Experiences and lessons learned from interventions in the Lake Victoria Basin: The Lake Victoria Environmental Management Project

The Lake Victoria basin has experienced a myriad of environmental changes leading to its degradation, and necessitating various interventions to be implemented. The purpose of this study was to review early development initiatives, past and ongoing interventions in order to document experiences and lessons learned from them. The methods used in this study include review of published articles, project reports, and personal opinions of experts and project implementers in the lake basin. There are numerous threats to the lake basin, the major ones being poor land use and agricultural practices, catchment deforestation, destruction of wetlands, pollution loading, fishing malpractices and invasion by exotic aquatic weeds. These threats have resulted in rampant land and wetland degradation, leading to poor water quality and consequent water loss, a decline in the diversity of the commercial fisheries, and the lake’s biodiversity in general, unsustainable use of natural resources, increased poor human health and food insecurity, with high levels of poverty among the riparian communities. Initiatives for socio‐economic development within the lake basin began as early as the turn of the 20th century, while intervention studies started as early as the 1920s. Current lake management intervention projects, such as the Lake Victoria Environmental Management Project (LVEMP), undertaken by the riparian states of the East African Community, have invested heavily in the lake basin, with the goal of addressing the above‐noted threats to the lake. Some pilot projects undertaken through the LVEMP include: (i) water quality and quantity monitoring; (ii) industrial and municipal management; (iii) fisheries studies; (iv) water hyacinth control; (v) wetlands; (vi) land use; (vii) catchment afforestation; and (viii) micro‐projects to alleviate poverty, to cite a few examples. Phase 1 of the LVEMP was a major effort in the history of the lake basin; hence, its critical examination. To this end, this study highlights, in chronological order, the experiences, achievements, challenges and lessons learned with regard to Phase 1 of the LVEMP.     

Geographic Information Systems (GIS) for the Determination of Inundation Maps of Lake Mogan,Turkey

Abstract

The use of geographic information systems (GIS) allows for a very efficient analysis of spatial hydrologic data for water resources projects especially for water control studies. In this respect, flood hydrographs for Mogan basin, Turkey for different durations and return periods are determined by using Soil Conservation Service (SCS) method. The basic parameter of the SCS method, curve number (CN), is evaluated by using GIS employing digital land use and hydrologic soil group data derived from analog maps. A Digital Elevation Model (DEM) of Mogan basin is constructed by making use of topographic maps with a scale of 1:25,000. Flood hydrographs for these three productive subbasins of Lake Mogan are attached and superimposed to obtain the total flood hydrographs. Total flood hydrographs entering into Lake Mogan are routed by Puls Method to determine the outflow hydrographs from the lake; then, associated lake levels are computed. Furthermore, inundation maps of Lake Mogan are obtained; these results are presented by GIS techniques.     

基于复合云模型的太湖流域水环境质量风险评价

针对太湖流域水环境质量风险评价问题,提出了评价指标体系。根据2011—2015年7个断面的实测数据对现有指标进行筛选,计算各指标的属性重要度,并选取较为重要的4个水质指标和富营养化指数;对实测水质数据和地表水环境质量标准等级,采用Shannon熵和云模型相结合的方法,利用最大隶属度原则得到太湖流域各年水环境质量风险评价的结果。结果表明该流域水环境质量处于中等风险水平,需要采取相应措施降低发生水污染事件的风险。评价结果可以为太湖流域的水质改善提供一定的科学依据。     

Carrying capacity and vulnerability of four Asian lakes: A comparative study

To present axes for evaluating the water resources, lake environment and water use in a lake and its watershed, a comparative study was done for four East Asian lakes; lake Kasumigaura (Japan), Lake Laguna (Philippines), Lake Songkhla (Thailand) and Lake Dianchi (China). Two axes were then determined from the relationship between: (1) water use and water supply rate, and (2) water use and water quality. To clarify the meanings ‘carrying capacity’ and ‘vulnerability’, the maximum population density in the lake basin and total nitrogen concentration in the lake water were calculated and discussed to decide the direction of environmentally sound management of the drainage basin.     

