Development of a small lake: Ecotourism enterprise for Pandin Lake,San Pablo City,Philippines

This study examines the development of Pandin Lake, a small lake in the Philippines, particularly the unconventional evolution of the ecotourism enterprise for the lake and the accompanying issues. The study concludes that Pandin Lake ecotourism development is mainly an endogenous initiative and that the intervention of the relevant administrative agencies is critical in addressing the contemporary issues. This study discusses the following issues: (i) the reasons for studying small lakes in the Philippines; (ii) Pandin Lake and its administration; (iii) the ecotourism enterprise evolution and issues regarding the lake; and (iv) the conclusions. It also addresses the extant gap in Philippine lake literature: specifically the scarcity of scholarly works on development‐oriented studies, noting the field is dominated by limnology and aquaculture studies, and on small lakes, noting the field concentrates heavily on studies of big lakes.     

A common basis for analysis,evaluation and comparison of offstream water uses

Many analyses of water uses and their impacts on available resources fail to reflect the contribution of return flow to existing supply, misuse the term “efficiency”, and assume immediate savings by changes in irrigation. Sound resources management requires a method of analysis applicable to all classes of offstream water uses. Drawing on previous analysis, a Water Uses Assessment Equation is proposed: a methodology founded on the principle of rigorous water accounting. Examples of applications are provided together with misleading analyses and conclusions that might be avoided in the future through use of the equation.     

从南四湖水利管理局水管体制改革实践看管养分离运行机制

南四湖水利管理局自2006年以来按照国务院水管体制改革实施意见和水利部水管体制改革实施方案要求,全面推行了水利工程管理和维修养护分离。总结了水管体制改革取得的显著成效,结合基层工作实际分析了管理和养护运作过程中存在的一些问题,提出了完善措施及建议。     

Contribution to decision‐making on establishing the maximum water level for Lake Vegoritida

The water level in Lake Vegoritida, Greece, has undergone great changes over the past decades attributable to severe water abstraction directly from the lake and its catchment, which affected not only the conditions of the natural environment, but also social and economic conditions. The water level of the lake is currently rising, with discussion of an agreeable decision about the desired maximum lake water level becoming a source of conflict among the lake stakeholders. The present study provides a framework for a participatory management plan, with the perspective of engaging all levels of lake stakeholders in the process of deciding and establishing the maximum lake water level. Kolb's learning cycle is used as a methodological vehicle in the proposed process of participatory decision‐making. Its contribution to decision‐making includes (a) identification of lake stakeholders and the issues arising from a potential establishment of a maximum lake water level; and (b) three suggested water level scenarios to facilitate a future constructive discussion directed to establishing a maximum water level in Lake Vegoritida.     

Socio‐economic and institutional assessment of Malaysia's first biosphere reserve: Chini Lake

Despite being designated the first UNESCO Biosphere Reserve in Malaysia, the Chini Lake Basin experiences continuing management challenges attributable to existing sectoral management practices and differences in demands of multiple stakeholders. Accordingly, a socio‐economic survey and stakeholder consultative process were undertaken, involving relevant stakeholders in the lake basin. The consultative process involved: (a) identification and prioritization of relevant stakeholders; (b) assessment of their socio‐economic activities and perceptions; (c) organization of focus group discussions between basin stakeholders; and (d) development of management recommendations in collaboration with stakeholders. The results of this study indicated the local community's way of living has changed from traditional occupations to a wage economy. Overlapping functions and lack of communication were among the major identified challenges facing by Chini Lake. Multiple strategies were proposed to promote environmental protection and good governance of Chini Lake, including formation of special area plans and strengthening institutional arrangements to sustainably manage the Chini Lake catchment. An effective authority also is necessary to improve communication and coordination of programmes by the various basin agencies and communities.     

Patterns of Lake Balkhash water level changes and their climatic correlates during 1992–2010 period

