Abstract. Urban Green Space (UGS) has been broadly treated as a valuable and limited resource to handle the challenges brought by high-density urban environment. Green stormwater management has been prompt around the world. To reduce the potential conflicts between stormwater management and other requirements on UGS (especially human needs), the research community and governments encourage the urban planners and designers to integrate stormwater analysis into UGS design. However, the professional term and operation of the traditional hydrological model is a huge challenge to the designers who haven’t touched hydrological knowledge. This study developed a method to simulate and quantify stormwater in UGS by the particle system in the design platform- Rhinoceros +Grasshopper. In this method, we adopted five groups of urban objects such as terrain, building footprint etc. to ease procedures and performance. To overcome the issue the abstracted particle movement cannot reflect the infiltration features of land cover, we introduced categorising locations of the particles and the UGS retaining stormwater hypothesis. To test the feasibility of the method, we tested the three parameters of the integrated model: iteration times, rainfall depth ( selected rainfall event) and particle radius. The comparison tests prove: (1) too small iteration times would lead the particles to stop on the way to the bottom of the terrain, so we set at least 4000 iteration times for simulation; (2) the sensitivity to the selection of rainfall event and particle size is relatively low, the simulation results vary by 1%; (3) too small particle numbers will impact the accuracy of analysis, so we should balance accuracy and work efficiency of work; (4) the stormwater volume estimation based on the particle system is acceptable. The experiments confirm the method can effectively support preliminary UGS design work.

Abstract. With the growth of urban population and the increasing urban density, urban green space has become a kind of precious and limited resources. It not only has a positive impact on the health of urban residents with high work-life pressure but also offers opportunities as part of blue-green solutions for sustainable urban water management. Therefore, to effectively utilise the limited green spaces, experts are exploring a way of organising the green space layout to balance human needs and other urban developing requirements (e.g., in this case, urban stormwater management) within the certain common area. With this target, translating the space accessibility to human and other urban developments on green space into space parameter is a critical step to organize space model for the multi-functional green space. Although there are plenty of existing spatial parameters developed for evaluating human accessibility (such as travel distance, land-use, spatial connectivity etc.), there isn’t a way to organize them to satisfy the diverse evaluation needs from different research purposes. Besides, most of them are suitable for analyzing space on a city scale or at least a precinct scale in a 2D model. To the accurate design on a micro-scale, it is still a big challenge. The reason is some parameters for city analysis don’t work on a micro-scale, and some parameters should be reorganised in the evaluation algorithm or should include more micro-scale factors. Thus, this paper, based on the characteristics of human behaviour, redefines the complex concept- accessibility and develop measurable parameters with feasible factors on micro-scale. Overall, this paper presents: (1) a new definition of walking accessibility of green space; (2) evaluation criteria (3) parameters (depth and Integration) reflecting connectivity criteria (4) Parameters (travel time and speed, slope, direction changes) relating travel distance criteria with updated evaluation algorithm and factors. This paper aims at useful spatial parameters and evaluation measures that are applicable to integrate human needs within multi-functional green space design, especially green stormwater management design.