Archimedes Screws Turbines (ASTs) are a new form of small hydroelectric powerplant that can be applied even in low head sites. ASTs offer a clean and renewable source of energy and are safer for wildlife and especially fish than other hydro generation options. As with other energy solutions, ASTs are not a global solution for all situations. However, in terms of sustainable development, ASTs can offer many economic, social, and environmental advantages that make them an important option for providing sustainable hydropower development. Archimedes screws can operate in low water heads (less than about 5 m) and a range of flow rates with practical efficiencies of 60% to 80% and can generate up to 355 kW of power. ASTs increase the number of suitable sites where it is possible to develop sustainable hydropower, including in undeveloped, hard to access regions and small communities. At many low head sites, ASTs may be more cost-effective, with lower installation and operating costs than alternative hydropower systems. An AST may also reduce the disturbance of natural sedimentation and erosion processes and have smaller impacts on fish and other fauna. ASTs can often be retrofit to existing unpowered dams or weirs, providing new hydropower capacity for very little marginal environmental impact. This review outlines the characteristics of ASTs, then discusses and analyzes how they could benefit the sustainability of hydropower development.

Climate change is a complex and long-term global atmospheric-oceanic phenomenon which can be influenced by natural factors such as volcanoes, solar, oceans and atmosphere activities which they have interactions between or may be as a result of human activities. Atmospheric general circulation models are developed for simulation of current climate of the earth and are able to predict the earth's future climate change. In this paper, the performance of GFDL CM2.1, CSIRO Mk3 and HadCM3 AOGCMs were assessed and evaluated in the study of the climate change effects on temperature and precipitation in Taleghan basin. The results show that HadCM3 model in comparison with CSIRO Mk3 and GFDL CM2.1 models has indicated the better performance in this region.

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According to the importance of climate change, the necessity of develop a fast and accurate tool is undeniable. Although the comparison of a statistical model with specialized models which were designed regard to non-linear complexities of a phenomenon is not common, in this study ARIMA statistical model was analyzed and evaluated with GFDL CM2.1 and CGM3 Atmosphere-Ocean General Circulation Models (AOGCMs) in order to investigate on the effects of climate change on temperature and precipitation in the Taleghan basin. The results showed although GFDL CM2.1 model showed better performance in MAE and R 2 validation criteria and the predicted temperature had similar trend with the observational data, the difference between the model results and observations is significant. The CGM 3 model showed better performance in R 2 for precipitation, temperature and MAE for long term average of precipitation in addition to having similar trend to the observed data. However, for long term average of both temperature and precipitation, the general predicted trend had a considerable distance with the observational values. In contrast, although the statistical ARIMA model predictions had some fluctuations, they had better conformity to the general trend of observations. These results show that contrary to popular belief, in some cases like this investigated case, even cheap statistical models can likely provide acceptable results.