Stream power

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

Comparison of hydraulic geometry between sand- and gravel-bed rivers in relation to channel pattern discrimination

Abstract: A comparison has been made between the hydraulic geometry of sand- and gravel-bed rivers, based on data from alluvial rivers around the world. The results indicate a significant difference in hydraulic geometry among sand- and gravel-bed rivers with different channel patterns. On this basis, some diagrams for discrimination of meandering and braided channel patterns have been established. The relationships between channel width and water discharge, between channel depth and water discharge, between width-depth ratio and water discharge and between channel slope and water discharge can all be used for channel pattern discrimination. The relationship between channel width and channel depth can also be used for channel pattern discrimination. However, the accuracy of these relationships for channel pattern discrimination varies, and the depth-discharge relationship is a better discriminator of pattern type than the classic slope-discharge function. The cause for this difference has been explained qualitatively. To predict the development of channel patterns under different natural conditions, the pattern discriminator should be searched on the basis of independent or at least semi-independent variables. The relationship between stream power and bed material grain size can be used to discriminate channel patterns, which shows a better result than the discriminator using the slope-discharge relationship. Copyright (C) 2004 John Wiley Sons, Ltd.

Transport and deposition of plutonium-contaminated sediments by fluvial processes, Los Alamos Canyon, New Mexico

Abstract: Between 1945 and 1952 the development of nuclear weapons at Los Alamos National Laboratory, New Mexico, resulted in the disposal of plutonium into the alluvium of nearby Acid and (to a lesser degree) DP Canyons. Previous research has identified some of this material in the Rio Grande and defined its distribution in the regional river system. The purpose of this paper is to explore the connection between the disposal sites and the main river, a 20 km link formed by the fluvial system of Acid, Pueblo, DP, and Los Alamos Canyons. Empirical data from 15 yr of annual sediment sampling throughout the canyon system has produced 458 observations of plutonium concentration in fluvial sediments. These data show that, overall, mean plutonium concentrations in fluvial sediment decline from 10 000 fCi/g near the disposal area to 100 fCi/g at the confluence of the canyon system and the Rio Grande. In finer detail, the concentrations fluctuate with downstream distance depending on the trap efficiency of various reaches, as controlled by hydraulic conditions. Temporal data from sites repeatedly sampled show the passage of waves of contaminated sediment through the canyon system. Field mapping identified 108 deposits of sediment, including active bed load, flood plains, bars, channel fills, and slack-water deposits. Volumes of sediment in these deposits (calculated from field measurements of the dimensions of the features), combined with the mean concentration values, produced a first approximation of the amount of plutonium in each deposit. The geographic distribution of deposits and plutonium is clustered: of the 1000 mCi of plutonium in the canyon system, 78% is in lower Pueblo Canyon, 18% is in lower Los Alamos Canyon, and the remainder is in the upper reaches of the system. Simulations using a computer model for water, sediment, and plutonium routing in the canyon system show that discharges as large as the 25 yr event would fail to develop enough transport capacity to completely remove the contaminated sediments from Pueblo Canyon. Lesser flows would move some materials to the Rio Grande by remobilization of stored sediments. The simulations also show that the deposits and their contaminants have a predictable geography because they occur where stream power is low, hydraulic resistance is high, and the geologic and/or geomorphic conditions provide enough space for storage.

Flow-driven soil erosion processes and the size selectivity of eroded sediment on steep slopes using colluvial deposits in a permanent gully

Abstract: Colluvial deposits with loose, coarse material are easily erodible in permanent gullies, but the mechanisms of erosion and sedimentation during overland flow remain obscure. Hence, the processes and mechanisms of the transportation of soil particles by overland flow were investigated in this study. Experiments were carried out in a 5.0 m long by 1.0 m wide flume using colluvial deposits. The slope gradient varied from 36 to 84%, and the flow rate ranged from 0.72 L m − 2 min − 1 to 2.88 L m − 2 min − 1 . The runoff rate and sediment yield rapidly increased with increasing overland duration. Runoff and sediment were highly variable when the flume was treated with a high flow rate compared with a low flow rate, with the fluctuation of sediment concentration under the high flow rate usually reaching 500 g L − 1 . The slope gradient and overland flow rate have strong impacts on sediment transport capacity. The mean flow velocity and the unit stream power can be an optimal composite force predictor for estimating sediment transport capacity. Experimental results also revealed that the percentage of gravel-sized particles increased with increasing flow rate and slope gradient, but silt and clay fractions observed opposite trend. The average enrichment ratio (ER) of gravel was usually 2.16 L m − 2 min − 1 , the bed load transport became an important mechanism; however, the simulation model overestimated these values.

Empirical predictors of annual bed load travel distance, and implications for salmonid habitat restoration and protection

Abstract: Measurements of annual travel distance (Lb) of bed load sediment at 16 locations in Alaska, the intermountain USA, west coast USA and Scotland are strongly correlated with bankfull channel width (r2 = 0·86, p < 0·001). Travel distance of particles is probably limited by trapping in bars, which have a longitudinal spacing proportional to channel width. Increased abundance of woody debris reduces bar spacing and may reduce Lb. Longer cumulative duration of bed load transporting flows in a year appears to increase Lb. Other predictors of annual travel distance such as stream power per unit length, drainage area and bankfull discharge were less well correlated with Lb (r2 ranging from 0·27 to 0·51). Stream power per unit bed area, basal shear stress and slope were not significantly related to Lb (r2 < 0·05). Most correlations were improved when regressions were limited to data from the west coast USA. Travel distance estimates can be used to help identify reaches that may take longer to recover from large, short-term increases in sediment supply. Published in 2001 by John Wiley & Sons, Ltd.