摘要:

AbstractWeekly interflow and permeability data were obtained for 15 sites in two field plots in North Yorkshire. Both plots are similar in terms of lithology, slope, micro‐relief, climate and soil type, one being dominated by rough pasture grasses and the second by bracken. One factor which explained 75 per cent of the variation in interflow was the difference between topsoil and subsoil permeabilities, the former always being the greater. This permeability difference is discussed in terms of soil texture, porosity and plant‐rooting systems. Textural contrasts are considered insufficient to cause the large‐scale variations in permeability observed throughout the year. Being a fixed variable, texture cannot influence a characteristic which varies from one week to the next. Contrasts in total porosity between topsoil and subsoil also effected no discernible influence on measured permeability differences, although measures of association increased as smaller pores were excluded from the analysis. Utilizing only those pores drained at 20 cm of water tension, highly significant correlations were established. In the plot dominated by bracken, greater ‘lateral permeabilities’ are produced by well‐developed systems ofPteridiumrhizomes. As the advancing front of such rhizomes extends forwards at quoted rates of up to 45 cm/yr, the rear portions decay, leaving horizontal ‘tubes’ in the soil. Recognized omissions from this analysis are the effects of soil fauna and desic

ISSN:0360-1269    

DOI:10.1002/esp.3290010102

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe distinction between clast‐dominant, matrix‐dominant and well‐graded tills is important in view of the influence of texture on the definition and function of till fines. Till fabric includes a wide range of features of both primary and secondary origin including folds, thrusts, fissures (the macrofabric), disposition of clasts (the mesofabric) and organization of the matrix (the microfabric). The results of fabric analysis of pebble, granule, sand, silt and clay in small depositional landforms beneath currently‐active glaciers are described. Deformation fabrics are distinguished in freshly deposited end moraines and flutes. The sand‐size material in deformed till may or may not behave in the same way as larger clasts, depending on the degree to which the till is matrix‐dominant. While clasts in saturated subglacial till tend to align themselves sub‐parallel to the depositional surface, the matrix usually retains abundant pore spaces. With slow, unloaded drainage, clast fabrics appear to be little modified. Such material is potentially unstable and any subsequent increase in overburden and hydraulic pressures may cause slope collapse and flowtill development. It is concluded that examination of a wide range of fabric parameters provides a means of distinguishing tills of diverse origins and of assessing their potentia

ISSN:0360-1269    

DOI:10.1002/esp.3290010103

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe peakedness of a basin and its variation with drainage area were analyzed for three areas. Peakedness of a basin is calculated as mean flow as a percentage of highest flow. A fitted power curve relating ‘Peakedness index’ (PI) to drainage area for each of the three areas indicates a break point in a basin of about 300 km2. This break point divides the basins into small basins which are more peaky and large basins which are less peaky. The break point is an outcome of a difference in order of magnitude between channel flow velocity from the headwater sources and hillside flow velocity. When the basin responds to hillslope flow the runoff from the head water sources has already flown about 30 km downstr

ISSN:0360-1269    

DOI:10.1002/esp.3290010104

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractData are presented on daily fluctuations of soil pH in organic soils overlying Carboniferous Limestone in Co. Clare, Eire. High rainfall leads to a drop in pH, as acid waters percolate through the soil, but after rainfall the solution of carbonates in the soil or the solution of the bedrock leads to a return of soil pH to alkalinity. Carbonates tend to remain in the soil on poorly drained sites but solutional removal of calcium occurs on freely drained sites and in the latter case the return to alkalinity is not so rapid. The presence ofCalluna vulgarisis thought to be important as it appears to increase the acidity of percolating soil waters. On freely draining sites bedrock erosion may progress to such an extent that deep runnels form, down which soil may be lost.

ISSN:0360-1269    

DOI:10.1002/esp.3290010105

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractCertain observed characteristics of scree slopes; namely concavity of profile, straight slope angle less than the angle of repose, and good size sorting of particles, are not consistent with an angle of repose model for accumulation. An alternative model is proposed based upon rockfall and surface stone movement and is tested against experimental data of particle movement in the field. It is found that the mechanical model of stone movement generated adequately explains the motion of particles on scree slopes and that it is in keeping with the characteristics of many screes. The static features of some Isle of Skye screes were also measured and the straight‐concave slope form with good downslope sorting of material, characteristic of the rockfall process, was found to be presen

ISSN:0360-1269    

DOI:10.1002/esp.3290010106

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractA list of formational free energy data is provided for a range of common rock forming minerals. Free energy changes accompanying their decomposition to realistic stable products are calculated and shown to be in agreement with persistence observations. Weathering mechanisms and environmental controls are discussed.

ISSN:0360-1269    

DOI:10.1002/esp.3290010107

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe riffle‐pool sequence has not been subjected to the same level of intensive research as the meandering planform, although riffles and pools may be a fundamental prerequisite for meandering. The pseudo‐cyclic oscillation of the bed in a riffle‐pool stream suggests the application of a variety of techniques of spatial series analysis, which provide objective measures of riffle wavelength, and suggest processes capable of explaining riffles and pools and their relationship with meanders.The second‐order autoregressive process is suggested as a stochastic process which models the bed‐profile oscillation. Velocity pulsations associated with large scale turbulent eddies are probably responsible for accretions and erosions which interact with the flow to maintain these perturbations, so that sections lagged by distances of 2πw are positively correlated.The effect of the riffle‐pool sequence on flow geometry is far more significant than the effects of plan geometry or of downstream variations, which supports the view that this feature is a fundamental aspect of channel morphometry. There is a tendency, however, for curved reaches to exhibit reduced variance of roughness, velocity, and water surface slope, which reinforces the minimization hypothesis. The extreme temporal variation between riffle and pool flow characteristics demands that any classificatory scheme uses scale‐free and stable measures, and a discriminant analysis using hydraulic exponents represents a convenient summary of

ISSN:0360-1269    

DOI:10.1002/esp.3290010108

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractRelationships between slope form and stream magnitude, drainage area and stream gradient are investigated in a small upland catchment experiencing active stream incision. Profiles selected on a stratified random basis provide data on five slope form variables. The observed relationships suggest a spatial sequence of slope form, associated with a downstream increase in discharge, characterized by decreasing overall slope convexity and increasing mean slope angle and attributed to a reduction in the relative length of the upslope convexity with respect to the essentially stream‐controlled main slop

ISSN:0360-1269    

DOI:10.1002/esp.3290010109

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290010110

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290010111

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY