改进的GRACE约束正演法及其在尼皮贡湖陆地水储量变化估计中的应用

准确估计北美尼皮贡湖的陆地水储量(Terrestrial Water Storage,TWS)变化对该区域水资源调控具有重要意义.GRACE和GRACE-FO时变重力场被广泛用于定量估计TWS变化,然而截断与滤波处理会削弱信号幅度,造成信号泄漏.对于小区域尺度的研究,该现象尤为显著.约束正演法能减小泄漏误差,但是面对多质量块,传统迭代策略的收敛性能受初值影响大.为此,本文采用多个质量块分批迭代的策略,改进约束正演法在尼皮贡湖的收敛性能.模拟实验结果表明,在无偏差空间约束下,本文方法与逐格网点同时迭代和多个质量块同时迭代的策略相比,在尼皮贡湖区域绝对偏差的均方根分别降低了2.27 mm·a^-1和1.77 mm·a^-1.进一步,利用改进方法估计尼皮贡湖TWS变化,并与卫星测高数据进行对比.研究结果表明,本文方法显著降低了尼皮贡湖TWS的信号泄漏影响,恢复后的TWS信号幅度约为逐格网点同时迭代和多个质量块同时迭代策略的1.2倍.经泄漏改正后,GRACE/GRACE-FO反演的尼皮贡湖TWS与卫星测高水位变化时间序列的长期趋势相吻合.本文可为研究其他小尺度区域TWS提供一定参考.

     

基于多源数据分析维多利亚湖流域水储量变化

本文利用CSR发布的GRACE RL06时变重力场模型,结合两种水文模式、卫星测高、降雨和蒸散等多源数据,从多个角度综合系统地分析维多利亚湖流域2003-01-2017-06的陆地水储量变化.比较了正向建模方法和单一尺度因子对泄漏误差的改正效果,经对比采用正向建模方法在此流域效果更好.基于多源数据得出以下三点与此前研究不同的结论：（1）GRACE RL06版本数据探测到流域内的水储量在2003-01-2017-06呈增加趋势,球谐位系数和Mascon产品得到的变化速率分别为14.9 mm·a^-1和16.7 mm·a^-1,观测误差小于RL05版本的结果,RL05版本低估了流域水储量的变化速率;（2）2013-01-2016-02期间GRACE和测高探测到湖泊水量增长,而水文模式探测到流域内水储量减少,推测这一现象由大坝蓄水造成;（3）受El Niño事件影响,2016-03-2017-06流域降雨减少,流域水储量减少,GRACE球谐位系数和Mascon探测到的变化速率分别为-100.3 mm·a^-1和-129.7 mm·a^-1.本文结果表明卫星观测数据可为在缺乏直接观测数据的情况下分析人类活动和自然变化对区域水储量的影响提供一种可行的途径,这也为研究我国湖泊流域水储量变化提供参考.

     

Impact of water resource exploitation on the hydrology and water storage in Baiyangdian Lake

Water resources development and exploitation are critical for a viable and sustainable modern human society. Unfortunately, however, there is a considerable water storage depletion and environmental degradation in especially (semi)‐arid river basins due to the forces of population growth, urbanization, industrialization and intensive agricultural irrigation. Addressing water storage depletion is not only a question of research, but is very much a question of developing appropriate countermeasures to preserve valuable/fragile ecological systems. As one such effort, this study analyzes the hydrology and storage in Baiyangdian Lake as affected by water resources development and exploitation in the Baiyangdian Lake Catchment of Northern China. Three models, WetSpass (Water and Energy Transfer between Soil, Plants and the Atmosphere under quasi‐Steady State), WATBUD (Water Budget) and MODFLOW (USGS three‐dimensional finite‐difference groundwater flow model) were used in combination to simulate the hydrogeologic conditions in the lake catchment for 1956–2008. The model‐calibrated values are in good agreement with the measured values, with R² > 0·8 and RMSE < 10% of measured values. Runoff, the primary source of water for the lake storage, has steadily declined due mainly to multiple dam construction and reservoir impoundments in the headwater valleys and rivers in the catchment. In addition to dwindling runoff, groundwater levels have declined considerably due to over‐abstraction, mainly for agricultural irrigation. Additionally, evaporation or evapotranspiration is increasing in the lake catchment due to rising temperatures. The worsening hydrological conditions, amid the harsh semi‐arid climate, have resulted in considerable depletion of the storage and hydrology of Baiyangdian Lake. Sustainable countermeasures like agricultural water‐saving and infusion of external water (e.g., via by the South–North Water Transfer Project) could be a viable option for preserving not only the hydrology of the lake catchment, but also storage in Baiyangdian Lake. Copyright © 2010 John Wiley & Sons, Ltd.     

