Effects of mixed land use on urban stormwater quality under different rainfall event types

Haibin Yan; David Z Zhu; Mark R Loewen; Wenming Zhang; Stacey Zhao; Bert van Duin; Lei Chen; Khizar Mahmood

doi:10.1016/j.scitotenv.2024.175124

Effects of mixed land use on urban stormwater quality under different rainfall event types

Sci Total Environ. 2024 Nov 10:950:175124. doi: 10.1016/j.scitotenv.2024.175124. Epub 2024 Jul 30.

Authors

Haibin Yan¹, David Z Zhu², Mark R Loewen¹, Wenming Zhang¹, Stacey Zhao³, Bert van Duin⁴, Lei Chen³, Khizar Mahmood³

Affiliations

¹ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
² Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada; School of Civil and Environmental Engineering, Ningbo University, Zhejiang 315211, China. Electronic address: dzhu@ualberta.ca.
³ Climate & Environment, City of Calgary, AB T2P 2M5, Canada.
⁴ Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada; City & Regional Planning, City of Calgary, AB T2P 2M5, Canada.

PMID: 39089374
DOI: 10.1016/j.scitotenv.2024.175124

Abstract

The joint effect of mixed land uses and rainfall event types was studied using a two-year field monitoring program in four urban catchments in Calgary, Alberta, Canada. Event mean concentration (EMC) and event pollutant load (EPL) were employed to evaluate the total suspended sediment (TSS), nitrogen and phosphorus. The correlation analysis showed that most nitrogen and phosphorus components (except for NO₂^-/NO₃^- and TDP) predominantly exist in particulate form in the study areas. The correlation for EPL was notably stronger than EMC, which can be attributed to varying rainfall characteristics. The differences in EMCs and EPLs of TSS, nitrogen and phosphorus across catchments indicated that the complexity and spatial distribution of mixed land use can influence the generation and transportation of pollutants in urban runoff. The impacts of rainfall characteristics on stormwater quality are integrated rather than driven by a single rainfall characteristic. Brief but intense events tended to elevate TSS, nitrogen and phosphorus concentrations, especially in complex land-use catchments. Events with long antecedent dry days and short duration also resulted in increased pollutant concentrations, while events with long duration and low intensity could result in higher EPLs. The effect of mixed land use on water quality can vary depending on rainfall event types. Seasonal variations were found in EMC and EPL of TSS, nitrogen and phosphorus, with higher values in the spring and summer than the fall. Seasonal variations are mainly influenced by rainfall conditions, temperature and anthropogenic activities (e.g. lawn fertilization and de-icing with sands). MLR considering rainfall characteristics is an effective method for predicting stormwater quality within a single catchment. Considering complexity and spatial distribution of mixed land use can improve the accuracy of the harmonized MLR model. This research provided insights into understanding the complexities introduced by mixed land use and rainfall event types in urban stormwater quality.

Keywords: Event mean concentration; Event pollutant load; Mixed land use; Nutrients; Rainfall event types; Total suspended solids.