Stormwater management impacts of small urbanising towns: The necessity of investigating the 'devil in the detail'

Spencer Browne; Anna Lintern; Behzad Jamali; João P Leitão; Peter M Bach

doi:10.1016/j.scitotenv.2020.143835

Stormwater management impacts of small urbanising towns: The necessity of investigating the 'devil in the detail'

Sci Total Environ. 2021 Feb 25:757:143835. doi: 10.1016/j.scitotenv.2020.143835. Epub 2020 Nov 20.

Authors

Spencer Browne¹, Anna Lintern¹, Behzad Jamali², João P Leitão³, Peter M Bach⁴

Affiliations

¹ Department of Civil Engineering, Monash University, Clayton 3800, VIC, Australia.
² Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales UNSW Sydney, NSW 2052, Australia.
³ Swiss Federal Institute of Aquatic Science & Technology, Dübendorf, Switzerland.
⁴ Swiss Federal Institute of Aquatic Science & Technology, Dübendorf, Switzerland; Institute of Environmental Engineering, ETH Zürich, Zürich 8093, Switzerland; Department of Civil Engineering, Monash University, Clayton 3800, VIC, Australia. Electronic address: peterbach@gmail.com.

PMID: 33316523
DOI: 10.1016/j.scitotenv.2020.143835

Abstract

In many parts of the world, small towns are experiencing high levels of population growth and development. However, there is little understanding of how urban growth in these regional towns will impact urban runoff. We used the case study of Wangaratta, located in South-East Australia, between 2006 and 2016, to investigate land cover changes and their impacts on urban runoff discharge. Detailed spatio-temporal analysis (including neighbourhood composition analysis and supervised classification of aerial imagery) identified that population, land use and land cover changes in Wangaratta, although subtle, were mostly driven by residential growth in the outskirts of the town, where there were large increases in impervious surface area. Overall, the urban growth was minimal. However, in spite of these small changes, a sub-catchment only SWMM model showed that the increase in impervious surface area nevertheless resulted in a statistically significant increase in total runoff across the town. Particularly, this increase was most pronounced for frequent and shorter storms. The analysis of urban development pattern changes coupled with urban hydrological modelling indicated that land cover changes in regional towns, especially when analysed in detail, may result in hydrological changes in the urban region (likely to be exacerbated in coming years by changing climate) and that adaptation efforts will need to adopt a variety of approaches in both existing and growth zones. Our findings highlight the necessity of detailed fine-scale analyses in small towns as even subtle changes will have substantial future implications and robust planning and adaptation decisions are even more important when compared to larger cities due to the greater economic constraints that small towns face and their important relationship with the surrounding hinterlands.

Keywords: Geographic information systems (GIS); Imperviousness; Land use change; Spatio-temporal analysis; Stormwater runoff; Urban planning.