Watershed management in the Lake Ohrid region of Albania and Macedonia

Lake Ohrid is the oldest lake in Europe and one of the oldest lakes in the world, formed 4–10 million years ago. Lake Ohrid serves as a refuge for numerous freshwater organisms from the tertiary period, whose close relatives can be found only as fossils. A breeding programme that artificially hatches the native and endemic trout supports the natural recruitment of lake Ohrid trout and since 1935 the lake has been stocked with more than 600 million young trout. The critical transboundary issue for Lake Ohrid water quality is phosphorus pollution. The current phosphorus load of the lake is estimated at 150 ton per year and needs to be reduced to 50 ton per year to keep the mean concentration of phosphorus below 7 mg m^–3 in the lake water. In 1996, a Memorandum of Understanding between the Macedonian and Albanian governments was signed and a binational Lake Ohrid Management Board was established, with substantial funding by the Global Environmental Facility. Both governments agreed to undertake appropriate legal, institutional, investment and technical measures to protect Lake Ohrid. The Lake Ohrid Conservation Project has four main goals: (i) to develop the institutional legal and regulatory framework for environmental management in the Lake Ohrid watershed; (ii) to establish a comprehensive binational monitoring programme, (iii) to mobilize and secure commitments from all the stakeholders in the watershed who will need to take measures to prevent degradation of the lake; and (iv) to increase public awareness and participation. Harmonizing Albanian and Macedonian laws and regulations may be the Lake Ohrid Conservation Project’s greatest challenge, particularly on fisheries and wastewater treatment issues.     

A national research and development blueprint for sustainable lake basin management in Malaysia

The deterioration of water quality in lakes resulting from unsustainable catchment practices requires concerted efforts to address them, in the form of cooperation among government agencies and institutions, private bodies and the community‐at‐large. Research that provides an understanding of a lake's ecosystem is an important aspect of making informed decisions for sustainable management and governance of lakes. The present study describes the findings of literature reviews on Malaysian lakes, and the national efforts made to establish an agenda for lake research and development in Malaysia directed towards integrated lake basin management (ILBM). The main findings and outcomes of the National Lake Research Blueprint workshop in April 2014 on the issues facing lakes and reservoirs are highlighted. Seven research themes were identified, namely (i) ecosystem services and socio‐economic development, (ii) governance, (iii) water quality and pollution, (iv) eco‐hydrology and basin management, (v) biodiversity and natural products, (vi) physical limnology and hydrodynamics and (vii) technology. The goal is to enhance research and development on sustainable lake basin management directed to conservation and development targets. The findings of this study provide an integrated research framework that can support ILBM governance elements (pillars) elsewhere, and to call for researchers to participate in much‐needed research areas.     

洱海水质评价

本文对洱海流域水环境状况进行了系统全面评价。评价结果表明洱海污染源以面源为主，湖面降水和内源释放次之，工业和城镇生活的污染贡献率相对较低。洱海的主要超标污染物是总磷和汞，其中总磷污染最为严重。洱海从1992～2001年富营养化水平保持在中营养水平，现正处于中营养向富营养湖泊的过渡阶段。洱海在1993～2000年之间，总硬度和总氮上升趋势明显。洱海运行水位对洱海水体总磷的变化影响明显。     

Poyang Lake basin: a successful, large-scale integrated basin management model for developing countries

Protection of water environment while developing socio-economy is a challenging task for lake regions of many developing countries. Poyang Lake is the largest fresh water lake in China, with its total drainage area of 160,000 km2. In spite of rapid development of socio-economy in Poyang Lake region in the past several decades, water in Poyang Lake is of good quality and is known as the "last pot of clear water" of the Yangtze River Basin in China. In this paper, the reasons of "last pot of clear water" of Poyang Lake were analysed to demonstrate how economic development and environmental protection can be coordinated. There are three main reasons for contributing to this coordinated development: 1) the unique geomorphologic features of Poyang Lake and the short water residence time; 2) the matching of the basin physical boundary with the administrative boundary; and 3) the implementation of "Mountain-River-Lake Program" (MRL), with the ecosystem concept of "mountain as source, river as connection flow, and lake as storage". In addition, a series of actions have been taken to coordinate development, utilisation, management and protection in the Poyang Lake basin. Our key experiences are: considering all basin components when focusing on lake environment protection is a guiding principle; raising the living standard of people through implementation of various eco-economic projects or models in the basin is the most important strategy; preventing soil and water erosion is critical for protecting water sources; and establishing an effective governance mechanism for basin management is essential. This successful, large-scale basin management model can be extended to any basin or lake regions of developing countries where both environmental protection and economic development are needed and coordinated.     

