摘要:

AbstractThe divergent and yet related problems of post‐Hortonian studies of drainage density and channel network geometry are viewed against the difficulties of defining first‐order channels and basins. It is proposed that the junction of an unbranched perennial (or blue‐line) channel with another perennial channel be taken as the starting point for definitions and that the entire contour‐crenulation network tributary to that point be considered the first‐order stream. It is shown that the concept of network diameter may be used to describe the networks so delimited and that it appears to provide a useful starting point for interregional comparisons. Finally, an analysis of Blyth and Rodda's (1973) data on channel lengths and discharge indicates that network diameter may be as closely related to discharge as is channel leng

ISSN:0360-1269    

DOI:10.1002/esp.3290030302

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractProcesses operative in the divideward sections of streams and channels are reviewed, and the effects of their action over long periods of time are modelled for insight into long‐term valley head development. Upper valley axis profiles eventually become concave upwards over time but may show earlier convexity and convexo‐concavity. After any particular length of development different upper valley axis forms can exist in areas of different climate and hydrological response characterist

ISSN:0360-1269    

DOI:10.1002/esp.3290030303

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractOne of the fundamental mechanisms operative during pre‐overland flow soil erosion is crusting. The form of the crust, its relationship to infiltration, have been described by earlier workers. But the way in which a crust forms and develops through a single storm has not been considered. A set of controlled laboratory experiments were undertaken to look at this. In these experiments a constant rainfall intensity was used, and supplied by a rainfall simulator, the soil was held constant throughout the experiments. The areal development through a single storm event was looked at by means of time sequence air photographs, and the vertical development by the study of time sequence thin sections. The results show how crust formation may be regarded as a discrete rapid event with respect to time. The rapid development moves towards an equilibrium state prior to the initiation of overland flow. A model of the mechanisms of crust development is also formulate

ISSN:0360-1269    

DOI:10.1002/esp.3290030304

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe clay and silt mineralogy of the Cretaceous bedrocks of the Rother drainage basin is restricted to seven minerals. The mineralogy of soils and alluvium is similar to the bedrock upon which they are developed although minor variations can be found. The mineralogy of bedrock, soils and alluvium is reflected to some extent in the suspended sediment of rivers draining over them, and three different mineral assemblage zones are identified. Subtle controls of mineralogical variation in suspended sediment may include the ratio of groundwater/surface runoff contribution to river flow, rate of reaction of soil and bedrock to precipitation, preferential settling of non‐platy grains in quieter stretches of water, and the precipitation of material from solution as waters equilibriate with the atmospher

ISSN:0360-1269    

DOI:10.1002/esp.3290030305

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractDelimitation of a single fan component within an alluvial fan complex system is facilitated by observing contour offsets on topographic maps which indicate the position of the intersection point. Two different types of intersection points are discussed. Israeli topographic sheets of the Dead Sea area provide examples.

ISSN:0360-1269    

DOI:10.1002/esp.3290030306

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA large data bank of morphometric, cover and climatic data for over a thousand drainage basins of all sizes in the British Isles was set up by the N.E.R.C. Flood Study. The paper describes the selection of these ‘independent’ variables, their degree of correlation, their portrayal of regional variability in the British Isles and their success as predictors of flood variables. The internal adjustment of drainage basins is confirmed, as is the basic physical division of Brit

ISSN:0360-1269    

DOI:10.1002/esp.3290030307

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractStudies on sandy soils of the Cottenham Series in mid‐Bedfordshire confirm in the field the relationships between splash erosion, rainfall energy and ground slope obtained in the laboratory experiments of other workers. Only 0·06 per cent of the rainfall energy contributes to splash erosion and rates are low, attaining a maximum of 0·082 kg m−2y−1on a slope of 11°. The major role of splash action is in the detachment of soil particles prior to their removal by overl

ISSN:0360-1269    

DOI:10.1002/esp.3290030308

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractDry valleys and gullies in fluvioglacial sands and gravels in North Norfolk are fossil forms. Interpretation of their origin demands detailed morphological analysis, but the inevitable ambiguities of form require additional information on the sedimentology of the deposits and associated regolith. Soil mechanical data and stability analysis predict the observed modal slope angles, assuming the water table to be at or near the surface. This suggests that valley formation involved impeded drainage, and slope processes such as shallow slab slides and solifluction over permafrost. The debris was subsequently evacuated from the valleys by meltwater. The stability analysis also explains the different modal slope angles observed at two locations. Slope angle frequency distributions are composite, however, and include data from varying locations up‐valley. Up‐valley variations in slope angle are seen to reflect variations in the nature of the regolith and consequent changes in soil mechanical properties, as well as changes in valley relief. The up‐valley trends in the nature of the regolith are commensurate with a model of headward valley erosion, with a ‘younger’, less weathered regolith at the present va

ISSN:0360-1269    

DOI:10.1002/esp.3290030309

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractObservations of stream behaviour during rainfall indicate that previous notions of a simple expanding and contracting network need review and refinement. In a small rural catchment near Armidale, N.S.W. changes in flowing stream length during rainfall have been depicted on flow length graphs which indicate a varied network response to similar rainfall amounts. Channel flow phenomena include discontinuous flow, the generation of flow points within the channel and movement of water downslope from saturated depression sources. Localized physical controls have a significant effect on stream growth which is a sensitive indicator of the catchment response to rainfall. During rapid changes in stream length total flowing length and discharge are highly correlated. A model of the pattern of network expansion and contraction involves several phases of flow contraction.

ISSN:0360-1269    

DOI:10.1002/esp.3290030310

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0360-1269    

DOI:10.1002/esp.3290030311

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY