ABSTRACT
Desertification has advanced over portions of the semiarid region of Ceará, assuming variable
intensity, which threatens the sustainability of environmental systems. In this scenario, there is
a need for environmental assessment and monitoring of desertification. How to evaluate and
monitor areas already affected, or leaning to desertification in Ceará? Among the methodological
proposals, the use of indicators has been adopted for the identification of vulnerable areas,
with the support of geoprocessing tools. The areas chosen for study were two municipalities
located in the semiarid hinterlands of Ceará: Santa Quitéria, with an approximate extension of
4,261 km2, in the Centre-North hinterlands; and Independence, located in the Crateús’s hinterlands,
with an area of 3,219 km2. The objective of this study was to evaluate the desertification
and degradation of the drylands of the hinterlands of Santa Quitéria and Independência through
biophysical and socioeconomic indicators, with the support of geotechnologies in contribution
to the environmental monitoring. The research was structured in three main stages: survey and
collection of data and cartographic and tabular information; fieldwork; and treatment and
analysis of information in the Geographic Information System (GIS). For the construction of a
geographic database of the study areas, they were obtained cartographic data from institutions
as the Secretariat of Water Resources (SRH), the Brazilian Institute for Geography and Statistics
(IBGE), the State Department of Highways (DER-CE) were used; the municipal mesh, the Institute
of Colonization and Agrarian Reform (INCRA) and the Institute for Agrarian Development
of Ceará (IDACE); elevation information and creation of a Digital Elevation Model
(DEM) in Shuttle Radar Topography Mission (SRTM), radar images, with 90m of spatial resolution.
The geomorphological features and the physiognomic pattern of the vegetation cover
and land use classes were obtained from the visual and digital interpretation of satellite images
by CBERS4, in the 1: 100,000 scale. The spatial analysis was performed in ArcGIS 10.4 software,
which allowed the storage and manipulation of data to generate thematic maps, in a scale
of 1: 200,000. From a systemic approach, the integrated characterization of the abiotic, biotic
and anthropic components allowed the identification of 16 environmental systems and subsystems
in the study municipalities. At a later stage, environmental systems were evaluated through
the application of two groups of indicators of desertification: geobiophysical and socioeconomic.
The geobiophysical indicators were: permoporosity; slope; water erosion; thickness; cover
and vegetation stratum; aridity and vulnerability to droughts. The group of socioeconomic indicators
analyzed: water abstraction; vegetable extractivism; temporary agricultural production;
livestock and land structure. Each indicator was composed of five classes, dispose in values
from one to five. The highest value attributed corresponded to better conditions for the conservation
of natural resources. The geobiophysical indices of desertification (IGBD) were derived
from the arithmetic mean obtained from the sum of values assigned to each indicator, divided
by the total number of indicators. The analysis of socioeconomic indicators (ISED) evidenced
the direct causes of pressure on the natural resources of the desertification processes in the
hinterlands of Santa Quitéria and Independência. As a result of the evaluation, the environmental
systems were classified into three levels of susceptibility: low, moderate and high, represented
in the Susceptibility Maps to Desertification. It was concluded that the environmental susceptibility
of the environmental systems of Santa Quiteria and Independence to desertification
reached two levels of intensity: moderate and moderate to high.
Keywords: Desertification. Indicators. Semiarid lands. Remote Sensing. GIS.
