Water quality estimation in consideration of pollutant runoff and internal production in Lake Biwa, Japan.

Lake Biwa is the largest lake in Japan, and water quality in the lake is heterogeneous. Therefore, it is important for water quality management that spatial distribution of water quality in the lake should be clearly understood. The objectives of this study are to show a methodology and to develop a simulation system to calculate COD distribution in Lake Biwa taking internal COD production into consideration. This study also aims to examine transition of COD in the lake using the simulation system. In the simulation system, runoff loads of COD from the Lake Biwa basin are calculated by Macro Model for each tributary. The external COD concentration in 233 inshore meshes of the Lake Biwa water surface was calculated using the runoff loads. The internal COD was calculated using relationships among limiting nutrients, chlorophyll-a and COD. Then, the spatial distribution of water quality in Lake Biwa was calculated both for the external and internal COD by spline technique. Simulations using the system were implemented for 1986-1998, and a clear difference in characteristics between a drought year and a flood year was shown. In the result, it was shown that the simulation system developed here was available to calculate COD distribution in Lake Biwa, and that it had the possibility to explain the recent phenomenon of COD increase in the lake.     

Response of Hydrodynamics and Water-quality Conditions to Climate Change in a Shallow Lake

Lake water resources operation and water quality management come up with higher challenges due to climate change. The frequency and intensity of extreme hydrological events are increasing under global warming, which may directly lead to more uncertainty and complexity for hydrodynamic and water-quality conditions in large shallow lake. However, studies about effects of climate change on lake hydrodynamic and water-quality conditions are not enough. Thus, a coupled model is es-tablished to investigate the potential responses of lake water level, flow field and pollutant migra-tion to the changing climatic factors. The results imply that water flow capacity and self-purification in the Hongze Lake can be improved by west, northwest, north, south and southeast winds indi-cating wind filed change has a great effect on the hydrodynamic and water-quality conditions in large shallow lake. It is further observed that both hydrodynamics and water quality are more sensitive to rainfall change than to temperature change; compared to the effect from temperature and rainfall, the effect from wind field appear to be more pronounced. Moreover, the results verify the feasibility of coupling basin hydrological model with lake hydrodynamic and water quality model. To the best of knowledge, the coupled model should not be used until independent calibra-tions and verifications for hydrodynamics and water quality modeling, the hydrological model and the coupled model.

     

Influence of influent tributaries on water quality changes in Lake Mogan, Turkey

Lake Mogan, located in the steppes of central Anatolia, is a vital Turkish ecological system, in terms of its water resources, flora and fauna. The lake also is a unique recreational area for Ankara, the capital of Turkey. However, the lake is currently threatened by severe pollution, being under the risk of serious degradation because of (i) uncontrolled urbanization; (ii) point and non‐point source pollution; (iii) inefficient sewerage systems; (iv) sediment transportation and pollution via influent creeks to the lake; (v) uncontrolled soil erosion in its drainage basin; (vi) inappropriate flood control measures; and (vii) severe degradation of the natural wetlands within its drainage basin. This study evaluates the influence of its influent creeks on the water quality of Lake Mogan, mainly because the creeks are believed to be responsible for the major pollutant load reaching the lake, and because the extensive database documenting this situation has not previously been critically evaluated. Accordingly, this study reviews (i) change in the water quality of Lake Mogan between 1993 and 2002; (ii) the water quality classification of the major influent creeks feeding Lake Mogan; and (iii) the influence of the influent creeks on the water quality of the lake between 1993 and 2004.     

千岛湖现状污染负荷分析与限制排污总量研究

根据千岛湖水质现状和水功能区划,确定2015年和2020年千岛湖水质保护目标的污染物浓度,核算现状污染负荷量。将现状CODMn、NH3-N和TP污染负荷量作为千岛湖CODMn、NH3-N和TP的纳污能力,即千岛湖湖区CODMn、NH3-N和TP指标纳污能力分别为16420 t/a、2225 t/a和434 t/a。采用狄龙模型核算千岛湖TN指标的纳污能力,2015年千岛湖TN质量浓度目标值为0.88 mg/L,对应湖区限排总量为3468 t/a;2020年将千岛湖TN质量浓度目标值进一步提高至0.8 mg/L,此时对应湖区TN限排总量为3176 t/a。     

Strategy of water pollution prevention in Taihu Lake and its effects analysis

Taihu Lake, the third largest freshwater lake in China, is located in the Chanjiang Delta of the Yangtze River. Its waters are used by agriculture, industry and as major drinking water for several cities including Shanghai and Wuxi. The lake also is important for tourism, aquaculture and flood control. Taihu Lake and its surrounding areas are facing three major water-related threats: deteriorating water quality with inflow and runoff from its watershed; flooding during the rainy seasons; and water shortages during drier months. Noxious algae blooms are occurring with increasing frequency and water quality continues to decline. Remedial actions implemented to date have been ineffective. This paper proposes that the problems could be remedied by constructing a by-pass channel (BPC), which would divert low-quality water from the lake during low precipitation periods and allow better quality water to flow into the lake during high flow periods. This remedial action would simultaneously deal with the deteriorating water quality of Lake Taihu and maintain its water level at a desired level. A preliminary assessment of this strategy shows that, if the BPC were implemented, the water quality of Taihu Lake would be improved significantly in few years, the flood disaster would be greatly mitigated, and the water shortage problem in the basin would be alleviated.     

