Formation and water environmental evolution of the Nansihu Lake

Through high-resolution research of sedimental chronology and the sediment environmental indexes, such as graininess, minerals, magnetic parameters, pigment content, organic carbon and chronology in Ds-core and Ws-core in Nansihu Lake, the authors analyze the formation cause of the Nansihu Lake and its water environmental changes. Historical documents are also analyzed here in order to reach the conclusion. Researches indicate that the Nansihu Lake came into being about 2500 aBP and its evolution succession can be divided into four stages. In this evolution process, several scattered lakes merge into one large lake in the east of China. This process is distinctively affected by the overflow of the Yellow River, the excavation of the Grand Canal and other human activities.

Characteristics of Water Environment in Regions of Zhaling and Eling Lakes near Waterhead of Yellow River

Conditions of the water environment in the region of the Zhaling and Eling lakes, which are located in the frozen earth zone on the Qingzang plateau, are unique. The equilibrium of the water quantity of the two lakes is maladjustment under the condition of a dry and cold climate in which evaporation is greater than precipitation. The Zhaling and Eling lakes have been atrophying, leaving three lake terraces and star studded lagoons around the two lakes since Holocene. When these lagoons were separated from the original lakes, they became cut lake basins, and were transformed from fresh water lakes into salt water lakes, salt lakes or salt playas owing to strong evaporation. This kind of evolutionary process will continue in the future.

Ecological and environmental water demand of the lakes in the Haihe-Luanhe Basin of North China

The purpose of this paper is to present a brief concept of the ecological and environmental water demand of lake. The present situation and affecting factors of lake ecological system in the Haihe\|Luanhe Basin of North China was analyzed. The calculating method of the ecological and environmental water demand of the lake basis on the water body and the calculating method of the ecological and environmental water demand of the lake basis on the aquatic ecosystem, wetland and vegetation were compared and discussed. As the examples of Baiyangdian Lake and Beidagang Lake in Haihe\|Luanhe river basin, the ecological and environmental water demand of the two lakes was calculated to be 27×10\+8m\+3. It is 6.75 times to the water demand according to the calculating method of the ecological and environmental water demand of the lake basis on the water body. The research result indicated: (1) The calculating methods of the ecological and environmental water demand of the lake basis on the aquatic ecosystem should be better than only basis on the water body of lake. (2) The data, such as area of the vegetation kind around and in the lake, the vegetation coefficient, the evaporating amount of the vegetation and the vegetation water demand itself around and in the lake are lack and urgent need. Some suggestions for controlling and regulating the water resource of the lake in North China were proposed.

Current Situation and Comprehensive Control Measures of Water Environment in the Chaohu Lake

Based on the analysis of current situation of water environment in the Chaohu Lake,general ideas and measures of controlling the water environment were proposed. In respect of control ideas,controlling outbreaks of blue-green algae should be as one of control goals; it is needed to combine reducing the quantity of blue-green algae with decreasing eutrophication level to make the decrease in the quantity of blue-green algae larger than their natural increase until outbreaks of blue-green algae are eliminated; all kinds of techniques should be combined closely,integrated and innovated,and corresponding safeguard measures should be adopted. In respect of control measures,controlling sources of pollution and intercepting pollutants are basic measures,of which improving sewage treatment capacity and standard greatly is a key measure,and actively controlling pollution from large-scale livestock and poultry breeding is one of main measures; rivers polluted heavily should be controlled,and using microorganisms to purify small and moderate rivers can be as one of preferred techniques; blue-green algae should be dredged deeply to reducing their quantity; water should be transferred from the Yangtze River to the Chaohu Lake or the Hauihe River to purify water bodies and increase environmental capacity; reed wetland should be restored on a large scale to increase vegetation coverage from 5% to 20%; dredging should be combined with the elevation of basement of restored reed wetland.

Multisource Disaster Chain and Control in Regional Water Environment of the Dongjiang Lake in China

On the background of analysis on region water environment safety in the Dongjiang Lake of south-central China, the source of pollution of water environment and its control are studied. The concept of region environment disaster chain is put forward on the basis of combination study on the disaster chain theory and pollution problem in regional water environment. Through identification and analysis of pollution disaster resources in regional water environment of the Dongjiang Lake, the annual emission of the chemical oxygen demand (COD), ammonia nitrogen, total phosphorus (TP) and heavy metal (Cd, As, Pb) are counted. According to evaluation on structure proportion of contaminants in the Dongjiang Lake, agricultural non-point source is the uppermost pollution source, which accounted for 87.74% in total pollution load. Ammonia nitrogen, TP and COD are mainly contaminants accounted for 94.27% in total pollution load. By analyzing danger of contaminants in the lake, basic form of disaster chain of water environment pollution is built elementarily. It shows characteristics of branches and trunk basin disaster chain and embodies multisource disaster implication chain caused by human activities. Then, disaster resources chain-cutting methods for pollution prevention and control of regional water environment of the Dongjiang Lake are analyzed.

Extracting water body data based on SDWI and threshold segmentation:A case study in permafrost area surrounding Salt Lake in Hoh Xil,Qinghai-Tibet Plateau,China

There are a large number of lakes,rivers,and other natural water bodies distributed in the permafrost area of the Qinghai-Tibet Plateau(QTP).The changes in water bodies will affect the distribution of water resources in sur-rounding areas and downstream areas,resulting in environmental impact and bringing potential flood disasters,which will induce more serious issues and problems in alpine and high-altitude areas with a fragile habitat(such as the QTP in China).Generally,effective,reasonable,and scientific monitoring of large-scale water bodies can not only document the changes in water bodies intuitively,but also provide important theoretical reference for subsequent environmental impact prediction,and disaster prevention and mitigation in due course of time.The large-scale water extraction technology derived from the optical remote sensing(RS)image is seriously affected by clouds,bringing about large differences among the extracted water result products.Synthetic aperture radar(SAR)RS technology has the unique advantage characteristics of all-weather,all-day,strong penetration,and not being affected by clouds,which is hopeful in extracting water body data,especially for days with cloudy weather.The data extraction of large-scale water bodies based on SAR images can effectively avoid the errors caused by clouds that become prevalent at present.In this paper,the Hoh Xil Salt Lake on the QTP and its surrounding five lakes are taken as the research objects.The 2-scene Sentinel-1 SAR image data covering the whole area on 22 August 2022 was used to verify the feasibility of extracting water body data in permafrost zones.Furthermore,on 22 August 2022,the wealth here was cloudy,which made the optical RS images,e.g.,Sentinel-2 images full of clouds.The results show that:using the Sentinel-1 image and threshold segmentation method to extract water body data is efficient and effective with excellent results in permafrost areas.Concretely,the Sentinel-1 dual-polarized water index(SDWI),calculated by combining dual vertical–vertical(VV)polarized and verti-cal–horizontal(VH)polarized data is a useful index for water extraction and the result is better than each of the VV or VH polarized images.

Potential Renaturalisation of Lakes as An Element Building Up Water Resources： An Example of Mosina Lake, Poland

Water deficits observed in many regions of the world make it necessary to implement measures intended to improve this situation. Poland is one of the countries with the poorest water resources in Europe due to its natural conditions and human impact. As a result of land reclamation carried out over decades, many elements of its hydrographic system have been changed, and some of them, like lakes, have disappeared altogether. In the days of the socio-economic transformation and more frequent extreme events, what seems worth considering is the renaturalisation of non-existing lakes, an idea presented in this paper on a selected example.

Assessment of Aquatic Physico-chemistry and Eutrophication Rate at the Lake Tondano

The purpose of this research was conducted to determine the physical factors, namely water temperature, total dissolved solids, total suspended solids, electrical conductivity and chemical water including pH, phosphate, BOD （biochemical oxygen demand）, COD （chemical oxygen demand）, DO （dissolved oxygen）. The factors of physics and chemistry can affect the rate of eutrophication. The data obtained through laboratory analysis of physical and chemical parameters of water samples. Water samples were taken from 8 observation stations. Highly variable results were obtained in each observation station. Data physical parameters were tested with statistical multiple linear regression to determine the effect on water quality, the results show that the physical properties do not affect the rate of eutrophication in Lake Tondano. That is, the amount of total dissolved solids content and total suspended solids, will not affect the rate of eutrophication in Lake Tondano. The results of multiple linear regression satistik test against chemical parameter data that is phosphate, BOD, COD and DO showed as a significant effect on the rate of eutrophication in lakes. The higher phosphate levels will be higher as the increase of the rate of eutrophication in Lake Tondano.

