Classification and Prediction of Channel Morphology Within Selected Third-Order Basins (Southwestern Nigeria)

Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 y. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This study aims to analyze the link between tectonic uplift rates and landscape morphology based on slope and channel morphometric indexes. To achieve this objective, we selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif (a Palaeozoic massif of NW Europe, principally located in Belgium) that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm yr−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our analysis indicates that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronic, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.

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Long-term Consequences of Upstream Impoundment

Environmental Conservation ◽

10.1017/s0376892900008183 ◽

1980 ◽

Vol 7 (4) ◽

pp. 325-332 ◽

Cited By ~ 92

Author(s):

Geoffrey E. Petts

Keyword(s):

Human Impacts ◽

Channel Morphology ◽

Long Term Effects ◽

Third Order ◽

First Order ◽

Channel Form ◽

Sediment Loads ◽

Flood Magnitude ◽

Invertebrate Population

Since 1970 a large number of environmental problems have been identified as resulting from the long-term effects of human impacts. Consideration of human activity within the environment as three orders of impact, provides a basic framework for the appreciation and evaluation of long-term problems. Consequent upon dam construction, major changes of flood magnitude and frequency and of the quantity and calibre of sediment loads (first-order impacts), will induce the readjustment of channel morphology and ecology (second-order impacts). However, the macrophytic and macro-invertebrate population, for example, are also adjusted to channel morphology—particularly channel shape and substrate composition—so that further readjustments of the macrophyte and macro-invertebrate populations may be effected by changes of channel form (third-order impacts).

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Geomorphological Analyses of Third-Order Basins in Southwestern Nigeria

Geography of the Physical Environment - Drainage Basin Dynamics ◽

10.1007/978-3-030-79634-1_21 ◽

2022 ◽

pp. 455-475

Author(s):

A. O. Olusola ◽

O. D. Onafeso ◽

O. A. Fashae ◽

S. Adelabu

Keyword(s):

Third Order ◽

Southwestern Nigeria

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Spatial variability in channel and slope morphology within the Ardennes Massif, and its link with tectonics

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-6981-2010 ◽

2010 ◽

Vol 7 (5) ◽

pp. 6981-7006 ◽

Cited By ~ 1

Author(s):

N. Sougnez ◽

V. Vanacker

Keyword(s):

Morphological Characteristics ◽

Channel Morphology ◽

Transient Signal ◽

Tectonic Activity ◽

River Channels ◽

Fluvial System ◽

Third Order ◽

Erosion Processes ◽

Wide Range ◽

Uplift Rates

Abstract. Geomorphic processes that produce and transport sediment, and incise river valleys are complex; and often difficult to quantify over longer timescales of 103 to 105 years. Morphometric indices that describe the topography of hill slopes, valleys and river channels have commonly been used to compare morphological characteristics between catchments and to relate them to hydrological and erosion processes. This work focuses on a wide range of slope and river channel morphometric indices to study their behavior and strength in regions affected by low to moderate tectonic activity. We selected 10 catchments of about 150 to 250 km2 across the Ardennes Massif that cover various tectonic domains with uplift rates ranging from about 0.06 to 0.20 mm year−1 since mid-Pleistocene times. The morphometric analysis indicates that the slope and channel morphology of third-order catchments is not yet in topographic steady-state, and exhibits clear convexities in slope and river profiles. Our data indicate that the fluvial system is the main driver of topographic evolution and that the spatial pattern of uplift rates is reflected in the distribution of channel steepness and convexity. The spatial variation that we observe in slope and channel morphology between the 10 third-order catchments suggests that the response of the fluvial system was strongly diachronous, and that a transient signal of adjustment is migrating from the Meuse valley towards the Ardennian headwaters.

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Probe size and 5th-order aberration

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125609 ◽

1987 ◽

Vol 45 ◽

pp. 134-135 ◽

Cited By ~ 1

Author(s):

Zhifeng Shao

Keyword(s):

Electron Probe ◽

Spherical Aberration ◽

Wave Length ◽

Cylindrical Symmetry ◽

Electron Wave ◽

Third Order ◽

The Third ◽

Probe Radius ◽

Small Probe ◽

Probe Size

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.

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Children’s Recall of Approximations to English

Journal of Speech and Hearing Research ◽

10.1044/jshr.1602.201 ◽

1973 ◽

Vol 16 (2) ◽

pp. 201-212 ◽

Cited By ~ 3

Author(s):

Elizabeth Carrow ◽

Michael Mauldin

Keyword(s):

Language Development ◽

Fourth Order ◽

Third Order ◽

Memory Processes ◽

The Third ◽

General Index ◽

General Linguistic

As a general index of language development, the recall of first through fourth order approximations to English was examined in four, five, six, and seven year olds and adults. Data suggested that recall improved with age, and increases in approximation to English were accompanied by increases in recall for six and seven year olds and adults. Recall improved for four and five year olds through the third order but declined at the fourth. The latter finding was attributed to deficits in semantic structures and memory processes in four and five year olds. The former finding was interpreted as an index of the development of general linguistic processes.

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