Stream power

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

Large wood storage in channelized and unmanaged sections of the czarny dunajec river, polish carpathians: implications for the restoration of mountain rivers

Abstract: The amounts and distribution pattern of large wood stored in a 17 km long reach of the wide, mountain Czarny Dunajec River, southern Poland, were investigated following a 7-year flood to determine the potential of naturally recruited woody debris for restoration of mountain rivers affected by channelization and channel incision. The quantity of stored wood as well as the number and mean mass of wood accumulations were found to be directly related to the length of eroded, forested banks and river width, and inversely related to unit stream power at the flood peak. A regression line for the relationship with river width testifies to the existence of minimum channel width, below which no wood was typically retained in the river. Numerous wood accumulations of relatively high mass were retained in wide, multi-thread river sections. In these sections, wood was deposited in a variety of depositional sites, considerably contributing to the diversity of physical and biotic processes in the river. In contrast, very small number of wood accumulations of relatively low mass were retained in narrow, single-thread sections of regulated or bedrock channel. Here, wood was mainly deposited along the channel margins and has exerted little influence on the river functioning. The recognised pattern of wood storage indicates that in a mountain river wider than the height of trees growing on its banks, environmentally-significant quantities of large wood are deposited in wide, multi-thread sections already remaining in a relatively healthy environmental state but cannot be retained in narrow, channelized or incised river sections. This questions the utility of naturally recruited large wood for restoration of mountain rivers affected by channelization and channel incision. Successful restoration of such rivers would require the previous reduction of their transporting power or should be undertaken with the use of artificially placed wood structures.

Deriving rock uplift histories from data-driven inversion of river profiles

Abstract: Reconstructing the evolution of Earth’s landscape is a key to understanding its future evolution and to identifying the driving forces that shape Earth’s surface. Cosmogenic nuclide and thermochronological investigations are routinely used to quantify Earth surface processes over 10 2 –10 4 yr and 10 6 –10 7 yr, respectively. A comparison of the rates of surface processes derived from these methods is, however, hampered by the large difference in their time scales. River profiles bridge this time gap and record the regional uplift history over 10 2 –10 7 yr. Here I present an integrative inverse modeling approach to simultaneously reconstruct river profiles, model thermochronological and cosmogenic nuclide data, and derive robust information about landscape evolution over thousands to millions of years. An efficient inversion routine is used to solve the forward problem and find the best uplift history and erosional parameters (such as the exponents of discharge [ m ] and slope [ n ] in the stream power equation) that reproduce the observed data. I test the performance of the algorithm by inverting a synthetic data set and a data set from the Sila massif (Italy). Results show that even complicated uplift histories can be reliably retrieved by the combined interpretation of river profiles and thermochronological and cosmogenic nuclide data.

Oscillations in arid alluvial-channel geometry

Abstract: Arid alluvial channels on piedmonts and valley floors often exhibit an oscillating pattern of narrow, deeply incised reaches and wide, shallow reaches with a characteristic wavelength. How do these oscillations develop and what controls their wavelengths? To address these questions we developed a two-dimensional numerical model that couples erosion and deposition in a channel bed with cross-sectional widening and narrowing. This model is inherently unstable over a range of spatial scales dependent on the channel width, depth, and slope. In the initial phase of model evolution, wider-than-average channel reaches become zones of distributary flow that aggrade, lose stream power, and further widen in a positive feedback. Simultaneously, narrower-than-average reaches incise, gain stream power, and further narrow. In the second stage of model evolution, this instability is balanced by the diffusive nature of longitudinal profile evolution, and solitary topographic waves propagate in the upstream direction with a characteristic wavelength and amplitude. The model predicts a specific quantitative relationship between the oscillation wavelength and channel width, depth, and slope that is verified by a database of channel geometries in southern Arizona.

Impact of climate change on future discharges and flow characteristics of the Tana River, Sub-Arctic northern Fennoscandia.

Abstract: . Climate change is expected to have a substantial impact on hydrology on both a global and regional scale. Although the anticipated warming is expected to be greatest in the northern regions and cause alteration in the hydrological cycle, it has yet to be resolved, to what extent these hydrological changes will alter such flow characteristics as flow velocity, bed shear stress and stream power in Sub-Arctic rivers. Future changes in the fluvial erosion potential are studied in the Sub-Arctic Tana River, on the border of Finland and Norway. We modelled future discharge scenarios for the years 2070 to 2099 with a conceptual hydrological model incorporating three emission scenarios, with two global and one regional climate model. These simulated flood discharges were used as input hydrographs to model flow characteristics with a two-dimensional hydraulic model. Differences in the spatial distribution of flow characteristics between frequent (HQ1/2a) and infrequent floods (HQ1/250a) were examined. Compared to the present, in most simulations, both HQ1/250a and HQ1/2a flood discharges diminished, with spring floods occurring earlier also. Although the relative reduction in flow characteristics (velocities, bed shear stresses and stream powers per unit area) was more notable in 1/2a compared to 1/250a floods, the discharge peaks of the former would theoretically still be able to transport the fine sediments that form the river bed. Based on most of the climate scenarios, autumnal floods become more frequent in the future and hence, their role in sediment transport may become more significant compared to the present-day situation.