Within Work Package 3 of the WATRUN project, the Helmholtz Centre for Environmental Research (UFZ) is developing a planning tool for NBS for stormwater management. The planning tool is based on the MUST-B approach, which divides a highly complex urban environment into simple modular units that can be easily scaled and used to perform stormwater runoff simulations.
As the basis for the planning tool, the database was created in close collaboration with other project partners, particularly from the three case study regions (Figure 1). The structure of the database allows for easy use of the data as input to the modeling and simulation processes, and allows for an automated iteration process necessary to develop some scenarios.
Figure 1: Structure of modelling database
Hydrologic and hydraulic modeling and simulation concepts are currently being developed and the urban blocks for the case study sites are being created. Each urban block contains information on permeable and impermeable surfaces such as rooftops, streets, and parks. The blue green infrastructure is modeled in each block and the impact on urban water runoff is studied for the entire case study site (Figure 2).
Figure 2: Implementation of the blue green infrastructure (Nature based Solution) for the reduction of the urban water runoff.
Once the current situation of the case study sites is modeled and validated, the scenarios for the implementation of the NBS are developed. The scenarios include a uniform distribution of NBS across all blocks or a selective distribution depending on the pollution load of the blocks. This means that blocks that produce large volumes of runoff with comparatively low pollution loads are selected for NBS implementation for local stormwater storage, infiltration, and evapotranspiration. Meranwhile, blocks that have higher pollutant loads are selected for connection to the existing sewer networks, so that the heavily polluted runoff is treated at the wastewater treatment plant. The overall goal will be to reduce the runoff to eliminate the (combined) sewer overflow, which is the one of main sources of the pollution of waterbodies.
Authors: Ganbaatar Khurelbaatar, Daneish Despot, and Jan Friesen (21/06/2023)