The variation in Lake Balkhash water levels during the period from 1992 to 2010 and their relationship with climate dynamics were investigated in this study, using satellite altimetry data and meteorological records from climate stations located in the lake catchment basin. The altimetry‐derived water level demonstrated a general water level increase, reaching a mean value of 8.1 cm year^?1 in July 2005, with a maximum value of 342.52 m. The increased Lake Balkhash water level was accompanied by an overall upward trend in precipitation and temperature in the catchment basin during the study period. A strong increase in the winter and spring temperature was the main contributor to the general upward temperature trend, whereas a significant change of summer and autumn precipitation was the major contributor to the annual precipitation trend. Neither precipitation nor temperature increased uniformly across the entire lake drainage basin. The study results identified the most pronounced climate change occurring in the mountainous part (>2000 m above sea level) of the basin, in the upper reaches of the Ili river, which is the main water inflow to the lake. Statistical analysis indicated the Lake Balkhash water level is strongly correlated with both precipitation and temperature. The correlations were investigated for three altitudinal strata (<1000 m, 1000–2000 m, >2000 m) corresponding to the lower, middle and upper reaches of the Ili river. The best correlations were obtained for the upper reaches of the Ili river, indicating a changing snow cover and glacier equilibrium are the main factors controlling the water level trends in Lake Balkhash.     

Development of a system‐based water balance model to assess interrelated physical and anthropogenic constraints in lake and reservoir watersheds,applied to Coeur d'Alene Lake,Idaho, USA

This study presents a methodology for the development of a water balance model that uses publicly available data in a manner useful to water scientists and managers who manage complex lake and reservoir watersheds. The approach was applied to Coeur d'Alene Lake, a naturally occurring lake that is controlled by a dam located on its outlet (Spokane River) in North Idaho, USA. As in many other areas, the region surrounding Coeur d'Alene Lake has experienced high rates of population growth in recent years, and there is concern that, as consumptive water use increases, the lake will eventually not be able to be managed to simultaneously maintain the federally mandated minimum flow requirements in the Spokane River and also maintain the target summertime elevation of 2128 feet (648.6 m) for recreation and hydropower purposes. The complexity caused by the competing uses at Coeur d'Alene Lake makes it an excellent case study for similarly characterized watersheds. Both a natural flow model and regulated elevation model were developed, and sensitivity analysis was conducted on both models to evaluate which lake processes have the greatest effects on lake elevation, thereby requiring the most attention. A ‘low‐flow’ scenario was modelled to demonstrate the usefulness of the model and to inform Coeur d'Alene Lake regional stakeholders regarding the interrelationship between current water policy and the lake's physical behaviour under stressed conditions that could result from climate change. Model result indicates that, while lake elevation may be maintained at the summertime elevation of 2128 feet (648.6 m) under a low‐flow scenario, the outflows in the Spokane River start to approach the minimum flow requirements in the month of August. The developed approach is useful where publicly available data exist and allows for economic, yet rigorous, water resources systems evaluation without requiring significant field data collection.     

Degradation of Lake Ziway,Ethiopia: A study of the environmental perceptions of school students

Lake Ziway in Ethiopia is a freshwater lake supporting multitude uses, including irrigation, fishing, water supply and recreation. However, the lake is being degraded primarily because of various land‐ and water‐use activities in its watershed. Recognizing these human impacts on the lake's water quality and quantity, the perceptions of school students were surveyed under the belief that the future of the lake is largely dependent on this younger generation. The goal of this study was to better understand how students actually recognize the extent to which various human activities impact the water quantity and quality of Lake Ziway. As major stakeholders in their communities, the perceptions of school students from four high schools regarding the changes to the lake over time were investigated. Students were contacted by purposive sampling, based on criteria of student academic performances, and their proximity to the lake. Their perceptions were studied on the basis of an interview survey. The majority of students indicated that high levels of human activities, especially water abstractions and water pollution, were the main lake impacts. Students believe there is a lack of sustainable utilization and protection of the lake. They suggested coordinated activities among all lake stakeholders in the participation and decision‐making process to properly manage the lake. Provision of awareness to both local administrations and local communities, concern for establishing an appropriate regulatory body and allocating a sufficient budget, and strict controls on flower farm practices in the lakeshore, also was considered to be of high priority as a means of conserving the sustainability of the lake. The result derived from this survey has important implications for facilitating improved school curricula, and for federal, regional and district level water resource management authorities, in setting priorities and developing policies for the sustainability of Lake Ziway.     

