摘要:

AbstractA mathematical analysis of log‐quadratic hydraulic geometry relations explains the association between the shapes of the depth and velocity curves, and identifies other properties of the relations. By considering the nature of resistance variation, a mathematical and physical argument is put forward to account for the particular shapes apparently adopted by these curve

ISSN:0360-1269    

DOI:10.1002/esp.3290040302

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractReduced major axis analysis is used to describe monthly temperature averages for daily maxima, minima, means and ranges at a sequence of bedrock microenvironments in the alpine zone of the Colorado Front Range. Seven thermistors buried at 1 cm in bedrock provide comparative data on easterly, southerly and westerly aspects, and also upon the impact of snow accumulation (⩽0.5m to ≥4.0m deep) against an east‐facing rock wall. Intersite temperatures commonly differ by less than 5°C and, rarely, by more than 10°C. The freezing intensity of freeze‐thaw cycles occurring within the confines of a seasonal snow patch rarely dropped to −5°C, while at snowfree, vertical faces freezing dropped to −5°C quite commonly. Comparison with laboratory established criteria for effective freeze‐thaw weathering (abundant moisture and freezing to at least −5°C) suggests that moisture rich microsites lack adequate freezing intensity, while adequately frozen sites lack moisture. Available data suggest that the overlap between freeze‐thaw and hydration weathering requires

ISSN:0360-1269    

DOI:10.1002/esp.3290040303

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractOwing to experimental difficulties, the transport stage at which collisions between moving ‘bedload’ grains might become significant has never been investigated, yet the existence or otherwise of such collisions is of some importance in the understanding of the mechanics of sediment transport, in particular the theory developed by Bagnold. Application of the basic principles of gaseous kinetic theory to ‘bedload’ grains moving in saltant trajectories and the adoption of a ‘characteristic’ saltation path leads to the prediction that grain‐grain collisions should dominate in the transport of coarse sands over plane beds in water flows above a transport stage of about 2, i.e. when the mean boundary fluid shear stress exceeds the critical boundary shear stress for grain motion by about 4 times. Above this stage interrupted saltations should always occur, with the ‘bedload’ grains held above the stationary bed by a combination of fluid and solid momentum transfer mechanisms. A classification of the types of grain motions is given and evidence is presented for the existence of an upward decrease in grain collision frequency and of grain concentration at the top of t

ISSN:0360-1269    

DOI:10.1002/esp.3290040304

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThis paper describes laboratory testing of 148 samples collected from Southern Alberta for erosion by wash and splash. Rainfall intensity was held constant during these tests. Soil aggregation was the most significant variable explaining soil loss. The significance of other soil properties, such as organic carbon and clay content is variable, depending on the interrelationships among aggregate stability, organic content, and clay content of particular soils. Variations in erodibility of the major soils examined are explained by the resistance of aggregates to compaction and dispersion. Splash detachment and wash transport are the dominant erosion mechanisms in inter‐rill area

ISSN:0360-1269    

DOI:10.1002/esp.3290040305

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractVariation in solute concentrations of soil and stream water during throughflow events was studied at Bicknoller Combe, Somerset, England. The main hydrological process acting in the catchment involves a delayed throughflow discharge pulse a day or two after the rainfall event. During the period of storm runoff, coincident with the rainfall, the solutes in the stream are diluted, but their concentration in the throughflow remains unchanged. During the delayed throughflow pulse, concentrations of both soil and stream water increase. This is due to additional leaching from the soil in hollows where saturated moisture conditions prevail. The results suggest that two distinct erosional environments may exist: on the spurs, leaching seems to be related solely to infiltration processes, whilst in the hollows, saturated throughflow also contributes to the solute removal. This contrast in erosional processes may perhaps account for the difference in slope form and development between the hollow and spur zones.

ISSN:0360-1269    

DOI:10.1002/esp.3290040306

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractAs part of an investigation of mass movement on outslopes of contour surface‐mines in West Virginia, discriminant analysis was used to determine whether selected spoil properties could statistically distinguish failed and unfailed embankments. The analysis utilized the variables degree of saturation, liquid limit, and shrinkage limit, and the a priori assignment of samples into either actively failing, unfailed, or regraded categories.Results were encouraging, with seventy‐four percent of the samples being correctly classified. All misclassifications involved samples from active or regraded landslides, suggesting the method was conservative.Performance of discriminant analysis could probably be improved by modifying the sampling p

ISSN:0360-1269    

DOI:10.1002/esp.3290040307

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractRecent ground movements, varying in importance from superficial slips to large sliding masses, are reported for slopes at Runswick Bay, North Yorkshire. The role of water in controlling both the timing and rate of such movements is stressed. An unexpected consequence of an attempt to limit coastal erosion is reported. Failures are expected to continue.

ISSN:0360-1269    

DOI:10.1002/esp.3290040308

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractSorted stripes found on the volcanic scoria and glacial deposits of sub‐Antarctic Marion Island indicate a distinct preferred orientation. Despite uniformity of slope and material, the stripes are predominantly aligned parallel to the wind. It is suggested that melting of needle ice by the early morning sun is of only limited importance in the sub‐Antarctic owing to the almost continual overcast conditions. The effect of the wind is so great that in exposed situations stripes are formed on horizontal surfa

ISSN:0360-1269    

DOI:10.1002/esp.3290040309

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA test is proposed for Bagnold's postulate that the normal weight stress due to moving ‘bedload’ is balanced by a solid transmitted stress due to the rate of change of momentum produced by grain impacts on unit area of the stationary bed. The test involves derivation of an expression for normal momentum transfer due to saltating grains at moderate transport stages when grain‐to‐grain collisions and partial suspension during saltation may be ignored. A dimensionless number, Φ, (a grain Froude Number) is derived, given byŪ2/gwhereŪis the mean grain forward velocity, g is the gravitational acceleration andL̄is the length of a single saltation ‘jump’. Equilibrium demands that Φ be unity during bedload transport involving saltating grains if Bagnold's postulate is correct. Experimental data shows Φ<1, the discrepancy between theory and experiment being due to the existence of lift forces acting upon bedload grains. Bagnold's postulate is correct for concentrated dispersions of grains, as in grain flows, when fluid lift forces may be neglected due to high parti

ISSN:0360-1269    

DOI:10.1002/esp.3290040310

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290040311

出版商:John Wiley&Sons, Ltd    

年代:1979

数据来源: WILEY