摘要:

AbstractIf the random model, in which all topologically distinct channel networks are equally likely, is assumed valid, then general explanations of network structure from basin geomorphic processes cannot be expected. Tests for the random model are therefore critical to the direction of future work. Proposed tests are based on frequencies of basins of different magnitudes or diameters, and on network maximum widths. Network topology is also shown to be potentially significant in the prediction of basin hydrographs. Network width commonly varies by a factor of 2 × for a given drainage area and drainage density, and is shown to influence peak discharge in proportion. Lag‐to‐peak can also be predicted better, using network topology. The paper pursues these applications of network topology using random walk theory and simulated random netw

ISSN:0360-1269    

DOI:10.1002/esp.3290010302

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractA circuit design is reported which is demonstrated to be capable of receiving and recording the underwater sound of inter‐particle collisions on natural stream beds during the process of bedload transport. Field trials were undertaken in a natural stream with sand‐sized bedload particles. The results obtained, for a constant stream stage, give support to the idea of the occurrence of short period oscillations in the rate of bedload transp

ISSN:0360-1269    

DOI:10.1002/esp.3290010303

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe random model of drainage basin composition is founded on the assumptions that (a) natural channels are topologically random in the absence of geological controls and (b) for channel networks developed in similar environments, the exterior and interior link lengths are independent random variables with a common distribution for each type. The effectiveness of this model in estimating the values of geomorphic variables and in explaining and predicting geomorphic relationships is illustrated by several examples. The data required for these examples were obtained from map studies of 30 channel networks, comprising a total of about 8700 links, in eastern Kentucky. A common factor in the success of all three applications of the model is the way in which the planimetric features of drainage basins are determined by their underlying topologic structure.

ISSN:0360-1269    

DOI:10.1002/esp.3290010304

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractPrevious works dealing with the influence of a stone cover on runoff yield showed that runoff, attributed to the sealing effect of the topsoil by raindrops impact, was negatively related to the per cent of stone cover and stone size. These works were conducted on gentle slopes (3–11·5 degree) with a per cent of stone cover generally lower than 50 per cent, and composed of gravels. The present study deals with the runoff yield of steep talus slopes (26–36 degree) whose per cent of stone cover is very high (90–100 per cent), composed of cobbles and boulders. Three stimulated rainstorms were performed at various rainfall. intensities and durations on each one of six plots representative of the North eastern sector of Sinai. Although the contiguous stony cover prevented surface sealing by raindrops impact, runoff developed quite quickly on most slopes, and reached at peak discharge, after approximately ten minutes, up to 56 per cent of the rainfall. Differences between plots, in time lag, peak discharge and other hydrological variables, could be attributed mainly to the properties of the upper stony layer, with stone size as the most influential factor. Contrary to previous works, a positive relationship, was obtained between stone size to runoff yield. The result is explained by the process of water concentration. Each cobble and boulder behaves, on a smaller scale, like a bare rocky surface and yields per unit area water amounts beyond the infiltration rate of the limited uncovered areas. For a given stony cover the effect of water concentration is quicker with the big blocks than with gravels. A series of graphs trying to relate theoretically the relative importance of sealing and water concentration processes in runoff generation, at various conditions of stone cover and stone size, is proposed. The graphs enable to reconcile the results of the present study with those of previous

ISSN:0360-1269    

DOI:10.1002/esp.3290010305

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractExtensive recording of currents, collection of water samples and routine meteorological and tide records provide a base for this study of the dynamics of Australia's largest river, the Murray, during one of its rare floods in 1974. The results suggest that the Coorong. a narrow lagoon extending from the river mouth to the Southeast, at right angles to prevailing winds, was formed as a flood escape mechanism. Geological evidence displays the existence of similar geometries formed in the past in an area which at one time was a deep gulf of the Southern Ocean extending into Australia. The same mechanism may have been at work elsewhere in the world.

