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Title: Mapping and monitoring land degradation in southern New Mexico using Landsat data
Author: Wang, Ming-Chih Jason
ISNI:       0000 0001 3560 7142
Awarding Body: University of London
Current Institution: King's College London (University of London)
Date of Award: 2000
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This research aims to determine the effectiveness of satellite remote sensing, in particular the technique of linear mixture modelling, in mapping and monitoring land degradation in the Jornada Basin, Southern New Mexico, USA. Land degradation in the Jornada area is characterised by shrub encroachment, deterioration of soil resources (i. e. increased erosion, changes in soil texture, and decreases in soil nutrient status and water-holding capacity) and often a reduction in vegetation cover. In this research, linear mixture modelling, regression models, and spectral vegetation indices are applied to Landsat TM imagery in order to assess their utility for mapping and monitoring land degradation. Linear mixture modelling has been used to estimate the proportions of green vegetation, dry vegetation, shade, and soils. The results of this study indicate that mixture modelling is a reasonably accurate technique to measure these materials. The correlation of the field-measured and model-estimated green vegetation, dry vegetation, and total vegetation proportions are 0.93,0.86, and 0.93 respectively. Moreover, the results of mixture modelling improve when the shade element is removed. In contrast, many of the correlations between vegetation indices and the various vegetation parameters are not significant or result in low R2 values. Indeed many of SVIs' R2 values are even lower than those provided by regressions of the field data to individual TM spectral bands. The application of mixture modelling to multiple-date imagery suggest that mixture modelling can identify successfully the patterns and the extent of extreme change and thus shows potential for monitoring of rangeland resources. Furthermore, the maps of vegetation and soil types provided by mixture modelling have been manipulated to estimate the shrub to grass ratio, a soil degradation index, and an index that combines both these indicators of land degradation. These indices have been found to be more sensitive to change than any of the individual mixture maps.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available