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Remote monitoring of land degradation in arid/semiarid regions


Ray, Terrill Wylie (1995) Remote monitoring of land degradation in arid/semiarid regions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/65EA-Y568.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Land degradation is a serious and growing problem on a world-wide scale -- 11% of the Earth's vegetated surface having suffered serious damage in the last 45 years. Human activity, especially sprinkler irrigation agriculture, can cause dramatic changes in arid regions as the fragile natural plant cover is stripped off and its root system destroyed in the process of cultivation. Satellite and airborne remote sensing data covering the Manix Basin of Eastern California over the last two decades shows that abandoned fields there suffered progressive degradation, as the topsoil eroded due to the lack of protective plant cover. Blowing sand buried and disrupted the downwind plant cover, which caused the downwind area to lose its protection against wind erosion and expanded the region of damage. Because the amount and kind of plant cover is an important marker both of where wind erosion has occurred and where it is likely to occur in the future, especially designed satellite monitoring systems should be able to sense to signatures of undisturbed and disturbed vegetation cover in arid regions. However, this problem cannot be addressed by standard vegetation indices, because of the adaptation of arid region plants to the scarcity of water. Furthermore, weekly to monthly sampling will be necessary because blowing sand visible to satellite remote sensing is highly dependent on the local weather, and this can change within a few months. A new vegetative index suitable for arid regions is proposed for the wavelength region from 0.4-1.0 [...]. The detection and identification of arid region plant communities requires a highly calibrated remote sensing system with higher spectral resolution than that currently offered by Landsat Thematic Mapper. The way in which regions of blowing sand can appear and disappear with rapidity demonstrates the need for a remote monitoring system that can survey large areas on a regular basis. Such a system must be supported by focused ground observations and a continuing analysis of the satellite data.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Planetary Science and Geophysics
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Planetary Sciences
Minor Option:Geophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Murray, Bruce C.
Thesis Committee:
  • Murray, Bruce C. (chair)
  • Albee, Arden Leroy
  • Anderson, Donald L.
  • Muhleman, Duane Owen
  • Wyllie, Peter J.
  • Blom, Ron
Defense Date:11 May 1995
Record Number:CaltechETD:etd-11062007-083125
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4423
Deposited By: Imported from ETD-db
Deposited On:21 Nov 2007
Last Modified:21 Dec 2019 04:41

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