ISSN:0360-1269    

DOI:10.1002/esp.3290010306

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTo obtain a better understanding of the colluvial deposits in two catchments in the Luxembourg Ardennes, structural aggregates from forest and farmland soils were subjected to the impact of falling water drops. The changes that the aggregates underwent and the material eroded from them were studied in thin section. Predictably, forest aggregates were more resistant to water‐drop impacts than those from farmland. Farmland aggregates tended to slake upon wetting and to break down into many micro‐aggregates having a size‐frequency distribution similar to that of the micro‐aggregates in the undisturbed soil. The forest aggregates were eroded slowly under water‐drop impact, losing material from their surfaces or occasionally shearing into several smaller equally resistant aggregates. The size‐frequency distributions of the break‐down products differed from the micro‐aggregates in the untreated aggregates or original forest soil, probably because of bonding by organic material. The differing composition of the aggregates points to the importance of oriented clay and planes for the lack of stability of the farmland aggregates. It can be concluded that agricultural colluvium is probably largely deposited by processes other than splash and that splash is an important process, but not the only one, in the formation of colluvi

ISSN:0360-1269    

DOI:10.1002/esp.3290010307

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe identification of channel capacity associated with a particular frequency of peak discharges is necessary for discharge estimation for planning purposes at ungauged sites. Although lichen limits have been suggested to be useful for this purpose, previous studies have not elaborated their hydrological significance. Lichen limits are clearly defined on the sides of rock channels in New England. Australia and they are analyzed in relation to discharge at 6 gauging stations with up to 52 years of continuous record. It is demonstrated that the lowest lichen limit is maintained by peak discharges which occur on average at least once or twice each year. Recurrence intervals based on Annual Series and on Annual Exceedance Series are calculated and for the annual series are fairly consistent for the lowest lichen limit and range from 1·14 to 1·37 years. Lichenometry can be applied to the analysis of river channels in relation to the frequency of peak discharges. By reference to growth curves based upon lichens on Armidale tombstones it is shown that lichenometry may be employed to indicate dates for channel modification due to the removal of blocks and to dam construction and also to date the rock surface between lichen limits. Detailed analysis of the record from gauging stations indicates that where several lichen limits occur in a channel cross section each limit is related to periods when peak discharges exceeded the limits on at least 5 occasions. The lichen‐free surfaces were then recolonized byParmelia spp.and the size of the lichen thalli indicates the time elapsing since these frequent high dischar

ISSN:0360-1269    

DOI:10.1002/esp.3290010308

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractThe major controls of rockfall activity are divided into two interacting groups.(a)Climatic factors which, through their control of temperatures and the availability and state of water, are primary controls of rockfall trigger mechanisms.(b) Geologic factors which,viacliff form (plan, profile, dissection etc.) and the character and availability of materials, influence the type, spatial distribution and intensity of rockfall activity.Detailed examination of these controls suggest that both seasonal and daily patterns of rockfall activity can vary markedly over a very small area.The implications of this variability for the design and interpretation of rockfall inventories are discussed using sample data from Surprise Valley, Jasper National Park, for the period from May‐October 1969. On a seasonal basis rockfall activity showed a major spring peak with secondary maxima in the fall and associated with major summer storms. Two sites of differing aspect and morphology were studied in more detail revealing marked differences in the mean hourly frequency (0·94:0·20), mean hourly probability (0·40:0·16, hours with rockfall/hours observed) and daily pattern of rockfall activity. The west facing site showed equal hourly probability of rockfalls from 1000to 2000hr whereas the east facing slope had a greater hourly probability when it was in the sun (11001400hr) than in the shade (1400‐1900hr). The differences in rockfall frequency and probabilities reflect the physical characteristics of the individual sites whereas the daily pattern of rockfalls is related to microclimate.These results suggest that if future inventory studies are to make a significant contribution, they must be carefully designed field experiments in which.(i) Data are restricted to the study or comparison of single continuously observed sites.(ii) Study sites and/or data periods are carefully selected to isolate and investigate specific controls e.g. the influence of cliff form, aspect, periods of rainfall etc. on rockfall patterns.(iii) Good on‐site microclimate data are available.Also comparison of frequency measures based on the arithmetic mean should be avoided since the distribution of rockfalls per hour closely follows a Poisson distribution with occasional high values which unduly influence the value of the arithmetic mean. It is suggested that rockfall probabilities, based on the binary decision of whether or not a rockfall occurs in a given period, are a more useful measure for daily patterns of rockfall

ISSN:0360-1269    

DOI:10.1002/esp.3290010309

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290010311

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290010312

出版商:John Wiley&Sons, Ltd    

年代:1976

数据来源: WILEY