The investigation of stormwater runoff by utilising a combination of green infrastructure in different sized urban residential catchment

Lobwein, Mark (2020) The investigation of stormwater runoff by utilising a combination of green infrastructure in different sized urban residential catchment. [USQ Project]

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This dissertation investigates the performance of green infrastructures in urban residential catchments in Ipswich, Queensland. In total there were 4 catchments designed and tested. They were divided up by the total lots contained within the catchment. There was the single lot that contained 1 lot, the street or neighbourhood catchment that contained 10 lots, the subdivision catchment that contained 100 lots and finally, the suburb or cluster of subdivision catchment that contained 1000 lots. The aim is to identify the optimum combination in all of these different catchments.

The pre-development, post development tand the inclusions of the green infrastructure were modelled using the MUSIC software package from eWater. The MUSIC software has become the benchmark software for analysing stormwater water quality in South East Queensland. However, the software still requires further investigation with regards to its frequent flow management capabilities. Because of the absence of research, this dissertation will carefully analyse all of the results outputted from this software. Although not the major aim of this dissertation, the paper also aims to assist in the understanding and development of the software’s ability to model and assist in the management of frequent flow.

From the 20 models created with MUSIC (Appendix C), results will be outputted and presented in a number of hydrographs. They will represent the amount of urban runoff discharged, after treatment, on the different scaled catchments. Urban runoff velocity, retention and volume can be determined off the hydrographs. The best or ideal outcome will be to mimic or improve the pre-developed flow conditions.

It was found that all green infrastructure reduce the peak discharge. However, some infrastructure have little to no impact of the retention and velocity of urban runoff. Unexpectedly, the combination of green infrastructures either had no effect to the urban runoff or increased the runoff from the original infrastructure. This was assumed to be a calculation error from the software, when calculating bypass from one node to another.

Constructed wetlands were the best performing green infrastructure with having only minor runoff from these devices. This greatly improves the natural, pre-development conditions. These results were predictable when understanding the wetland’s mechanics and processes. Although, these devices performed the best, the cost and land application must be considered in the decision process. Constructed wetlands consume a great deal of land. Their cost to design and construct was the most expensive of all the green infrastructures within this dissertation. Therefore their application can be acknowledged as over-engineering for the selected catchments in this investigation. It is suggested that these be placed downstream of larger catchments. It was discovered that the bio-retention basin, in the larger catchments, did assist in approximately returning the post development back to pre-development conditions. These devices take up small amount of area of land. The use of retaining can dramatically reduce this further. The cost of design and construction of bio-retention are considered reasonable. Therefore, the bio-retention basin was the optimum solution. For the smaller catchments that did not have the basins installed, single lot and neighbourhood/street catchments, the optimum solution was the green roof. Although this did not return to natural pre-developed conditions, it was the best performing solution in the smaller catchments.

There was no sufficient evidence that suggested that the catchment size has effects of the green infrastructure treatment in the model. The results varied between all of the catchment sizes. There was no definite proportion relationship between these two variables, catchment size and green infrastructure performance, that could be distinguished. Therefore with regards to catchment sizing, these findings were mixed and inconclusive.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Chowdury, Rezaul
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 23 Aug 2021 00:10
Last Modified: 26 Jun 2023 04:11

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