Seepage regime in the foundation of the Sayano-Shushenskoe dam during construction and operation

Conclusions  

Structural changes in U.S. agriculture: Implications for African American farmers

Structural changes in U.S. agriculture, influenced by technological and institutional forces, have altered the economic and social characteristics of rural America, especially that segment of rural America populated by farmers and their families. Changes in the structure of agriculture have greater implications for small scale farmers, many of whom are African American, in that strategic options for their farm-firms are constrained to: increasing their farm size, exiting farming, and obtaining off-farm employment to survive. This article presents a rationale for public support of limited resource farmers, identifies structural trends in U.S. agriculture and their impacts on African American farmers, discusses economic problems unique to these farmers, and recommends needs for specific public policies and development programs.     

Savings,pension rights and taxation

Summary The voluntary saving rate has declined in The Netherlands over the last thirty years. In this paper the increasing share of transfer income in total income, with a high propensity to consume, and the increase in collective pension schemes are simultaneously used to explain this development. Furthermore, the influence of taxes is modelled. The planning horizon of the representative consumer is treated as a parameter to be estimated. The planning horizon obtained (about 4.5 years) appears to be short compared to expected residual lifetime, implying rather small interest elasticities. The estimation results indicate that, in case the obligatory pension schemes are diminished, the representative consumer offsets the loss in pension benefits for 75 per cent by voluntary, additional accumulation of nonhuman wealth in the long run. The working of the model is illustrated by simulation experiments.I wish to thank two anonymous referees, Prof. J. Pen, G.M.M. Gelauff, J.J. Graafland, W. Vossers and other colleagues of the CPB for their helpful comments.     

Removal and storage of ash of thermal power stations,variants and prospects of development

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 24–28, November, 1994.     

Impact of flood alleviation schemes on aquatic macrophytes

Geomorphological, engineering and ecological surveys were carried out at 18 flood alleviation schemes in the UK to evaluate their environmental performance. As no pre-scheme river corridor surveys had been carried out at any of the sites to enable the environmental impact to be directly assessed, controls were established in natural sections adjacent to five of the engineered reaches. A space–time substitution enables the pre-scheme conditions to be estimated for comparison with the engineered reach. The physical characteristics of the channel at bankfull conditions exert a strong influence on plant community composition. Paired assessments were carried out for engineered/control reaches on five rivers and this revealed which species and habitats were most affected by various engineering treatments. The general conclusion was that dredging, widening and straightening rivers reduces the number of desirable species, whereas two-stage channels and schemes involving the construction of flood banks at the edge of the meander belt maintained the richness and preserved and enhanced the occurrence of key species. Data from every cross-section, engineered and control reaches, enabled a model to be developed relating species occurrence to physical habitat features. This can be used to predict, at the stage of appraisal or design of a project, the likely response of the river to any particular engineering works. Given information on the existing condition in the river, it enables the environmental impact of the scheme, in terms of its effect on river bed plant species, to be assessed.     

The fish ladder at the itaipu binational hydroelectric complex on the paraná river,Brazil

A study was carried out from 23 October to 19 November 1992 to determine the ability of fish to ascend the fish ladder at the ITAIPU dam, to identify the species attracted and to evaluate possible fish selection. The results show that some species of fish can ascend the ladder during the migratory period; the dam is non-selective with respect to species, but selective with respect to fish size as a result of the presence of reduced openings. The ladder was ascended by both scaly species from surface waters (agile movers) and by deep water species which were characterized by slow movements. An average of 2892 fish ascended the ladder each day. The weight and length of fish recorded ranged from 336.0 to 3676.0 g and from 30.2 to 71.3 cm, respectively. The largest group of migrating fish was the curimba (Prochilodus scrofa). The high ratio of 72% of fish in the gonadal development stage, classified as ‘maturing’, indicates that the species caught in the ladder were migrating for reproduction purposes.     

Public utility valuation and risk under incentive regulation

The objective of providing inducements for public utilities to seek to improve the efficiency of their operations has been a longstanding regulatory concern. Among the evolving strategies for furthering that objective is a shift toward what has come to be referred to as incentive regulation. We examine here how this departure from past regulatory practice will affect the market value and market risk of the utility firm, and the specific manner in which an incentive mechanism can be implemented in order to achieve a desired valuation outcome. A particular focus is the establishment of boundaries on allowed rates of return under incentive regulation which are consistent with that desired outcome. The likely impact on utility ratepayers is considered.