Friendship and Cooperation

The Chinese National Committee on Large Dams is honoured to be the host of ICOLD 55th Executive Meeting in Beijing from 18 to 23 May 1987,by the accep-     

Least‐cost analysis and the O and M problem

A major problem affecting public projects in many developing countries is that of inadequate standards of operation and maintenance (O and M). There are various reasons but the overriding one is the shortage of public funds and foreign exchange. Despite the efforts now being made to alleviate the problem it is likely to continue to be a major constraint which should be taken fully into account in the planning and analysis of public projects.

In the planning of irrigation, water supply, power and other projects a choice often exists between technical alternatives with high capital costs and low recurrent costs and others with the opposite pattern of expenditure. Apart from technical factors the final selection is usually based on least‐cost economic analysis, using the conventional discounting methodology whereby all costs, both capital and recurrent, are discounted at what is taken to be the opportunity cost of capital (usually 8 to 15%). These relatively high discount rates favour low capital — high recurrent cost alternatives, even though in practice these are often not desirable, because of the O and M difficulties that will occur.

In many developing countries capital funds for public projects are readily available, from foreign aid, whereas recurrent finance, which is normally provided by the government, with little foreign assistance, is much scarcer. It is argued that in such cases the use of a single discount rate for all types of expenditure is unrealistic. A better . approach would be to apply different interest rates for different types of expenditure, to take account of their differing opportunity costs. In the situation of capital abundance and recurrent funds scarcity, for example, capital costs would be valued differently from recurrent costs. This would be done by means of shadow pricing, the costs for the various types of expenditure being adjusted to take account of their relative opportunity cost, in the same way as adjustments are made for unskilled labour, foreign exchange and other factors in conventional economic analysis.     

Changes in the Coastline and Water Level of the Akşehir and Eber Lakes Between 1975 and 2009

The Ak?ehir and Eber Lakes, relatively shallow, small freshwater lakes with an area of 361 km² and 150 km² and average depth of 7 m and 2 m (1998), respectively in southwestern Turkey, have experienced a severe decline in water levels in recent decades. This study aimed to investigate coastline and water level changes of lakes and identify the causes for the decline in lake levels. Nine Landsat images from different times, monthly temperature, precipitation, discharge, lake level records and population data were used to analyze these changes. From 1975 to 2009, the water surface areas of the Ak?ehir and Eber Lakes decreased from 356,929 to 126,482 km² and from 119,882 to 85,663 km², a loss of 64.5% and 28.4% over the 34-year period, respectively. From 1975 to 2004, the Ak?ehir Lake level declined by 2.67 m from 956.02 m to 953.35 and the Eber Lake level declined by 2.03 m from 966.75 m to 964.72 m from 1975 to 2004 based on ground lake level data (in situ). The results of the temperature and precipitation analysis showed that although the annual mean climatic factors vary substantially, they show small increasing trend over the record periods. Annual discharge records on the Akarçay River and its tributaries decreased over the basin during the same period. Irrigation systems, three dams and seven pounds built in recent decades for agricultural irrigation and domestic use, made the major impact on lowering the lake levels because they derive water from the river for human use upstream of the lakes’ catchments. Population growth, rising water consumption for agricultural and domestic purposes and building dams has led to lake levels declining. The change of lake levels might depend more on anthropogenic factors than on climatic factors.     

Seminar on Cavitation and Cavitation Erosion in Water Conservancy and Hydroelectric Engineering

61 specialists and scholars assembled at the Institute of Xinjiang ShiheziAgriculture from August 25 to 30,1988,for a seminar on cavitation and cavitationerosion occurred in water conservancy and hydroelectric engineering.The partici-pants came from 33 design and research institutes,universities,factories allover the country.The main subjects under discussion of the conference are:1.     

Mini and Small Hydropower in Europe——Development and Market Potential

For centuries, Small HydroPower (SHP) has been an importantsource of energy in all Europeancountries possessing waterpotentials. With the invention of moresophisticated turbines in the twenti-eth century, mini and small hydroplants were used for electricity gen-eration and became the main source     

人生需要Cakes and Ale

<正>《寻欢作乐》[英]威廉·萨默塞特·毛姆著叶尊译译林出版社2014年版我们定义生活里正常的男人女人大概是这样的:长相普通,性格大众,礼貌而妥帖,忙忙碌碌,日复一日。这样的人很多,但总是没什么吸引力,事实上,人们乐意见到、谈论乃至结交的是那些不那么"正常"的人类,就像毛姆所塑造的罗西那样。评价这部小说,少不得要聊些二     

El Niño-Southern Oscillation and Rainfall Variability in Central and Southern Sudan

