The North Glasgow Integrated Water Management System (NGIWMS) concept outlines the creation of a pioneering drainage system, using a scheduled ancient monument and modern technology, to unlock regeneration within Scotland’s Central belt. Using exemplar sustainable drainage principles, the concept will use the canal to provide flood risk reduction, water quality management and habitat improvement for local communities.
Re-thinking the use of existing infrastructure
The establishment of the Metropolitan Glasgow Strategic Drainage Partnership over 10 years ago has created a collaborative culture which is now receptive to progressing projects such as the NGIWMS. Most recently, Scottish Canals, Glasgow City Council and Scottish Water formed a drainage partnership that will administer the drainage infrastructure as part of this project. Collective appetite to innovate is now delivering the NGIWMS and supporting the development and realisation of non-standard solutions urban surface water management. Historically, the canal system has been considered as infrastructure with a single primary purpose –navigation. However, it has a number of unique hydrological, hydraulic and cultural aspects.
Using the Forth and Clyde Canal
The primary driver for the creation of the NGIWMS has been the existence and potential of the Forth and Clyde Canal system, locally comprising of the Glasgow branch. This system, although historic in nature, has some unique characteristics, being constructed into the urban centre of Glasgow, having an ability to convey significant flows away from this area, providing the potential to mitigate the effects of development and provide a resource across the Central belt of Scotland - whilst also recognising its status as a Scheduled Ancient Monument
The location and nature of the canal provides significant opportunities to function as a conveyance system, it currently operates with low inputs from existing feeders, which maintain levels within the system and ensure there is a positive flow to maintain water quality and operations. Previous work developed a hydraulic model of the canal system, incorporating a representation of the canal hydrology and providing a significant understanding of the potential of the canal to convey flows from future development.
The canal has valuable hydrological characteristics relating to the response time of the system to extreme events. Due to its physical characteristics it has a critical duration; the time in which extreme rainfall events cause peak effects, which is significantly longer than that which relates to development areas and associated drainage infrastructure. This feature allows the future drainage infrastructure and the canal to develop a cooperative relationship working in balance with each other.
Supporting economic regeneration
To fully utilise the potential of the canal system in supporting future drainage and resource capabilities, the potential for the canal system to create additional capacity by drawing down the normal water level of the canal in advance of an extreme rainfall event has been explored. The summit pound of the Forth and Clyde Canal covers a significant geographical area. This creates a unique opportunity to drain water from the canal system, into streams and rivers before any rainfall event and then to be ‘primed’ to receive runoff from developments and surrounding areas.
The concept is supporting the development and regeneration of 260ha of land, which is otherwise constrained due to lack of drainage capacity. The project evaluated the concept and the alternative traditionally engineered solution, which would require a 2km tunnel to connect to the existing water environment, to develop a business case justification. This demonstrated that use of the existing canal infrastructure realised significant cost efficiencies compared to traditional engineering solutions.
Optimising with the canal
The NGIWMS project includes SUDS that will attenuate runoff from rainfall events up to the 0.5% Annual Exceedance Probability (AEP), equivalent to the 200-year return period event and allow for future climate change. Flows equivalent to the greenfield runoff rates, will be drained by gravity to the canal system. During events up to the 3.33% AEP the canal will absorb and convey attenuated runoff, however, during, more extreme events, the summit pound of the canal system will be lowered.
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