镇江金山湖水体污染源解析

分析了2012年金山湖各监测段的水质情况,并对金山湖水体污染源进行解析。结果表明,运粮河入流水质较差,金山湖TN值超标;降雨地表径流是金山湖的第一大污染源,并且城镇地表径流所产生的污染物的负荷及浓度要远高于农田地表径流;由于截污工程的实施,工业生产废水与城镇生活污水对污染的贡献率较低。     

气候变化对可可西里盐湖流域湖泊水量变化的影响分析

湖泊是气候变化的敏感指示器。为了研究气候变化对湖泊水量的影响,以盐湖流域为研究区,应用统计方法对1989—2018年降雨、气温、蒸发进行线性趋势和突变分析,采用多源卫星遥感技术对湖泊面积等水文要素进行监测,分析湖泊面积与气象要素、湖泊面积与湖泊水量之间的相关性。利用VIC模型模拟径流并结合计算的冰川水量得到盐湖径流组成,定量探讨气象要素对湖泊水量变化的影响,综合分析2011年前后气象要素影响流域湖泊水量的差异。结合统计分析与水文模型定量计算可知:年降雨量、年平均气温显著升高,年蒸发量呈下降趋势,且与湖泊面积有较好的相关性。湖泊面积与湖泊水量间相关性较高,可间接体现气象要素对湖泊水量变化的影响。2011年前卓乃湖和盐湖水量变化主要受降雨量影响,库赛湖和海丁诺尔湖水量变化主要受气温影响;2011—2014年4个湖泊水量变化主要受降雨量影响;2015—2018年4个湖泊水量变化中降雨增加量、冻土释水和地下水补给增加量、冰川融水量对湖泊扩张的贡献约为34.48%、57.66%、7.86%,气温变化成为影响湖泊水量变化的主要因素,降雨量影响次之。     

Phosphates in Lake Chapala, Mexico

Lake Chapala, the most important lake in Mexico, has suffered from cultural eutrophication problems for many years, manifested by the growth of aquatic vegetation and an increase in primary productivity. It was found that about 70% of the total phosphorus entering Lake Chapala is orthophosphate, thus increasing the biological availability of nutrients in the lake. In addition, the hydrologic imbalance in the lake, caused by the over‐use of water resources along the Lerma–Chapala basin, has significantly increased the hydraulic residence time of the inflow waters, thus increasing the effects of the added phosphorus, and creating conditions that increase the lake’s eutrophication status. The shallow characteristics of the lake and the action of the wind forces produce rapid changes in water quality, especially in the distribution of phosphate. The focus of this paper is on the development of a historical orthophosphate balance in Lake Chapala, quantifying the main point and non‐point sources that contribute to the enhancement of this nutrient in the lake. The estimation of the amount of phosphate in the lake can be used to determine appropriate management practices to reduce the phosphate loads on the lake.     

Present status of submerged macrophyte growth in Lake Biwa: Recent recovery following a summer decline in the water level

Whole‐lake areal distribution of submerged macrophyte growth in Lake Biwa was surveyed using aerial photographs in 1994 and 2000, when unusual declines in the water level of approximately 1 m occurred in the dry summers. The estimated total areas of the submerged macrophyte communities were 1441 ha for 1994 and 2825 ha for 2000. In the shallow and eutrophic southern basin, the bottom area covered by vegetation gradually increased year by year after 1994, and the ratio of this area to the total surface area of the basin in 2000 amounted to 52%. The dominant species were two natives, Hydrilla verticillata and Myriophyllum spicatum, and one exotic, Egeria densa. Changes in physical conditions and water quality associated with the decline in the water level, as well as the reactions of submerged plants to aquatic environments and ecosystem dynamics, are discussed.     

