Financially sustainable management strategies for urban wastewater collection infrastructure – development of a system dynamics model

Abstract

Causal loop diagrams are developed for wastewater collection networks to identify complex interactions and feedback loops among physical, financial, and social sectors. Causal loop diagrams are then incorporated into a novel system dynamics based decision support tool that can be used for financially sustainable management of wastewater collection networks. Data requirements to develop the decision support tool are discussed along with how can the decision support tool be used to manage a utility.The presented causal loop diagram is the first known attempt to lay out the interrelationships among system components using a formal technique. The causal loop diagram establishes the existence of several interacting feedback loops and demonstrates that the management of wastewater collection networks constitutes a complex dynamic system for which traditional management tools are deemed inadequate. The use of causal loop diagrams can be useful to mitigate effects of the silo-based organizational culture prevalent in many water utilities.The system dynamics model is the first known decision support tool to quantitatively simulate the influence of interrelationships and feedback loops in wastewater collection network management. The model is a mathematical representation of the causal loop diagram to capture cost drivers and revenues sources in the system. It also includes a set of policy levers which allows formulation of various financing and rehabilitation strategies. The model can be used to develop short- and long-term management plans. The impact of financing and rehabilitation strategies on system performance can be simulated and evaluated in terms of financial and service level metrics. The decision support tool can also be used by utilities to ensure essential data is collected and flows within organizational units.