摘要:

AbstractShallow water depths on steep slopes of as much as fifty per cent can be measured easily by weighing a light flume and the water it contains. Because water accelerates along the flume, a good approximation of the steady state depth is obtained when the recording balance is fixed to its bottom end.From the unit discharge and the depth, and not from measurements of the surface velocity, the Darcy‐Weisbach friction coefficient can be calculated. The present results show that this friction coefficient is larger in thin sheet flows than that calculated from the equation for rough turbulent flow. This latter could fit at a Reynolds Number of 50,000. When the regime is laminar (Re<2,440) the Darcy‐Weisbach friction coefficient always exceeds the theoretical value of 96/Re. The great relative depth of standing and travelling waves could account for this discrepancy together with turbulence and wake formation around bottom grains.Herein it is assumed that a regime can prevail where a laminar superlayer glides over a turbulent sublayer in the vicinity of bottom grains, because the ratio of the surface velocity to the mean velocity can greatly exceed 1.5, especially on steep slopes.Until photographs of the streamlines are taken, no statement about flow regimes in supercritical sheet flow can be m

ISSN:0360-1269    

DOI:10.1002/esp.3760050202

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractDetailed observations of rockfall were kept on a weekly basis over a two year period. The results indicate that there is both a seasonal distribution of rockfall with maxima in February‐March and November–December, and continuous small scale rockfall throughout the year.There appears to be some connection between rockfall and frost processes, while the peculiar geotechnical properties of the lava flows in county Antrim, in particular the presence of microfractures, would seem to be the main underlying cause for the observed activ

ISSN:0360-1269    

DOI:10.1002/esp.3760050203

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA method of analysis for predicting the time development of hillslope profiles is presented. The technique is based upon the assumption of weathering limited erosion and assumes that the local surface normal erosion rate is dependent upon the local flux of erosional agent and a function of the local slope gradient. This technique has been previously applied with success to analogous erosional processes in the sand blasting, chemical and energetic atom bombardment induced ablation of solids. The analysis shows how linearly segmented profiles can develop from initially curved surfaces and indicates the progress of profiles to stable end forms. Actual application to geomorphological situations is limited by lack of knowledge of micro‐environmental erosion fluxes and the gradient dependence of erosion and it is suggested that field observations and laboratory simulations could be helpful in determining the utility of the analysis technique outlined her

ISSN:0360-1269    

DOI:10.1002/esp.3760050204

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractMeasurements of bank erosion on rivers in Devon over a 2½ year period produced mean rates ranging from 0.08 to 1.18 metres per year and a maximum rate of 2.58 metres per year. These values are compared with rates derived from maps for various time periods between 1840 and 1975. The map rates are generally lower than the field rates and the question of whether this difference is due to the method of measurement, the magnitude‐frequency of events, a change in discharge conditions or the inherent variation in channel activity is discussed. Published data on bank erosion rates are reviewed and the Devon rates are found to coincide with the worldwide distribution. An analysis of factors likely to influence the spatial distribution of erosion rates reveals a square‐root relationship to catchment area and the importance of bank material. Implications of the measured rates for development of flood plains are exam

ISSN:0360-1269    

DOI:10.1002/esp.3760050205

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractInfiltration is the single most important parameter in deriving the net quick response rainfall which contributes to stream flood discharges.Rainfall simulation is used to study the infiltration characteristics in a typical catchment, the Six Mile Water in N. Ireland. The design of the simulator was such that it could be easily moved from one test area to another within the catchment to examine the effect of soil and slope variation. The simulator was first calibrated in controlled laboratory conditions and later the calibration was checked in the field.The simulator was mounted over an undisturbed plot of 37 m2and the surface runoff from the area measured by means of a collecting channel located along a lower edge of the plot. Soil moisture variations were monitored using a soil moisture neutron probe. Soil classification tests and gravimetric moisture contents were carried out on each plot.The field tests were carried out with variations in rainfall intensity, initial conditions, changing seasons, and for different plots within the catchment area. The results obtained are unique in that they present data obtained under field conditions for undisturbed soil within a natural catchment. The infiltration behaviour was found to depend upon rainfall intensity, initial conditions of the plot under consideration, seasonal temperature, and a slope of the plot. The data showed that while a classical Horton type equation for infiltration was suitable for the later stages of each test result when significant surface runoff was taking place, the model failed to represent early response adequately due to storage effects being omitted in the equation. A modified form of Horton equation is proposed, which models more accurately the infiltration characteristics of the full period of each test run.

ISSN:0360-1269    

DOI:10.1002/esp.3760050206

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractAn hypothesis from which a general principle covering deformation of alluvial boundaries may be developed is proposed, namely—flow of fluid past a deformable boundary will deform the boundary so as to increase the resistance to flow. Upon attainment of a local maximum of resistance to flow the boundary shape will cease to change. Evidence from channel bed forms, meander geometry and armoured beds is presented to support the hypothesis. One implication of the hypothesis is that channels will adjust so that sediment movement is maximized. The authors would like geomorphologists to test this in their work on landscape evolutio

ISSN:0360-1269    

DOI:10.1002/esp.3760050207

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractWater samples collected in the Negro River drainage basin (Patagonia, Argentina) during two different field trips—the first in May 1972 and the second in January 1973—were analysed for the major dissolved inorganic constituents. Q‐mode factor analyses demonstrate that two factors account for over 98 per cent of the variance in both sample suites. They represent: a) the direct influence of solution of evaporites and associated carbonate rocks in an arid environment‐type; b) the influence of the weathering products of metamorphic, igneous rocks, and varied non‐calcareous sediments. R‐mode factor analyses of the two sets of data suggest that although the main mechanisms controlling water chemistry were essentially the same, the principal sources of dissolved solids differed significantly in each separate occasion. Further, the major mechanisms controlling its water chemistry are within a wide spectrum of the so‐called ‘

ISSN:0360-1269    

DOI:10.1002/esp.3760050208

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe distributions of specific catchment area and specific dispersal area values over the hillside studied by Anderson and Burt (1978) relate much more closely to the observed distributions of soil water matric potential than do the occurrences of contour concavity on which the authors rely. Highest potential always occurred in the zone of large specific catchment area except immediately after rainfall, when it occurred in the zone of small dispersal area. Isolines of low potential persistently conformed to those of specific dispersal area.

ISSN:0360-1269    

DOI:10.1002/esp.3760050209

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3760050210

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3760050211

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY