Resilience of distribution networks under crisis scenarios - Executive Summary - Gondwana can now also take resilience into account in the operational optimisation, for instance, of drinking water supply under crisis scenarios

A method and a tool were developed to quantify and optimise the resilience of drinking water distribution systems under crisis scenarios. The calculation of a resilience indicator was implemented in Gondwana, the software platform for the optimisation of distribution systems. Gondwana has thus been adapted for operational optimisation. The method and tool were tested on the Helmond-Mierlo (Brabant Water) drinking water distribution system. Maximising the resilience under a crisis scenario, such as a pipe fracture, is achieved by modifying valve positions in order to maximise the supply of water to customers. The results of a case study show that the current system, thanks to its ample dimensions, is resilient to pipe fractures, and that there is little room for improvement in this specific instance. Naturally, this cannot be assumed to be the case for other areas and instances. Drinking water utilities can apply the approach developed to test the resilience of existing and new or projected infrastructures under different crisis scenarios. They can therefore identify sensitive areas and elaborate automated operational plans for crisis scenarios. The approach also offers the possibility of including resilience as a performance indicator in the design of new infrastructures, and of weighing this indicator against other objectives, such as installation costs and water quality.

Interest: enabling maximum supply of drinking water, even under crisis scenarios – Drinking water distribution systems are vulnerable to all sorts of threats and crisis scenarios, from the aging of the infrastructure, which can lead to component failure, to natural disasters like flooding and earthquakes, cyber-attacks and contaminations (intentional or not). Such crisis scenarios can impact the performance of a distribution system, with a resulting decrease in the quantity and the quality of the water supplied. Drinking water utilities are therefore concerned about the resilience of their distribution systems, and about how they can maximise this resilience. A method is therefore needed to quantify the impact of crisis scenarios on the distribution of drinking water to customers, to assess the performance of distribution systems, and to automatically optimise the configuration of a network, for the purpose of minimising impact and maximising resilience.

Approach: definition of resilience and optimisation of valve positions – First, a measurable indicator for resilience was elaborated. The relationship between the water actually supplied and the demand for water was chosen. This indicator quantifies the capacity of a distribution network to supply water under a crisis scenario, and therefore the impact that such a scenario has on customers. This indicator was implemented in the Gondwana optimisation platform developed by KWR. This also requires the use of a pressure-dependent pipe network simulator, which is a simulator in which the water supplied depends on the pressure available at a point of use in the network. The approach behind the Scenario Planner tool was then used to draw up an inventory of possible crisis scenarios. This provided an overview of the different threats to the different components of a water distribution system. Lastly, the approach was used in a case study: five different crisis scenarios (shut-down of specific pipes) were calculated for the Helmond- Mierlo distribution network (Brabant Water). The resilience of the current network was calculated under each scenario, after which the valve positions were automatically manipulated to maximise the resilience.

Report – This research is described in the report Veerkracht van leidingnetwerken onder crisisscenario’s (BTO-2019.040).