Response of artificial lake algae growth to water quality and meteorological conditions in plateau area

The problem of water environment caused by algal blooms is very common and serious.Effective methods of algal bloom control are one of the focuses of current research.Compared to natural lakes,the artificial lake environment is relatively simple,and it is a good place to study the effects of meteorology and water quality on algae growth.The study selected three typical artificial lakes in Kunming City of Yunnan province as research areas.The water quality,meteorology and algae growth characteristics of these three artificial lakes were monitored and analyzed,the response relationship of artificial lake algae growth to water quality and meteorological conditions were revealed.Results showed that nitrogen nutrients,N/P ratio and the temperature of water environment,air CO2 concentration are the mainly factors affecting the growth of algae in these three lakes,and the total phosphorus concentration has no significant effect on algae growth.The research conclusions can provide a basis for exploring the mechanism of environmental factors affecting algae growth and the governance of eutrophication of lakes in the plateau.

Three decades of changes in water environment of a large freshwater Lake and its relationship with socio-economic indicators

Tai Lake(Ch: Taihu) has attracted international attention forcyanobacteria blooms.However, the drivers of cultural eutrophication, especially long-term socio-economic indicators have been little researched. The results of research demonstrate how socioeconomic development affected quality of water and how it has been improved by anthropogenic activities. This study described variability in indicators of water quality in Tai Lakeand investigated thedrivers. Significant relationships existed between concentrations of annual mean total nitrogen(TN), total phosphorous(TP), chemical oxygen demand(COD) and biological oxygen demand(BOD), and population, per capital gross domestic production(GDP) and sewage discharge(p < 0.05). However, mechanisms causing change varied among TN, TP, COD and BOD. Before 2000, the main contributors to increases in concentrations of TN were human population, GDP and volumes of domestic sewage discharges. After 2000, discharges of industrial sewage become the primary contributor. After 1998, the regressions of annual mean TN, TP and COD on per capital GDP, population and domestic sewage discharge were reversed compared to the former period. Since 1999, an apparent inverted U-shaped relationship between environmental pollution and economic development has developed, which indicated that actions taken by governments have markedly improved quality of water in Tai Lake. The statistical relationship between BOD and per capital GDP didn't conform to the Kuznet curve. The Ushaped Kuznet curve may offer hope for the future that with significant environmental investments a high GDP can be reached and maintained without degradation of the environment, especially through appropriate management of industrial sewage discharge.

Water environmental planning and management at the watershed scale:A case study of Lake Qilu,China

Water environmental planning and management has become essential for guiding the water pollution control activities.Past water pollution control activities have been site specific,with little thought on water quality standard reaching at the watershed scale.Based on the watershed approach,a seven-step methodological framework for water environmental planning and management was developed.The framework was applied to water environmental planning and management of the Lake Qilu watershed in Yunnan Province,China.Results show that the reduction amount of total nitrogen(TN)under the plan is 1,205 tons per year so that the target of environmental capacity can be reached in 2020.Compared with traditional methods,the framework has its prevalence and could be generalized to analogous watersheds.

Eco-environmental vulnerability assessment for large drinking water resource： a case study of Qiandao Lake Area, China

The Qiandao Lake Area （QLA） is of great significance in terms of drinking water supply in East Coast China as well as a nationally renowned tourist attraction. A series of laws and regulations regarding the QLA environment have been enacted and implemented throughout the past decade with the aim of negating the harmful effects associated with expanding urbanization and industrialization. In this research, an assessment framework was developed to analyze the eco-environ- mental vulnerability of the QLA from 1990-2010 by integrating fuzzy analytic hierarchy process （FAHP） and geographical information systems （GIS） in an attempt to gain insights into the status quo of the QLA so as to review and evaluate the effectiveness of the related policies. After processing and analyzing the temporal and spatial variation of eco-environmental vulnerability and major environ- mental issues in the QLA, we found that the state of eco- environmental vulnerability of the QLA was acceptable, though a moderate deterioration was detected during the study period. Furthermore, analysis of the combination of vulnerability and water quality indicated that the water quality showed signs of declination, though the overall status remained satisfactory. It was hence concluded that the collective protection and treatment actions were effective over the study period, whereas immediately stricter measures would be required for protecting the drinking water quality from domestic sewage and industrial wastewater. Finally, the spatial variation of the eco-environmental vulnerability assessment also implied that specifically more targeted measures should be adoptedin respective regions for long-term sustainable develop- ment of the QLA.

Change of lake area in the southeastern part of China's Badain Jaran Sand Sea and its implications for recharge sources

Understanding the relationship between the changes in lake water volume and climate change can provide valuable information to the recharge sources of lake water. This is particularly true in arid areas such as the Badain Jaran Sand Sea, an ecologically sensitive area, where the recharge sources of lakes are heatedly debated. In this study, we determined the areas of 50 lakes （representing 70% of the total permanent lakes in this sand sea） in 1967, 1975, 1990, 2000 and 2010 by analyzing remote-sensing images using image processing and ArGIS software. In general, the total lake area decreased from 1967 to 1990, remained almost unchanged from 1990 to 2000, and increased from 2000 to 2010. Analysis of the relationship between these changes and the contemporaneous changes in annual mean temperature and annual precipitation in the surrounding areas suggests that temperature has significantly affected the lake area, but that the influence of precipitation was minor. These results tend to su- pport the palaeo-water recharge hypothesis for lakes of the Badain Jaran Sand Sea, considering the fact that the distribution and area of lakes are closely related to precipitation and the size of mega-dunes, but the contemporaneous precipitation can hardly balance the lake water.

Major Elements in Lake Muhazi,Rwanda,East Africa

The aim of this study undertaken at Lake Muhazi in Rwanda was to determine and analyze the major elements present in water. The presence of many major elements （Al, As, Ba, C, Ca, Cu, Fe, H^＋, K, Mg, Mn, N, P, S, Si, and Zn） was determined by spectroscopic technique. The concentrations of the elements were measured in water samples taken from three different locations of the lake from May to August 2008. The lake is polluted by water flow from mountain sides surrounding the lake. Other causes of pollution could be the use of agrochemicals in the sugar land, which surrounds the lake, and human activities near the lake. Finally, we proposed the strategies that can be applied in order to ensure good conservation of the environment and to prevent augmentation of heavy materials into the lake.

Estimation of the rational water area for controlling wind erosion in the dried-up basin of the Ebinur Lake and its effect detection

埃比纳·莱克区域被描述为“一个格林迷宫”在“ Xinjiang MapRecords：河的记录“然而，在 1910 出版了在这个区域的生态学和环境严重由于人的活动的影响被堕落了在期间最近 40 年。渴起来，有 107.4 km^2 的一个区域的湖盆在它的西北的部分形成，是没有植被，盖住 byunconsolidated 淤泥沉积物，并且在北方 Xinjiang 成为了灰尘天气的主要灰尘来源之一，并且有 4.8x10 ~ 6t 的年度数量的灰尘被大风从有 164 天的 Alataw 山脉差距从这个区域吹一年里的发生的大风。为在弄干起来的湖盆在湖区域和有效地控制的风侵蚀改进生态学的埃比纳·莱克的合理的水区域和流入在在弄干起来的湖盆分析在沉积物的小粒的作文之间的当前的生态的问题和关系以后用水平衡方程被估计并且灰尘天气，和最近的年里的生态的效果被监视。为在弄干起来的湖盆在湖区域和有效地控制的风侵蚀改进生态学的 theEbinur 湖的水区域应该至少是 800 km^2，这被考虑，并且湖应该在 7.92x10 ~ 上的再装的表面流量和地下水的年度体积 8 m^3。

Developing a comprehensive evaluation method for Interconnected River System Network assessment:A case study in Tangxun Lake group

The Interconnected River System Network (IRSN) plays a crucial role in water resource allocation, water ecological restoration and water quality improvement. It has become a key part of the urban lake management. An evaluation methodology system for IRSN project can provide important guidance for the selection of different water diversion schemes. However, few if any comprehensive evaluation systems have been developed to evaluate the hydrodynamics and water quality of connected lakes. This study developed a comprehensive evaluation system based on multi-indexes including aspects of water hydrodynamics, water quality and socioeconomics. A two-dimensional (2-D) mathematical hydrodynamics and water quality model was built, using NH3-N, TN and TP as water quality index. The IRSN project in Tangxun Lake group was used as a testbed here, and five water diversion schemes were simulated and evaluated. Results showed that the IRSN project can improve the water fluidity and the water quality obviously after a short time of water diversion, while the improvement rates decreased gradually as the water diversion went on. Among these five schemes, Scheme V showed the most noticeable improvement in hydrodynamics and water quality, and brought the most economic benefits. This comprehensive evaluation method can provide useful reference for the implementation of other similar IRSN projects.

