USE OF GIS IN IDENTIFICATION OF RISK AREAS AND SOCIAL VULNERABILITY DUE TO LOCAL RAINFALL Lidiane

This study aimed to present the contributions of GIS to detect areas of risk and social vulnerability in João Pessoa City, according to obtained data from civil defense. The spatial distribution of the region's communities was accomplished and extracted risk areas that have been affected with the precipitation anomalies occurred in the years 2011 and 2012. Also, maps of topography were obtained and slope hypsometric eminent assess the risks of irregular occupations in the study area. Finally, João Pessoa lacks management policies for the appropriate use of the soil and for natural disaster prevention.


Introduction
Over the years, the urbanization process and disordered occupations have aggravated the duration, intensity and frequency of natural disasters caused by heavy rains as landslides, floods and landslides.This could be caused by the high surface temperature of the city, which increases global warming, but also due to the heat which is irradiated by the heat engines and refrigeration systems (Lombardo, 1985).
In Brazil, this process is characterized by the intense pace and acceleration (Santos, 1990), being product of speculative logic that results in urban voids, concentrations of noble Corresponding author: lidiane.geo@gmail.com.
areas in poverty with inappropriate occupation of urban sites (Carlos, 2001); becoming in hazardous environmental areas with growing vulnerabilities (Veyret, 2007;Beck, 1986).
In recent decades, the record number of natural disasters in various parts of the world is considerably increasing.This is due mainly to the increase in population, disorganized occupation and the intense process of urbanization and industrialization.Among the main factors that contribute to lead to these disasters in urban areas are the soil sealing, densification of buildings, conservation of heat and air pollution.(Kobiyama, et al., 2006).Kobiyama et al., (2006)  beginning to be widely studied by many researchers around the world (Lohmann et al., 2006;Chavas et al., 2009;Harmsen et al., 2009;Campos et al., 2010).In João Pessoa, PB, there is also the inordinate use of soil in some areas of the city.

Investigation Area
João Pessoa City (Figure 1) is located at  According to the profile of the municipality prepared by the municipal government has João Pessoa, the city has 49.69 km² of environmental preservation.

Raster and vectors data
To develop this study, has been used  Figura 3: Print screen of database used.
The procedure snip the risk areas was accomplished through a query attributes through SQL language and its mathematical operators, which own GIS software and this can be seen in Figure 4.  From the image we extracted SRTM elevation contours and topographic map and made the slope with the aid of a tool that is in the software, the 3D Analyst, allowing the understanding of relief.Figure 6 shows the schema that must be followed to obtain the desired data.

Results and Discussion
The operations of queries and extraction of information from risk areas, resulted in a map of the spatial distribution of communities, with their respective areas of risk, shown in

( 2007 )
addressed the issue of urban climate and found that urbanization and human activities are consequences this process.Due to removal of the canopy and the new paving streets, soils are increasingly impervious, as well as drainage systems become increasingly inefficient.What has caused major disasters in recent years is the disorderly occupation along the riverbanks and buildings in inappropriate areas such as hills and slopes.These areas are known as areas of risk, employed according to social vulnerability of the population, and these areas are also susceptible to natural disasters such as landslides and floods.
Flooding associated with hydrometeorological phenomena such as tropical storms, or hurricanes, monsoons, the El Niño or La Niña are considered hazardous natural events (Ayala, 2001).Approaches to understand these processes include the study of previous events.Moreover, using flood simulations, forecasting and flood maps prepared with the help of Geographic Information Systems (GIS), radar and remote sensing (Merzi & Aktas, 2000) techniques are crucial in the development and evaluation of risks and public management.Regarding the problem that occurred in various parts of Brazil and managerial accountability, the geoprocessing techniques are contributing to the organization of urban space, the identification of risk areas susceptible to landslides, floods and landslides.As the weather in the forecast of torrential rain control and time series of rainfall site.This work has as study area João Pessoa City -PB, aiming to use GIS techniques to identify areas of risk in vulnerable conditions according to the heavy rainfall, as well as to report the occurrence of rain and disorders occurred between the years 2011 and 2012.
the eastern end of the state of Paraíba, between the coordinates 08° 07 'south latitude and 34° 52' west longitude.It borders to the north with Cabedelo City, across the Jaguaribe river, to the south with Conde City, by the Gramame river, on the east by the Atlantic Ocean, and on the west with Bayeux City, by the Sanhauá river and Santa Rita City by the Mumbaba river and Paraíba river.It has a population of 723.515 inhabitants and the area of the territorial unit is approximately 211.474 km² and population density 3421.30(inhabitants/km²) (IBGE, 2010).Due to urban growth, the city grew eastward and currently presents a diverse urban site at the foot of the slopes, and coastal plain boards.
shapefiles from João Pessoa City and their communities, which were made available by PMJP, information risk areas, type of risk, historical occurrences of disasters granted by the Civil Defense of the Municipality, rainfall data obtained by AESA and data relief surface extracted from SRTM images, of the Embrapa's site.The shapes were acquired, entered into the GIS software, ArcGIS ®, allowing visualization of the spatial distribution of communities, as shown in Figure 2.

Figure 2 :
Figure 2: Map of the spatial distribution of existing communities in João Pessoa City.

Figure 4 :
Figure 4: Print screen to query spatial risk areas in communities.
about the heavy rains during the period of 19 is January 20, 2011, with the 89.08 mm rainfall according to information obtained by the Executive Agency for Water Management in the State of Paraíba (AESA) caused serious damage, among them stood out as Civil Defense (2012), a series of floods, with several affected communities in the region, such as the São José, Tito Silva, Santa Clara, São Rafael and Novo Horizonte communities.

Figure 7 .
Figure 7. Risk areas show no spatial correlation with each other, having effective characteristics related to social vulnerability and disadvantaged areas or unoccupied within the city.

Figure 7 :
Figure 7: Map of the spatial distribution of communities of João Pessoa City and their respective areas of risk.

Figure 8 :
Figure 8: Map of the spatial distribution of risk areas in João Pessoa City.

Figure 11
Figure 11 (a) and (b): Situation in the affected areas after heavy rainfall occurred in January 2011.Source: Civil Defense (2012).