## 4 Discussion  
In this paper, we present a structured methodology for analysing the potential influence of SUDS implementation at the catchment scale in the context of expected climate change. The methodology aims to provide a comprehensive overview of the evolution of  
Figure 15: Evolution of infiltration and runoff for the maximum, average, and minimum precipitation scenarios for the extreme cases of CN = 70 (right column) and CN = 99 (left column). The green dashed line represents the average annual precipitation, while the yellow dashed line shows the average annual runoff relative to the 2010–2024 baseline, respectively. hydrological processes and balances at the catchment scale resulting from different SUDS implementation scenarios. It includes a comprehensive strategy for identifying catchments affected by SUDS implementation, processing territorial and meteorological information, establishing a comparative baseline, and generating simulated scenarios. Currently, there are no established SUDS standards that explicitly address future climate scenarios. Nevertheless, urban planning in the UK and northern Europe increasingly integrates SUDSs as a mitigation strategy, as does urban planning in the USA, China, and Australia [44, 45]. However, as [PERSON] and [PERSON] have demonstrated, projected increases in runoff under future climate scenarios--particularly under high-emission pathways--may exceed current design thresholds if only minimal climate change allowances (e.g., 20-30%) are applied. This is despite recommendations suggesting allowances of up to 40% to account for more extreme events [46]. Our approach differs from previous ones mainly in terms of spatial scale. While the vast majority of previous studies focus on neighbourhoods or mixed developments (see, for example, references [47, 48, 49, 50, 51, 52, 53, 54, 55, 56]), only a few demonstrate SUDSs at the catchment scale (see references [57, 58, 59, 60, 61]). We advocate defining the catchment as the only unit of study. We expect that this approach will provide a more comprehensive view of hydrological systems than focusing on smaller areas. This approach is also more in line with the original SUDS paradigm, which aims to preserve natural dynamics at the catchment scale. The method presented here is not suited to analysing the ability of SUDSs to retain runoff at urban or smaller scales, but rather at catchment scale. Furthermore, in contrast to previous approaches, we compare the effectiveness of SUDSs in maintaining natural hydrological balances against a baseline defined by historical weather data and the actual distribution of land use. In the example presented in this paper, we used actual urban land use rather than the potential state of the catchment prior to urbanisation. This scenario can easily be included in the method by defining land use in the absence of urban development such that the baseline refers to this situation, enabling the SUDS effect to be targeted to restore the original conditions in the context of climate change. Existing studies on the effectiveness of SUDSs typically do not define a baseline for comparison, instead analysing the effect of SUDSs in absolute terms. For example, [PERSON] et al. [62] merely examine the absolute reduction in peak flows, reporting values ranging from 23% to 97%. However, they neither establish a reference hydrological condition nor consider how these reductions compare with pre-urbanisation runoff patterns. Few studies focus on assessing the ability to restore natural hydrological conditions rather than simply comparing the effectiveness of different SUDS configurations [63, 64]. We assume that the natural balance must be maintained at catchment scale, initially in terms of runoff and infiltration (aquifer recharge). While many civil engineering approaches focus on small-scale interventions within urban environments, driven by infrastructure-specific performance metrics [65], hydrologists must adopt a broader, system-based perspective.