Impact of Urban Stormwater Runoff on Cyanobacteria Dynamics in A Tropical Urban Lake

Abstract

Worldwide, eutrophication and cyanobacteria blooms in lakes and reservoirs are a great concern for water resources management. Coupling a catchment hydrological model and a lake model has been a strategy to assess the impact of land use, agricultural practices and climate change on water quality. However, research has mainly focused on large lakes, while urban reservoirs and their catchments, especially in tropical regions, are still poorly studied despite the wide range of ecosystem services they provide. An integrated modelling approach coupling the hydrological model Storm Water Management Model SWMM and the lake ecological model DYRESM-CAEDYM is proposed for Lake Pampulha (Brazil). Scenarios of increased imperviousness of the catchment and of reduction in the load of nutrients and total suspended solids (TSS) in dry weather inflow were simulated. Runoff water quality simulations presented a fair performance for TSS and ammonium (NH4+) while the dynamics of total phosphorus (TP) and nitrate (NO3−) were poorly captured. Phytoplankton dynamics in the lake were simulated with good accuracy (Normalized Mean Absolute Error, NMAE = 0.24 and r = 0.89 in calibration period; NMAE = 0.55 and r = 0.54 in validation period). The general trends of growth, decline and the magnitude of phytoplankton biomass were well represented most of the time. Scenario simulations suggest that TP reduction will decrease cyanobacteria biomass and delay its peaks as a consequence of orthophosphate (PO43−) concentration reduction in the lake surface layers. However, even decreasing TP load into Lake Pampulha by half would not be sufficient to achieve the water quality objective of a maximum concentration of 60 µg chla L−1. Increased imperviousness in the catchment will raise runoff volume, TSS, TP and NO3− loads into Lake Pampulha and promote greater cyanobacteria biomass, mainly in the beginning of the wet season, because of additional nutrient input from catchment runoff. Recovering Lake Pampulha water quality will require the improvement of the sanitation system. The lake water quality improvement will also require more sustainable and nature-based solutions for urban drainage in order to reduce non-point pollution through infiltration and retention of stormwater and to enhance natural processes, such as chemical sorption, biodegradation and phytoremediation. The integrated modelling approach here proposed can be applied for other urban reservoirs taking advantage of existing knowledge on Lake Pampulha.

Using multiple isotopes to identify sources and transport of nitrate in urban residential stormwater runoff

“…Yan et al, (2019) indicated that stormwater runoff was regarded as the largest source of total nitrogen (TN), chemical oxygen demand (COD), and ammonium nitrogen (NH4 + -N) in the Taihu Basin, China. Silva et al, (2019) demonstrated that increasing impervious areas in the catchment enhanced the nutrient inputs from stormwater runoff, carrying total suspended solids (TSS), total phosphorus, and nitrate (NO3 -) into Lake Pampulha, Brazil at the beginning of the wet season.…”

Tropical cities research boundaries: a bibliometric analysis to bridge the gaps through multi-dimensional and cross-disciplinary features

“…Furthermore, Upadhyay et al (2021) indicated that variations in soil temperature and moisture conditions under climate change scenarios may hinder future soil carbon dynamics by mediating soil nutrient availability in urban soils in Varanasi city, India. Understanding the effects of climate change on urban tropical areas is also crucial for addressing issues like eutrophication and pollution (Silva et al, 2019) and for flood damage estimation and mitigation (Tabucanon et al, 2021). Therefore, when planning for sustainable, biodiverse, and resource-efficient tropical cities, it is essential to consider these social and economic impacts.…”

“…These challenges encompass a wide range of areas, including human health, productivity, urban planning, sanitation, resilience, and biodiversity. They are already manifesting as increased risks of heat stroke and disease transmission (e.g., Burkart et al, 2011;Coccolo et al, 2016;Lee J. M. et al, 2019), reduced human comfort due to high levels of thermal stress (e.g., Roth, 2007;Méndez-Lázaro et al, 2016;Ramsay et al, 2021), heightened energy consumption driven by increased cooling demand (e.g., Gamero-Salinas et al, 2021), decreased water availability and heightened pollution (e.g., Chow and Yusop, 2013;Pérez-Villalona et al, 2015;Silva et al, 2019), alterations in local flora and fauna distribution caused by inadvertent climate modification (e.g., Roth and Chow, 2012;Oh et al, 2018;Alue et al, 2022), air pollution challenges (e.g., Vailshery et al, 2013;Nipen et al, 2022), and the resilience challenges of the health-sanitation nexus (Macedo et al, 2022). Therefore, the development of tools and mechanisms to adapt to climate change and conserve urban resources and biodiversity in tropical cities is crucial due to the challenges they face.…”

Sistemas de drenagem urbana e o saneamento: uma análise cienciométrica

“…Destacam-se ainda as temáticas vinculadas às doenças de veiculação hídrica (Aguiar et al, 2019); aos aspectos relacionados à prevenção de doenças e propostas de promoção da saúde (Souza & Freitas, 2008); a contextualização do saneamento rural (Resende et al, 2018); a execução orçamentária vinculada ao plano diretor da cidade de Teresina, no estado do Piauí (Nascimento & Gomes, 2018); e uma simulação do cenário associado ao aumento da impermeabilização na bacia hidrográfica e das cargas de sólidos suspensos totais, fósforo total e nitrato na Lagoa da Pampulha, Belo Horizonte/MG (Silva et al, 2019).…”