Abstract

In this study, the effects of the El Niño-Southern Oscillation (ENSO) on the rainfall variability in the central (Savannah) and southern (Equatorial) regions of Sudan are examined. The annual rainfall data from 12 rainfall stations for 49 years are used in this examination. The results of the study show that the areal annual regionally averaged rainfall values in the two regions have decreased markedly since the early 1960s, with co-existence between the driest years and the warm ENSO events. The correlation between the annual regional rainfall values and the ENSO events is found to be relatively higher for the Savannah region than for the Equatorial region. Two regional ENSO-rainfall prediction models are developed, one for each region. These models use the ENSO sea surface temperature. The results of the models test show that both models can significantly improve the predictability of the annual rainfall values, which is essential for the planning and the management of water resources in Sudan     

The Research and Application of BP Neural Networks in River-basin Water and Sediment

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河海大学Water Science and Engineering创刊

国家新闻出版总署日前正式批复，同意河海大学创办英文期刊Water Science and Engineering（水科学与水工程）。该刊为季刊，面向国内外公开发行，国内统一连续出版物号为：CN32—1785／TV。     

Private and Social Cost—Benefit Perspectives and a Case Application on Reservoir Sedimentation Management

ABSTRACT

Management of a river system is usually a difficult task due to conflicting water use purposes.

The Jacui river (southern Brazil) has a drainage area of 70000 km², with hydroelectric plants in its upper reach and three navigation dams in the middle and lower reaches. The former dams are used to meet peak power demand, producing great flow variations during weekdays and volume reduction during weekends. The navigation dams do not allow year round navigation due to sediment deposition, low-flow and upstream flow fluctuation.

A hydrodynamic model was used to study flow routing, to test operation rules for the navigation dams and to forecast the levels in real time. In this paper, the calibration of the model and the operational criteria to be applied to each of the navigation dams during low-flow periods are presented.

The model was calibrated with two recorded events showing maximum errors compatible with the river navigation requirements. Dam operation simulations showed that with the help of the model, intermittent navigation conditions can be established for the low-flow season.     

The Eternal Cause That Keeps Abreast of the Time and Promotes Harmony between Man and Nature

~~The Eternal Cause That Keeps Abreast of the Time and Promotes Harmony between Man and Nature     

Concentrations and loads of nutrients and major ions in the Niagara River, 1975–2018

Environment and Climate Change Canada has monitored Niagara River water quality in support of the Great Lakes Water Quality Agreement since establishing a fixed site at Niagara-on-the-Lake in 1975. Using over 40 years of data from this site along with the Fort Erie location added in 1983, we examine the status and trends of concentrations and loadings of nutrients and major ions and assess evidence of sources between the two stations. Trends were observed for the majority of measured parameters and there is strong agreement between trends in concentrations and loadings which are generally higher at the downstream site; however, upstream/downstream differences indicate relatively little loading occurs along the length of the river itself. For total phosphorus (TP), inputs from Lake Erie via the Niagara River account for the majority of loading to Lake Ontario and, in some years, exceed the 7000 MTA Lake Ontario target. Between 2014 and 2018, we calculate the mean Niagara River TP loading to be 5275 MTA. We highlight the major changes in water quality constituents over time, including TP, and reveal increased seasonal consumption of TP and SiO₂, reflecting potential increases in the biological productivity in Lake Erie. The long and rich Niagara River dataset, which comprises year round sampling (including rare winter data), provides detailed tracking of changing Great Lakes water quality and could be further utilized to assess the impacts of climate change, improve understanding of diatom and harmful algal bloom dynamics, and enhance knowledge of in-lake major ion and nutrient dynamics.     

Total and methyl mercury accumulation in 1994–1995 Lake Michigan lake trout and forage fish

As part of the Lake Michigan Mass Balance Project, total and methyl mercury were determined for lake trout (Salvelinus namaycush) and five forage fish species collected from Lake Michigan near Saugatuck, Michigan, and Port Washington, Sheboygan Reef, and Sturgeon Bay, Wisconsin, between 1994 and 1995. With a mean concentration of 179 ng/g wet wt., whole lake trout total mercury (Hg_T) concentrations ranged between 27.6 and 348 ng/g wet wt. For combined sites, 1–4 yrs, 5–6 yrs, 7–11 yrs, and 12–15 yrs lake trout mean Hg_T concentrations were 73.7, 130, 212, and 280 ng/g, respectively. Forage fish species alewife (Alosa pseudoharengus), bloater (Coregonus hoyi), slimy sculpin (Cottus cognatus), deepwater sculpin (Myoxocephalus thompsoni), and rainbow smelt (Osmerus mordax) had mean Hg_T concentrations of 63.8, 55.3, 36.7, 51.4, and 35.2 ng/g wet wt., respectively. With the exception of alewife, bloater, and slimy sculpin, all fish species contained approximately 100% methyl mercury (MeHg). Field bioaccumulation factors (BAF) were consistent with a Lake Michigan food chain that is more efficient at transferring MeHg to higher trophic levels than some inland lakes. This and other studies of lake trout from Lake Michigan document decreasing Hg_T concentrations in lake trout from 1971 to 1985 and constant or increasing concentrations between 1985 and 2000. These observations were supported by a similar trend in Lake Michigan Hg sediment fluxes. To our knowledge, this is the most intense two year study of mercury in fish for any Great Lake or other large fresh water system and is one of the most complete studies of mercury cycling in the Lake Michigan food chain.     

Are Pulp and Paper Mills Sources of Toxaphene to Lake Superior and Northern Lake Michigan?

Toxaphene was a broad-spectrum pesticide consisting of a mixture of highly chlorinated bornanes and bornenes. After its ban in 1982, toxaphene concentrations have shown a general decline in the environment as a whole and in most of the Great Lakes specifically. Recent work, however, shows that toxaphene concentrations are not decreasing in fishes from Lake Superior and northern Lake Michigan. Non-atmospheric, relatively localized sources are a possible explanation for these observations. For example, toxaphene could be inadvertently produced and released by pulp and paper mills, which could be synthesizing toxaphene-like compounds as a byproduct of bleached paper production. Reported here is a study of surficial river sediment collected upstream and downstream from seven pulp and paper mills, from five areas of previous toxaphene use, and from two presumed pristine locations. Concentrations of toxaphene found downstream are similar to those found upstream from each of the pulp and paper mills. Concentrations in sediment from rivers near previous toxaphene use locations were higher than concentrations in the background samples. These data suggest that pulp and paper mills are not now sources of toxaphene but that toxaphene used as a pesticide in the Great Lakes basin (although these uses were very small compared to its use in the southern US) could be a potential source.     

Water distribution systems and on-farm irrigation practices: limitations and consequences for Afghanistan’s agricultural productivity

The absence of a reliable water supply to farmers is the single most important impediment to food security and agricultural expansion in Afghanistan. Agricultural water supply and distribution systems are reviewed, and a pragmatic strategy is outlined to increase water capital and to better utilize available water. The development and dissemination of on-farm practices that improve water management through community-based approaches represent the best opportunity for improving farmer livelihoods, maintaining social stability and developing a sound agriculture-based economy in the immediate future, independent of the success or failure of national water policies.     

What's in a name? Taxonomy and nomenclature of invasive gobies in the Great Lakes and beyond

The species identities, scientific names, and relationships of Eurasian gobies that invaded the Laurentian Great Lakes – and other species that are predicted to invade in the future – are evaluated here using recently resolved DNA characters. The Round Goby and the Freshwater Tubenose Goby entered the Great Lakes ca. 1990 via ballast water originating from Black Sea ports. The Round Goby spread extensively throughout the Great Lakes and adjacent rivers, whereas the Freshwater Tubenose Goby recently began to expand its range. Both species also are widely invasive in Eurasia, dispersing via canals and shipping. Several of their relatives – the Monkey, Racer, and Bighead gobies – also are invasive in Eurasia, and are predicted to invade the Great Lakes. We discuss results from phylogenetic analyses of DNA sequences from 4 mitochondrial and nuclear gene regions, and provide a revision of their scientific nomenclature. The Freshwater Tubenose Goby was redefined as Proterorhinus semilunaris, which is markedly different and distinctive from the Marine Tubenose Goby Proterorhinus marmoratus. The genus Neogobius, as formerly defined, contained multiple evolutionary lineages and incorrect scientific names. We thus restricted Neogobius to just 4 species—including the Round Goby Neogobius melanostomus and the Black Sea Monkey Goby Neogobius fluviatilis. Several previously recognized subgenera, which were incorrectly grouped in Neogobius, were elevated to the level of genera. Notably, the Racer Goby became Babka gymnocephalus and the Bighead Goby now is Ponticola kessleri. These changes made the names consistent with their true relationships and species characters, which are essential for identifying and characterizing these gobies in invasive and native habitats.     

Modelling and control strategy testing of biological and chemical phosphorus removal at Aved?re WWTP.

The biological phosphorus removal process is often implemented at plants by the construction of an anaerobic bio-p tank in front of the traditional N removing plant configuration. However, biological phosphorus removal is also observed in plant configurations constructed only for nitrogen removal and simultaneous or post-precipitation. The operational experience with this "accidental" biological phosphorus removal is often mixed with quite a lot of frustration, as the process seems to come and go and hence behaves quite uncontrollably. The aim of this work is to develop ways of intentionally exploiting the biological phosphorus process by the use of instrumentation, control and automation to reduce the consumption of precipitants. Means to this end are first to calibrate a modified ASM2d model to a full-scale wastewater treatment plant (WWTP), including both biological and chemical phosphorus removal and a model of the sedimentation process. Second, based on the calibrated model a benchmark model is developed and various control strategies for biological phosphorus removal are tested. Experiences and knowledge gained from the strategies presented and discussed in this paper are vital inputs for the full-scale implementation of a control strategy for biological phosphorus removal at Aved?re WWTP, which is described in another paper. The two papers hence show a way to bridge the gap from model to full implementation.