Banca de QUALIFICAÇÃO: BENEDITA CLEIDE DE SOUZA CAMPOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : BENEDITA CLEIDE DE SOUZA CAMPOS
DATE: 09/12/2019
TIME: 09:30
LOCAL: Auditório Lab. Geofísica
TITLE:

NUMERICAL MODELING OF BARREIRAS AQUIFER SYSTEMS IN THE SOUTH REGION OF NATAL-RN, CONSIDERING VARIABLE RECHARGE ASSOCIATED WITH SOIL OCCUPANCY RATES AND INCREASE OF THE SEWERAGE SYSTEM

KEY WORDS:

Barreiras Aquifer; Hydrogeological Modeling; Visual MODFLOW; Recharge Variation; Natal-RN

PAGES: 43
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Supplying the city of Natal/RN with an estimated population of 877,640 people is already a major challenge for water resource managers, especially when the Barreiras Aquifer, the main source of supply, is partially contaminated by nitrate due to direct infiltration of sewer water in the soil. With "Natal 100% Saneada” project [Natal with 100% sewer system], which aims to implement an infrastructure for the collection and treatment of sanitary effluents, preventing it from being infiltrated, the problem of nitrate contamination is expected to be solved. However, this action may trigger a new threat to the Barreiras Aquifer, represented by the artificial recharge deficit (urban recharge). Given this context, this research aims to evaluate the impacts of the hydrogeological behavior of the Barreiras Aquifer System in the southern region of Natal, considering the variation of natural and urban recharge from the operation of the sewage system. The methodology involved the development of the conceptual hydrogeological model by collecting geological data (lithology, aquifer geometry, potentiometric level measurements), hydrogeological parameters (hydraulic conductivity, hydraulic load, recharge), geomorphological (topography) and hydrographic (rivers and ocean) for the elaboration of hydrogeological modeling using the Visual MODFLOW computational platform. A conceptual hydrogeological model with two geological layers, which were used for vertical discretization, was adopted for the Aquifer System. For the horizontal discretization, it was used a mesh defined in 476 rows and 391 columns, in a modeled area of approximately 96 Km2, having as contour condition the Potengi River, the Pitimbu River and, the Atlantic Ocean. Recharge in the research area was determined considering the existence of natural recharge and urban recharge. To differentiate these two types of recharge, the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Built-up Index (NDBI) methods were used. With these methods, it was possible to zone three areas (Guarapes, Parque das Dunas and Ponta Negra) as high natural recharge rate and low urban recharge rate, with 279 mm/year infiltration and an area (Urban Zone) of high artificial recharge rate and low natural recharge rate, with infiltration of 889.34 mm/year. In the current stage of the research, there is a coherence between the conceptual hydrogeological model and the mathematical model, with the latter having a root mean square (RMS) error of 16%. These data should be refined, seeking the modeling calibration with an RMS ≤10%. Subsequently, simulations will be performed mainly through variations in the 4 individualized zones, emphasizing the gradually reduced artificial recharge situations. In addition to this research, the behavior of nitrate concentrations in the study area was analyzed to evaluate the current situation of the Aquifer, as well as the evolution of this contamination, from the concentration patterns originated by urban occupation. The methodology used was through the systematization of a database, gathering information from previous studies, such as information from well analysis distributed in the Rio Grande do Norte Water and Sewage Company (CAERN), from 2012 to 2018. The result showed three different contamination zones for the area, based on the population densification structure and the current situation of the sewage networks implemented in the city of Natal

BANKING MEMBERS:
Externo à Instituição - ANTONIO MAROZZI RIGHETTO - IGARN
Externo ao Programa - 2149478 - JOSE BRAZ DINIZ FILHO
Presidente - 1714488 - LEANDSON ROBERTO FERNANDES DE LUCENA
Externa à Instituição - NATALINA MARIA TINOCO CABRAL - FUNASA