Management Options to Improve Water Quality in Lake Peipsi: Insights from Large Scale Models and Remote Sensing

Nutrient pollution causes frequent blooms of potentially harmful cyanobacteria in Lake Peipsi (Estonia/Russia). Although external nutrient loading has reduced since the 1990s, lake water quality has barely improved, and eutrophication is still considered a threat to lake biota and water usage. To understand the recovery dynamics of the lake it is necessary to analyse the effects of land use and lake management on water quality to develop mitigation strategies. Comprehensive analysis has thus far failed due to information gaps inherent to conventional monitoring strategies. We show how two large-scale hydrological models using Earth observation data provide spatial information on pollution and can help explain the causes of past and current lake eutrophication. WaterGAP3.2 provides valid estimates of present and probable future phosphorus concentration in the lake water, based on past hydrological conditions. WaterWorld models spatial potential water quality and a scenario of optimal pollution reduction. Remotely sensed optical water quality data can be used to analyse recent, spatial water quality dynamics. The spatial and temporal algae distributions and can help explain eutrophication causes at Lake Peipsi and its catchment, adding value to in situ monitoring and supporting river basin management with large scale data.

     

Water quality assessment of a tropical coastal lake system using multivariate cluster,principal component and factor analysis

Statistical techniques represent a reliable tool for classifying, modelling and interpreting surface water quality monitoring data, particularly for lakes. The complexity associated with the analysis of a large number of measured variables, however, is a major problem in water quality assessments. Multivariate analysis, such as cluster analysis and factor analysis (FA), was utilized in this study for the analysis of water quality data (including water discharges and 28 water quality parameters) for Akkulam–Veli Lake, a tropical coastal lake system in Kerala, India. This lake is partially divided into two sub‐systems, namely Veli Lake and Akkulam Lake. Akkulam Lake exhibits freshwater characteristics, in contrast to Veli Lake, which exhibits saline water characteristics because of its close proximity to the sea. Thus, studying this lake provides insights into water quality variations in both a freshwater and saline water lake in a tropical region. Water quality patterns and variations in Akkulam–Vela Lake over three seasons, including pre‐monsoon (PRM), monsoon (MON) and post‐monsoon (POM), also were studied, utilizing multivariate techniques. The organic pollution factor played a significant role on lake water quality during PRM. The influence of organic pollution tends to decrease during MON and POM, a particular situation faced by urban lakes in tropical regions. Polluted stretches in a lake system during different seasons can easily be ascertained by hierarchical cluster analysis. Further, the factors affecting a lake system as a whole, as well as for a particular sampling site, can easily be identified by FA. Improved water quality can be observed during POM. Akkulam and Vela lakes exhibit a wide variation in water quality during all seasons, a finding that corroborates a water flow obstruction from Akkulam Lake to Veli Lake because of the bund existing between the two lakes. The location of the bund is identified as the major reason for different hydrochemical processes in A–V Lake.     

Prioritization of pollution potential zones for conservation activities of a lake system

Many coastal lakes are under serious threats due to increased pressures associated with population growth, accelerated eutrophication, invasive species and toxic contamination. The extent of the pollution depends almost entirely on the characteristics and processes taking place in the lake basin. The objective of this study was to identify the pollution potential zones (very high, high, medium and low) in the Akkulam–Veli (A–V) Lake Basin (Thiruvananthapuram, Kerala) using GIS‐enabled, multithematic overlay analysis. The primary characteristics considered were geomorphology, lithology, land use, soil, slope and population density. The results of this study indicated the major portion of the lake basin exhibits very high or high pollution potential zones, with the drains passing through the very high pollution potential zone being mainly responsible for the contamination of the lake water. High population density, predominant commercial use and settlement with mixed tree crop, level and gentle slope (low slope) are the factors responsible for the very high pollution potential. The organic pollutants in the lake system increase with the increased extent of the very high pollution potential area. This analysis approach will help authorities to identify the underlying causes of lake water quality degradation and plan and implement effective measures for protecting the lake. This process can also be utilized by scientists elsewhere to facilitate lake protection.     

