Stream power

About: Stream power is a research topic. Over the lifetime, 1135 publications have been published within this topic receiving 51324 citations.

Bedl oad transport and fl ow resistance in steep channels – introduc tion to the issues in the context of mountain basins of the Central Eu ropean region

Abstract: Although sediment transport in the uppermost parts of mountain basins may be supply- limited, bedload transport in small torrents represents a potential hazard during extraordinary floods. The authors attempt to review recent worldwide research of bedload and hydraulics the results of which could potentially be applied in local steep channels. Approaches to the calculation of flow resistance (Manning relationship, logarithmic and power-law relationships) and critical conditions of the incipient motion of a bed particle (critical shear stress, stream power, flow velocity and discharge) are closely discussed in order to describe hydraulic and bedload transport conditions in steep headwater streams. Difficulties are pointed out in connection with the estimation of critical conditions of bedload transport in headwater streams with poorly sorted bed material and more or less developed bedforms. In the second part of the paper the authors present two pilot studies from the Western Carpathians and test potential applicability of specific formulas in this region. Results of the formulas point to relatively nonselective character of bedload transport during high magnitude floods in Beskydian headwater streams. An important role is played by the intensity of sediment delivery to active channels in limited sediment-supply conditions. The authors also point out that a majority of bedload transport and flow resistance equations were originally created on the basis of flume experiments or they were tested in Alpine torrents and therefore it is supposed that they might work well in local torrents after being calibrated to local conditions.

The topographic threshold of gully erosion and contributing factors

Abstract: The topographic threshold is based on the power relationship between area and slope and is widely applied in gully-erosion research; however, this relationship requires further testing. Accordingly, the Alamarvdasht Lamerd and Fadagh Larestan regions in Fars Province, Iran, were selected as case studies to explore the topographic threshold for gullies. Thirty active gullies were identified in each study area during field surveys, and data describing land use and land cover, drainage areas, slope, and the physical and chemical properties of the soils were assembled. Multivariate analysis was conducted using SPSS to determine the effects of these factors. Using the power relationship between the catchment area and slope for each gully, the analyses explored critical controls for gully development. The results showed that surface runoff was the most significant effective factor for gullies in the study areas. Sparse ground cover, fine-textured soils, and inappropriate land use contribute to gully development. The results suggest that the relationship between slope and drainage area in the Fadagh Larestan case study is S = 0.0192 A−0.159 for gully headcut areas and S = 0.0181 A−0.258 at gully outlets. The corresponding values of the exponent β at the gully headcuts and outlets at Fadagh were − 0.15, and −0.25, respectively. The corresponding relationships for gullies in the Alamarvdasht Lamerd area for the gully headcuts and outlets were S = 0.0143 A− 0.061 and S = 0.0073 A−0. 18, respectively, with β values of − 0.06 and − 0.18. This study provides a basis for determining the thresholds for initiating gully development. Analyses of the effective factors provide clues to improve the management of bare lands to prevent the initiation of gully erosion.

Method and system for renewable energy store in temperature-pressure tank of energy and conversion to electrical energy

Abstract: The subject of the invention is a method and system for renewable energy store in temperature-pressure tank of energy and conversion to electrical energy. It makes possible conversion of variable stream of renewable energy, especially of wind, tide and the sun, to constant stream of electrical energy. Considerable part of renewable energy stream is accumulated in substance in artificial or natural tank (6). The heat collected in tank (6) is transferred to transmission agent, which as the gas with pressure drives turbine (11) and electrical generator (12). Renewable energy stream sensor (15) gives the information about actual renewable energy stream power to control system (3). Proper steering of: converter (4) /or mirror and heater in the sun energy system version/ and control modules (8, 10, 14, 13), additionally using of energy accumulated in rotating mass of turbine rotor (1) /in wind and tides energy system version/ gives possibility of receiving constant stream of electrical energy. While renewable energy stream is present, it is possible the simultaneous work of generator (2) with converter (4) /or mirror and heater in the sun energy system version/ and generator (12) what gives even two times bigger output power of the system. If conversion of voltage produced by converter (4) and/or generator (12) to voltage of electrical grid is needed transformer (16) can be used. Moreover transformer (16) power is lower than power of generator (2) /or mirror and heater in the sun energy system version/. It is worth of mentioning that in heat exchanger (14) additional stream of heat is received, which can be used for other purposes.