Hydrologic and hydraulic aspects and efficiency assessment of bioretentions: models, principles, and design criteria of the 3rd generation LID practices

Author(s)

Marcus Nóbrega Gomes Júnior

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2019-12-16

Examining board members

Eduardo Mario Mendiondo; Marcio Hofheinz Giacomoni; Nilo de Oliveira Nascimento

• Advisor: Eduardo Mario Mendiondo

Abstract

Urbanization associated with climate change makes planning and management of water resources a complex task. In terms of floods, several structural solutions seek to tackle the problem of excessive peaks, excess runoff volumes and worsening water quality in urban centers. Different approaches worldwide provide new lines of thought regarding the management of water resources, the application of mitigation techniques for urban drainage and its design criteria. Best Management Practices (BPM) and Low-Impact Development (LID) stand out. Overall, their scopes focus on applying their fundamental principles towards sustainable development goals (SDGs). CTs (compensatory techniques) can be subdivided into (i) source control, (ii) micro-drainage scale and (iii) basin scale. However, there is still a great divergence regarding design and simulation aspects of the hydrological-hydraulic-qualitative behavior of these techniques. Regarding to bioretentions, several attributes make them one of the most attractive from the point of view of: (a) improvement of the visual aspect, (b) improvement of water quality, (c) protection against erosion, protection against floods and reduction at your risk. The latter, however, has been extensively discussed about its real applicability and/or effectiveness for bioretentions since these techniques are usually designed with the primary objective of improving water quality. Thus, the objective of this work is to propose a physically based mathematical model to simulate the flow in an unsaturated porous medium, to enable the evaluation of the hydraulic behavior of bioretentions. The stored volume, output flow, saturation layer position, and ponding depth height are mathematically resolved as state variables for a given input hydrograph and hyetograph boundary condition. In order to assess an updated rainfall scenario for the city of São Carlos - SP, a new IDF curve, maximizing statistical adjustment indicators, was created. Once the hydraulic model was elaborated and calibrated via reduced-scale experiments, using volumes and flows equivalent between real and reduced scale, the project of a compensatory technique in real-scale at EESC-USP Campus II was elaborated and the evaluation of its generalized efficiency, considering indicators such as (i) flood potential, (ii) reuse potential and (iii) construction risk and uncertainty, was performed. Implementation and maintenance cost functions were constructed in such a way as to be a constituent part of the generalized efficiency versus cost relationship for current precipitation scenarios (1961-2018) and future scenarios (2015-2050 and 2050-2100). (AU)

• FAPESP's process: 18/20865-0 - Sizing, economic analysis and dynamic-modular design of biorretentions from the perspective of climate change and land use
• Grantee: Marcus Nóbrega Gomes Júnior
• Support Opportunities: Scholarships in Brazil - Master