Stream power

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

Large-scale assessment of spatial variability in stream power distribution: An indicator of channel erosion and deposition potential

Abstract: Channel morphodynamics, governed by erosion and deposition processes, constitute a relevant aspect of integrated water management planning, and development of sustainable fluvial projects. According to the Water Framework Directive, there is a need for hydromorphological recognition and channel geomorphic adjustment at the national level. Such a large scale excludes field measurements as the primary research method. Instead, methods that require less resources and are based on relatively simple process representations are required. The stream power (SP) concept, combining the effect of channel gradient and discharge, has been widely used for quantitative measurements in geomorphic works at different spatial scales, but not at the national level so far. The primary objective of this study was to estimate total and specific stream power, and detect erosion and deposition patterns along the river network in Poland. Given the dominant role of stream slope in SP spatial variations, the specific objective was to assess the vertical accuracy of high-resolution DEM representing water surface elevations along the river course, and to propose a method for extraction of elevation points along river reaches that increase the accuracy of DEM-derived stream slopes. We demonstrated that DEM generally overestimates the elevation by more than 0.5 m, significantly affecting the DEM-derived stream slope estimation. By extracting minimum water surface elevation from DEM within a 15 m radius from the target cell (river segment endpoint), a substantial improvement was achieved. The difference between the actual and DEM-derived water surface elevation dropped to 0.16 m. The results indicated that the distribution of dominating processes in Polish rivers is strongly governed by the character and origin of the terrain relief and lithological diversity. For regions with flat relief, most channels are generally in the state of equilibrium, whereas in upland and mountainous regions, erosion processes are dominant. This study demonstrates the potential use of the SP concept for mapping channel sensitivity to erosion and deposition dominance at a national scale, which can be relevant for integrated river catchment management.

Sediment quality characteristics of salmonid spawning grounds

Abstract: This thesis focuses upon the sediment characteristics of salmonid spawning grounds in a number of lowland and upland catchments in England and discusses the implications of spatial and temporal variability of channel-bed sediment composition upon different stages of the salmonid life-cycle. Substrate samples were obtained by using freeze-coring techniques, thus avoiding the problems of elutriation of fine-sediments which have hindered many studies in the past. Spatial variability is assessed within-site, between-sites and between catchments. Temporal development of channel-bed sediments is assessed both between and within spawning seasons in two upland streams, one of which is regulated. Overall change in sediment quality is demonstrated by changes in armour layer particle-size and variability in the fine-grained sediment population. Vertical infiltration of fine-grained sediments was successfully quantified by analysing core-section loadings over time. Results are explained in terms of mechanisms and processes occurring at each scale. A typology of streams has been developed based upon a continuum of granulometric characteristics which ranged from coarse-grained upland sites to fine-grained (sandy) lowland sites. Sediment quality of a number of lowland streams, based upon indices derived from the literature, were classed as unsuitable by this methodology, largely because of the high loadings of fine-grained sediments (in excess of 14% sub 1.0 mm material). As these streams are known to support good salmonid populations, the usability of such indices is criticised. A model is presented to predict percent weight fine-sediment (sub 1.0 mm) from maximum unit stream power. Error margins limited this application however. The use of freeze-coring techniques for sediment quality assessment are discussed in the light of the results.

Analysis of runoff aggregation structure and energy expenditure pattern for Choyang creek basin on the basis of power law distribution

Abstract: The main purpose of this study is to analyze runoff aggregation structure and energy expenditure pattern of Choyang creek basin within the framework of power law distribution. To this end geomorphologic factors of every point in the basin of interest, which define tractive force and stream power as well as drainage area, are extracted based on GIS, and their complementary cumulative distributions are graphically analyzed through fitting them to power law distribution. The results indicate that three distinct behavioral regimes are observed from the complementary cumulative distributions of three geomorphogic factors. Based on the parameter estimation of power law distribution by maximum likelihood drainage area and stream power can be judged as scale invariance factor without finite scale while tractive force as scale dependence factor with finite scale. Furthermore, it is judged that tractive force would not follow power law distribution because it shows limited complex system behaviors only within the small extent of scale. The exponent of power law distribution for drainage area obtained in this study by maximum likelihood is larger than the previous researches due to the difference of parameter estimation methodologies. And the exponent for stream power is smaller than the previous researches due to the scaling property of channel slope for the basin of interest.

Effects of fluctuating levels of lake superior on morphological adjustments in the neebing‐mcintyre floodway, thunder bay, Ontario Canada

Abstract: The Neebing-McIntyre Floodway, a relatively straight, trapezidal flood-control channel, was constructed in 1983 to dispose of the combined flows of the Neebing and the McIntyre rivers into Lake Superior. Because of its location in a transitional fluvial/lacustrine environment, related processes had direct and indirect impacts on its morphological readjustments. During the post-construction period (1983-88) the combined peak flows of the Neebing and the McIntyre rivers never exceeded the two-year design floods for the floodway, resulting in relatively low stream power and sediment transport rates. The average rate of sedimentation in the new channel (1100 m3 y−1) was thus much lower than the designers' estimated volume (11 800 m3 y−1). These low-flow events coincided with high water levels in Lake Superior in 1985-86, reinforcing the normal backwater effect in the floodway and further dampening its stream power. During this event the floodway behaved hydraulically almost like a reservoir, with fluctuating water levels and wind-generated waves as the principal geomorphological agents of bank erosion. Estimates based on volumetric surveys indicate annual rates of bank erosion ranging from 0.03 to 0.16 m3 m−1 of bank length, with an average annual rate of 0.1 m3 m−1. The bank materials are composed of highly erodible sandy loam and loamy sand, which have a tendency to disperse and liquefy relatively easily. There are no significant spatial variations in erosion rates along a given bank but contrasts in the magnitude of erosion between the north and the south banks can be related to the relative exposure of a bank to average wind velocities, total duration of winds and the effective wind-wave fetches.