Framework for surface water quality management on a river basin scale: Case study of Lake Iseo, Northern Italy

River (DESERT) and lake (EVOLA) water quality models are used to simulate the influences of alternative water quality management scenarios on the quality of receiving surface waters in the Lake Iseo basin, Northern Italy. The scenarios are representative of the European Union Directive on Urban Waste Water Treatment (91/271/EEC) and of the regional authority’s objective to reduce the total phosphorus loads from point sources entering Lake Iseo and to restore the lake as close as it is practically possible to its former natural qualitative state. Application of DESERT shows that the regional ‘Water Clean Up Plan’ can achieve similar reductions in total phosphorus concentrations in the basin’s main river system, Oglio River, to the 91/271/EEC directive, but at notably lower economic costs. Application of EVOLA to Lake Iseo shows that it is not practical to achieve the regional authority’s objective of a specific total phosphorus concentration in the lake by 2016. Instead, the results show that a more realistic, but higher, total phosphorus concentration can be achieved by 2016. The results of both modelling exercises indicate the usefulness of DESERT and EVOLA for comparing and assessing water quality management scenarios and for revising the regional authority’s final objectives with regards to total phosphorus concentration in Lake Iseo, as well as the regional ‘Water Clean Up Plan’ for restoring and safeguarding the quality of the basin’s surface waters.     

Optical and biological properties of Lake Ülemiste, a water reservoir of the city of Tallinn I: Water transparency and optically active substances in the water

Optical and biological measurements were performed in Lake Ülemiste in the summer of 1997 (four measurement days), and from May to October in 1998 (12 measurement days). This kind of data, describing the type and amount of optically active substances in the water, phytoplankton characteristics, the underwater light field, and temperature–oxygen situation in the lake are necessary when estimating the ecological state of the lake. Lake Ülemiste is the main drinking water reservoir of Tallinn, the capital of Estonia. Phytoplankton abundance and biomass, chlorophyll a and suspended matter were determined from collected Lake Ülemiste water samples in the laboratory. Spectrophotometrical processing of the filtered and unfiltered water was carried out to describe the beam attenuation coefficient spectra and optical influence of yellow substance in the water. Vertical profiles of downwelling irradiance of the PAR (400–700 m) region of the spectrum (and from these data the averaged over depth diffuse attenuation coefficient) were determined. The relative transparency of the water was estimated by using a Secchi disk. Passive optical remote measurements were episodically made from aboard a boat. Results obtained confirmed that Lake Ülemiste is turbid (almost hypertrophic), comparable with most turbid lakes in Estonia (e.g. Lake Võrtsjärv) and Finland (Lake Tuusulanjärvi). Its chlorophyll a content varied within the range 13–121 mg m^–3, phytoplankton biomass 3–107 mg L^–1, phytoplankton abundance 65 000–999 000 mL^–1, suspended matter 8–34 mg L^–1, effective concentration of the yellow substance 6–30 mg L^–1, diffuse attenuation coefficient of light in the PAR region 1.0–3.3 m^–1 and a Secchi disk depth of 0.5–1.75 m. The temporal variation of the spatial averages of these parameters during 1998 was analysed. Almost all characteristics showed an increase from May to midsummer with a maximum in late July or in August (correspondingly the Secchi depth values were minimal in late summer). The amount of yellow substance was an exception, which was nearly constant during the observation period. The maximum level of chlorophyll a content in July and August 1998 markedly exceeded that in 1997, despite the fact that the summer of 1997 was sunny, but the summer of 1998 was cold and rainy. The correlative relationships between the different parameters were investigated together with the respective data for other lakes. They show that the data of Lake Ülemiste supplemented the correlation graph in the region of turbid lakes, whereby in all cases the correlation coefficient increased following the addition of Lake Ülemiste data. The highest correlation coefficient was obtained when light attenuation coefficient values were correlated with a sum of weighted concentrations of chlorophyll a, yellow substance and suspended matter (multiple regression analysis).     

Eutrophication of lakes in urbanized areas: The case of Yaounde Municipal Lake in Cameroon, Central Africa

A 1 year qualitative and quantitative evaluation of phytoplankton and chlorophyll‐a, as well as some physicochemical parameters, was recorded in a shallow tropical lake in Cameroon: the Yaounde Municipal Lake. Physicochemical measurements also were regularly made in its main tributary (Mingoa Stream). These analyses aimed to assess the lake's trophic status and to propose measures for controlling its degradation process. The Secchi disk transparency was low and rarely exceeded 100 cm. Conductivity was higher near the lake bottom. The oxygen deficiency, and sometimes anoxia, recorded from a 2.5 m depth leads to high quantities of ammonium‐nitrogen. The total phosphorus concentrations varied from 80–2290 µg P L^?1 and the total Kjeldhal nitrogen concentrations fluctuated between 3 and 15 mg  L^?1. Upstream to the lake, in the Mingoa Stream, total phosphorus concentrations ranged from 0.6–3.8 mg P L^?1 and total Kjeldhal nitrogen concentrations ranged from 10–22 mg  L^?1. There are up to 102 phytoplankton‐specific taxa, with Euglenophyta and Chlorophyta particularly more diversified. The phytoplankton biomass and chlorophyll‐a concentrations reached 225 µg mL^?1 and 566 mg m^?3, respectively. The analyses pointed out the allogenic nature of the functioning of this ecosystem as a result of bad waste management in the surrounding landscape. Urgent actions need to be undertaken in order to rehabilitate this lake, which rapidly shifted to a hypertrophic status.     

