太湖流域1991年大水与城镇洪涝问题

继１９５４年之后，１９９１年太湖流域再一次发生了流域性大水，由于经济发达的苏州、无锡、常州地区及众多的工厂企业被淹，城市设施和工厂企业的直接经济损失达８０多亿元，占水灾损失总数的８０％，成为流域水灾的主要损失。本文以大量的资料和统计数字，阐术了１９９１年太湖流域城镇洪涝灾害的情况和特点，分析了产生洪涝灾害的原因，提出了解决城镇洪涝问题的对策。根据太湖流域１９９１年防汛斗争的经验，参照全国防汛斗争的     

湖泊富营养化的生态修复策略

由于工业化的发展和人类生产活动的加剧,大量有机污染物不断排入湖泊并在其中积累,致使湖泊产生了富营养化现象,当前我国湖泊污染及富营养化问题非常严重。文中论述了湖泊富营养化的现状及危害,分析了产生的原因,指出生态修复是治理的最佳途径。因此,湖泊治理应该遵循先控源截污、后生态恢复,即先改善基础环境,后实施生态恢复的战略路线。     

3D-modelling of Lake Kivu: Horizontal and vertical flow and temperature structure under spatially variable atmospheric forcing

With the increasing extraction of methane from Lake Kivu, there is a growing need to evaluate the effect of such operations on the lake’s permanent density stratification. This requires understanding of the spatial structure and variability of flow velocities and constituents in Lake Kivu. In this study, we develop a 3D hydrodynamic model of Lake Kivu, set-up within DELFT3D at a 750 m grid spacing and forced by COSMO-CLM atmosphere model results at a 2.8 km grid spacing. Validation shows that the model correctly reproduces the generation and breakdown of the temperature stratification in the upper mixed layer and predicts flow velocity magnitudes and directions similar to measurements both at the surface and at greater depth. Analysis of currents reveals a surface current pattern with two clockwise circulations, one around the whole lake and a smaller one in the northern part, with velocities around 0.1 m/s. This pattern is consistently present over an (ensemble-)averaged day, both in the wet and in the dry season, while day-by-day variations are large. Time-averaged deep currents are found to be a few mm/s at maximum. However, the variations can be substantial, with standard deviations up to 2 cm/s for the currents at 220 m depth, attributed to internal seiches. The temperature stratification, present during the entire wet season, is found to first break down in the dry season in the southern part of the lake. This is explained by the spatial differences in the wind stress and the evaporation heat fluxes during the dry season.     

Regime shifts observed in Lake Kasumigaura,a large shallow lake in Japan: Analysis of a 40‐year limnological record

Lake Kasumigaura, which is composed of the two basins (Nishiura and Kitaura), is a large, shallow, hypereutrophic lake. Phytoplankton and water quality records from the past forty years were analysed to elucidate whether or not, when, and what type of certain regime shifts may have occurred, based on using inferential regime shift detectors. Characteristics of the phytoplankton and water quality changes were similar at 6 sampling sites in the two basins, with 20 water quality parameters being classified into four groups, based on cluster analysis. Shifts in dominant plankton groups (DPGs) and water quality occurring almost concomitantly, concentration on the period from 1987 to 1992 (Shift A) and from 1997 to 2001 (Shift B), with those observed for the two basins usually being similar with small differences. Two types of inferential regime shift detectors (sequential t‐test type; Rodionov's RSD and sequential F‐test type: package strucchange in R) yielded similar timings and significances of the shifts. Furthermore, changes in skewness and conditional heteroskedasticity (package early warnings in R) usually represented early warning signals before the shifts. Correlation analysis and ratios of dissolved inorganic nitrogen (DIN) vs. total phosphorus (TP) supported the hypothesis that phosphorus was the phytoplankton biomass limiting nutrient, except for one period for the Nishiura basin. Neither the nitrogen:phosphorus (N/P) ratio hypothesis and ammonia–nitrate (NH₄‐N/NO₃‐N) hypothesis satisfactorily explain the DPGs before and after Shift A (Microcystis spp. and Planktothrix spp., respectively), although it may be possible that these ratios triggered the DPG change in this shift. A considerable increase in silicon was observed for Shift B when the DPGs changed from cyanobacteria to diatoms. Further studies on the accurate types and triggers of the regime shifts are necessary to better understand the interactions between ecosystem and water quality for this and similar lakes elsewhere.     

抚仙湖北岸生态调蓄带工程入湖污染物减排效益核算

抚仙湖属珠江流域西江水系的源头型深水湖泊,湖岸陡峭,岸滩不发育,湖泊生态系统十分脆弱,水质一旦被污染将很难恢复。近年来受流域内人类活动强度持续加剧与全球气候变化的双重驱动影响,抚仙湖水位持续降低、河湖水污染问题日益突出,湖泊水质保护问题迫在眉睫,因此,2017年针对入湖污染负荷占比最大且农田面源污染问题最为突出的抚仙湖北岸片区实施了集截污、调蓄、水质净化、水资源回用、清水置换、湿地补水建设于一体的抚仙湖北岸生态调蓄带工程,并将1179.09亩农田改建为调蓄带湿地。从实施效果来看,调蓄带工程2018—2021年期间减少的TN、TP入湖负荷量分别为245.84 t、28.99 t,调蓄带对抚仙湖北岸片区农田面源负荷削减率均超过81%;从生态调蓄带入湖污染物减排效益贡献大小来看,土地利用方式变化＞湿地水质净化＞湖滨湿地补水＞水资源回用＞清洁水资源置换;从调蓄带入湖污染物减排效益持续提升来看,水资源回用和清洁水资源替换潜力有待进一步挖掘和提升。     

西部重要湖泊测量中控制系统的解决方法

我国西部部分重要湖泊测量属国家水利前期工作项目,西部地区湖泊众多,多数湖泊位于高海拔地区,因为地处偏远,人迹罕至,交通条件不便,自然环境恶劣,导致大多数湖泊未开展过系统科学的测量工作,湖泊基本情况不清,历史资料空白,不能满足湖泊开发治理、生态环境保护、水资源管理、科学研究等工作需要,因此国务院决定开展此工作。概述了西藏五大湖泊测量中的控制系统解决方法,采用世界IGS跟踪站与湖泊控制网站点进行联测得到精准的控制点的平面坐标,解决了测区无平面坐标引据点的问题;采用基于EGM2008地球重力场模型解算出湖泊控制网站点的高程,解决了测区高程引据点少的问题。控制成果经过了验证,对西部部分重要湖泊测量起到了决定性作用。     

基于高通量测序的东湖蓝藻动态变化研究

采用高通量测序(High-throughput sequencing technology)和实时荧光定量PCR技术,结合水质参数的检测,研究了东湖两个不同富营养化程度湖区蓝藻整年丰度和群落结构的变化,并统计分析蓝藻与环境参数之间的关系。结果表明:(1)两区域微囊藻在6~7月达到全年最高值,但拷贝数相差近20倍。(2)两区域蓝藻门在属水平的变化也有显著差异,H区蓝藻在4~11月主要由浮丝藻属(Planktothrix)(4~6月)、微囊藻属(Microcystis)(6~9月)、聚球藻属(Synechococcus sp. PS717)(7~11月)交替演变,L区蓝藻主要是由束丝藻属(Aphanizomenon)(4~6月)和聚球藻属(Synechococcus sp. PS717)(4~10月)组成,并且与H区在相对丰度变化上比较,L区较平稳。(3) RDA分析表明,Tw、p H、NH4-N是影响H区蓝藻属水平分类差异的主要因素,影响L区蓝藻属水平差异的主要因素是Tw、TP、p H。(4)与以往传统藻类计数相比,还发现了以往显微观察难以发现的聚球藻属和拟柱孢藻属等,且聚球藻属在东湖蓝藻门中占优势地位,应在以后的研究中得到更多的关注。     

基于湖心水库的洞庭湖治理新理念

基于"湖心水库"的基本思想,提出"变湖为库、清污分流、蓄洪排污、流水不腐"的洞庭湖全新治湖理念。利用二维水动力模型,分析了西洞庭湖湖心水库建设对行洪、补水、水环境的影响,探讨其运用的可行性。结果表明:湖心水库的分洪蓄水能有效降低西洞庭湖内洪峰水位,缓解湖区的防洪压力;湖心水库的补水在枯水期能有效抬升开湖航道水位,改善通航条件;同时湖心水库的补水增大了开湖航道及湘江尾闾航道内水流流速,加速了水体交换,对洞庭湖水环境有利。     

Water quality and transparency characteristics during the Planktothrix abundance period in shallow Lake Kasumigaura,Japan

Cyanobacterial blooms in lakes cause serious environmental problems on a global scale. Planktothrix (a filamentous cyanobacterium) blooms occurred during winter and spring from 2007 to 2011 in Lake Kasumigaura, a eutrophic lake located in Japan. This study analysed water quality during the period of Planktothrix abundance (2007–2010) at the centre of Lake Kasumigaura and compared it to that in the succeeding period, which did not have Planktothrix blooms (2012–2015). The average phytoplankton biovolume during the abundance period was larger than that in the succeeding period, which would contribute to the high chemical oxygen demand (COD_Mn; annual average of 9.7 mg/L) in the abundance period, compared to the succeeding period (7.6 mg/L). The total phosphorus concentration peaked in spring and summer in the abundance period, but only in summer in the succeeding period, whereas the seasonal variation in total nitrogen concentration between the two periods was relatively small. The annual average transparency (Secchi disc depth) increased before the abundance period due to a decrease in fixed suspended solid, which is comprised mainly of inorganic matter. It is likely that the change in irradiance conditions affected the occurrence of Planktothrix blooms.     

不同空间分辨率遥感数据识别湖泊的误差分析

湖泊面积及空间分布是表征水情变化的重要指示因子,对研究气候变化和人类活动对水资源的影响具有重要作用。如何利用遥感影像进行湖泊制图和面积估算是当前遥感应用研究中的难点问题。从实际应用需求出发,采用GF-1/WFV(Wide Field View)、Landsat-8 OLI(Operational Land Imager)、MODIS(Moderate-Resolution Image Spectroradiometer)遥感数据,选用安徽省受人类活动影响较大的54个湖泊为研究区域,采用NDWI二值分割法得到湖泊水体信息,使用30,500 m和1 000 m 3种空间分辨率的遥感影像进行湖泊制图,探讨制图精度与湖泊形态之间的关系。结果表明:湖泊分形维数值越大,湖泊形态越复杂, Kappa系数越高,面积误差越小;遥感影像分辨率越高,湖泊制图结果的Kappa系数和总体精度越高。