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Hillslope soil moisture gradients in...

Yeakley, Jon Alan.

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Hillslope soil moisture gradients in an upland forested watershed.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Hillslope soil moisture gradients in an upland forested watershed./
Author:	Yeakley, Jon Alan.
Description:	160 p.
Notes:	Source: Dissertation Abstracts International, Volume: 54-08, Section: B, page: 4061.
Contained By:	Dissertation Abstracts International54-08B.
Subject:	Environmental Sciences. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9402620

Hillslope soil moisture gradients in an upland forested watershed.
Yeakley, Jon Alan.

Hillslope soil moisture gradients in an upland forested watershed. - 160 p.

Source: Dissertation Abstracts International, Volume: 54-08, Section: B, page: 4061.

Thesis (Ph.D.)--University of Virginia, 1993.

Ecologists have long attributed distribution of forest type to hillslope moisture gradients. Hydrologists in the southern Appalachians have been unable to establish the existence of hillslope soil moisture gradients after decades of measurement. This study determined the existence, controls and dynamics of hillslope soil moisture in an upland forested watershed (WS2) at the Coweeta Hydrologic Laboratory.Subjects--Topical Terms:

676987
Environmental Sciences.

Hillslope soil moisture gradients in an upland forested watershed.
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035 $a (UnM)AAI9402620
035 $a AAI9402620
040 $a UnM $c UnM
100 1 $a Yeakley, Jon Alan. $3 1931518
245 1 0 $a Hillslope soil moisture gradients in an upland forested watershed.
300 $a 160 p.
500 $a Source: Dissertation Abstracts International, Volume: 54-08, Section: B, page: 4061.
500 $a Major Adviser: Herman H. Shugart.
502 $a Thesis (Ph.D.)--University of Virginia, 1993.
520 $a Ecologists have long attributed distribution of forest type to hillslope moisture gradients. Hydrologists in the southern Appalachians have been unable to establish the existence of hillslope soil moisture gradients after decades of measurement. This study determined the existence, controls and dynamics of hillslope soil moisture in an upland forested watershed (WS2) at the Coweeta Hydrologic Laboratory.
520 $a A hillslope transect with a distinct forest vegetation gradient was instrumented with a time domain reflectometry network at two depths. Soil moisture was monitored during a severe autumn drought and subsequent precipitation recharge.
520 $a In the shallow layer (0-30 cm), soil moisture gradients persisted throughout the measurement. Topography was found to exert dominant control. In the deeper layer (0-90 cm), soil moisture gradients were found only during the drought. Control on soil moisture was due to both topography and storage before the drought. After recharge, soil moisture holding capacity exerted dominant control on soil moisture content in the rooting zone.
520 $a A physically-based hydrology model was used to simulate hillslope soil moisture for a 14 year period of hourly climate input. The model consisted of three modules: (1) objective terrain analysis (TAPES-C); (2) a dynamic interception canopy module; (3) a hillslope hydrology module (IHDM4) with a 2-D Richard's equation of subsurface moisture dynamics. Calibration and validation of the model used measured streamflow and hillslope soil moisture data. Simulations were performed for divergent and convergent hillslope planforms.
520 $a Hillslope soil moisture gradients persisted throughout the simulations. Moisture gradients varied with precipitation minus potential evapotranspiration (PPT-PET), ranging 2% to 15% for the divergent hillslope. The convergent hillslope showed a different response due to a persistent near-saturated state near the hillslope outflow. Response times of mean soil moisture content to PPT-PET increased with depth. Soil moisture gradient magnitude decreased with increasing PPT-PET.
520 $a Space-time correlation between soil depth and drought duration was evident. Moisture content and gradients were more variable in the upper layers. Top layers exhibited short term energy states below stress potentials for vegetation. These results indicate hillslope moisture control on forest vegetation distribution is realized at the regeneration stage of tree life history in deep-soiled humid mountain watersheds.
590 $a School code: 0246.
650 4 $a Environmental Sciences. $3 676987
650 4 $a Hydrology. $3 545716
650 4 $a Biology, Ecology. $3 1017726
690 $a 0768
690 $a 0388
690 $a 0329
710 2 0 $a University of Virginia. $3 645578
773 0 $t Dissertation Abstracts International $g 54-08B.
790 1 0 $a Shugart, Herman H., $e advisor
790 $a 0246
791 $a Ph.D.
792 $a 1993
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9402620