Modelling Effects of Remedial Programs to Aid Great Lakes Environmental Management

Computer simulation of remedial programs was carried out employing a large and diverse information base on both point and nonpoint pollutant sources in the Great Lakes basin to provide a more holistic environmental management perspective. The process utilizes a cascading system of sub-basin unit area pollutant loads (classified by land use and land form), per capita municipal pollutant inputs, river transmission factors, and remedial program effectiveness, in terms of reduced loadings to the lakes and costs. It was employed by PLUARG (Pollution from Land Use Activities Reference Group) to determine scenarios of remedial programs which apparently were practicable and would achieve target lake loads of phosphorus most cost-effectively. The analysis, presented here for Lake Erie, Lake Ontario, and southern Lake Huron, provides a means of evaluating the effectiveness of various remedial program options to fulfill commitments by Canada and the United States to load reductions for these lakes. The methodology can be extended to other pollutants as sufficient data become available to permit a suitable degree of resolution for management decisions.     

Drainage basin security of hazardous chemical fluxe in the Yodo River basin.

The Yodo River basin consists of three major tributary basins (and other small river basins) namely Uji, Katsura and Kizu, which overlap respectively Shiga, Kvoto and Nara prefectures' administrative areas. Lake Biwa, the largest lake in Japan, drains water through the Uji river. The water quality of the lake, in terms of BOD, continuously improved over the last decade. However, the quality in terms of COD did not show any improvement in spite of a large amount of infrastructure finance being introduced. Eutrophication of the lake still continues, showing no improvement in the nitrogen concentration level. Non-point as well as point source control is not strong enough. There is a gap between BOD and COD evaluations of the lake water quality. Hazardous chemical fluxes are estimated based upon PRTR reports of Japan (2001). PCBs are still discharged into the lake, although the report of Shiga Prefecture showed zero discharge. Dace fish monitoring clearly showed that PCB contamination of the fish had not changed since the 1980s in spite of a ban on use and production of PCBs in the 1970s. There is still leakage of PCBs into the lake. The major exposure of dioxins to Japanese is fish rather than meat and eggs. The risk of water contamination must take into consideration not only drinking water safety but also ecological magnification of food chains in water. The ecological health aspect of hazardous chemicals is also important, such as organotins with imposex of sea snails. Finally, public participation in hazardous chemical management is very important using the method of risk communication based upon the annual report of PRTR in Japan.     

综合保护工程对杭州西湖生态环境的影响

通过对综合保护工程实施前后西湖生态环境变化情况的调查、监测,评价综合保护工程对西湖生态环境的影响。研究结果表明,综合保护工程对西湖生态环境有着显著的影响。工程实施后,西湖的自然形态发生了很大的变化,流域内污染物削减量明显,入湖溪流和西湖水质改善效果明显,流域内生物多样性有所增加。研究成果对我国城市湖泊的治理与生态修复具有较强的示范与借鉴作用。     

岱海湖水位对气候要素与土地利用的响应

利用Mann-Kendall检验、Hurst系数法、基于有序聚类法的t检验等方法分析湖区水位演变趋势;利用Partial Mantel检验法,并通过构建缺失资料地区的湖区水文模型,探究了典型半干旱区湖泊岱海湖水位对气候要素与土地利用变化的响应。结果表明：岱海湖水位1959—2018年呈现显著下降趋势,于1982年和2005年发生突变,未来水位将呈现持续降低趋势;岱海湖春季受融雪影响导致水位较高,秋季受用水影响导致水位较低,且秋季水位降低在四季中最为明显;气候变化与水土资源开发利用是影响半干旱区湖泊水位变化的主要因素,在气候变化条件下,岱海湖水位对气温变化最为敏感,对日照变化的响应次之;由于岱海湖流域降水-产流-下渗机制较为复杂,岱海湖水位对降水变化的响应具有滞后性,流域林草面积增加可能是引发岱海湖水位降低的重要因素。     

再生水为水源的城市湖池生态环境需水量计算

以再生水为湖池水源可缓解城市水资源紧缺现状,但存在因再生水水质标准低、易发生水体富 营养化的问题。计算湖池生态环境需水量,定期对湖池进行补水和换水,以保证湖池生态环境的健康。 基于污染物质平衡原理,采用换水周期法,建立兼顾水量和水质生态环境需水计算模型。以西安市沣庆 湖为例,估算生态环境需水量,计算结果为:沣庆湖换水周期冬季为125ｄ、夏季为53ｄ。沣庆湖年平均生 态环境需水量为24．37万ｍ3。     

Modeling the effects of human influences on water quality and quantity in the Zarrineh River Basin,Iran

This study aims to analyze the environmental and economic impacts of land use change and water abstraction in the Zarrineh River basin, which is Lake Urmia’s main inflow source in the north-west of Iran. The Soil & Water Assessment Tool (SWAT) is used to model water quantity and quality in the basin. Environmental Kuznets Curves (EKC) are used to assess the relationship between environmental degradation and the development of the agricultural sector. Two scenarios were employed to identify the effects of dam construction and land use change on stream flow, evapotranspiration, groundwater recharge and nitrate loads in the area. The SWAT model showed a satisfactory to very good performance for monthly stream flow at most of the gauges in calibration and validation periods as well as a reasonable performance for nitrate loads. The estimated EKC indicates that the environmental degradation in the inverted U-shape that has passed its peak and the rate of degradation has decreased. Based on the scenarios, the dam has a strong impact on nitrate loads in the basin and water inflow into Lake Urmia. Results verify that human influences have had negative impacts on the Zarrineh River basin. In particular, the extensive development of the agricultural sector has not only drastically reduced the inflow of water to Lake Urmia accelerating the drying up of the lake, but it has also increased nitrate loads. Therefore, it can be recommended to take counter measures within the catchment area to improve the ecological status of Lake Urmia.     

Updated phosphorus loads from Lake Huron and the Detroit River: Implications

The binational Great Lakes Water Quality Agreement (GLWQA) revised Lake Erie’s phosphorus (P) loading targets, including a 40% western and central basin total P (TP) load reduction from 2008 levels. Because the Detroit and Maumee River loads are roughly equal and contribute almost 90% of the TP load to the western basin and 54% to the whole lake, they have drawn significant policy attention. The Maumee is the primary driver of western basin harmful algal blooms, and the Detroit and Maumee rivers are key drivers of central basin hypoxia and overall western and central basin eutrophication. So, accurate estimates of those loads are particularly important. While daily measurements constrain Maumee load estimates, complex flows near the Detroit River mouth, along with varying Lake Erie water levels and corresponding back flows, make measurements there a questionable representation of loading conditions. Because of this, the Detroit River load is generally estimated by adding loads from Lake Huron to those from the watersheds of the St. Clair and Detroit rivers and Lake St. Clair. However, recent research showed the load from Lake Huron has been significantly underestimated. Herein, I compare different load estimates from Lake Huron and the Detroit River, justify revised higher loads from Lake Huron with a historical reconstruction, and discuss the implications for Lake Erie models and loading targets.     

太湖典型小流域非点源污染物流失规律研究

由农业产生的非点源污染是湖泊的主要污染源.为了研究太湖流域非点源污染负荷流失规律,选择了宜兴梅林小流域为研究对象,对降雨过程中径流流量及其污染物浓度随降雨-径流变化过程进行了监测研究.采用统计和系统分析方法,建立径流量和非点源污染负荷输出量之间的数学统计模型,得出该流域非点源污染物流失规律,以期将此方法推广到与该流域相似的其它地区的非点源污染研究中去,对太湖流域水污染综合治理也具有重要意义.     

盐湖流域空-天-地立体监测系统结合VIC模型径流模拟初探

盐湖流域属于无资料地区且基础资料稀缺,使用传统方法开展水文模拟存在困难。为了研究盐湖流域生态环境、水文气象等变化,综合利用卫星遥感、无人船等技术,建立盐湖流域空-天-地立体监测系统,构建盐湖水位-面积-容积关系曲线,并通过月尺度遥感数据解译了盐湖月尺度湖泊面积,推算了盐湖蓄变量和盐湖入湖月尺度径流量。通过收集并整理中国区域地面气象要素驱动数据集CMFD和MODIS LAI叶面积指数等数据,构建了基于多源数据的VIC模型,开展盐湖流域湖泊径流模拟研究。结果表明,盐湖流域径流模拟纳什系数NSE和相对误差分别为0.87和11.81%,表现出实际径流的丰枯变化情况。盐湖流域空-天-地立体监测系统结合VIC模型能够模拟盐湖流域的月尺度径流变化过程,对无资料区域河湖水文模拟具有一定参考意义。     

简述乌伦古湖入湖水量及湖水位情势分析

由于乌伦古河河川径流具有连续枯水年且枯水时段长的特点,且乌伦古河在连续枯水年份出现断流是一种不可抗拒的自然因素,需要在流域综合规划指导下,具体研究吉力湖和布伦托海入湖水量及水位变化情势,尽可能恢复乌伦古河流域原有生态,保障洄游性鱼类所需要的流量要求,显著减少布伦托海湖水向吉力湖倒灌发生的时间和倒灌水量,使乌伦古湖和周边生态系统有所好转。     

Restoration scheme for macrophytes in a hypertrophic water body, Wuli Lake, China

This report analyses the relevant factors that influence the restoration of macrophytes in hypertrophic water bodies, including hydrology, water quality and sediment. Wuli Lake in China is used as a case study for the goal of achieving limno‐ecosystem protection and sustainable development. This report also identifies and discusses some potential macrophyte restoration measures, including pollution control at the source and reducing external pollutant loads to the lake, and environmental restoration measures to improve lake water quality and sediment conditions. The potential for the sustainable management of the lake ecosystem also was explored from the perspective of new restoration systems and mechanisms.