高原湖泊水质变化趋势及驱动因素研究:以四川邛海为例

邛海是四川第二大湖泊,地处高原,距离西昌市城区不足5 km,生态位置重要。本文以近20年邛海湖区主要水质监测数据为依据,采用M-K检验定量解析了水生态环境历史变化特征,建立邛海污染物浓度、营养状态指标的时空对应关系,分析其驱动因素,识别风险并提出对策建议。结果表明:(1)1980s-2000年是有记录以来邛海水质最差的时期,总氮(TN)、总磷(TP)浓度远超地表水Ⅲ类标准;(2)2003—2020年,邛海氨氮(NH₃-N)、高锰酸盐指数(COD_Mn)年际变化总体呈下降趋势,TN、TP、透明度、溶解氧浓度年际变化趋势总体不明显,COD_Mn、TN、TP浓度在研究期间出现多个显著变化过程;(3) 2003—2020年,邛海营养状态整体为中营养水平,综合营养状态指数TLI(Σ)为33.82±6.88,叶绿素a(Chl.a)浓度为(4.234±3.903) μg/L,TLI(Σ)和Chl.a浓度年际变化没有显著趋势;(4)多年数据统计表明,邛海宾馆所在区域水质最差,邛海湖心水质最好,2003—2020年COD_Mn、TP等指标最大单月浓度均出现在邛海宾馆所在水域;(5)COD_Mn浓度在枯水期低于丰水期,NH₃-N浓度在枯水期高于丰水期,TP浓度高值和低值集中出现在枯水期,TN各月浓度没有显著差异,Chl.a浓度与COD_Mn、TP、NH₃-N浓度呈显著正相关,从水体中氮磷比来看,磷是邛海藻类生长限制性元素;(6)面源污染主要通过邛海大小支流入湖,环湖湿地对邛海面源污染削减效果总体有限,未来邛海发生水华的风险较大,建议以小流域为单元推进陆源污染控制,按照“游在邛海,吃、住在城区”的理念布局旅游发展,探索用“物理+生态”方式调控和预防邛海水生态系统失衡的问题。     

Monitoring the water balance of Lake Victoria, East Africa, from space

Using satellite gravimetric and altimetric data, we examine trends in water storage and lake levels of multiple lakes in the Great Rift Valley region of East Africa for the years 2003–2008. GRACE total water storage estimates reveal that water storage declined in much of East Africa, by as much as , while altimetric data show that lake levels in some large lakes dropped by as much as 1–2 m. The largest declines occurred in Lake Victoria, the Earth’s second largest freshwater body. Because the discharge from the outlet of Lake Victoria is used to generate hydroelectric power, the role of human management in the lake’s decline has been questioned. By comparing catchment water storage trends to lake level trends, we confirm that climatic forcing explains only about 50decline. This analysis provides an independent means of assessing the relative impacts of climate and human management on the water balance of Lake Victoria that does not depend on observations of dam discharge, which may not be publically available. In the second part of the study, the individual components of the lake water balance are estimated. Satellite estimates of changes in lake level, precipitation, and evaporation are used with observed lake discharge to develop a parameterization for estimating subsurface inflows due to changes in groundwater storage estimated from satellite gravimetry. At seasonal timescales, this approach provides closure to Lake Victoria’s water balance to within . The third part of this study uses the water balance of a downstream water body, Lake Kyoga, to estimate the outflow from Lake Victoria remotely. Because Lake Kyoga is roughly 20 times smaller in area than Lake Victoria, its water balance is strongly influenced by inflow from Lake Victoria. Lake Kyoga has been shown to act as a linear reservoir, where its outflow is proportional to the height of the lake. This model can be used with satellite altimetric lake levels to estimate a time series of Lake Victoria discharge with an rms error of about .     

淀山湖水量的初步研究

分析了淀山湖水量的主要补给来源及淀山湖水量受潮沙影响的泄流规律,并用1988年的实测资料研究枯水年型的淀山湖水量平衡。计算结果表明:淀山湖区在1988年降水稀少,但它可获取邻近河湖及长江等水体的水源补给,使湖水量达到年内基本平衡。     

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.     

Local variability of sedimentation rate in Lake Arendsee, Germany

We measured the thickness and the dry weight of recently deposited sediment along several transects across Lake Arendsee in order to quantify the sedimentation rate and its local variability. As a time marker, we used an artificial marl layer that was deposited by a remediation program in the year 1995. A portion of the sediment deposited during the year was transported from the littoral and the top of the submerged hills to the foot of the slope, where we found the greatest deposition. Within the same lake, the deposited sediment layer varied by a factor of 4 between minimal and maximal values over the same time periods. Lake Arendsee is a holomictic and eutrophic lake with depletion of oxygen in summer time.     