EFDC(Environmental Fluid Dynamics Code)模型在湖库水环境模拟中的应用进展

EFDC模型是当前广泛使用的三维水环境生态模型,也是美国环保局(USEPA,United States Environmental Protection Agency)推荐使用的模型之一。本文简述了EFDC模型的发展历程和基本原理,并对近5年来,EFDC模型在湖泊和水库环境下,关于水动力、水质及富营养化、沉积物及毒物、环境容量和TMDLs(Total Maximum Daily Loads)计划等方面的主要研究成果进行评述。同时,本文也探讨了当前湖库水环境模拟研究中存在的主要问题,并对其发展趋势和前景进行了展望。

西藏易贡湖流域地表水水化学特征及其控制因素

为探究易贡湖流域地表水水化学特征及其控制因素,以藏东南易贡湖流域为研究对象,采集了26组地表水样,绘制了水样点主要离子线性变化趋势图、Gibbs图及Piper三线图等,运用相关分析、线性趋势分析、数理统计和离子比等方法。分析了研究区地表水主要离子特征及其控制因素,揭示了研究区地表水水中的主要物质来源。结果显示:易贡湖流域地表水阳离子主要为Ca^(2+)、Mg^(2+),K^(+)和Na^(+)含量较低,4种阳离子的含量关系为:Ca^(2+)>Mg^(2+)>Na^(+)>K^(+),阴离子主要为HCO_(3)^(-)、SO_(4)^(2-)和Cl-,NO_(3)^(-)和F^(-)含量较低,阴离子含量关系为:HCO_(3)^(-)>SO_(4)^(2-)>Cl->NO_(3)^(-)>F^(-),H_(2)SiO_(3)浓度值变化平稳,围绕6.9 mg·L^(-1)上下波动变化,pH值沿程变化平稳,在7.84~8.37之间,水体属于弱碱性。Ca^(2+)、Mg^(2+)和HCO_(3)^(-)是构成易贡湖流域地表水中的3种主要离子,水化学类型以HCO_(3)^(-)Ca·Mg或HCO_(3)^(-)Ca型为主。岩石溶滤作用是主要控制因素,阳离子交替吸附作用和蒸发浓缩作用均相当微弱,人为活动影响十分有限。

不同调水方式对巢湖水质影响模拟

引调水工程是目前用来改善湖泊水质的重要手段,然而引调水的调水路线、来水水量以及来水水质对湖泊水质改善效果都至关重要。本文以“引江济巢”工程为例,针对巢湖的浅水湖泊特征,考虑引调水入湖后不仅对水量和水质有直接改善作用,还可能因为湖区水动力条件改变及内源释放影响水质,通过构建二维水动力水质模型,模拟不同调水路线、水量下湖区水动力条件,进一步考虑不同来水水质和底泥释放对水质改善的影响。结果显示,调水对流场的扰动在丰水年较弱、枯水年较强,流量对湖区水质影响随流量增大而增强,来水水质的优劣是决定湖区水体水质是否改善的关键。整体而言,西湖区受调水影响较小,东湖区能够对全湖水质变化起到指示作用。调水方案应基于湖泊实际水量与水质状态综合考虑调水流量与水质制定。

乌梁素海浮游植物群落特征及湖区富营养状态研究

乌梁素海是黄河流域最大的湖泊湿地,是重要的天然水生态屏障。为摸清乌梁素海浮游植物群落结构、水体富营养状态及环境因子的影响,于2022年7月和9月在乌梁素海湖区设置3个采样点,对浮游植物和水环境指标进行调查监测,并对湖区营养状态和影响浮游植物的环境因子进行分析研究。结果显示:(1)两次调查共鉴定浮游藻类8门108种(属),绿藻和硅藻在种类上占主要优势。共筛选优势种7种,丰度的主要贡献物种为蓝藻门,其中伪鱼腥藻和环离鞘丝藻是绝对优势种。(2)Shannon-Wiener多样性指数均值为2.15,湖心水体污染程度高于湖区的南部和北部。(3)营养状态为轻度富营养~中度富营养。(4)浮游植物丰度受电导率、总磷和溶解氧影响,建议重点对总磷加强监测,并采取有针对性的措施进一步改善乌梁素海生态状况。研究成果可为乌梁素海水生态保护治理提供参考。