Land Degradation Detection, Mapping, and monitoring in the Northwestern part of Hebei Province, China, Using RS and GIS Technologies Brightness Tasseled Cap Indicator The result illustrated that the highest value of brightness positive change was in Cong Li County; it was 6.998% for the total area of that county, while the lowest value was 1.786% in Lai Shui County. The greatest percentage of brightness negative change was 11.321% of the total area of Xuan Hua County, while the lowest value was 1.240% in Lai Shui County. This county had the highest value (96.973%) of brightness no-change value. The lowest negative difference value of brightness indicator for the study area was 8.379% of the total area of Xuan Hua County. The brightness positive change rate in the district within the period from 1987 to 1996 was 14.885 km2.yr-1, while it was 29.771 km2.yr-1 for the brightness negative change rate. Table 3 and figures 7, 8 show the results of brightness indicator. Table 3. County-level Tasseled Cap brightness indicator results of the Northwestern part of Hebei Province for the period from 1987 to 1996
Generally, there were a vegetation increase, soil moisture increase, and soil bareness decrease in the region during the study period. There were a higher positive change in the greenness indicator values, a higher positive change in wetness indicator values, and a decrease in the brightness indicator values. Normalized Difference Vegetation Index (NDVI) The results of the NDVI indicated that the highest value of NDVI positive change (vegetation increase) was 13.321% for the total area of Lai Shui County. The highest negative change (vegetation degradation) was 8.511% in Cong Li County. The highest positive net difference (between the positive and negative changes) was 9.813% for the area of Lai Shui County, while the lowest was 3.949% of the area of Cong Li County. The highest positive change rate was 23.932 km2.yr-1 for Zhu Lu County for the period 1987 to 1996. The highest value of NDVI negative change rate was 14.7092.yr-1 in Cong Li County. Table 4 and figures 9, 10 show the results. From the statistical analysis, the result illustrated there was a highly significant correlation coefficient between Tasseled Cap greenness indicator and the NDVI at 99% confidence level. The other correlations between brightness, wetness, and the NDVI were weak. Table 5 shows the results of the statistical analysis.  Figure 3. County-level Greenness positive change map of the Northwestern part of Hebei Province during the period from 1987 to 1996  Figure 4. County-level Greenness negative change map of the Northwestern part of Hebei Province during the period from 1987 to 1996  Figure 5. County-level Wetness positive change map of the Northwestern part of Hebei Province during the period from 1987 to 1996  Figure 6. County-level Wetness negative change map of the Northwestern part of Hebei Province during the period from 1987 to 1996  Figure 7. County-level Brightness positive change map of the Northwestern part of Hebei Province during the period from 1987 to 1996 |
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