The current problems of Lake Baikal ecosystem conservation

The greatest world reservoir of fresh water, the unique Lake Baikal, is at risk from anthropogenic influence. Three stages of economic activity in the lake region can be distinguished: (i) poor economic uses, (ii) increase of economic uses after the construction of the hydropower station dam on the outflow of the lake, and (iii) intensive increase of economic activity, characterized by the intensive use of mineral fertilizers, transportation, log rafting, growth of population around Baikal, mass development of tourism, the construction of the Baikal-Amur railroad and pulp combines. Chemical and biological pollution of the lake, fishing and hunting, the state of coasts and protected areas are discussed. The regions most affected are listed. The greater long-term influence is an increase in the mineralization of tributary waters due to forest cutting and land cultivation. Though the influence does not cause a decline in water quality, the properties of the Baikalian water in local sites of pollution can significantly differ from their initial state. The quality of water, however, is within the limits of requirements for fresh drinking water.     

地表雨水径流对上海海港新城滴水湖水质的影响分析

滴水湖是一个面积约4．5km^2的人工湖，位于上海海港新城的市中心。降雨期间，城市地表径流经过规划的网状水系汇入到滴水湖，经过与湖沟通的海闸排到东海。根据远景规划，滴水湖的水质需要满足城市娱乐和景观用水要求。因此，维持滴水湖良好的水质显得尤为重要。耦合一个简单的城市降雨一径流模型，CE-QUAL-W2水质模型被用来模拟远景年滴水湖的水质。模拟了3个不同年降雨概率的典型年。即2003（90％）、2004（50％）和2002（10％）年。模拟的污染指标主要有溶解氧（DO）、藻类、生化需氧量（BOD5）、总磷（TP）、氨氮（NH3-N）和总氮（TN）。结果显示，在3个典型年里滴水湖的综合水质能够维持在地表水Ⅲ～Ⅳ类。比较而言，在90％降雨保证率年，滴水湖的水质最好，因为地表径流最小以至携带的地面污染负荷最少。从各污染指标的日平均值来看，在各个典型年里DO优于Ⅲ类，因此远景年的水质对湖中的鱼类等生物几乎没有负面影响。     

太湖流域典型支沟生态环境调查研究——以新沟河为例

为应对太湖流域水污染问题,我国2005年开始实施了引江济太工程,提高了太湖湖区和引排干流的水体自净能力和水环境容量,而对于太湖流域众多分支河网水质的直接改善作用有限,该部分相关研究与关注也较少。以引江济太工程主要通道新沟河为例,选取典型支沟(湖)开展多种生态环境因子的调查与分析。研究结果表明:支沟(湖)均为Ⅳ类以下水质,其中大部分为劣Ⅴ类,主要特征污染因子为氮磷营养盐等;浮游植物Shannon-Wiener多样性指数和Pielou均匀度相对较高的河段出现在北阳湖、西横河西段等区域。总体上支沟(湖)生态环境情况空间分布特征明显,环境质量健康程度如水质级别、富营养化程度、生物物种多样化和均匀化等指标,均与不同区域的水体交换能力和环境容量表现出显著的相关性。从污染源的角度来看,支沟(湖)的生态环境威胁主要来自于生活污水排放与富营养化等陆源污染。     

常熟市昆承湖生态修复对策

结合历史数据和现状调查,对常熟市昆承湖水下地形、沉积物、污染源和湖泊水环境质量现状进行了研究。结果显示昆承湖水体都达到富营养化阶段。面临的主要问题有湖泊生态系统退化、点源污染、面源污染、城镇生活污水、渔业养殖污染和河网水体污染等。提出了污染综合防治、河口强化净化型湿地建设、生态护坡与湖滨带湿地建设、湖区养殖围网拆除、清淤与湖盆形态修复、湖区植被恢复与生态修复和湖泊生态管理等一系列整治对策。     

