Dimensionamento de reservatório de lote para redução do volume de escoamento superficial na cidade de Barreiras, BA

Resumo

The aim of this study was to verify the feasibility of micro-reservoirs installation to reduce the volume of runoff in the urban area of Barreiras, Bahia, Brazil, to pre-urbanization levels. A micro watershed was delineated from altimetry data from the Shuttle Radar Topography Mission, and its area was classified according to the land use and occupation. Excess rainfall was estimated for design rainfall 5-60 minutes long, with return period of 20 year, to the conditions of current occupation and pre-urbanization. With the excess rainfall depths obtained it was estimated the micro-reservoir volume needed to reduce the runoff depth to predevelopment levels, considering the most critical situation. The total area of the micro watershed was 119ha, being 65.16% corresponding to residential lots, 11.38% to wastelands, 0.26% to squares and 23.20% to streets. For the 60 minutes long design rainfall, it achieved total depth of 87mm and excess rainfall depths of 50 and 22mm for the current occupation and pre-urbanization conditions, respectively this design rainfall, the micro-reservoir volume needed, estimated in 15m³, was considered not feasible for installation in existing residential lots.