Climate changes impacts on subtropical urban drainage with low impact developments

• Autor(a) principal: Lago, César Ambrogi Ferreira do
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/18/18138/tde-19062018-163056/
• topic: Climate changes; Drenagem urbana subtropical; Low impact developments; Mudanças climáticas; Subtropical urban drainage; Técnicas compensatórias

Low impact developments (LID) have been used to mitigate the effects of urbanization on the hydrological cycle. However, there is a lack of studies on LID performance in subtropical climates and under potential impacts of climate change scenarios. This dissertation evaluated the impacts of two climate change scenarios (RCP 4.5 and 8.5) on urban drainage with pollutants and their effect on LID practice efficiency located in a subtropical climate, with Cfa classification according to Köppen and Geiger. First, the inlet quantity and quality parameters were calibrated. The buildup/washoff model was evaluated, comparing load calibration and concentration of pollutants: chemical oxygen demand (COD), total organic carbon (TOC), phosphate (PO4) (NH3), iron (Fe), cadmium (Cd) and zinc (Zn). Pollutant washing was studied in the area of the bioretention catchment using historical rainfall data between 2013 and 2017, analyzing the influence of the buildup/washoff parameters of each pollutant in the input mass. Afterwards, Eta5x5km (INPE) climate change scenarios were disaggregated to 5-minute intervals by the modified Bartlett-Lewis method. The disaggregated series was used to estimate the impacts of climate change on urban drainage into the bioretention. Therefore, a simple model, developed specifically for the study bioretention cell, was used to estimate the qualitative-quantitative efficiencies of each period of the climate change scenarios. According to the data acquired from INPE, climate change will result in a fall in the volume of rainfall in São Carlos, resulting in lower volumes of surface runoff. The impacts on pollutant washing, however, vary according to the buildup/washoff parameters, explained by a sensitivity analysis. Climate change does not affect the bioretention quantitative efficiency very much: 81.7% from 1980 to 1999 to 81.4% and 81.3% from 2080 to 2099 for CPR scenarios 4.5 and 8.5. The pollutant removal efficiencies, as well as the washing, depend on buildup/washoff characteristics. One of the main consequences of climate change is a drop in the runoff quality. However, even with quantitative efficiency being maintained, bioretention is capable of mitigating this increase in the concentration of pollutants in urban drainage. Thus, the LID will help preserve the quality of downstream rivers, whose volumes will already have diminished by the decrease in rainfall volume.