The paper describes the development of a DENET computer model that involves the application of an evolutionary optimization technique, differential evolution, linked to the hydraulic simulation solver, EPANET, for optimal design of water distribution networks. A model is formulated with the objective of minimizing cost and this formulation is applied to two benchmark water distribution system optimization problems—New York water supply system and Hanoi water distribution network. The study yielded promising results as compared with earlier studies in the literature and encouraged to reformulate the model for a new objective of maximizing network resilience. The results of the analysis demonstrate that DENET can be considered as a potential alternative tool for economical and reliable water distribution network planning and management.

A new approach called spatial system dynamics (SSD) is presented to model feedback based dynamic processes in time and space. This approach is grounded in control theory for distributed parameter systems. System dynamics and geographic information system (GIS) are coupled to develop this modeling approach. The SSD modeling approach offers a single modeling framework for developing conceptually different models. It also provides the much-needed capability to model feedback based complex dynamic processes in time and space while giving insight into the interactions among different components of the system. The proposed approach is superior to existing techniques for dynamic modeling such as cellular automata and GIS and addresses most of the limitations present in these approaches. The SSD approach can be used to model a variety of physical and natural processes where the main interest is the space–time interaction, e.g., environmental/water resources processes, natural resources management, climate change, and disaster management. The applicability of the proposed approach is demonstrated with an application to flood management in the Red River basin in Manitoba, Canada.

The coincidence of floods and coronavirus disease 2019 (COVID‐19) is a genuine multihazard problem. Since the beginning of 2020, many regions around the World have been experiencing this double hazard of serious flooding and the pandemic. There have been 70 countries with flood events occurring after detection of the country's first COVID‐19 case and hundreds of thousands of people have been evacuated. The main objective of this article is to assess challenges that arise from complex intersections between the threat multipliers and to provide guidance on how to address them effectively. We consider the limitations of our knowledge including “unknown unknowns.” During emergency evacuation, practicing social distancing can be very difficult. However, people are going to take action to respond to rising waters, even if it means breaking quarantine. This is an emergency manager's nightmare scenario: two potentially serious emergencies happening at once. During this unprecedented year (2020), we are experiencing one of the most challenging flood seasons we have seen in a while. Practical examples of issues and guides for managing floods and COVID‐19 are presented. We feel that a new approach is needed in dealing with multiple hazards. Our main messages are: a resilience approach is needed whether in response to floods or a pandemic; preparation is vital, in addition to defense; the responsible actors must be prepared with actions plans and command structure, while the general population must be involved in the discussions so that they are aware of the risk and the reasons for the actions they must take.This article is categorized under: Engineering Water > Methods