春季巢湖水温和水体叶绿素a浓度的变化关系

根据2007年3-6月的巢湖逐时气象观测资料和水环境监测资料,分析了水体叶绿素a浓度、水温和气温的时间变化规律以及相互之间的关系.结果表明:水温日变化幅度小于气温日变化幅度,多项式拟合决定系数较高,为0.81;水温与水体叶绿素a浓度逐时变化关系不稳定,线性拟合决定系数变化范围为0到0.91,平均为0.35;水温日平均与...     

五大连池水质现状及近30年前后变化

2012—2013年春、夏、秋季,对五大连池11个采样点的水质变化进行研究,分析湖水水质现状,比较30年前后湖泊的水质变化并评估五大连池富营养化程度.结果表明,五大连池不同部分、季节、年份的水质参数指标波动剧烈,可能是受水产养殖及氮、磷浓度变化影响,2池和3池浮游生物量及叶绿素a浓度明显较低;同1980s相比,水质变化较大,一些指标显示水质已趋向好转,但5池却接近重度富营养化,说明近几年的还湿、迁居等保护措施初见效果,但整个湖泊水质恢复需要漫长过程.     

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．     

青海湖水量平衡及水位变化预测

青海湖是我国最大的内陆湖泊,流域面积29661km~(2),水面高程超过3000m,受人为活动影响相对较少,基本上还处于半自然状态。水量平衡计算结果表明,有观测资料的近30年来,青海湖处于负平蘅状态,水位下降了2.96m,平均每年下降10.2cm。如果未来湖区的气候大体保持过去的情况,水位将再下降5.8m,经过57年才能平衡。如果考虑“温室效应”所引起的西北地区未来气候变化,水位亦将下降,每年平均下降10.1cm。     

基于水平衡模型的呼伦湖湖泊水量变化

针对北方寒旱区呼伦湖水位下降、水面萎缩的现象,根据气候特征,利用月水量平衡模型探究湖泊水文过程并揭示其变化规律.在此基础上,利用不同气候条件下各水平衡项对于湖泊水位的影响程度确定水位升降的直接原因.基于1963-1980年间水位的实测数据,根据水量平衡原理及其他辅助计算判断出湖泊与周边区域存在着地下水的交换,且具有一定的规律性,即历年11月至次年3月期间的累积降雪融化渗入土壤中形成浅层径流补给湖泊,而7、8月份湖泊补给周边草原.基于以上规律,根据周边坡面汇流、地下水与湖泊交换量的年内变化特征,利用水平衡方程式推算湖泊1981-2008年逐月水位变化,并与其他研究成果比较,吻合度较高.不同气候条件下,径流量对于湖泊水位的影响程度最为突出,是水位变化的主控因子.     

Water storage mapping of pyroclastic covers through electrical resistivity measurements

The knowledge of the geological setting of pyroclastic covers and their water content distribution represents crucial information for stability analyses of slopes potentially subject to debris-flow phenomena. The study we here present would provide a contribution to this issue by means of an approach based on electrical resistivity measurements. Specifically, we describe the results of high-resolution 2D resistivity surveys carried out in a test area on Sarno Mountains (Campania Region – Southern Italy), where shallow landslides involving pyroclastic soils periodically occur triggered by critical rainfall events. We discuss the results in relation to the geology of the area in order to locate characteristic horizons of pyroclastic soils below the ground surface. Then, on the basis of a laboratory characterization of pyroclastic samples collected from the same test area at representative depths, we provide an estimation of the soil water content distribution in the field. Finally, we analyze temporal variations of the soil water content distribution by comparing the data of two surveys carried out in the autumnal and spring seasons, respectively.     

GRACE估算陆地水储量季节和年际变化

利用最新公布的GRACE GFZ RL04数据,分析了2003年1月～2007年12月全球27条流域和陆地水储量的季节性和年际变化.结果表明,相近流域季节性变化相位接近.2003年1月～2007年12月陆地水储量季节性变化为1572.4 km3,其中变化最大流域为亚马逊河,其次分别为鄂毕河、尼罗河和尼日尔河等流域.5年来 GRACE陆地水储量的年际变化为-75.4±40.3 km3/a,其中亚马逊河、勒拿河和马更些河等流域的年际变化呈现正增长,而刚果河、密西西比河、恒河、育空河和雅鲁藏布江等流域则相反.GRACE与GLDAS数据均表明2006年后陆地水储量年际变化存在明显增加.     

