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Mechanical effects of chaparral dist...

Terwilliger, Valery Jane.

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Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California./
Author:	Terwilliger, Valery Jane.
Description:	218 p.
Notes:	Chair: Susan W. Beatty.
Contained By:	Dissertation Abstracts International49-08B.
Subject:	Physical Geography. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8822903

Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California.
Terwilliger, Valery Jane.

Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California. - 218 p.

Chair: Susan W. Beatty.

Thesis (Ph.D.)--University of California, Los Angeles, 1988.

Two influences of vegetation on soil slippage were investigated on unstable hillsides covered by chaparral, prescription burned chaparral, and grassland. Reinforcing effects of roots were established and vegetation influences on soil stability through modification of soil water were investigated. Direct shear tests were conducted on large (25 cm diameter x 61 cm) "undisturbed" soil samples extracted throughout slip-prone soils under the three vegetation types. Small (6.1 cm diam x 2.5 cm) root-free cores extracted from each large shear surface were sheared to establish the strength of soil without roots. Absolute and relative contributions of roots to soil strength were very significant throughout all three vegetation types. Unburned chaparral tended to be punctuated by sporadic root reinforcement of high magnitude whereas burned chaparral and grassland landscapes had more uniform root-reinforcement of lower magnitude. A two dimensional infinite slope analysis suggested that the average amount of root-reinforcement could prevent failure of a saturated 20$\sp\circ$ hillside. The analysis was then expanded to three dimensions to examine effects of differing distributions of root-reinforcement on soil slip dimensions.Subjects--Topical Terms:

893400
Physical Geography.

Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California.
LDR:02728nam 2200265 a 45 001 941650
005 20110519
008 110519s1988 ||||||||||||||||| ||eng d
035 $a (UMI)AAI8822903
035 $a AAI8822903
040 $a UMI $c UMI
100 1 $a Terwilliger, Valery Jane. $3 1265748
245 1 0 $a Mechanical effects of chaparral disturbances on soil slip patterns in the transverse ranges of southern California.
300 $a 218 p.
500 $a Chair: Susan W. Beatty.
500 $a Source: Dissertation Abstracts International, Volume: 49-08, Section: B, page: 3075.
502 $a Thesis (Ph.D.)--University of California, Los Angeles, 1988.
520 $a Two influences of vegetation on soil slippage were investigated on unstable hillsides covered by chaparral, prescription burned chaparral, and grassland. Reinforcing effects of roots were established and vegetation influences on soil stability through modification of soil water were investigated. Direct shear tests were conducted on large (25 cm diameter x 61 cm) "undisturbed" soil samples extracted throughout slip-prone soils under the three vegetation types. Small (6.1 cm diam x 2.5 cm) root-free cores extracted from each large shear surface were sheared to establish the strength of soil without roots. Absolute and relative contributions of roots to soil strength were very significant throughout all three vegetation types. Unburned chaparral tended to be punctuated by sporadic root reinforcement of high magnitude whereas burned chaparral and grassland landscapes had more uniform root-reinforcement of lower magnitude. A two dimensional infinite slope analysis suggested that the average amount of root-reinforcement could prevent failure of a saturated 20$\sp\circ$ hillside. The analysis was then expanded to three dimensions to examine effects of differing distributions of root-reinforcement on soil slip dimensions.
520 $a Available soil water contents and hydraulic potential in burned and unburned chaparral were monitored from tensiometers and electrical resistance blocks. Soil under burned vegetation remained moister during a dry period than soil under unburned vegetation on 2 out of 3 slopes studied. Daily increases in available soil water content and in hydraulic head were greatest for a given storm where antecedent soil water levels were lowest. Laboratory wetting trials on soil cores also strongly confirmed that when given abundant water, drier soils wet up more and faster than initially moister soils.
590 $a School code: 0031.
650 4 $a Physical Geography. $3 893400
690 $a 0368
710 2 $a University of California, Los Angeles. $3 626622
773 0 $t Dissertation Abstracts International $g 49-08B.
790 $a 0031
790 1 0 $a Beatty, Susan W., $e advisor
791 $a Ph.D.
792 $a 1988
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=8822903