Date of Award

2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Earth & Environmental Systems

Abstract

Vegetation deterioration has received an increasing amount of attention in the last few decades. It is considered a main indicator of land degradation processes. The Tabuk area, located in the northwest region of Saudi Arabia, has experienced vegetation deterioration as the major facet of land degradation processes. The study utilized Landsat-5 TM data, professional agricultural reports, and topographic maps, supported with intensive fieldwork to monitor vegetation deterioration and its causes and consequences. The data used in this study has been analyzed using remotely sensed methods by pre-processing data, visual interpretation, and Normalized Differences Vegetation Index (NDVI). Climatic analysis also applied, especially to explain the variations in temperature and rainfall. Human impact analysis provided an environmental evaluation of overgrazing, woodcutting, and conservation. Statistical analysis assisted in obtaining simple statistics for the thirty vegetation samples and led to advanced analysis using T test and point biserial coefficient. Geographic Information Systems (GIS) was used in displaying TM images for obtaining scale and producing images as JEPG files. The study came to the following findings and observations: Landsat-5 TM data has limited use in detecting vegetation deterioration in arid lands due to low spatial resolution. NDVI did show vegetation differences between 1988 and 1999. Climatic analysis demonstrated that the area is characterized by stressful arid conditions and a paucity of rainfall over the entire area. Overgrazing and woodcutting have impacted several sites. Statistical analysis has quantified differences in vegetation and the relationship between NDVI and vegetation cover, human impact, and conservation. In conclusion, NDVI assisted in analyzing major differences in vegetation and was useful in evaluating degradation in arid lands. Along with NDVI, human impact and climatic analyses are shown to be indicators of land degradation processes within this study area.

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