A review of modelling methodologies for flood source area (FSA) identification

Flooding is an important global hazard that causes an average annual loss of over 40 billion USD and affects a population of over 250 million globally. The complex process of flooding depends on spatial and temporal factors such as weather patterns, topography, and geomorphology. In urban environments where the landscape is ever-changing, spatial factors such as ground cover, green spaces, and drainage systems have a significant impact. Understanding source areas that have a major impact on flooding is, therefore, crucial for strategic flood risk management (FRM). Although flood source area (FSA) identification is not a new concept, its application is only recently being applied in flood modelling research. Continuous improvements in the technology and methodology related to flood models have enabled this research to move beyond traditional methods, such that, in recent years, modelling projects have looked beyond affected areas and recognised the need to address flooding at its source, to study its influence on overall flood risk. These modelling approaches are emerging in the field of FRM and propose innovative methodologies for flood risk mitigation and design implementation; however, they are relatively under-examined. In this paper, we present a review of the modelling approaches currently used to identify FSAs, i.e. unit flood response (UFR) and adaptation-driven approaches (ADA). We highlight their potential for use in adaptive decision making and outline the key challenges for the adoption of such approaches in FRM practises

Automated Pipe-sizing of Storm Sewer or Combined Sewer Systems Based on Hydrodynamic Modelling

This paper introduces a method for automated pipe-sizing of storm sewer or combined sewer systems based on hydrodynamic modelling. The methodology includes three steps. Initially, Graph theoretical description of network topology (e.g. “Sewer branch order”) is utilized for classification of the studied sewer network’s topology. Then, the network is decomposed hierarchically into a number of subsystems based on the network topology. Finally, the pipe sizing is carried out subsystem by subsystem with no flooding in the whole system as the objective. To verify the results of the method, the algorithm is tested on a real world sewer network, and then the solution is compared with the global optimal solution. As proved by the case study, the author-designed method could guarantee a near-optimal solution that is very close to the global optimal solution, while requires dramatically less computational effort than global optimization method. Compared with evolutionary methods, the method has its own advantages, since it does not require any parameter for configuration and execution control, and could produce unique solutions as long as the design principles are fixed

Modelling cities and water infrastructure dynamics

Urban water systems are under increasing pressure due to the impact of climate change, population growth and urbanisation. In order to make our urban water systems more adaptable to these challenges new water management strategies must be developed. During the last 20 years many new decentralised technologies have emerged and their integration with existing centralised technologies, in particular, creates complex interactions. To deepen our understanding of these interactions at the city scale and to identify possible transition strategies the development of a potential strategic planning tool is thus proposed. This paper focuses on the evolution of the urban environment and water system, in space and time, in the tool. The dynamics of the model is shown for alpine cities. Numerous test cases are stochastically generated by means of the virtual infrastructure benchmarking approach and evolved over time. Different scenarios for the development of the urban environment and water system are statistically evaluated. An increase of rainfall intensities of more than 10% was identified as critical for the performance of the combined sewer systems investigated. By using DAnCE4Water such critical points in the time line of system performance can be identified.</p