Is water quality based stormwater management actually feasible? A SWMM based study of the trade-offs of various stormwater management approaches

Abstract

Extreme weather events caused by climate change are becoming more frequent all across the world, particularly in the Northern Hemisphere, where these events manifest themselves as more severe or long-lasting rainfalls. Because the typical response, infrastructure refurbishment, is costly and time consuming, it is necessary to develop and implement alternative, more resource efficient, stormwater management methods. The methods must benefit both the urbanites as well as the natural environment, but they must be grounded on a comparative examination of alternatives. The purpose of this paper is to evaluate the trade-offs between several stormwater control strategies in the context of climate change, such as no intervention, water quality-based intervention, water quantity-based intervention, and a combined approach. Each of the aforementioned approaches is considered to have intrinsic advantages and disadvantages that should be examined and quantified. Analysis of these trade-offs is critical because it provides some insight into the feasibility of implementing various stormwater management strategies for protecting the environment. The SWMM software was used to analyse the various scenarios, and the model was built using data from multiple national databases as well as data sets provided by the Municipality of Viimsi in Estonia. This study confirmed that water quality protection can be prioritized even in densely populated areas without jeopardizing citizens’ well-being or causing unnecessary floods. This can be accomplished even with simple rule-based control if the necessary hardware, such as sensors and flow devices for digitalizing and combining inter-linking stormwater infrastructure are installed on-site. Through the SWMM simulations it was determined that digitalization of the stormwater solutions allows for a 30-92% reduction in flow, and consequently a 50-90% reduction in pollution load entering the Baltic Sea.