖区差异较大的问题,基于城陵矶、鹿角、南嘴、小河嘴和杨柳潭5个水文站1953—2013年的水文资料,采用天然水位资料法、年保证率法、最低年平均水位法、生态水位法、湖泊形态分析法及最小空间需求法,分别对东洞庭湖、南洞庭湖和西洞庭湖的最低生态水位进行了计算,并与前人关于洞庭湖生态水位的研究成果进行了对比分析。结果表明:东洞庭湖、南洞庭湖和西洞庭湖的最低生态水位分别为22.62 m、27.19 m和28.11 m,相应的湖面面积分别为373.85 km~2、406.88 km~2和142.19 km~2,从保护洞庭湖自然保护区的角度看,确定的最低水位是合理的。     

基于遥感数据的洪泽湖库容曲线推求

基于洪泽湖区域21景ETM+遥感影像,解译得到洪泽湖的水面变化时间序列数据;结合三河闸(闸上)实测水位数据,推导了洪泽湖水位水面面积函数关系,运用积分方法得到洪泽湖库容曲线,并与现有库容曲线进行了对比分析。结果表明:洪泽湖周边水域圈圩养殖区是早期形成的,2000—2015年间圈圩总体上得到一定的控制,但在洪泽湖西岸有进一步加剧的趋势;水位-水面面积函数的选取对低水位水面面积推算有影响,进而对湖泊死库容计算产生累计误差影响;遥感影像数据越丰富、影像之间的湖泊水位差越小,则库容曲线越准确。     

Satellite altimetry for Indian reservoirs

Satellite radar altimetry has immense potential for monitoring fresh surface water resources and predicting the intra-seasonal, seasonal, and inter-annual variability of inundated surface water over large river basins. As part of the Preparation for the Surface Water and Ocean Topography mission scheduled for launch in mid-2022, the present study aimed to evaluate the performance of radar altimetry over the inland water bodies of India. The Joint Altimetry Satellite Oceanography Network (Jason) and Satellite with ARgos and ALtiKa (SARAL/AltiKa) data were used to derive the water levels of 18 major reservoirs in India by incorporating the geophysical and propagation corrections into the radar range. In situ gauge data were used to evaluate the performance of the altimetry-derived water level time series from 2008 to 2019. The results showed a strong correlation between Jason-2 and in situ data with the determination coefficient (R²) and root mean squared error (RMSE) ranging from 0.96 to 0.99 and from 0.28 m to 1.62 m, respectively. The Jason-3 data had the highest correlation with the in situ observation (R² = 0.99) and the lowest correlation (R² = 0.82), with RMSE values ranging from 0.11 m to 1.18 m. With an R² range of 0.93–0.99 and an RMSE range of 0.20–1.05 m, the SARAL/AltiKa mission presented greater accuracy than the Jason altimetry mission. The estimated water levels can be utilized in remote, inaccessible, or ungauged areas and in international transboundary rivers for water storage and river discharge estimations. However, the accuracy of remotely sensed data depends on such factors as along-track distance, water body area, and geographical and terrain conditions near water bodies.     

1975－2015年洪泽湖水沙变化趋势及成因分析

淮河流域洪涝灾害频繁,洪泽湖对其防洪除涝起关键性作用。掌握洪泽湖水沙变化趋势及突变点对流域水资源管理、水沙调节有重要的现实意义。利用入、出洪泽湖各支流代表水文站1975-2015年实测年径流量和年输沙量数据,分析入、出洪泽湖水量和沙量分布特征。通过Mann-Kendall(M-K)秩相关检验法和Pettitt突变点识别法研究入湖、出湖水沙量年际变化趋势和突变点。在此基础上,从流域降雨、水资源开发利用和水库滞沙三个方面分析了洪泽湖水沙变化的主要影响因素。研究表明:洪泽湖入湖、出湖水量年际变化趋势一致,无明显减小趋势,且无显著突变点。入湖沙量有小幅减小趋势,出湖沙量M-K统计值超过95%显著性水平,有明显减小趋势。入湖、出湖沙量发生突变的年份为1991年。对影响因素的分析得到:降雨量变化是水量变化的重要影响因素。1993-2015年,入湖水量呈不明显减小趋势则与流域用水量明显增加、水资源开发利用程度不断提高有关。上游水库建设是导致洪泽湖沙量有明显减小趋势的主要原因,1991年治淮工程的实施,水库复建和水土保持等措施是沙量突变的主要原因。     

