USE OF GEOTECHNOLOGIES APPLIED IN THE FLOOD MAPPING IN SCENARIOS OF LAND USE: A CASE STUDY ON NEIGHBORHOOD ALTO SUMARÉ - MOSSORÓ/RN
Urban growth, Remote Sensing, GNSS, GIS, Northeast Brazil
Floods have become frequent events in urban spaces around the world and have been analyzed both as a consequence of events related to climate change and disorderly changes in urban space. In the Municipality of Mossoró/RN, there was an accelerated process of urban occupation in the last 10 years, fostered by the Federal Government program Minha Casa Minha Vida. Even though it is a program where the projects precede planning under good engineering practices, in which the implementation of drainage infrastructure is observed and, mandatorily, require evaluation and seal of the municipality authority, problems of flooding occurred in Alto Sumaré neighborhood, treated as a study area. In the analysis of urban growth, remote sensing images available in Google Earth Pro were used and treated in Geographic Information System (GIS) environment. This analysis allowed estimating for the Alto Sumaré neighborhood the percentage of urban sprawl of 180.75% between 2010 and 2017 and 112.75% between 2017 and 2019. The elaboration of Digital Surface Model (DSM) calibrated with control points in the field, based on planialtimetric surveys techniques with Global Navigation Satellite System (GNSS) and referred to the Brazilian Geodesic System, allowed the evaluation of flooding points. The results indicated that the drainage devices installed in the residential developments of the Alto Sumaré neighborhood were guided by the concept of incomplete cushioning, because most of the damping ponds implanted do not have bottom discharger. The absence of this equipment promoted a false safety effect, as it imposes rapid flow when the volumes of the ponds are reached, which increases the contribution area and, therefore, the flow downstream, causing flooding. Accumulation volumes for recurrence times of 5, 10 and 25 years, appreciating the contribution sub-basins of each pond and low topographies identified in the DSM, indicated greater accumulated volume than accumulation capacity reserve at pond Cidade Jardim 1 and Res. Monte Olimpo, for instance, in the 3 recurrence times. Thus, the calculations show that the damping capacity of most ponds is insufficient.