Urban stormwater is sometimes a risk, sometimes a resource. To address both aspects, the Three Points Approach (3PA) is advocated. This research applied the 3PA to map stormwater approaches in two Chinese and four European cities. While all cities have targets for the Technical Design Domain, none have targets for all domains; and thereby lack interventions to maximize benefits of frequent small events in the Day-to-Day Domain or minimize flood risks of rare large events in the Extreme Domain. Using open global precipitation data cities’ stormwater targets were expressed as more comparable rain depths, demonstrating that event depths within the Day-to-Day Domain in Chinese cities, cover much of the same range as those within the Technical Design Domain in the European cities. Expressing targets as depths in the context of the 3PA framework may facilitate transdisciplinary and transnational knowledge sharing, paving the way for management strategies covering all three domains.

The current study investigates the microscale mechanical properties of the constituent phases and their influence on the macroscale properties of multi-phase steels with different microstructural constituents. Two steels, a Transformation Induced Plasticity (TRIP) and an enhanced ductility Dual Phase (DH) steel were produced in a continuous annealing line (CAL). Optical microscopy and EBSD results were utilized for segmentation of microstructural phase constituents. Macroscale mechanical properties were obtained using tensile testing and microscale properties with nanoindentation mapping. The hardness of each constituent is extracted from the hardness maps using a clustering algorithm. TRIP steel shows a homogeneous distribution of retained austenite in ferrite matrix and a small amount of bainite/martensite which is non-banded. In contrast, DH steel shows heterogeneous microstructures where martensite/bainite/retained austenite is found to be banded in the ferrite matrix. Both steels exhibit notable variations in hardness across their constituent phases, which are associated with the resulting microstructural characteristics. Nanoindentation results show that overall hardness/strength in TRIP steel is contributed from ferrite (66 %), retained austenite (33 %) and martensite/bainite (1 %). Whereas in DH steel, it is contributed from ferrite (55 %), mixture of RA, martensite/bainite (∼40 %) and martensite (∼5 %). The macroscopic behavior of TRIP and DH steels was explained and discussed using the rule of mixtures in conjunction with the microscopic properties of individual phases.