Evaluation and mapping of rangelands degradation using Remotely Sensed Data

In: Sociedade & natureza: revista do Departamento de Geografia da Universidade de Uberlândia, Band 1, Heft 1

Abstract

The empirical and scientifically documents prove that misuse of natural resource causes
degradation in it. So natural resources conservation is important in approaching sustainable
development aims. In current study, Landsat Thematic Mapper images and grazing gradient
method have been used to map the extent and degree of rangeland degradation. In during
ground-based data measuring, factors such as vegetation cover, litter, plant diversity, bare soil,
and stone & gravels were estimated as biophysical indicators of degradation. The next stage,
after geometric correction and doing some necessary pre-processing practices on the study
area's images; the best and suitable vegetation index has been selected to map rangeland
degradation among the Normalized Difference Vegetation Index (NDVI), Soil Adjusted
Vegetation Index (SAVI), and Perpendicular Vegetation Index (PVI). Then using suitable
vegetation index and distance parameter was produced the rangelands degradation map. The
results of ground-based data analysis reveal that there is a significant relation between
increasing distance from critical points and plant diversity and also percentage of litter. Also
there is significant relation between vegetation cover percent and distance from village, i.e.
the vegetation cover percent increases by increasing distance from villages, while it wasn't the
same around the stock watering points. The result of analysis about bare soil and distance
from critical point was the same to vegetation cover changes manner. Also there wasn't
significant relation between stones & gravels index and distance from critical points. The
results of image processing show that, NDVI appears to be sensitive to vegetation changes
along the grazing gradient and it can be suitable vegetation index to map rangeland
degradation. The degradation map shows that there is high degradation around the critical
points. These areas need urgent attention for soil conservation. Generally, it shows that the
most parts of rangelands in studying area have been degraded. So conservation priorities on
degraded rangelands have been recognized based on current degradation.