MOSART-urban: a semi-distributed regional urban flood modeling framework

Abstract:

Modeling urban hydrological processes at the regional or larger scales is challenging. On the one hand, current urban flood models are highly distributed, data hungry and computationally demanding. On the other hand, urban infrastructure data are rarely available. We try to tackle this dilemma by developing a semi-distributed, physically based model called Model for Scale Adaptive River Transport – urban module, MOSART-Urban. MOSART-urban is design to capture dominant urban processes in a computationally efficient framework. It is based on a riverine component of Earth System Models (ESMs), MOSART, which represents routing processes in hillslope, tributaries, and main channel for non-urban areas. MOSART-urban replaces the hillslope component of MOSART by simulating surface runoff from impervious street areas, based on the extensively available street maps. It also adds a surface storage component to account for stormwater retention ponds. The street network conveys the surface runoff from urban areas through the street inlets and grates into below-ground storm drain networks. Since the data for these inlets and grates are rarely available, their spatial distribution is estimated through the node degree of the street network. The node degree represents the number of connected streets to each node i.e., the contributing drainage network, which is used to determine the total number of inlets within this contributing network. The storm drain and the street network are coupled through the inlets, i.e., the water can flow from the street to the storm drain and vice versa (overflow). The proposed framework is tested at representative synthetic and realistic urban watersheds, achieving satisfactory performance with efficient computing. It is therefore suitable for representing urban hydrological processes in land surface or Earth System Models at the regional or larger scales.