Macro Drainage and Retention of First Rain in Closed Catchments (PAP014886)

Código

PAP014886

Autores

João Abner Guimarães Junior, ANTONIO MAROZZI RIGHETTO, L. F. F. Moreira

Tema

Urban Floods

Resumo

This paper deals with an unconventional solution of urban drainage for Natal city, RN, Brazil. The city is on closed drainage basins so that runoffs flow radially to the lowest points where lagoons or hydraulic detention reservoirs are situated. Originally, under natural conditions, the shallow areas formed ponds during rainy periods. However, urbanization and bad planning for land use increased runoff and shallows so that resulting quickly in frequently flooding damages. Construction of reservoirs with sufficient volumes to store rainwater and / or pumping systems to transfer the surplus water to other places were continuously implemented as the developing city urbanization occurred. This macro drainage alternative has been established itself in the city. However, as the system drainage increased and becomes complex it should be necessary to integrate water diversion by some new transposition system. The present study refers to the design of the Integrated South Zone Macro Drainage System of Natal City. The main system project design evolves sizing of the main gallery, tunnel type built by nondestructive method. Macro drainage system involves six neighborhoods, a large part of south zone of Natal city. In order to solve permanently the problem of flooding it was designed an integrated drainage system, consisting of a complex system of detention reservoirs, which correspond resizing existing ponds, interconnecting them in series by galleries and tunnels, which act as spillways system to the Potengi estuary. The implementation of this system reduces to acceptable levels the risk of flooding in the area. The design system evolves also water quality aspects. The effluent quality of an urban drainage system changes enough during the rainy season with the washing of paved drainage basin, gradually reducing their polluting head. This aspect justifies thus the incorporation of absorption devices for the retention of the first rain in the design and construction of macro drainage systems. In the design of detention reservoirs. It considers also the effective precipitation (Pefe) which determines the volume capacities of the hydraulic detention reservoir.