Spatial aggregation of time-variant stream water ages in urbanizing catchments

Date of Acceptance: 25/03/2015

Stream biodiversity: The ghost of land use past

The influence of past land use on the present-day diversity of stream invertebrates and fish was investigated by comparing watersheds with different land-use history. Whole watershed land use in the 1950s was the best predictor of present-day diversity, whereas riparian land use and watershed land use in the 1990s were comparatively poor indicators. Our findings indicate that past land-use activity, particularly agriculture, may result in long-term modifications to and reductions in aquatic diversity, regardless of reforestation of riparian zones. Preservation of habitat fragments may not be sufficient to maintain natural diversity in streams, and maintenance of such biodiversity may require conservation of much or all of the watershed.

Improving Colorado Mountain Highway Culvert Stream Crossings for Trout Passage

Highways can be effective barriers to animal migration. Where highways cross over streams, a passageway, typically a culvert, not designed for fish access can cut off an organism from miles of habitat. Traditional methods of culvert design, to convey floodwaters, reduced access to aquatic and riparian range. The Colorado Department of Transportation likely has numerous culverts that restrict aquatic passage. This paper provides guidance to CDOT for assessment of stream geomorphic conditions affecting culvert performance for fish passage, understanding aquatic organism habitat requirements, and incorporating ecological parameters into culvert designs that benefit fish and other organisms. A case study illustrates culvert problems in a difficult geomorphic setting including a fish passage assessment to evaluate stream stability for long-term culvert reliability.

Simultaneous synthesis of heat exchanger networks with pressure recovery: optimal integration between heat and work

The optimal integration between heat and work may significantly reduce the energy demand and consequently the process cost. This paper introduces a new mathematical model for the simultaneous synthesis of heat exchanger networks (HENs) in which the pressure levels of the process streams can be adjusted to enhance the heat integration. A superstructure is proposed for the HEN design with pressure recovery, developed via generalized disjunctive programming (GDP) and mixed-integer nonlinear programming (MINLP) formulation. The process conditions (stream temperature and pressure) must be optimized. Furthermore, the approach allows for coupling of the turbines and compressors and selection of the turbines and valves to minimize the total annualized cost, which consists of the operational and capital expenses. The model is tested for its applicability in three case studies, including a cryogenic application. The results indicate that the energy integration reduces the quantity of utilities required, thus decreasing the overall cost.

Report on the Hydroida : collected during the exploration of the Gulf Stream by L. F. de Pourtalès, assistant United States Coast Survey / by Geo. J. Allman, M.D., LL.D., ...

v.5:no.2 (1877)

Analysis of Hyporheic Flow Induced by a Bar in a Gravel Stream: an Experimental Study

Thesis (Master, Civil Engineering) -- Queen's University, 2016-06-01 00:03:02.939

On Ukrainian Gas Transit and South Stream. There may be more than meets the eye. CEPS Commentaries, 21 March 2014

The EU relies to a considerable degree on imports to meet its demand for natural gas. Whereas Norwegian export pipelines are directly connected to the EU gas system, a major share of Russian gas flows through the Ukrainian territory before reaching consumers located other consumers located down in the supply chain (e.g. Slovakia, Hungary or Italy). But is the Ukrainian gas transit route still a risk? Will the construction of the South Stream pipeline further reduce the importance of Ukraine as a transit country? Or is there more at stake here than meets the eye?

Nord Stream on the liberalising EU gas market. OSW Point of View, March 2010

Nord Stream increases Gazprom’s flexibility as far its export routes are concerned; it enables them to be changed with regard to the market or political situation. Nevertheless, this expensive pipeline may contribute to a further drop in the price competitiveness of Russian gas. Accordingly, increasing the attractiveness of Russian fuel and ensuring profitable sales is steadily becoming the main challenge for Gazprom in the EU against a backdrop of increasing competitiveness on the market.

The declared end of South Stream and why nobody seems to care. CEPS Commentary, 5 December 2014

More than seven years after the South Stream pipeline project was first announced in June 2007, it finally seems to have been dropped by Russia’s President Vladimir Putin on his visit to Turkey this week. This CEPS Commentary looks at the ostensible reasons for President Putin’s decision as well as on what’s potentially behind them. It concludes that the EU may actually benefit from this decision in being able to secure more gas with less political interference from Russia.

At any price: Russia is embarking on the construction of South Stream. OSW Commentary No. 98, 2012-12-07

Gazprom is determined to continue its efforts to build the South Stream gas pipeline regardless of the slump on the European gas market and the fact that there is sufficient capacity already in the existing transport infrastructure. The official inauguration of the maritime section of South Stream was held on 7 December this year, but the construction itself will commence in 2014. The agreements concluded so far, both intergovernmental and between corporations, are necessary for the launch of the construction of the new pipeline, but still do not guarantee that the project will be completed on time. First of all, some legal problems have yet to be resolved, such as the evaluation of the compliance of the planned actions with the ‘third energy package’ or the fact that ecological surveys required under European law need to be carried out. Secondly, given the present situation on the European gas market and medium-term forecasts, the high cost of implementation of this project and the maintenance expenses of existing pipelines – which are not being used to full capacity – the new project seems to be unfeasible. However, Gazprom’s determination in its efforts to build the pipeline proves that Russia is ready to take a high economic risk to maintain its dominant position on the European gas supply market; it will restrict the possibilities of alternative infrastructural projects being implemented (above all, the EU’s Southern Corridor) and use the construction of new pipelines as an instrument of political pressure on the present transit countries (especially Ukraine).

Unconfirmed but still feared: the tidal wave of Bulgarians and Romanians one year later. EPC Commentary, 15 January 2015

This time last year politicians and media were stoking fears over the massive floods of Romanians and Bulgarians who were about to invade the UK (but not only) as the employment restrictions for these EU citizens were being lifted in nine remaining EU Member States. These fears have proven to be unfounded. Nevertheless, major national and EU developments will continue to feed this debate.

Turkish Stream and its implications for the EU. European Policy Brief No. 34, March 2015

“A first assessment is that this would not work”, EC Vice-President in charge of Energy Union Mr. Maros Sefcovic said in an interview with The Wall Street Journal at the World Economic Forum in Davos on the 22nd of January. He was commenting on the recent announcement by President Vladimir Putin and Gazprom’s Alexei Miller. Indeed, the Russian gas giant’s CEO announced that South Stream would be replaced by a new project, Turkish Stream, linking Russia to the European part of Turkey and this in addition to the existing 16 billion cubic meters (bcm) Blue stream. This policy brief looks at the various implications this new reality could have for Europe’s energy security.