基于富营养化阈值的松花湖水环境容量分析

通过对松花湖水体中浮游植物的绝对优势种——铜绿微囊藻(Microcystis aeruginosa)单藻株生长与磷、氮定量关系的室内模拟研究,得出松花湖富营养化发生的阈值为：总磷浓度0．065 mg/L,总氮浓度0．843 mg/L．利用风险分析理论和蒙特卡罗随机模拟方法,在分析2002-2004年松花湖水体中总磷和总氮浓度实际分布规律的基础上,提出了计算湖、库总磷和总氮水环境容量的不确定性方法．通过对松花湖磷、氮水环境容量的计算,得出松花湖流域总磷和总氮的最大允许排放量为2123．78 t/a和7018．82 t/a,为了使松花湖富营养化发生的概率在0．001以下,总磷和总氮需要分别削减3208．34 t/a和18648．91 t/a．     

德国柏林市Stechlin湖原生动物群落多样性特征的初步研究

本文报道了作者在1994年秋季至1995年冬季利用PFU（Polyurethane Unit Foarm,聚氨酯泡沫塑料块）人工基质和结合传统的采集自然基质方法研究德国柏林市郊Stechlin湖原生动物群落多样性特征的结果,通过连续采样调查,首次记录了该湖128种原生动物,实验结果表明：在相同采样时间内,3个不同生境类型的采样站PFU原生动物的群集速度及个体丰度存在明显差异;在相同采样时间和地点,PFU人工基质能够采集到比自然基质更为多的原生动物种类,从而进一步证实了PFU方法应用在原生动物群落多样性研究上的优势作用。     

1960—2019年鄱阳湖五河流域陆地水储量变化及其对主湖区水量的影响

流域内地表水、土壤水和地下水等水储量组分相互作用和影响,共同构成了陆地水储量(TWS)的动态变化格局。本文以GRACE卫星数据为基准,利用GLDAS数据解析1960-2019年鄱阳湖“五河”流域TWS的时空变化特征及各组分对其变化的贡献,采用相关分析方法分析TWS对降水的滞后响应关系,并进一步采用多元线性回归分析方法探究了“五河”流域TWS及各组分对鄱阳湖主湖区水量的影响。结果表明:“五河”流域年TWS在1960-2011年(P1)以-0.07 mm/a的下降,而在2012-2019年(P2)以3.37 mm/a的速率上升。相较于P1阶段,P2阶段春、夏季TWS盈余增强,秋、冬季TWS亏损减弱。春、夏季流域西部TWS变化逐渐由地表水转变为地下水储量主导,流域东部TWS变化主要由地下水储量主导;秋、冬季流域TWS变化主要为地下水储量主导,且地表水对TWS变化的贡献减弱。流域TWS对降水变化的响应滞时呈现夏、秋季短(1个月)而冬、春季长(3~6个月)的季节模式。地下水储量和土壤水对TWS变化的贡献增加会延长TWS对降水的响应滞时,而地表水对响应滞时起相反的作用。“五河”流域TWS与鄱阳湖主湖区水量具有显著的正相关性,地表水和地下水储量增加对湖区水体的增长具有正向作用,而土壤水增加对湖区水体的增长具有反向作用。本研究解析了近六十年鄱阳湖“五河”流域陆地水储量的变化及其对主湖区水量的影响,可为流域水安全管理提供参考。     

Modeling of climate change impacts on Lake Burullus,coastal lagoon (Egypt)

Coastal lagoons are particularly vulnerable to climate change, in particular, Sea Level Rise (SLR) due to their shallowness. Lake Burullus provides a variety of socio-economic services as the second largest coastal lagoon in Egypt. Recently, it has experienced significant ecological deterioration. Thus, its ecosystem is fragile in the face of anthropogenic induced changes. The main objective of the current study is to investigate the climate change impacts on characteristics of Lake Burullus. A depth averaged hydro-ecological modeling system, MIKE21, was applied to develop an eco - hydrodynamic model for the lake. The developed model was calibrated and verified for two successive years: July 2011–June 2012 and July 2012–June 2013. The model simulations exhibited good agreement with the measurements during the calibration and verification processes. Six different Regional Climate Models (RCMs) were compared, using six different statistical metrics, to determine the most accurate one for the study area. The required meteorological input, including surface air temperature, precipitation, and evaporation were derived from the selected RCM. The meteorological input was extracted for two different years in the 21 ^st century considering one Representative Concentration Pathways (RCPs) scenario, based on the Intergovernmental Panel on Climate Change (IPCC) 5th Report. Regional SLR projections for the Mediterranean Sea for the selected RCP scenario and the two studied years were obtained. These future climate change estimates were used to modify the validated model of the lake. A sensitivity analysis was applied to assess effect of future climatic conditions and SLR, separately. The results revealed that the lake water depths will increase and it will be warmer and more saline. Significant spatial variability of the studied parameters under climate change forcing is expected. Consequently, climate change is going to restrict the lake's ability to preserve the present-day species. An urgent management plan involving adaptation works, should be implemented to reduce such potential species losses in Egyptian lagoons.