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.     

The use of models for synthesizing knowledge for integrated lake basin management, and facilitating implementation of the World Lake Vision

Integrated water resources management (IWRM) is becoming increasingly accepted as the most logical and effective means of managing aquatic ecosystems for their sustainable use. Despite efforts to provide practical examples of the application of IWRM, we still lack knowledge on how to best consider and integrate the potentially large quantity of data and information, both scientific and socioeconomic, which must be considered in pursuit of the goal of sustainable water resources. The unique features of (i) an integrating nature; (ii) long water retention time, and (iii) complex response dynamics make the management of lakes and reservoirs particularly difficult to achieve. Although the World Lake Vision has provided substantial management guidance to address some of the complex issues facing lake and reservoir management, additional work directed to analysing the interactions and linkages between the scientific/technical and the socioeconomic components of the sustainability ‘equation’ is needed. This report examines the use of mathematical models as a synthesizing tool in developing and applying management strategies for lakes and reservoirs. The different types of available models, and the criteria that can be used to select the ‘best’ model for a given situation, also are discussed, as is the important role of environmental indicators in the process. A case study focusing on the restoration of Lake Fure in Denmark provides an illustrative example of the application of the approach discussed in this report.     

一起输水隧洞特大突泥涌水处理实例分析

牛栏江-滇池补水工程输水线路金奎地隧洞设计桩号K9+593处为灰岩与泥岩结合带,地质条件复杂,地下水位较高,施工开挖过程中先后发生两次较大规模的塌方和特大突泥涌水。初期拟采用超前大管棚、注浆及强支撑等支护措施进行处理,实际操作中管棚施工极为困难,处理效果极不理想,后决定采用绕线方案。分析了初始方案无法实施的原因,改线方案的技术要求和施工重点,相关经验可供类似工程突泥涌水处理借鉴。     

Adaptation of urban water supply infrastructure to impacts from climate and socioeconomic changes: The case of Hamilton,New Zealand

While the relations between climate variables and sectoral water demand have been well established in the literature, few studies have attempted to quantify changes in urban water usage with climate change. Concentrating on the city of Hamilton, New Zealand, we investigate possible water use and infrastructure needs for a range of climate and population projections. We find that water demand (at the monthly aggregate level) is largely driven by changes in population, and not significantly affected by changes in climate. However, as population increases, the effect of climate variables on per capita consumption will be magnified. Monthly aggregate changes may further mask potenially significant short-term shortages. In several scenarios, water supply shortages in 2030 occur with a 30--40% probability, suggesting needs for long-term capacity expansion or aggressive demand side management, rather than implementation of short-term management of water demand.     

Fishing community preferences and willingness to pay for alternative developments of ecosystem‐based fisheries management (EBFM) for Lake Naivasha,Kenya

Ecosystem‐based fisheries management (EBFM) is an important complement to existing fisheries management approaches to maintain ecosystem health and function; to translate goals and aspirations for sustainability into operational objectives, the preferences of the fishing communities should be considered for successful implementation of EBFM. This study analysed the preferences of the fishing community for alternative EBFM developments for Lake Naivasha, Kenya, and estimated the willingness to pay, using a choice experiment approach. Protection of fish breeding grounds, improving tilapia fish abundance and accessibility of fishing zones were identified as relevant EBFM attributes for the choice experiment. A monetary attribute (payment for fishing permit) was also included. In addition to a conditional logit model, mixed logit models are estimated to account for heterogeneity in preferences. This study results indicated fishing communities are most concerned about tilapia fish abundance and protection of fish breeding grounds. The welfare measures reveal that members of the Lake Naivasha fishing community are willing to pay a considerable sum of money for ecosystem services improvement, relative to their low income derived from fishing. These study findings highlighted that evaluating the preferences of the fishing community and valuing the fishery at an ecosystem level are vital to prioritize and choose between alternative interventions for sound implementation of EBFM.