Computer simulation of shelf and stream profile geomorphic evolution resulting from eustasy and uplift

Conference · Thu Apr 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5020994

Johnson, R M ^[1]

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1. Forest Service, Placerville, CA (United States)

A two-dimensional computer simulation of shelf and stream profile evolution with sea level oscillation has been developed to illustrate the interplay of coastal and fluvial processes on uplifting continental margins. The shelf evolution portion of the simulation is based on the erosional model of Trenhaile (1989). The rate of high tide cliff erosion decreases as abrasion platform gradient decreases the sea cliff height increases. The rate of subtidal erosion decreases as the subtidal sea floor gradient decreases. Values are specified for annual wave energy, energy required to erode a cliff notch 1 meter deep, nominal low tidal erosion rate, and rate of removal of cliff debris. The values were chosen arbitrarily to yield a geomorphic evolution consistent with the present coast of northern California, where flights of uplifted marine terraces are common. The stream profile evolution simulation interfaces in real time with the shelf simulation. The stream profile consists of uniformly spaced cells, each representing the median height of a profile segment. The stream simulation results show that stream response to sea level change on an uplifting coast is dependent on the profile gradient near the stream mouth, relative to the shelf gradient. Small streams with steep gradients aggrade onto the emergent shelf during sea level fall and incise at the mountain front during sea level rise. Large streams with low gradients incise the emergent shelf during sea level fall and aggrade in their valleys during sea level rise.

• OSTI ID: 5020994
• Report Number(s): CONF-9305259-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
CALIFORNIA
COASTAL REGIONS
EROSION
GEOMORPHOLOGY
ALLUVIAL DEPOSITS
COMPUTERIZED SIMULATION
CONTINENTAL SHELF
GEOLOGIC MODELS
SEA LEVEL
SHORES
STREAMS
TWO-DIMENSIONAL CALCULATIONS
WATER WAVES
WAVE FORCES
CONTINENTAL MARGIN
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGY
GRAVITY WAVES
LEVELS
NORTH AMERICA
SIMULATION
SURFACE WATERS
USA
580000* - Geosciences
540250 - Environment
Terrestrial- Site Resource & Use Studies- (1990-)