Recovery of Burrowing Mayflies (Ephemeroptera: Ephemeridae: Hexagenia) in Western Lake Erie

Burrowing mayflies (Hexagenia spp.) are native to western Lake Erie and were abundant until the 1950s, when they disappeared due to degraded water and sediment quality. Nymphs were absent from the sediments of most of western Lake Erie after the 1950s, although small, widely disjunct populations apparently persisted near shore. Sediment samples collected in 1993 revealed several small populations near the western and southern shores and beyond the mouths of the Detroit and Maumee rivers. A larger population was found in the southern island area, but nymphs were absent in the middle of the basin. By 1995, nymphs had spread throughout the western half and eastern end of the basin but remained absent from the middle of the basin. These data indicate that Hexagenia began recolonizing nearshore areas before offshore areas. Increasingly large swarms of winged Hexagenia on shore and over the lake between 1992 and 1994 further indicate that mayflies are recolonizing the basin. Factors that have permitted Hexagenia recovery in western Lake Erie probably include improved sediment and water quality attributed to pollution abatement programs implemented after the early 1970s, and perhaps environmental changes in the early 1990s attributed to effects of the exotic zebra mussel (Dreissena polymorpha)     

新疆博斯腾湖二维水质数学模型研究

博斯腾湖流域经济总产值占全州经济总量的80%以上,是巴州工农业生产的重要聚集区域。然而,随着流域社会经济的快速发展,流域污染物的产生量、入湖量和污水排放量日益增加,点源污染和面源污染逐年加剧,博斯腾湖已由淡水湖泊演变为微咸湖。因此,建立二维水质数学模型,分析矿化度变化规律,为博斯腾湖的环境管理及环境保护规划等提供科学依据。     

Study of water quality distribution in Lake Biwa in consideration of runoff pollutant loads from its catchment basin.

Many strategies for water quality conservation in Lake Biwa are being carried out mainly by reducing runoff pollutant loads into the lake. But influence of the runoff load reduction on the water quality in Lake Biwa has not been clarified enough so far. This study is aimed at discussing methodology to estimate water quality distribution in Lake Biwa using runoff pollutant loads from its basin. The runoff loads from the basin are calculated by Macro Model with GIS database of the Lake Biwa basin, and the water quality distribution in the lake is estimated by the spline technique with the calculated runoff loads. As a result, it has been proved that the methodology has enough reproducibility to estimate the water quality distribution in Lake Biwa and is available to examine the water quality in the lake.     

牛栏江—草海补水与西园隧洞协同运行方案研究

滇池草海是昆明城区居民休闲娱乐的重要场所和城市名片。为加快草海水体循环与交换、提升湖区水环境质量,近期陆续实施了牛栏江—草海应急补水工程、新老运粮河水体净化生态工程、海埂大堤水体置换通道工程和西园隧洞工程,为草海环湖截污和清污分流提供了必要的水资源条件,实现了湖区清污水的分向流动,缩短了清流区水体的换水周期。工程协同运行结果表明：草海清流区水质与牛栏江来水状况线性相关性显著,TP浓度主要受牛栏江来水影响与控制,TN浓度受入湖河流水质影响显著;清流区水质浓度与西园隧洞工程排水量相关性显著,并随着排水量增加呈现明显的改善趋势;牛栏江—草海补水工程适宜的补水规模为3.0 m3/s,在通过海埂大堤水体置换通道排水维持湖面良好水景观的同时,牛栏江来水应尽可能通过西园隧洞出口排水,以便最大程度地发挥草海各项水污染治理工程的综合效益。     

苏州市相城区水环境状况及污染防治对策

分析了苏州市相城区主要入阳澄湖(水源型湖泊)河道的水质现状,发现各水体水质均超出相应的标准限值,主要污染成因为:面源污染源强大,污水集中处理率偏低,水利工程破坏了天然的水力联系,工业企业布局散乱等。针对该区水环境形势的紧迫性,提出了面源控制、工业生态改造、污水处理、引水冲污、两湖强制性保护等污染防治对策。