洪泽湖入湖水沙序列的多时间尺度小波分析

为了分析洪泽湖入湖水沙序列的多时间尺度变化过程及特征,预测洪泽湖入湖水沙变化趋势,利用洪泽湖1975—2015年的年来水、来沙量数据,在统计分析的基础上,对洪泽湖年来水、来沙序列进行延伸和距平处理,采用小波分析方法对处理后的洪泽湖入湖水沙距平序列进行Morlet连续复小波变换,得到了小波变换系数的实部等值线图和模方等值线图,小波方差图和主周期变化趋势图。结果表明:洪泽湖近41 a年来水、来沙序列存在着多时间尺度特征,在不同的时间尺度下,洪泽湖年来水、来沙量丰枯变化趋势不同;年来水、来沙序列存在着同样的第一主周期,为30a特征尺度,在该特征尺度下,预测2015年之后未来短时间内洪泽湖年来水量、来沙量将分别进入到枯水期和少沙期且都将处于相应的峰值期。     

Expansion of Dreissena into offshore waters of Lake Michigan and potential impacts on fish populations

Lake Michigan was invaded by zebra mussels (Dreissena polymorpha) in the late 1980s and then followed by quagga mussels (D. bugensis) around 1997. Through 2000, both species (herein Dreissena) were largely restricted to depths less than 50 m. Herein, we provide results of an annual lake-wide bottom trawl survey in Lake Michigan that reveal the relative biomass and depth distribution of Dreissena between 1999 and 2007 (although biomass estimates from a bottom trawl are biased low). Lake-wide mean biomass density (g/m²) and mean depth of collection revealed no trend between 1999 and 2003 (mean = 0.7 g/m² and 37 m, respectively). Between 2004 and 2007, however, mean lake-wide biomass density increased from 0.8 g/m² to 7.0 g/m², because of increased density at depths between 30 and 110 m, and mean depth of collection increased from 42 to 77 m. This pattern was confirmed by a generalized additive model. Coincident with the Dreissena expansion that occurred beginning in 2004, fish biomass density (generally planktivores) declined 71% between 2003 and 2007. Current understanding of fish population dynamics, however, indicates that Dreissena expansion is not the primary explanation for the decline of fish, and we provide a species-specific account for more likely underlying factors. Nonetheless, future sampling and research may reveal a better understanding of the potential negative interactions between Dreissena and fish in Lake Michigan and elsewhere.     

入海水道二期对洪泽湖地区洪水风险的影响研究

为探究淮河入海水道二期工程对洪泽湖的泄洪能力以及周边滞洪区的影响,在对研究区河网概化及地形处理的基础上,建立了研究区河网一维、洪泽湖湖区与周边滞洪区二维耦合的水动力数值模型,并采用1991,2003,2006,2007四年实测历史洪水资料对模型进行率定及验证。基于现状工况、规划工况以及不同洪水量级,设计了5个对比方案对研究区进行洪水演进数值模拟,对不同洪水量级进行横向对比,对不同工况进行纵向对比,并对不同方案进行淹没面积分析和洪水影响分析。结果表明,入海水道二期工程的启用可以有效降低洪泽湖水位,提高洪泽湖的防洪标准和周边滞洪区的启用标准,减少同等洪水量级下的受影响人口数和区域GDP,为洪泽湖的防洪安全建设以及周边蓄滞洪区的稳定发展创造了条件。     

洞里萨湖的水位和面积变化特征

洞里萨湖是湄公河最大的连通湖泊,其水位、面积变化对洞里萨湖的结构和功能产生重要影响,辨识水位、面积演变规律对洞里萨湖区与湄公河三角洲防汛抗旱和生态环境保护具有重要指导意义。基于金边港、波雷格丹和甘邦隆站长系列的日均水位数据及湖区地形资料,定量分析了洞里萨湖水位、面积的年际与年内变化特征。结果表明:洞里萨湖水位涨落缓慢,涨水天数少于退水天数,涨水率高于落水率。洞里萨湖年际水位波动频繁,年平均水位、年最高水位、年水位极差值、年洪水历时、年平均洪水位、日涨水率年际变化总体呈小幅下降趋势,年最低水位、退水天数、日落水率年际变化呈上升趋势。洞里萨湖水位、面积年内呈单峰型变化,5月份最低,平均水位1.51 m,相应面积2 487 km²,实测最低水位1.11 m,相应面积2 053 km²;10月份最高,平均水位8.70 m,相应面积12 768 km²,实测最高水位为10.54 m,相应面积15 261 km²,多年平均年内水位变幅7.63 m,面积变幅10 628 km²。研究成果为下一步洞里萨湖区的综合治理规划奠定了基础。     

淮河与洪泽湖河湖关系研究进展及展望

系统研究淮河与洪泽湖的河湖关系,提出河湖关系是建立在水沙交换作用基础之上,河湖关系包括河流、湖泊和入湖三角洲演变、洪泽湖调蓄量变化以及出湖河道的演变和泄流能力这几个方面。同时阐述河湖关系的历史研究和演变过程,并分析河湖关系的现状。并在此基础上进一步展望河湖关系的研究趋势,认为河湖关系的研究还需要更多的理论基础以及技术条件。     

Hydrological Evolution of Wetland in Naoli River Basin and its Driving Mechanism

Naoli river basin(NRB), with an area of 24,863 km², is the largest basin and also the largest marsh distribution area in Sanjiang Plain, Heilongjiang, China. The hydrological evolution process of wetland in NRB has made a marked ecological responses for anthropic activities, also reflects the drying trend of the Sanjiang Plain, Northeast China. Global climate warming also contributes to the hydrological evolution process. The following key research results are obtained: (1) The monthly average water level of Naoli river at Caizuizi hydrological station in different ages showed a marked decline tendency, the annual mean water level dropped from 96.63 m during 1960–1969 to 95.59 m during 2000–2005, the water level drawdown is 1.04 m; (2) The annual runoff flowing into wetlands in NRB decreased. Duration of Naoli river and its tributaries being thoroughly frozen from riverbed to river-water-surface showed an prolonged trend, and the water level drawdown in frozen seasons increased. The water storage capacities of wetlands in NRB declined. (3) The interactions between ground water and surface water in wetland areas are close. The ground water level variation span is bigger than that of surface water level in wetland areas of NRB. The drawdown of ground water level promotes the surface water level to decline, correspondingly. In recent 20 years, the cultivated area extension of rice field in upstream NRB has made an adverse influence on the hydrological processes of wetlands. (4) The wetland area decrease and farmland area increase significantly contribute to the runoff depth decrease of wetlands in NRB. The runoff depth variability has been mostly posed by anthropic activities. (5) Reservoirs, ditches and dykes in NRB have greatly changed the runoff generation processes. Thickness of the seasonal frozen soil layer becoming thinner and the evaporation potential becoming bigger also contribute to the runoff depth reduction and the water level drawdown of rivers. The present study results will provide a scientific basic for developing an integrated watershed management program for NRB, especially, restoring the wetland hydrological processes, maintaining or improving the wetland structure and enhancing the wetland service functions.     

基于WebGIS的洪泽湖地区洪水预报预警系统

为了加强洪泽湖地区洪水风险管理,保障淮河下游防洪安全,采用WebGIS与水文学、水力学模型相结合,将一、二维耦合的水动力学模型内嵌于B/S系统进行洪水预报预警的方法。构建了一维洪泽湖地区河道、二维洪泽湖湖面及周边滞洪区相耦合的洪水演进模型,在此基础上开发了基于WebGIS的洪泽湖地区洪水预报预警系统,实现了对降雨、洪水进行实时监控、预报和对预警关注地点水位、流量变化、洪水淹没和超标洪水预警信息的可视化展示。系统进一步提升了洪泽湖地区的防洪数字化水平,可为避险减灾提供决策支持。     

基于MIKE FLOOD的洪泽湖周边滞洪区洪水演进模拟研究

基于实测断面资料建立了研究区的一维水动力模型,基于高精度DEM以及1∶10000地形图建立了研究区的二维水动力模型,并用MIKE FLOOD将一维模型和二维模型进行耦合,构建了洪泽湖周边滞洪区一、二维耦合的洪水演进数学模型。利用2003年历史洪水资料对模型参数进行了率定,并以2007年历史洪水资料进行了验证。以洪泽湖百年一遇设计洪水为模型上边界,二河闸、三河闸以及高良涧闸的现行调度方案的水位-流量关系为模型下边界,对洪泽湖百年一遇设计洪水方案进行模拟计算,当蒋坝水位达到14.33m时,洪泽湖周边滞洪区开始滞洪,得到开始滞洪后不同时段研究区内各类洪水风险要素的动态分布情况以及最大淹没水深、淹没历时,验证了模型的合理性,可用于蓄滞洪区洪水演算分析。