Stream power

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

Sediment Sorting in Two-phase Debris Flows Movement

Abstract: Sediment sorting of debris flow affects the kinetic and dynamic characteristics such as erosion along the distance,movement distance and impact force. A better understanding of sediment sorting will improve research of control engineering and sensitivity division. 105 experiments were conducted to study the effect of material composition,flow and gradient on sediment sorting of debris flow head with artificial preparation of sand. The results showed that the sediment sorting increases firstly and decreases secondly with the increase of the content of sand grain or gradient or flow. In order to consider the influence of each factor,sorting ratio( R) was defined as the function of stream power and underwater gravity of sediment. With the increase of W0. 5/ G',the sediment sorting of debris flow head increases firstly,decreases then. Finally,the model of sediments sorting of debris flow was established and validated.

River side track traffic system utilizing stream power

Abstract: PURPOSE:To eliminate public hazard and save energy by mounting a water wheel on a vessel, rotating it by flowing river water to get driving power, and running a running device on a track. CONSTITUTION:When a water wheel 2 is rotated by river water stream, a rotating power is transmitted through a power transmitter 3 to driving wheels 12 of a support/guide/running device 18 and runs a vessel 1 alongside a track 8. A magnet 14 then increases the adhesiveness between the support/guide/ running device 18 and rail 8, and a propelling force is given firmly to the running device 18 in propelling energy by water stream generated by the water wheel 2. Thus public hazard is eliminated and energy can be saved.

A GIS- and field-based investigation of main channel morphological sensitivity to tributary inputs at the watershed scale in Québec

Abstract: Confluences are key nodes of river networks, as a result of the dynamic mixing of water, sediment, wood or ice between tributaries and receiving channels. Geomorphically active tributaries have the potential to disrupt the balance of erosional and depositional processes along main river channels, thereby resetting downstream longitudinal patterns. In turn, main channels respond to or absorb these changes as a function of their spatial and temporal sensitivity, which varies with topography, energy conditions and the system’s capacity to recover following major past events. Consequently, confluence zones are areas of increased spatial heterogeneity, with important implications for the resilience of river ecosystems and their management. However, due to their complexity, tributary-main channel interactions represent a relatively understudied component in fluvial geomorphology. The objectives of this study are to 1) improve our understanding of the morphodynamics of active confluences characterized by high sediment load tributaries based on field observations in Gaspesie, Quebec and 2) propose a novel semi-automated GIS model that uses a fuzzy approach to integrate multiple key factors (unit stream power, valley confinement and sediment connectivity potential) to assess main channel confluence morphological sensitivity (CMS) to active tributaries at the scale of whole watersheds. The model was tested using digital elevation models (DEM) in Coaticook and Gaspesie watersheds, Quebec. Results of the field survey showed that despite all confluences being located in a generally homogeneous geological setting, considerable disparities in the morphological effect of tributaries exist. The fuzzy GIS model was able to identify sensitive locations along the main channel associated to geomorphically active tributaries and has thus the potential to be used as part of watershed geomorphic assessments, particularly when high-resolution (LiDAR) DEMs are available. These findings highlight the spatially contingent distribution of resisting and impelling forces along main channels, including tributary-main channel interactions, in influencing river behaviour.

Alluvial architecture of the Holocene Rhine-Meuse delta (the Netherlands) and the Lower Mississippi Valley (U.S.A.)

Abstract: Alluvial architecture describes the geometry, proportion, and spatial distribution of different types of fluvial deposits in an alluvial succession. Alluvial architecture is frequently subject of study, because natural resources commonly occur in ancient fluvial sequences. The ability of models to simulate alluvial architecture realistically is largely unknown due to a lack of natural data to test the models. Generating high-resolution datasets describing alluvial architecture of natural fluvial systems would help the development of better-performing models of fluvial stratigraphy. This Ph.D.-thesis describes the alluvial architecture of two Holocene fluvio-deltaic settings: the Rhine-Meuse delta (The Netherlands) and the Lower Mississippi Valley (U.S.A.). The research goals were: 1) to quantify alongstream variability of channel-belt dimensions; 2) to assess the relative importance of various external controls for the formation of fluvio-deltaic wedges; 3) to quantify and compare alluvial architecture of both study areas. The alluvial-architecture parameters explored include sand-body geometry (width, thickness, and width/thickness ratio), channel-belt deposit proportion (CDP), and connectedness ratio (CR). Two particular aspects of alluvial architecture are highlighted: 1) channel-belt geometry; 2) valley-wide patterns in alluvial architecture. Channel-belt geometry was determined using cross sections across eight channel belts in the Rhine-Meuse delta and one channel belt in the Lower Mississippi Valley. It was found that the width of all channel belts encased in cohesive deposits decreases by a factor of 4 to 6.5 in a downstream direction. The width/thickness ratio decreases by a factor of 2.5 to 5. These observations are related to variations in bank erodibility and stream power that influence lateral migration rates of channels. Valley-wide patterns in alluvial architecture were quantified using detailed cross-valley sections. For each cross section, the alluvial-architecture parameters were quantified. Alluvial architecture of both fluvio-deltaic systems appears to be similar and varies both spatially as well as temporally. For example, CDP and CR are twice as high in the upstream part than in the downstream part of both study areas. The observed trends in alluvial architecture are related to variations in aggradation rate, floodplain geometry, and channel-belt size. These in turn are related to changing external forcings, but also to variations in intrinsic fluvial processes. Tectonic movements affect alluvial architecture locally. The similarities in alluvial architecture suggest common controls, operating in both study areas in a similar manner. Factors that controlled alluvial architecture of areas include: river gradient, bank erodibility, floodplain width, base-level rise, aggradation, differential subsidence and neotectonics, and sediment supply. Despite the new results of this study, more work needs to be done with regard to characterisation of fluvio-deltaic successions in distal areas of deltas, assessing three-dimensional architecture, and implementation of architectural field-data into alluvial-architecture models. With regard to alluvial-architecture modelling, it is imperative to define realistic channel-belt geometries, because of the importance for alluvial architecture. The Rhine-Meuse delta is a suitable test case for alluvial-architecture simulation, because customary model parameters such as aggradation rates, avulsion frequency, channel gradient, channel width and depth, floodplain width and length, and channel-belt geometry are well-constrained.

The January 2014 Flashflood in the Ambato River (Catamarca, Argentina)- A Case Study of Megaboulders Fluvial Transport

Abstract: Megaboulders mantle the steep channels of mountainous rivers, and moderate incision rates by increasing channel roughness. Direct measurement of the transport of boulders in natural rivers is difficult, therefore there are few field studies on the subject. The transportation of megaboulders downslope in catastrophic floods in urban environments releases a destructive power. This study analyses the Ambato river flood that occurred in Argentina in January 2014 with an assumed recurrence interval of 1:100 years. The flood was caused by concentrated rainfall in the upper basin, at an elevation of 4000 m. The Ambato river forms a boulder alluvial fan drained by episodic floods. The 2014 flood caused casualties and economic losses in the village of El Rodeo in the province of Catamarca. Several houses and a bridge were destroyed and vehicles were swept away. All bedload sizes- including megaboulders with 2000 mm b-axis- were transported during the flood. The empirical equation for stream power value and the unit bedload transport rate of megaboulders were validated. An assessment of boulder mobility is necessary to mitigate flow hazards in mountainous urban areas. The effects of climate change in semi-arid environments would be greater if they involved increased precipitation or more extreme rainstorms due to events such as El Niṅo.