Author(s): L. Benard; B. Dobson; A. Mijic
Linked Author(s):
Keywords: Smart urban water management; Downstream impacts of dams; Multi-objective optimisation and control; Water pollution control; Integrated urban water management
Abstract: Water quality is an increasingly recommended goal for the management of water systems [1]. A range of studies have addressed how water resources and river quality interact and can be managed in a joint manner [2,3]. However, considerations of water resources and river quality often omit a critical factor – that wastewater systems exist on the same rivers as water supply systems. Actions taken for water supply, for example to abstract a given amount of water, will interact with the wastewater system, for example by changing the flow and dilution in effluent receiving waters [4]. We have identified that over half of the river catchments in England and Wales have both significant abstractions (>2 million litres/day) on and significant wastewater treatment plant (>100,000 people) discharges into the same rivers [4]. Using the CityWat case study of London’s urban water system [4], we investigate how control policies with increasing levels of complexity can improve river quality and supply reliability. We implement an ‘engineering judgement’ policy and a universal approximator policy, both are then optimised with an evolutionary multi-objective optimisation algorithm. The water quality improvements provided by these optimised policies are also compared against the impact on river water quality of adding additional stormwater storage designed to resemble the Tideway Tunnel. We find that, when evaluated in the baseline CityWat model, the more complex policies, although optimal with respect to the water quality and quantity objectives, do not yield significantly better improvements than the optimised engineering judgement policy. We also find that the policies can be augmented with the construction of the Thames Tideway Tunnel to provide further benefits. This implies that infrastructure investments should consider optimisation of operations to further increase river water quality, perhaps incorporating methods such as [7].
Year: 2021